From c46fd56447d57df2068c7a41c377710a04700f24 Mon Sep 17 00:00:00 2001 From: Joseph Ferano Date: Fri, 18 Sep 2026 11:56:22 +0700 Subject: [PATCH 1/4] Pool and Handle leave the language: two containers are enough, and a slab is a Vec you free less often --- lib/check.ml | 328 +-------------------------- lib/dev.ml | 9 +- lib/emit.ml | 56 +---- lib/js.ml | 10 +- lib/render.ml | 27 --- lib/types.ml | 42 +--- lib/x86.ml | 14 +- runtime/flan_rt.c | 295 +----------------------- test/programs/generics.flan | 4 +- test/programs/handles.flan | 103 --------- test/programs/pool-stale-region.flan | 25 -- test/programs/registry.flan | 13 +- test/test_acceptance.ml | 38 +--- test/test_flan.ml | 29 --- test/test_sanitize.ml | 1 - test/test_valgrind.ml | 4 +- test/valgrind.supp | 9 +- 17 files changed, 37 insertions(+), 970 deletions(-) delete mode 100644 test/programs/handles.flan delete mode 100644 test/programs/pool-stale-region.flan diff --git a/lib/check.ml b/lib/check.ml index ca3dc2a..f0b3730 100644 --- a/lib/check.ml +++ b/lib/check.ml @@ -425,7 +425,7 @@ let predicate_names = [ "ordered?"; "equal?"; "hashable?"; "numeric?"; "copyable this element type has to be built against a region allocator — see [region_only] below and [flan_alloc_region_only] in the runtime. That is a question about *release*, so it is asked of every arm a release would have - to reach and would not: a Vec, Map or Pool owns a block outright; an Option, + to reach and would not: a Vec or Map owns a block outright; an Option, a fixed array, a struct or a data type's case owns whatever its payload does. @@ -454,7 +454,7 @@ let owning_fields env n = let rec owning env ?(seen = []) (t : Types.t) = match t with - | Types.Vec _ | Types.Map _ | Types.Pool _ -> true + | Types.Vec _ | Types.Map _ -> true | Types.Option e | Types.Array (_, e) -> owning env ~seen e | Types.Named n -> not (List.mem n seen) @@ -471,7 +471,7 @@ let rec owning env ?(seen = []) (t : Types.t) = value is the whole of the question there. *) let region_only env (t : Types.t) = match t with - | Types.Vec e | Types.Pool e -> owning env e + | Types.Vec e -> owning env e | Types.Map (_, v) -> owning env v | _ -> false @@ -528,7 +528,7 @@ let tyvar_of (t : Types.t) = match t with Types.Var v -> Some v | _ -> None In the body this means a generic may not use a parameter twice without declaring [copyable?]. Since the repeal this gates the structural rules - only — what a struct, union or pool may own — not any use of a binding. + only — what a struct or union may own — not any use of a binding. A [Var] only ever survives the abstract pass. Inside an instantiation [env.subst] has made everything concrete, so this is [Types.is_move_only] @@ -664,27 +664,6 @@ let rec resolve env ?(seen = []) (t : Ast.texpr) : Types.t = (resolve env ~seen v) | "Map", _ -> fail loc "(Map K V) takes exactly two types" | "Result", _ -> unimplemented loc "(Result T E)" 6 - | "Pool", [ a ] -> - let e = resolve env ~seen a in - (* Lifted with the Vec's and pushed to the construction with it, and a - pool is the one of the three where that is not quite the same trade, - because a pool has a release point a Vec does not: [(release p h)] - recycles one slot while the pool lives on. In a region that costs a - block that stays allocated until [free-all] and is never handed back - — the slot itself is reused, since the next insert overwrites those - bytes, but whatever the dead element pointed at is stranded. - - That is a region leak bounded by the region, which is the bargain a - region already is: an arena's whole proposition is that nothing comes - back before the reset. It is not the unbounded leak the heap would - take, and it is not a use-after-free — nothing is released twice - because nothing is released once. Said here rather than left for a - reader to work out, because "reuse" is the word that makes a pool - look different from a Vec and it deserves an answer. *) - Types.Pool e - | "Pool", _ -> fail loc "(Pool T) takes exactly one type" - | "Handle", [ a ] -> Types.Handle (resolve env ~seen a) - | "Handle", _ -> fail loc "(Handle T) takes exactly one type" | _ -> fail loc "%s takes no type arguments — generics are milestone 5" name) @@ -857,8 +836,6 @@ let rec bind_ty subst (pat : Types.t) (arg : Types.t) = | Types.Slice p, Types.Slice a | Types.Ptr p, Types.Ptr a | Types.Vec p, Types.Vec a - | Types.Pool p, Types.Pool a - | Types.Handle p, Types.Handle a | Types.Option p, Types.Option a -> bind_ty subst p a | Types.Array (n, p), Types.Array (m, a) -> Int64.equal n m && bind_ty subst p a | Types.Map (k, v), Types.Map (k', v') -> @@ -878,8 +855,6 @@ let rec subst_ty subst (t : Types.t) = | Types.Map (k, v) -> Types.Map (subst_ty subst k, subst_ty subst v) | Types.Ptr e -> Types.Ptr (subst_ty subst e) | Types.Vec e -> Types.Vec (subst_ty subst e) - | Types.Pool e -> Types.Pool (subst_ty subst e) - | Types.Handle e -> Types.Handle (subst_ty subst e) | Types.Option e -> Types.Option (subst_ty subst e) | Types.Fn (ps, r) -> Types.Fn (List.map (subst_ty subst) ps, subst_ty subst r) | t -> t @@ -889,7 +864,7 @@ let rec generic_ty (t : Types.t) = match t with | Types.Var _ -> true | Types.Slice e | Types.Array (_, e) | Types.Ptr e | Types.Vec e - | Types.Pool e | Types.Handle e | Types.Option e -> generic_ty e + | Types.Option e -> generic_ty e | Types.Map (k, v) -> generic_ty k || generic_ty v | Types.Fn (ps, r) -> List.exists generic_ty ps || generic_ty r | _ -> false @@ -933,8 +908,6 @@ let rec mangle_ty (t : Types.t) = | Types.Map (k, v) -> Printf.sprintf "map-%s-%s" (mangle_ty k) (mangle_ty v) | Types.Ptr e -> "ptr-" ^ mangle_ty e | Types.Vec e -> "vec-" ^ mangle_ty e - | Types.Pool e -> "pool-" ^ mangle_ty e - | Types.Handle e -> "handle-" ^ mangle_ty e | Types.Option e -> "opt-" ^ mangle_ty e | Types.Fn (ps, r) -> Printf.sprintf "fn-%s-to-%s" @@ -972,7 +945,7 @@ let rec occurs_in ~needle (t : Types.t) = || match t with | Types.Slice e | Types.Array (_, e) | Types.Ptr e | Types.Vec e - | Types.Pool e | Types.Handle e | Types.Option e -> occurs_in ~needle e + | Types.Option e -> occurs_in ~needle e | Types.Map (k, v) -> occurs_in ~needle k || occurs_in ~needle v | Types.Fn (ps, r) -> List.exists (occurs_in ~needle) ps || occurs_in ~needle r @@ -1251,7 +1224,6 @@ let region_sym (t : Types.t) = match t with | Types.Vec _ -> "flan_vec_region_only" | Types.Map _ -> "flan_map_region_only" - | Types.Pool _ -> "flan_pool_region_only" | _ -> assert false let region_check env loc (target : Tast.expr) (after : Tast.expr) = @@ -1974,7 +1946,7 @@ and var ctx loc ~want name = (* What remains of spec-memory.md's ownership section after the repeal of 2026-09-18 is entirely in the types: move-only decides what may be copied, - the struct/union/pool rules below decide what may own what, and the + the struct/union rules below decide what may own what, and the allocator's capability decides what a free means at run time. Which frees run, and in what order, is the program's own business — the same contract Odin ships with — and the dev build's generation words are the net under @@ -3398,42 +3370,6 @@ and map_new_types ctx ~want loc args = "nothing here says what (map-new) maps — write the key and value \ types, as (map-new string i32), or give the binding a type") -(* The element type for [pool-new]. The same rule [vec-new] uses and for the - same reason: a [let] has no type annotation, so a local pool has nowhere - else to say what it holds. *) -and pool_new_elem ctx ~want loc args = - let named = - match args with - | { Ast.e = Ast.Var n; _ } :: rest - when lookup ctx n = None - && (not (Hashtbl.mem ctx.env.globals n)) - && type_named ctx n -> - Some (resolve_name ctx.env ~seen:[] loc n, rest) - | _ -> None - in - match named with - | Some (t, rest) -> - if move_only ctx.env.tvpreds t then - fail loc - "(Pool %s) holds a move-only element, and the type-erased runtime \ - copies and releases slots bytewise. Recursive teardown arrives with \ - drop (step 5 in NEXT.md)" - (Types.to_string t); - t, rest - | None -> - (match want with - | Some (Types.Pool t) -> t, args - | _ -> - fail loc - "nothing here says what (pool-new) is a Pool of — write the element \ - type, as (pool-new Enemy), or give the binding a type") - -(* The element type, or the reason this is not a Pool. *) -and pool_elem loc what (t : Types.t) = - match t with - | Types.Pool e -> e - | other -> fail loc "%s takes a (Pool T), found %s" what (Types.to_string other) - (* The element type, or the reason this is not a Vec. *) and vec_elem loc what (t : Types.t) = match t with @@ -3955,7 +3891,7 @@ and named_call ctx ~want loc name args = container is region-allocated or it does not exist, so there is always a [free-all] to point at. *) (match target.Tast.ty with - | (Types.Vec _ | Types.Map _ | Types.Pool _) + | (Types.Vec _ | Types.Map _) when region_only ctx.env target.Tast.ty -> fail loc "%s holds elements that own storage, and free releases the block \ @@ -3973,20 +3909,6 @@ and named_call ctx ~want loc name args = expect loc ~want (rt loc Types.Unit "flan_map_free" [ target; size_of loc k; size_of loc v; here loc ]) - (* The owner, not a slot. Every handle into it is stale afterwards and - answers None, which is a strictly better afterlife than a Vec's - binding gets — that one is a compile error and this one is a run-time - answer, because handles are copies and the checker cannot see them - all. That asymmetry is the reason handles exist. *) - | Types.Pool elem -> - expect loc ~want - (rt loc Types.Unit "flan_pool_free" - [ target; size_of loc elem; align_of loc elem; here loc ]) - | Types.Handle _ -> - fail loc - "free takes the owner, and a handle owns nothing — it is a copyable \ - number, so consuming one copy would say nothing about the others. \ - (release p h) recycles one slot; (free p) releases the pool" | other -> (* A field is never freed on its own: it would leave its owner partly dead with no way to say so. *) @@ -4064,18 +3986,6 @@ and named_call ctx ~want loc name args = (mk loc mty (Tast.Local d)) [ size_of loc k; size_of loc v ] mty); mk loc mty (Tast.Local d) ]))) - (* Refused by name rather than falling through to "clone takes a - (Vec T)". Copying a pool would duplicate every slot *and* every - generation counter, so a handle into the original would resolve in - the copy too — two live entities behind one identity, which is the - exact confusion the type exists to prevent. If a program wants a - second world it builds one and inserts into it, and the new handles - say they are new. *) - | Types.Pool _ -> - fail loc - "a pool cannot be cloned: the copy would carry the same slot \ - generations, so one handle would resolve in both and name two \ - different things. Build a second pool and insert into it" | _ -> let elem = vec_elem loc "clone" target.Tast.ty in let d = fresh_slot ctx (Types.Vec elem) in @@ -4095,219 +4005,6 @@ and named_call ctx ~want loc name args = mk loc (Types.Vec elem) (Tast.Local d) ])))) | _ -> fail loc "clone is (clone v) or (clone v allocator)") - (* ── (Pool T) and (Handle T), spec-memory.md ───────────────────── *) - (* The same type-erased shape the Vec has, for the same reason: size_of and - align_of are produced here because here is where the concrete element - type is known, and nothing below the call site has ever heard of it. *) - - (* (pool-new), (pool-new T), (pool-new a), (pool-new T a). *) - | "pool-new" -> - let elem, args = pool_new_elem ctx ~want loc args in - let a = allocator_arg ctx loc args in - let pty = Types.Pool elem in - let p = fresh_slot ctx pty in - (* [flan_pool_init] cannot fail — a pool with no slots allocates nothing — - but it goes under the guard anyway, so that the day it does allocate - the site is already the one that signals. *) - let attempt = - rt loc (Types.Int Types.I8) "flan_pool_init" - [ mk loc pty (Tast.Local p); a; size_of loc elem; align_of loc elem; - here loc ] - in - expect loc ~want - (mk loc pty - (Tast.Let ([ (p, mk loc pty (Tast.Zero pty)) ], - [ with_note loc (alloc_guard ctx loc attempt) - (reg_note loc "flan_dev_reg_note_pool" - (mk loc pty (Tast.Local p)) - [ size_of loc elem ] elem); - region_check ctx.env loc (mk loc pty (Tast.Local p)) - (mk loc pty (Tast.Local p)) ]))) - - (* (insert p x) -> (Handle T). The handle is the *only* way back to what was - inserted: a pool hands out no index and no pointer, because an index does - not notice a reuse and that is the entire point. *) - | "insert" -> - arity loc name 2 args; - (match args with - | [ target; x ] -> - let target = check ctx target in - let elem = pool_elem loc "insert" target.Tast.ty in - let x = check ctx ~want:elem x in - let hty = Types.Handle elem in - (* The element is bound before the loop so that a [retry] re-attempts - the allocation and not the expression that produced the value — - [push]'s rule, and for the same reason. *) - let e = fresh_slot ctx elem in - let h = fresh_slot ctx hty in - let attempt = - rt loc (Types.Int Types.I8) "flan_pool_insert" - [ target; addr_of loc (mk loc elem (Tast.Local e)); - addr_of loc (mk loc hty (Tast.Local h)); - size_of loc elem; align_of loc elem; here loc ] - in - expect loc ~want - (mk loc hty - (Tast.Let ([ (e, x); (h, mk loc hty (Tast.Zero hty)) ], - [ region_check ctx.env loc target - (with_note loc (alloc_guard ctx loc attempt) - (reg_note loc "flan_dev_reg_note_pool" target - [ size_of loc elem ] elem)); - mk loc hty (Tast.Local h) ]))) - | _ -> assert false) - - (* (resolve p h) -> (Option (Ptr T)). - - A pointer and not a value, and spec-memory.md settles it rather than this - lane guessing: its worked example under "Mutating something you matched" - is written out as (Option (Ptr Enemy)), for the reason stated a line - above it — "pattern bindings bind values, so a matched struct is a copy", - and a copy cannot be written back. Mutating the pooled thing in place is - what a pool is for, so (Option T) would answer a question nobody asked. - - An [Option] rather than a trap because the whole thesis is that a stale - reference *reports* — the same shape (get m k) has, and for the same - reason: absence is an answer, not a failure. - - The hole, said plainly: the (Ptr T) is invalidated by any [insert] that - grows the pool, exactly as a slice is invalidated by a [push]. The handle - survives that and the pointer does not. It is spec-memory.md's explicit - Zig/Odin contract one level down, and it is worth naming because it is - the silent-wrong-answer mode the handle just removed, reintroduced for - anyone who keeps the pointer across an insert. Chunked never-moving - storage is the fix and it costs code; taking the contract is the smaller - correct thing, given [as-slice] already established it. *) - | "resolve" -> - arity loc name 2 args; - (match args with - | [ target; h ] -> - let target = check ctx target in - let elem = pool_elem loc "resolve" target.Tast.ty in - let h = check ctx ~want:(Types.Handle elem) h in - (match h.Tast.ty with - | Types.Handle e when Types.equal e elem -> () - | other -> - fail loc "resolve takes a (Handle %s), found %s" - (Types.to_string elem) (Types.to_string other)); - let pty = Types.Ptr elem in - let oty = Types.Option pty in - let out = fresh_slot ctx pty in - let got = - rt loc pty "flan_pool_resolve" - [ target; h; size_of loc elem; here loc ] - in - (* The runtime answers a pointer or NULL and the Option is built here, - which is [get]'s arrangement: the runtime has no idea what an - Option's layout is, and keeping it that way is what lets one entry - point serve every element type. *) - let cond = - mk loc Types.Bool - (Tast.Prim (Tast.Ne, - [ mk loc (Types.Int Types.I64) - (Tast.Prim (Tast.Cast (Types.Int Types.I64), - [ mk loc pty (Tast.Local out) ])); - mk loc (Types.Int Types.I64) (Tast.Int (0L, Types.I64)) ])) - in - let some = mk loc oty (Tast.Some_ (mk loc pty (Tast.Local out))) in - let none = mk loc oty Tast.None_ in - expect loc ~want - (mk loc oty - (Tast.Let ([ (out, got) ], - [ mk loc oty (Tast.If (cond, some, none)) ]))) - | _ -> assert false) - - (* (release p h) -> bool: true if this call released it, false if the handle - was already gone. - - This is how a pooled value dies, and it is not [free]. [free] consumes - its argument as a move, and a handle is a copyable number that owns - nothing — consuming one copy would say nothing about the others. The pool - is the owner, so the release operation is on the pool and takes the - handle as an ordinary argument. spec-memory.md's two release points are - untouched: (free p) is release point 1 applied to the owner, and a - free-all of the region takes the pool with everything else. This is a - third thing and it is not a release point — it recycles a slot inside - storage the pool still owns. - - It answers a bool rather than () because the generational scheme makes a - double release *detectable*, which is worth handing to the caller: this - is the one place in the language where freeing something twice is an - answer instead of a refusal. *) - | "release" -> - arity loc name 2 args; - (match args with - | [ target; h ] -> - let target = check ctx target in - let elem = pool_elem loc "release" target.Tast.ty in - let h = check ctx ~want:(Types.Handle elem) h in - (match h.Tast.ty with - | Types.Handle e when Types.equal e elem -> () - | other -> - fail loc "release takes a (Handle %s), found %s" - (Types.to_string elem) (Types.to_string other)); - let got = rt loc (Types.Int Types.I8) "flan_pool_release" - [ target; h; here loc ] in - expect loc ~want - (mk loc Types.Bool - (Tast.Prim (Tast.Ne, - [ got; - mk loc (Types.Int Types.I8) (Tast.Int (0L, Types.I8)) ]))) - | _ -> assert false) - - (* (live p) — how many slots are live now. (len p) is the *slot high-water*, - which is deliberately the other number: 0..(len p) are the indices - (pool-handle p i) accepts, so a loop bounded by [len] visits every live - entry. Bounding it by the live count instead would silently skip entries - the moment anything had been released, which is precisely the kind of - quiet wrong answer this whole type exists to remove. *) - | "live" -> - arity loc name 1 args; - let target = check ctx (List.hd args) in - ignore (pool_elem loc "live" target.Tast.ty); - let n = rt loc (Types.Int Types.I64) "flan_pool_live" [ target; here loc ] in - expect loc ~want (mk loc index_ty (Tast.Prim (Tast.Cast index_ty, [ n ]))) - - (* (pool-handle p i) -> (Option (Handle T)): the handle of slot [i], or None - if that slot is dead. This plus (len p) is the whole of iteration, and - iteration is not a convenience — migrate-instances has to *enumerate* - live instances, and a pool behind generational handles gives that by - construction where a world arena and an owned region do not. It is the - reason plan.org's three storage strategies are not a free choice. - - An index out of 0..(len p) traps, exactly as (at v i) traps: an index is - an index here, and answering None for one would hide a bug rather than a - death. *) - | "pool-handle" -> - arity loc name 2 args; - (match args with - | [ target; i ] -> - let target = check ctx target in - let elem = pool_elem loc "pool-handle" target.Tast.ty in - let i = check ctx ~want:index_ty i in - let hty = Types.Handle elem in - let oty = Types.Option hty in - let out = fresh_slot ctx hty in - let got = rt loc hty "flan_pool_handle" [ target; i; here loc ] in - (* 0 is the never-valid handle — generation 0 is even, and a live slot's - generation is odd — so the runtime says "dead" with it and needs no - second return value. *) - let cond = - mk loc Types.Bool - (Tast.Prim (Tast.Ne, - [ mk loc (Types.Int Types.I64) - (Tast.Prim (Tast.Cast (Types.Int Types.I64), - [ mk loc hty (Tast.Local out) ])); - mk loc (Types.Int Types.I64) (Tast.Int (0L, Types.I64)) ])) - in - expect loc ~want - (mk loc oty - (Tast.Let ([ (out, got) ], - [ mk loc oty - (Tast.If (cond, - mk loc oty (Tast.Some_ (mk loc hty (Tast.Local out))), - mk loc oty Tast.None_)) ]))) - | _ -> assert false) - (* ── (Map K V), spec-memory.md ─────────────────────────────────── *) (* Every one of these is a named call over the same type-erased runtime the Vec uses, with the two sizes and the key's hash and equality pair produced @@ -4816,16 +4513,9 @@ and named_call ctx ~want loc name args = | Types.Map _ -> let n = rt loc (Types.Int Types.I64) "flan_map_len" [ a; here loc ] in expect loc ~want (mk loc index_ty (Tast.Prim (Tast.Cast index_ty, [ n ]))) - (* A pool's [len] is its slot high-water, not its live count, so that - 0..(len p) stays the range of valid indices the way it is for every - other container here. (live p) is the other number. *) - | Types.Pool _ -> - let n = rt loc (Types.Int Types.I64) "flan_pool_len" [ a; here loc ] in - expect loc ~want (mk loc index_ty (Tast.Prim (Tast.Cast index_ty, [ n ]))) | other -> fail loc - "len takes an array, a slice, a string, a Vec, a Map or a Pool, \ - found %s" + "len takes an array, a slice, a string, a Vec or a Map, found %s" (Types.to_string other)) | "at" -> (match args with diff --git a/lib/dev.ml b/lib/dev.ml index 0d3ec30..7088696 100644 --- a/lib/dev.ml +++ b/lib/dev.ml @@ -1462,11 +1462,10 @@ let reg_at t ~addr : (reg_entry option, string) result = anywhere, so nothing can fall behind [Types.to_string]. And it is allowed to fail, which matters more than it looks. Not every - recorded name is a type: [flan_rt.c] notes a pool's slot headers as - "pool slots", because after a free-all an address landing in them must not - come back as an element. That string is not Flan source and must not - become one — so a name that does not resolve is refused with the name - quoted, and never defaulted to bytes. *) + recorded name need be a type this session can spell — a note's name is + whatever string the noting site chose, not Flan source — so a name that + does not resolve is refused with the name quoted, and never defaulted to + bytes. *) let type_of_spelling t spelling : (Types.t, string) result = let refuse why = Error diff --git a/lib/emit.ml b/lib/emit.ml index 94cfa21..86d2f81 100644 --- a/lib/emit.ml +++ b/lib/emit.ml @@ -124,15 +124,6 @@ let rec ll (t : Types.t) = map's address — so the shape exists only so that a slot, a struct field and a copy in the IR are the right number of bytes. *) | Types.Map _ -> "%map" - (* items + slots + len + cap + live + free + allocator + epoch. Nothing here - reads a field of one either — every operation is a runtime call taking - the pool's address. *) - | Types.Pool _ -> "%pool" - (* A handle is one 64-bit number: the slot index in the low half and that - slot's generation in the high half. Packed rather than a two-field struct - so that copying, zeroing and [=] are what they are for an integer, with no - backend arm anywhere except the one comparison below. *) - | Types.Handle _ -> "i64" | Types.Option e -> Printf.sprintf "{ i8, %s }" (ll e) | Types.Var _ -> (* The checker rejects it by name — nothing reaches here. *) @@ -297,8 +288,6 @@ let rec lay m (t : Types.t) : int * int = | Types.Alloc -> 8, 8 | Types.Fn _ -> 8, 8 | Types.Vec _ | Types.Map _ -> 48, 8 - | Types.Pool _ -> 64, 8 - | Types.Handle _ -> 8, 8 (* [n x T] adds no padding of its own: T's size already carries its tail. *) | Types.Array (n, e) -> let s, a = lay m e in Int64.to_int n * s, a | Types.Option e -> let s, a, _ = lay_fields m [ Types.Int Types.I8; e ] in s, a @@ -543,19 +532,6 @@ let rec dty m d (t : Types.t) : int = ("allocator", Types.Alloc); ("gen", Types.Int Types.I64); ("epoch", Types.Int Types.I64) ] |> fun n -> ignore k; ignore v; n - (* Eight fields, shown as eight, for the reason the two above are. *) - | Types.Pool e -> - composite (Types.to_string t) - [ ("items", Types.Ptr e); - ("slots", Types.Ptr (Types.Int Types.U8)); - ("len", Types.Int Types.I64); ("cap", Types.Int Types.I64); - ("live", Types.Int Types.I64); ("free", Types.Int Types.I64); - ("allocator", Types.Alloc); ("epoch", Types.Int Types.I64) ] - (* An i64 under lldb, which is what it is. Splitting it into a two-field - composite would be describing a struct that is not there: the packing - is the runtime's, and [p h] answering with the number is honest. *) - | Types.Handle _ -> - basic (Types.to_string t) 64 "DW_ATE_unsigned" (* A pointer to code, and lldb is told exactly that and no more. DWARF has DW_TAG_subroutine_type for the signature behind it, and spelling one out here would buy a reader nothing they cannot get from the @@ -2043,11 +2019,6 @@ and prim f (e : Tast.expr) (p : Tast.prim) (args : Tast.expr list) = location. Signed, because a member may be declared negative. *) | Types.Enum _ -> ins f "%s = icmp %s %s %s, %s" t (icmp_op true p) (ll x.Tast.ty) a b - (* [Types.is_equatable] admits a handle and [is_comparable] does not, so - only [Eq]/[Ne] arrive here — one unsigned integer compare over the - packed (index, generation) pair. *) - | Types.Handle _ -> - ins f "%s = icmp %s i64 %s, %s" t (icmp_op false p) a b | t' -> failwith ("comparison on " ^ Types.to_string t')); t | (Tast.BitAnd | Tast.BitOr | Tast.BitXor | Tast.Shl | Tast.Shr), [ x; y ] -> @@ -2254,7 +2225,7 @@ and prim f (e : Tast.expr) (p : Tast.prim) (args : Tast.expr list) = lets an operation mutate the caller's container in place. Passing the header by value here would hand the runtime a copy to grow and leave the caller's untouched. *) - | Types.Vec _ | Types.Map _ | Types.Pool _ -> [ "ptr " ^ addr f a ] + | Types.Vec _ | Types.Map _ -> [ "ptr " ^ addr f a ] | t -> [ ll t ^ " " ^ value f a ]) args) in @@ -2325,11 +2296,6 @@ and cast f ~guard (x : Tast.expr) target = let concrete (t : Types.t) = match t with | Types.Enum _ -> Types.Int Types.I32 - (* A handle already *is* an i64 — see [ll] — so a cast involving one - changes the reading and never the bits. [pool-handle] tests one against - the never-valid zero, and the renderer splits one into its index and - its generation. Unsigned, because both halves are. *) - | Types.Handle _ -> Types.Int Types.U64 | t -> t in let src = concrete x.Tast.ty and target = concrete target in @@ -2360,7 +2326,7 @@ and cast f ~guard (x : Tast.expr) target = it, both sides being [ptr]. *) | Types.Ptr _, Types.Ptr _ -> "bitcast" (* Also not written in the surface language. [resolve] needs it: the - pool answers a pointer or NULL and the Option is built in the + runtime answers a pointer or NULL and the Option is built in the checker, so the null test is one integer compare on the address. *) | Types.Ptr _, Types.Int Types.I64 -> "ptrtoint" | _ -> failwith "unsupported cast" @@ -2707,10 +2673,6 @@ let header = {|; Generated by flan. The layout is C's: no object headers anywher ; nor value type appears in it, for the same reason: one type-erased runtime, ; handed the two sizes and a hash/equality pair at each call site. %map = type { ptr, i64, i64, ptr, i64, i64 } -; (Pool T) — slab storage handed out behind (Handle T). Type-erased in exactly -; the same way; the element type is nowhere in it. items and slots are grown -; together and share one cap, so a slot index is an index into both. -%pool = type { ptr, ptr, i64, i64, i64, i64, ptr, i64 } ; A handler frame: the one it displaced, the condition type it matches, and ; the lifted function that runs. Allocated on the establishing frame's stack. %handler = type { ptr, i32, ptr } @@ -2775,7 +2737,6 @@ declare void @flan_arena_destroy(ptr) declare void @flan_alloc_free_all(ptr, ptr, i64) declare void @flan_vec_region_only(ptr, ptr, i64) declare void @flan_map_region_only(ptr, ptr, i64) -declare void @flan_pool_region_only(ptr, ptr, i64) declare i8 @flan_alloc_can_free(ptr) declare i8 @flan_alloc_can_free_all(ptr) declare i64 @flan_alloc_epoch(ptr) @@ -2788,7 +2749,6 @@ declare i64 @flan_alloc_budget(ptr) declare void @flan_alloc_set_budget(ptr, i64) declare void @flan_dev_reg_enable() declare void @flan_dev_reg_note_vec(ptr, i64, ptr, i64) -declare void @flan_dev_reg_note_pool(ptr, i64, ptr, i64) declare void @flan_dev_reg_note_map(ptr, i64, i64, ptr, i64) declare i8 @flan_vec_init(ptr, ptr, i64, i64, i64, ptr, i64) declare i8 @flan_vec_reserve(ptr, i64, i64, i64, ptr, i64) @@ -2801,18 +2761,6 @@ declare i64 @flan_vec_len(ptr, ptr, i64) declare ptr @flan_vec_at(ptr, i32, i64, ptr, i64, ptr) declare void @flan_vec_as_slice(ptr, ptr, i32, i32, i64, ptr, i64, ptr) declare void @flan_vec_free(ptr, i64, i64, ptr, i64) -; (Pool T) and (Handle T). A handle crosses as the i64 it is; the pool, like -; every other owning container, crosses as its address. [resolve] answers a -; pointer or null and [pool-handle] answers a packed handle or the never-valid -; zero, so neither needs a second return value. -declare i8 @flan_pool_init(ptr, ptr, i64, i64, ptr, i64) -declare i8 @flan_pool_insert(ptr, ptr, ptr, i64, i64, ptr, i64) -declare ptr @flan_pool_resolve(ptr, i64, i64, ptr, i64) -declare i8 @flan_pool_release(ptr, i64, ptr, i64) -declare i64 @flan_pool_len(ptr, ptr, i64) -declare i64 @flan_pool_live(ptr, ptr, i64) -declare i64 @flan_pool_handle(ptr, i32, ptr, i64) -declare void @flan_pool_free(ptr, i64, i64, ptr, i64) ; (Map K V). The two ptr arguments before the location on put/get/clone are the ; hash and equality pair, which the checker emits per key type and passes here ; the way Odin hangs them off Map_Info. diff --git a/lib/js.ml b/lib/js.ml index aa661e4..97a7b4f 100644 --- a/lib/js.ml +++ b/lib/js.ml @@ -116,7 +116,7 @@ {1 What is refused, and why each} Pointers and [deref], [free], allocators and [with-allocator], [Map], - [Pool] and [(Handle T)], [declare-c] and the FFI, [embed], conditions and + [declare-c] and the FFI, [embed], conditions and restarts ([signal], [handler-bind], [restart-case], [invoke-restart]), and the type-erased container runtime's own entry points. The first group has no counterpart in a garbage-collected object graph; the FFI and [embed] @@ -235,14 +235,6 @@ let rec refuse_ty loc (t : Types.t) = "(Map K V) is not in the JS dialect yet — Odin's open-addressed map is a \ type-erased runtime over raw bytes and the JS answer is a Map keyed by \ a structural key, which is its own lane" - | Types.Pool _ -> - at loc - "(Pool T) is not in the JS dialect — a pool hands out slot indices into \ - storage it owns, which is the memory model this dialect leaves behind" - | Types.Handle _ -> - at loc - "(Handle T) is not in the JS dialect — a handle is an index into a Pool, \ - and there is no Pool here" | Types.Var n -> at loc "a type variable (%s) reached the backend, which cannot happen" n diff --git a/lib/render.ml b/lib/render.ml index 384231e..ae5a47d 100644 --- a/lib/render.ml +++ b/lib/render.ml @@ -187,33 +187,6 @@ let rec render c depth (e : Tast.expr) : Tast.expr list = does not own, and the walk is what [as-slice] is for: (print (as-slice v)) prints the elements and says at the call site that it borrowed. *) | Types.Vec _ -> [ lit "" ] - (* Opaque for the reason a Vec is: the slots are storage this function does - not own, and a walk over them would print the dead ones too — there is - no way to say "dead" inside a rendered element. (pool-handle p i) and - (resolve p h) are how a program looks, and they say it. *) - | Types.Pool _ -> [ lit "" ] - (* Its identity, which is what spec-memory.md says a handle prints — - "Ptr and Handle print their address or identity rather than recursively - dereferencing". Shown as index:generation rather than as the packed - number, because those are the two things a reader is trying to tell - apart when two handles disagree. *) - | Types.Handle _ -> - let h = cast (Types.Int Types.U64) e in - let u64 v = { Tast.e = v; ty = Types.Int Types.U64; loc } in - let idx = - u64 (Tast.Prim (Tast.BitAnd, - [ h; u64 (Tast.Int (0xFFFFFFFFL, Types.U64)) ])) - in - let gen = - u64 (Tast.Prim (Tast.Shr, [ h; u64 (Tast.Int (32L, Types.U64)) ])) - in - [ do_ [ lit "" ] ] - (* A function value is a code address, and printing the address would make - an inspection depend on where the image loaded. The signature is what a - reader can act on, so that is what is shown — and the inspector reaches - every local of a stopped frame, so a frame holding one has to render - rather than refuse. *) | Types.Fn _ as ft -> [ lit ("<" ^ Types.to_string ft ^ ">") ] | Types.Option t -> let tag = { Tast.e = Tast.Field (e, 0); ty = Types.Int Types.I8; loc } in diff --git a/lib/types.ml b/lib/types.ml index be8e5aa..62bc6f2 100644 --- a/lib/types.ml +++ b/lib/types.ml @@ -44,25 +44,6 @@ type t = so this is a container without generics — the concrete type is known only at the call site, which is exactly where the two numbers are produced. *) | Vec of t - (* [(Pool T)]: slab storage handed out behind [(Handle T)]. Owning and - move-only exactly as a [Vec] is, and built on the same type-erased - runtime over (size, align). It is not a second [Vec]: a [Vec]'s indices - shift when something is removed and a [Pool]'s slot index never moves, - which is the whole reason a handle into one stays meaningful. *) - | Pool of t - (* [(Handle T)]: a reference to something that can die, which reports that - it died rather than silently resolving to whatever reused its slot - (spec-memory.md, "Borrowing" — "Cross-referencing long-lived objects uses - (Handle a) into a pool, never a raw pointer or slice. A stale handle is - detectable"). - - It is a plain 64-bit number — a slot index in the low 32 bits and that - slot's generation counter in the high 32 — so it copies, compares and - zeroes like an integer and owns nothing. A zeroed handle is generation 0, - and a live slot's generation is always odd, so [Zero] of a handle is a - handle that resolves to nothing rather than one that resolves to slot 0. - See runtime/flan_rt.c's pool section for the packing. *) - | Handle of t | Option of t (* (Option T) *) | Fn of t list * t (* (Fn [T ...] R) *) | Var of string (* a type variable — milestone 5 *) @@ -113,8 +94,6 @@ let rec equal a b = | Ptr x, Ptr y -> equal x y | Alloc, Alloc -> true | Vec x, Vec y -> equal x y - | Pool x, Pool y -> equal x y - | Handle x, Handle y -> equal x y | Option x, Option y -> equal x y | Fn (ps, r), Fn (ps', r') -> List.length ps = List.length ps' @@ -137,8 +116,6 @@ let rec to_string = function | Ptr t -> "(Ptr " ^ to_string t ^ ")" | Alloc -> "Allocator" | Vec t -> "(Vec " ^ to_string t ^ ")" - | Pool t -> "(Pool " ^ to_string t ^ ")" - | Handle t -> "(Handle " ^ to_string t ^ ")" | Option t -> "(Option " ^ to_string t ^ ")" | Fn (ps, r) -> Printf.sprintf "(Fn [%s] %s)" @@ -153,10 +130,7 @@ let is_numeric = function Int _ | Float _ -> true | _ -> false [free] needs no analysis of its own. A struct that owns one is move-only too; that arrives with [drop], which is the step after this one. *) let rec is_move_only = function - (* A [Pool] owns its storage; a [Handle] into one owns nothing, which is the - point of it — handles are copied freely, and the pool is the single - owner that [free] applies to. *) - | Vec _ | Map _ | Pool _ -> true + | Vec _ | Map _ -> true | Option t -> is_move_only t | Array (_, t) -> is_move_only t | _ -> false @@ -179,11 +153,6 @@ let rec keyable = function | Float _ -> false (* NaN /= NaN, and 0.0 and -0.0 differ bytewise *) | Array (_, t) -> keyable t | Named _ -> true (* [Check] decides, by walking the fields *) - (* A [Handle] is not a map key, for the reason a [Ptr] is not: hashing an - identity is a different operation from hashing what it names, and a - handle whose slot has been reused hashes the same as it always did while - naming nothing. The type exists to make that difference visible, so - burying it under a key is the one thing it must not do. *) | _ -> false (* Ordering and equality are defined on machine types and on nothing else at @@ -191,14 +160,7 @@ let rec keyable = function unconstrained type supports only what every type supports (plan.org, Types). *) let is_comparable = function Enum _ -> true | t -> is_numeric t -(* [=] and [!=] admit one more type than [<] does. A [Handle] is a pair of - numbers in a 64-bit word, so "is this the same entity" is one integer - compare and is worth having — two handles are equal exactly when they name - the same slot at the same generation, so a stale handle is never equal to - the live one that replaced it. Ordering handles would compare a slot index, - which means nothing: allocation order is a free-list artefact. Hence two - predicates rather than one. *) -let is_equatable = function Handle _ -> true | t -> is_comparable t +let is_equatable = is_comparable (* [Never] is the type of an expression that does not produce a value: return, an early-returning `some`, exit. It fits anywhere, and that is the only diff --git a/lib/x86.ml b/lib/x86.ml index ffba06c..923d591 100644 --- a/lib/x86.ml +++ b/lib/x86.ml @@ -461,10 +461,10 @@ let alignof md t = snd (Emit.lay md t) let is_agg (t : Types.t) = match t with | Types.Int _ | Types.Float _ | Types.Bool | Types.Ptr _ | Types.Enum _ - | Types.Alloc | Types.Handle _ | Types.Fn _ -> false + | Types.Alloc | Types.Fn _ -> false | Types.Unit | Types.Never -> false | Types.String | Types.Slice _ | Types.Array _ | Types.Map _ | Types.Vec _ - | Types.Pool _ | Types.Option _ | Types.Named _ -> true + | Types.Option _ | Types.Named _ -> true | Types.Var v -> unsupported "type variable %s" v let is_void (t : Types.t) = match t with Types.Unit | Types.Never -> true | _ -> false @@ -1300,7 +1300,7 @@ let classify_c (l : loc) (t : Types.t) = match t with | Types.String | Types.Slice _ -> [ Aint (l, Types.Ptr Types.Unit); Alen l ] | Types.Unit | Types.Never -> [] - | Types.Vec _ | Types.Map _ | Types.Pool _ -> [ Aptr l ] + | Types.Vec _ | Types.Map _ -> [ Aptr l ] | _ when is_agg t -> unsupported "aggregate %s across the C boundary" (Types.to_string t) | _ when is_float t -> [ Aflt (l, t) ] @@ -2481,7 +2481,7 @@ and call_rt f ~sym ~args ~rty dst = call_native f ~sym ~chan:(rt_signals sym) ~args ~rty dst and call_native f ~sym ?(chan = false) ~(args : Tast.expr list) ~rty dst = - (* A Vec, a Map and a Pool are move-only and cross to the runtime as their + (* A Vec and a Map cross to the runtime as their *address*, which is what lets an operation mutate the caller's container in place. [eval] would hand over the address of a copy, and the runtime would grow that and leave the caller's header at length zero — which is @@ -2492,7 +2492,7 @@ and call_native f ~sym ?(chan = false) ~(args : Tast.expr list) ~rty dst = List.map (fun (a : Tast.expr) -> (match a.Tast.ty with - | Types.Vec _ | Types.Map _ | Types.Pool _ -> lvalue f a + | Types.Vec _ | Types.Map _ -> lvalue f a | _ -> eval f a), a.Tast.ty) args in @@ -2515,7 +2515,7 @@ and call_native f ~sym ?(chan = false) ~(args : Tast.expr list) ~rty dst = counter-example and is not: [check.ml] builds it as [rt loc Types.Unit] and [flan_rt.c] writes the two words through [void *out]. Every other [rt] builder in the file answers [Unit], an [Int], a - [Ptr], an [Alloc] or a [Handle]. + [Ptr] or an [Alloc]. - [crossable], which admits [String] and [Slice _] only as "a parameter" and refuses an aggregate return from a [declare] outright. @@ -2766,7 +2766,7 @@ and prim f (e : Tast.expr) (p : Tast.prim) (args : Tast.expr list) dst = touched until [call_rt], so answering [()] is already early enough. The test is [emit.ml]'s byte for byte, strict [>] included: bare [flan_dev_reg_note] is the runtime's own entry point and is never a - [Tast.Rt]; what [check.ml] builds is the [_vec], [_map] and [_pool] + [Tast.Rt]; what [check.ml] builds is the [_vec] and [_map] wrappers, each of which is longer than the prefix. The node's type is [Unit], so there is nothing to store and [dst] is untouched. *) | Tast.Rt sym, _ diff --git a/runtime/flan_rt.c b/runtime/flan_rt.c index d25f34c..492dc02 100644 --- a/runtime/flan_rt.c +++ b/runtime/flan_rt.c @@ -1663,284 +1663,6 @@ int8_t flan_vec_clone(flan_vec *dst, flan_vec *src, flan_allocator *a, return 1; } -/* ── (Pool T) and (Handle T), spec-memory.md ───────────────────────── - * - * A handle is a reference to something that can die, which reports that it - * died rather than silently resolving to whatever reused its slot. That is - * the whole design, and every decision below follows from it. - * - * THE PACKING. A handle is one int64_t: the slot index in the low 32 bits and - * that slot's generation counter in the high 32. One word, so it copies, - * zeroes and compares like the integer it is, and owns nothing — the pool is - * the single owner. 32 bits of index because a Vec's index is an i32 here and - * widening indices is one change across every container, not a pool question. - * - * LIVE IS ODD. A slot's generation starts at 0 and is bumped on every - * allocation and on every release, so an odd generation means live and an - * even one means dead. Two things fall out of that and both are load-bearing: - * a zeroed handle is generation 0, which is even, so it resolves to nothing - * rather than to slot 0 — ZII gives a handle field the right meaning for - * free; and iteration can ask a slot whether it is live without a second - * array or a spare bit. - * - * WRAPPING RETIRES THE SLOT. 32 bits is 2^31 allocate/release pairs on one - * slot — every frame at 60fps for a year and a bit — but "rare" is not an - * answer when the failure is the silent wrong one this type exists to - * prevent. So a release from generation 0xFFFFFFFF bumps to 0 and does *not* - * put the slot back on the free list. The slot is retired: dead forever, its - * payload leaked, and no future handle can ever collide with an old one. - * Leaking is defined behaviour here (spec-memory.md, "Leaking is defined - * behaviour") and one slot is a bounded price for making the collision - * unrepresentable rather than unlikely. - * - * TWO FAILURES, KEPT APART. A stale handle answers "gone" — it is an answer, - * not an error. A pool whose allocator was released traps, through the same - * epoch check a Vec gets. They answer different questions and must not be - * conflated, exactly as the Vec's generation and epoch words must not be. - * - * GROWTH IS TRANSACTIONAL, and that is not tidiness. spec-memory.md's - * StorageExhausted restart re-attempts *the same call*, so a failed grow has - * to leave the pool byte for byte as it was — including a cap that still - * agrees with the real block sizes, since the next attempt passes cap as the - * allocator's old_size. Two blocks grow together, so a resize-in-place of the - * first followed by a failure on the second would leave cap describing - * neither. Allocate both, copy, then release the old pair: the only state - * mutated after the last thing that can fail. - */ - -typedef struct flan_pool_slot { - uint32_t gen; /* odd: live. even: dead. 0: never allocated, or retired. */ - int32_t next; /* free-list link, -1 for the end. Meaningless while live. */ -} flan_pool_slot; - -typedef struct flan_pool { - void *items; /* cap payloads, size bytes each */ - flan_pool_slot *slots; /* cap slot headers, index-parallel with items */ - int64_t len; /* slot high-water: 0..len have ever been handed out */ - int64_t cap; - int64_t live; /* how many of those are live now */ - int64_t free; /* head of the free list, -1 when empty */ - flan_allocator *alloc; - int64_t epoch; -} flan_pool; - -static int64_t flan_handle_pack(int64_t i, uint32_t gen) { - return (int64_t)(((uint64_t)gen << 32) | (uint64_t)(uint32_t)i); -} - -static int64_t flan_handle_index(int64_t h) { - return (int64_t)(uint32_t)(uint64_t)h; -} - -static uint32_t flan_handle_gen(int64_t h) { - return (uint32_t)((uint64_t)h >> 32); -} - -/* The same epoch check a Vec gets, and for the same reason. A pool that never - * allocated has no allocator and nothing to check. */ -static void flan_pool_check(flan_pool *p, const uint8_t *loc, int64_t loclen) { - if (p->alloc) { - int64_t now = (int64_t)p->alloc->epoch; - if (now != p->epoch) flan_vec_stale_fail(loc, loclen, p->epoch, now); - } -} - -/* The same guard a Vec gets, at the same place and for the same reason — see - * the note above [flan_vec_region_only]. */ -void flan_pool_region_only(flan_pool *p, const uint8_t *loc, int64_t loclen) { - flan_alloc_region_only(p->alloc ? p->alloc : flan_context_allocator(), - loc, loclen); -} - -static flan_allocator *flan_pool_adopt(flan_pool *p) { - if (!p->alloc) { - p->alloc = flan_context_allocator(); - p->epoch = (int64_t)p->alloc->epoch; - } - return p->alloc; -} - -static int8_t flan_pool_grow(flan_pool *p, int64_t want, int64_t size, - int64_t align) { - flan_allocator *a = flan_pool_adopt(p); - int64_t cap = p->cap, sslot = (int64_t)sizeof(flan_pool_slot); - int64_t ibytes, sbytes, total; - void *ni, *ns; - if (want <= cap) return 1; - /* Doubling from four, exactly as the Vec grows. */ - if (cap < 4) cap = 4; - while (cap < want) { - if (cap > (int64_t)1 << 40) { cap = want; break; } - cap *= 2; - } - /* Two products and their sum, all three checked: the pool asks for the items - * and the slots as separate blocks but reports them as one number, and a - * wrap in either half is the same memcpy past the end the Vec's is. */ - if (!flan_mul_bytes(cap, size, &ibytes) - || !flan_mul_bytes(cap, sslot, &sbytes) - || !flan_add_bytes(ibytes, sbytes, &total)) { - flan_fail_bytes = FLAN_BYTES_UNREPRESENTABLE; - flan_fail_align = align; - flan_fail_id = (int64_t)(intptr_t)a; - return 0; - } - flan_fail_bytes = total; - flan_fail_align = align; - flan_fail_id = (int64_t)(intptr_t)a; - ni = a->proc(a, FLAN_ALLOC_ALLOC, NULL, 0, ibytes, align); - if (!ni) return 0; - ns = a->proc(a, FLAN_ALLOC_ALLOC, NULL, 0, sbytes, 8); - if (!ns) { - /* An allocator without can-free leaks the first block here. That is the - * defined outcome and not a new one: the request failed because the - * region is exhausted, and the region is about to be released whole or - * the ceiling raised and the call re-attempted. */ - if (a->caps & FLAN_CAN_FREE) - a->proc(a, FLAN_ALLOC_FREE, ni, ibytes, 0, align); - return 0; - } - if (p->len > 0) { - memcpy(ni, p->items, (size_t)(p->len * size)); - memcpy(ns, p->slots, (size_t)(p->len * sslot)); - } - if (p->items && (a->caps & FLAN_CAN_FREE)) { - a->proc(a, FLAN_ALLOC_FREE, p->items, p->cap * size, 0, align); - a->proc(a, FLAN_ALLOC_FREE, p->slots, p->cap * sslot, 0, 8); - } - p->items = ni; - p->slots = ns; - p->cap = cap; - return 1; -} - -int8_t flan_pool_init(flan_pool *p, flan_allocator *a, int64_t size, - int64_t align, const uint8_t *loc, int64_t loclen) { - (void)size; (void)align; - /* Null for the same reason and with the same answer flan_vec_init gives: - * the no-allocator-named case never arrives here as NULL. */ - if (!a) flan_null_alloc_fail(loc, loclen); - p->items = NULL; - p->slots = NULL; - p->len = 0; - p->cap = 0; - p->live = 0; - p->free = -1; - p->alloc = a; - p->epoch = (int64_t)a->epoch; - return 1; -} - -/* 1/0 for "did it fit", like every other allocating entry point. The handle - * goes out through [out] rather than being returned, so that the compiler's - * alloc_guard reads the answer and the handle separately. */ -int8_t flan_pool_insert(flan_pool *p, const void *elem, int64_t *out, - int64_t size, int64_t align, const uint8_t *loc, - int64_t loclen) { - int64_t i; - flan_pool_check(p, loc, loclen); - if (p->free >= 0) { - i = p->free; - p->free = p->slots[i].next; - } else { - if (p->len + 1 > p->cap && !flan_pool_grow(p, p->len + 1, size, align)) - return 0; - i = p->len++; - p->slots[i].gen = 0; - p->slots[i].next = -1; - } - p->slots[i].gen++; /* even -> odd: this slot is live */ - p->live++; - memcpy((uint8_t *)p->items + i * size, elem, (size_t)size); - *out = flan_handle_pack(i, p->slots[i].gen); - return 1; -} - -/* NULL when the handle names nothing, which the compiler turns into None. The - * index is bounded with the unsigned comparison flan_vec_at uses, because the - * low half of a handle can be any 32 bits at all. */ -void *flan_pool_resolve(flan_pool *p, int64_t h, int64_t size, - const uint8_t *loc, int64_t loclen) { - int64_t i = flan_handle_index(h); - uint32_t g = flan_handle_gen(h); - flan_pool_check(p, loc, loclen); - if (!(g & 1u)) return NULL; /* a zeroed or dead handle */ - if ((uint64_t)i >= (uint64_t)p->len) return NULL; - if (p->slots[i].gen != g) return NULL; /* the slot was reused */ - return (uint8_t *)p->items + i * size; -} - -/* 1 if this call released it, 0 if the handle was already gone. Releasing - * twice is therefore an answer rather than undefined behaviour — which is the - * generational scheme paying for itself a second time, since a pool is the - * one place a double free is *detectable* rather than merely refused. */ -int8_t flan_pool_release(flan_pool *p, int64_t h, const uint8_t *loc, - int64_t loclen) { - int64_t i = flan_handle_index(h); - uint32_t g = flan_handle_gen(h), was; - flan_pool_check(p, loc, loclen); - if (!(g & 1u)) return 0; - if ((uint64_t)i >= (uint64_t)p->len) return 0; - if (p->slots[i].gen != g) return 0; - was = p->slots[i].gen; - p->slots[i].gen = was + 1; /* odd -> even: dead, and every old handle with it */ - p->live--; - /* The wrap. See the header: the slot is retired rather than reissued. */ - if (was != 0xFFFFFFFFu) { - p->slots[i].next = (int32_t)p->free; - p->free = i; - } - return 1; -} - -int64_t flan_pool_len(flan_pool *p, const uint8_t *loc, int64_t loclen) { - flan_pool_check(p, loc, loclen); - return p->len; -} - -int64_t flan_pool_live(flan_pool *p, const uint8_t *loc, int64_t loclen) { - flan_pool_check(p, loc, loclen); - return p->live; -} - -/* The handle of slot [i], or 0 — the never-valid handle — if that slot is - * dead. This plus (len p) is the whole of enumeration, which is what - * migrate-instances needs and what a Vec behind an index cannot give: a Vec's - * indices shift under a removal and a pool's never do. Out of range traps - * rather than answering 0, because an index is an index here and 0..len are - * the valid ones. */ -int64_t flan_pool_handle(flan_pool *p, int32_t i, const uint8_t *loc, - int64_t loclen) { - uint32_t g; - flan_pool_check(p, loc, loclen); - if ((uint64_t)(int64_t)i >= (uint64_t)p->len) - flan_vec_bounds_fail(loc, loclen, (int64_t)i, p->len); - g = p->slots[i].gen; - if (!(g & 1u)) return 0; - return flan_handle_pack((int64_t)i, g); -} - -/* spec-memory.md's first release point, applied to the owner. Zeroed rather - * than left dangling, for the reason flan_vec_free zeroes. Every handle into - * it is stale afterwards and says so: len goes to 0, so the bound check - * answers "gone" for all of them. */ -void flan_pool_free(flan_pool *p, int64_t size, int64_t align, - const uint8_t *loc, int64_t loclen) { - flan_pool_check(p, loc, loclen); - if (p->items && p->alloc && (p->alloc->caps & FLAN_CAN_FREE)) { - p->alloc->proc(p->alloc, FLAN_ALLOC_FREE, p->items, p->cap * size, 0, align); - p->alloc->proc(p->alloc, FLAN_ALLOC_FREE, p->slots, - p->cap * (int64_t)sizeof(flan_pool_slot), 0, 8); - } - p->items = NULL; - p->slots = NULL; - p->len = 0; - p->cap = 0; - p->live = 0; - p->free = -1; - p->alloc = NULL; - p->epoch = 0; -} - /* ── (Map K V), spec-memory.md ────────────────────────────────────────── * * Odin's map, followed deliberately: open-addressed Robin Hood hashing at a @@ -2848,9 +2570,8 @@ int8_t flan_map_clone(flan_map *dst, flan_map *src, flan_allocator *a, * * The type name comes from the compiler; the *extent* comes from here, because * the header is the only thing that knows where the storage landed and how - * much of it there is. Three entry points rather than one because three - * headers are three layouts, and a pool is two blocks that are allocated and - * released together but are not adjacent. + * much of it there is. Two entry points rather than one because the two + * headers are two layouts. * * Each is called immediately after the operation that may have allocated — * every one of them, not only the first — because storage moves. A note is an @@ -2865,18 +2586,6 @@ void flan_dev_reg_note_vec(flan_vec *v, int64_t size, const char *type, if (v) flan_dev_reg_note(v->ptr, v->cap * size, size, type, typelen); } -void flan_dev_reg_note_pool(flan_pool *p, int64_t size, const char *type, - int64_t typelen) { - if (!p) return; - flan_dev_reg_note(p->items, p->cap * size, size, type, typelen); - /* The slot headers are the pool's own bookkeeping and not the element type, - so they are named for what they are. Recording them matters for the same - reason the items do: after a free-all their bytes are still readable and - an address landing in them must not come back as an element. */ - flan_dev_reg_note(p->slots, p->cap * (int64_t)sizeof(flan_pool_slot), - (int64_t)sizeof(flan_pool_slot), "pool slots", 11); -} - void flan_dev_reg_note_map(flan_map *m, int64_t ksize, int64_t vsize, const char *type, int64_t typelen) { if (!m || !m->data) return; diff --git a/test/programs/generics.flan b/test/programs/generics.flan index bc88775..14b1466 100644 --- a/test/programs/generics.flan +++ b/test/programs/generics.flan @@ -71,9 +71,7 @@ (do d (t x))) ;; The builtins that take a *type name* as an argument, over a variable. Each -;; reaches the one list of what names a type, so all three came at once. -;; (pool-new t) and (map-new t i32) are the other two; a Pool of a variable -;; needs it not to be move-only, which [copyable?] is. +;; reaches the one list of what names a type; (map-new t i32) is the other. (defn one-of [x $t] (Vec $t) {:where (copyable? $t)} (let [v (vec-new t)] diff --git a/test/programs/handles.flan b/test/programs/handles.flan deleted file mode 100644 index dbcd19b..0000000 --- a/test/programs/handles.flan +++ /dev/null @@ -1,103 +0,0 @@ -;;;; (Handle T) and (Pool T), spec-memory.md — "Cross-referencing long-lived -;;;; objects uses (Handle a) into a pool, never a raw pointer or slice. A -;;;; stale handle is detectable." -;;;; -;;;; The thesis, in one program: something holds a reference to an entity; the -;;;; entity dies; the slot is reused by a different entity; and the old -;;;; reference answers "gone" instead of answering wrong. Every other case -;;;; here is secondary to that one. -;;;; -;;;; It is all one function because a Pool is move-only exactly as a Vec is, -;;;; so passing one to a helper *consumes* it — there is no borrowing -;;;; parameter in the language yet. That is not a pool question and this -;;;; program does not work around it; see docs/BUILT.md. - -(defstruct Enemy [hp i32 kind i32]) - -;; The projectile does not hold an Enemy and does not hold an index. It holds -;; a handle, which is a number that owns nothing and copies freely — which is -;; why a struct may contain one where it may not contain a Vec. -(defstruct Projectile [target (Handle Enemy) damage i32]) - -(defn main [] i32 - (let [pool (pool-new Enemy)] - (let [a (insert pool (Enemy {.hp 10 .kind 1})) - b (insert pool (Enemy {.hp 20 .kind 2})) - c (insert pool (Enemy {.hp 30 .kind 3})) - sum 0] - (println (len pool)) ; 3 slots handed out - (println (live pool)) ; 3 of them live - - ;; Enumeration, which is what a world arena and an owned region do not - ;; give and which migrate-instances will need. (len p) is the slot - ;; high-water, so 0..(len p) visits every slot ever handed out, and - ;; (pool-handle p i) says which of them are still live. - (dotimes [i (len pool)] - (match (pool-handle pool i) - (Some h) (match (resolve pool h) - ;; resolve yields a *pointer*, not a copy: mutating the - ;; pooled thing in place is what a pool is for, and a - ;; pattern binding binds a value. - (Some e) (set sum (+ sum (.hp e))) - None (do)) - None (do))) - (println sum) ; 60 - - ;; A write through a resolved pointer is a write to the pooled entity. - (match (resolve pool b) - (Some e) (set (.hp e) 21) - None (do)) - (match (resolve pool b) - (Some e) (println (.hp e)) ; 21 - None (println -1)) - - ;; ── The thesis ──────────────────────────────────────────────── - ;; A projectile chasing b. b dies. The slot is reused by a fourth - ;; enemy, which lands in exactly that slot — and the projectile's - ;; handle says so rather than chasing the newcomer. - (let [shot (Projectile {.target b .damage 5})] - (println (release pool b)) ; true — this call released it - (println (release pool b)) ; false — it was already gone - (println (live pool)) ; 2 - (let [d (insert pool (Enemy {.hp 99 .kind 4}))] - ;; Printed as index:generation. Same slot, later generation — the - ;; two halves of the answer, visible. - (println b) - (println d) - (println (= d b)) ; false - (println (= d d)) ; true - (match (resolve pool (.target shot)) - (Some e) (println (.hp e)) - None (println -1)) ; -1, not 99 - (match (resolve pool d) - (Some e) (println (.hp e)) ; 99 - None (println -1)) - (println (len pool)) ; still 3 slots - (println (live pool)) ; 3 live - - ;; A zeroed handle is generation 0, which is even, and a live slot's - ;; generation is always odd — so ZII gives a handle field the right - ;; meaning for free rather than pointing it at slot 0. - (let [z (Projectile {.damage 1})] - (println (.target z)) - (match (resolve pool (.target z)) - (Some e) (println (.hp e)) - None (println -1))) ; -1 - - ;; a and c are untouched by any of it. - (match (resolve pool a) - (Some e) (println (.hp e)) ; 10 - None (println -1)) - (match (resolve pool c) - (Some e) (println (.hp e)) ; 30 - None (println -1)) - - ;; spec-memory.md's first release point, applied to the owner. The - ;; runtime leaves the pool empty, so a handle into it would resolve - ;; to None rather than into released storage — but that is not - ;; demonstrable from here and this program does not pretend it is: - ;; free consumes pool, so a resolve on the next line is a compile - ;; error. The runtime property is real and the checker makes it - ;; unreachable. - (free pool) - 0))))) diff --git a/test/programs/pool-stale-region.flan b/test/programs/pool-stale-region.flan deleted file mode 100644 index 028e92c..0000000 --- a/test/programs/pool-stale-region.flan +++ /dev/null @@ -1,25 +0,0 @@ -;;;; The epoch trap on the pool's side. spec-memory.md, "Dev builds detect a -;;;; released region". -;;;; -;;;; This is deliberately the *other* failure from a stale handle, and the two -;;;; must not be conflated — the same rule that keeps a Vec's generation word -;;;; and its epoch word apart. A stale handle is an answer: the entity died, -;;;; resolve says None, the program carries on. A released region is not an -;;;; answer at all: the storage the pool sits in is gone, the slot array with -;;;; it, and there is nothing left to ask. So one returns None and the other -;;;; traps naming the site. -(defn main [] i32 - (let [a (arena-new 4096)] - (let [p (pool-new i32 a)] - (let [h (insert p 7)] - (match (resolve p h) - (Some x) (println (deref x)) - None (println -1)) - ;; The region goes. p is still in scope, still looks fine, and h is - ;; still a perfectly well-formed handle — which is exactly the case a - ;; static rule cannot see. - (free-all a) - (match (resolve p h) - (Some x) (println (deref x)) - None (println -1))))) - 0) diff --git a/test/programs/registry.flan b/test/programs/registry.flan index e07ce6d..04da9dc 100644 --- a/test/programs/registry.flan +++ b/test/programs/registry.flan @@ -4,7 +4,7 @@ ;;;; nothing at run time can say what is at an address. The registry sidesteps ;;;; that: the allocator's *caller* knew the type, and a dev build writes it ;;;; down. What is asserted here is the consequence a program can see without -;;;; an inspector — whether an address is still live — and the three ways +;;;; an inspector — whether an address is still live — and the two ways ;;;; storage dies underneath one. ;;;; ;;;; This program is deliberately readable in a release build too, and prints @@ -48,17 +48,6 @@ (free-all frame) (println (reg-live q)))) ; 0 either way - ;; 3. And the pool, whose storage is the one place a (Ptr T) is handed to a - ;; program by name: (resolve p h) points into the middle of the items - ;; array, never at its base. Nothing but a containment lookup can answer - ;; for it. - (let [pool (pool-new i32)] - (let [h (insert pool 5)] - (match (resolve pool h) - (Some ip) (println (reg-live ip)) ; dev: 1 - None (println -1)) - (free pool))) - ;; Nothing is live by now except whatever the arena's own destroy leaves, so ;; the count is a statement about the table rather than about one address. (arena-destroy frame) diff --git a/test/test_acceptance.ml b/test/test_acceptance.ml index d3a0ac4..3fa5aa5 100644 --- a/test/test_acceptance.ml +++ b/test/test_acceptance.ml @@ -634,11 +634,11 @@ let () = — memcheck still says nothing — it makes the same read *answerable*, by a different tool. The two must not be blurred. *) outputs "registry, dev" ~dev:true "programs/registry.flan" - "1\n1\n0\n1\n0\n1\n0\n"; + "1\n1\n0\n1\n0\n0\n"; outputs "registry, release" "programs/registry.flan" - "0\n0\n0\n0\n0\n0\n0\n"; + "0\n0\n0\n0\n0\n0\n"; outputs "registry, release -O0" ~opt:"-O0" "programs/registry.flan" - "0\n0\n0\n0\n0\n0\n0\n"; + "0\n0\n0\n0\n0\n0\n"; (* free-all on an allocator that does not offer it traps rather than doing nothing, because "I released the region" and "I leaked the region" must not be the same program text. Its own case for the same reason the @@ -953,39 +953,7 @@ let () = end; (try Sys.remove exe with Sys_error _ -> ()); - (* (Handle T) and (Pool T), spec-memory.md. The thesis is one line of this - output and the rest is scaffolding for it: the same slot prints as - before a death and after the reuse, and the - projectile still holding the first is told -1 rather than the - newcomer's 99. At -O0 as well, because the null test resolve is built - out of is exactly the kind of control flow an optimiser launders, and - as a dev build, because a pool then lives in a frame the reload path - has to agree with on 64 bytes. *) - let handles_out = - "3\n3\n60\n21\ntrue\nfalse\n2\n\n\nfalse\ntrue\n-1\n99\n3\n3\n\n-1\n10\n30\n" - in - outputs "handles" "programs/handles.flan" handles_out; - outputs ~opt:"-O0" "handles, -O0" "programs/handles.flan" handles_out; - outputs ~dev:true "handles, dev" "programs/handles.flan" handles_out; - (* The epoch trap on the pool's side, and it is deliberately the *other* - failure from a stale handle. A stale handle is an answer and resolve - returns None; a released region is not an answer at all, because the - slot array went with the storage, so it traps. The two must not be - conflated, which is the same rule that keeps a Vec's generation word - and its epoch word apart. *) - let exe = compile "programs/pool-stale-region.flan" in - let code, text = run exe None in - if code <> 134 || not (contains text "programs/pool-stale-region.flan:") - || not (contains text "allocator was released") - || not (contains text "7") - then begin - incr failures; - Printf.printf - "FAIL a pool used after its region was released\n\ - \ got: %S (exit %d)\n wanted: exit 134, naming the site\n" - text code - end; (try Sys.remove exe with Sys_error _ -> ()); (* The same trap on the Map's side, and it is not the same code path: a diff --git a/test/test_flan.ml b/test/test_flan.ml index c8292b5..969e00e 100644 --- a/test/test_flan.ml +++ b/test/test_flan.ml @@ -1026,19 +1026,6 @@ let () = ~needle:"exactly two types"; rejects_check "Result is milestone 6" "(defn f [] (Result i32 i32) None)" ~needle:"milestone 6"; - (* (Handle T) and (Pool T) are built. What stays refused is the arity, for - the reason Vec's and Map's arities are, and the four shapes below — each - of which is a way of losing the one property the type exists to have. *) - rejects_check "Handle takes one type" "(defn f [x (Handle i32 i32)] ())" - ~needle:"exactly one type"; - rejects_check "Pool takes one type" "(defn f [x (Pool i32 i32)] ())" - ~needle:"exactly one type"; - (* A pool of an owning element used to be refused here, with the Vec's and - the Map's, and the three came down together: the reason all of them gave - was teardown, and a region has none. What replaced them is a run-time - branch on the allocator's can-free at the construction, so the *type* is - ordinary and only the tier is a question. See the arena rows below. *) - accepts "a pool of a Vec" "(defn f [x (Pool (Vec i32))] ())"; (* ── The region rule, spec-memory.md's arena rule ──────────────────── The compile-time half of it, which is the only half a checker row can @@ -1102,22 +1089,6 @@ let () = "(defvar g (Vec u8)) \ (defn f [] () (set g (vec-new u8)) (push g 1) (set (at g 0) 2) \ (println (len (as-slice g))) (let [c (clone g)] (free c)))"; - (* Ordering handles would order a slot index, which is a free-list artefact. - Equality is admitted and ordering is not, which is why there are two - predicates in Types rather than one. *) - rejects_check "handles do not order" - "(defn f [a (Handle i32) b (Handle i32)] bool (< a b))" - ~needle:"no built-in comparison"; - (* free takes the owner. A handle is a copyable number that owns nothing, so - consuming one copy would say nothing about the others — which is why a - slot is recycled by (release p h) and not by free. *) - rejects_check "free of a handle" - "(defn f [h (Handle i32)] () (free h))" ~needle:"a handle owns nothing"; - (* Cloning a pool would duplicate the generation counters with the slots, so - one handle would resolve in both copies and name two different things. *) - rejects_check "a pool cannot be cloned" - "(defn f [p (Pool i32)] () (let [q (clone p)] (do)))" - ~needle:"cannot be cloned"; rejects_check "try is milestone 6" "(defn f [] i32 (try 1))" ~needle:"milestone 6"; (* dotimes and defer are implemented, and a defer in a [let] is now one of diff --git a/test/test_sanitize.ml b/test/test_sanitize.ml index a3f2dfc..90e630d 100644 --- a/test/test_sanitize.ml +++ b/test/test_sanitize.ml @@ -138,7 +138,6 @@ let corpus = same directory; the new C here is three more path buffers, which is exactly what this tool is for. *) "programs/files.flan", []; - "programs/handles.flan", []; "programs/machine.flan", []; "programs/math.flan", []; "programs/math3.flan", []; diff --git a/test/test_valgrind.ml b/test/test_valgrind.ml index 2d646ef..4ce1f4e 100644 --- a/test/test_valgrind.ml +++ b/test/test_valgrind.ml @@ -191,7 +191,7 @@ let check label path args ~checks = link on its own. The seven programs here that abort by design — error, exhausted-unhandled, - free-all-refused, map-stale-region, pool-stale-region, slurp-unhandled, + free-all-refused, map-stale-region, slurp-unhandled, stale-region — are kept. A trap is a controlled abort after an fprintf, and "the trap still fires, in the same place, with the same message, under memcheck" is worth @@ -217,14 +217,12 @@ let corpus = "programs/exhausted-unhandled.flan", []; "programs/files.flan", []; "programs/free-all-refused.flan", []; - "programs/handles.flan", []; "programs/machine.flan", []; "programs/map-exhausted.flan", []; "programs/map-stale-region.flan", []; "programs/maps.flan", []; "programs/math.flan", []; "programs/math3.flan", []; - "programs/pool-stale-region.flan", []; "programs/pkg-macro.flan", []; "programs/pkg-diamond.flan", []; "programs/pkg-return.flan", []; diff --git a/test/valgrind.supp b/test/valgrind.supp index 2749f02..f36217c 100644 --- a/test/valgrind.supp +++ b/test/valgrind.supp @@ -25,11 +25,10 @@ # bytes a previous round wrote before the reset reports. test_valgrind.ml # asserts it as a control — it produced nothing before the runtime change # and six errors after. The corpus stayed clean across that change, and -# the sharp end of that is stale-region.flan, map-stale-region.flan and -# pool-stale-region.flan: all three read through a pointer into an arena -# that has been reset, all three are now reading bytes memcheck knows are -# undefined, and none of them reports — because the epoch trap fires -# first. The runtime's own guard beats the read. Interior overruns are +# the sharp end of that is stale-region.flan and map-stale-region.flan: +# both read through a pointer into an arena that has been reset, both are +# reading bytes memcheck knows are undefined, and neither reports — +# because the epoch trap fires first. The runtime's own guard beats the read. Interior overruns are # still invisible, for the structural reason above. # # 2. Hand-written LLVM IR. Expected to confuse the tool. It does not, and it From 4a563d0e67f13691c8c674604e0df2d494f11269 Mon Sep 17 00:00:00 2001 From: Joseph Ferano Date: Fri, 18 Sep 2026 12:16:05 +0700 Subject: [PATCH 2/4] The move-only concept follows the flow analysis out: everything copies, and the frees are yours --- lib/check.ml | 350 ++++++++--------------------- lib/prelude.ml | 37 +-- lib/types.ml | 11 - spike/generics/prelude-shapes.flan | 2 - test/programs/generic-runaway.flan | 2 +- test/programs/generics.flan | 8 +- test/programs/reload-generic.flan | 2 - test/programs/vec-in-struct.flan | 10 +- test/test_acceptance.ml | 14 +- test/test_flan.ml | 65 +++--- test/test_session.ml | 8 +- web/index.html | 32 +-- 12 files changed, 158 insertions(+), 383 deletions(-) diff --git a/lib/check.ml b/lib/check.ml index f0b3730..99c1675 100644 --- a/lib/check.ml +++ b/lib/check.ml @@ -406,20 +406,14 @@ let unimplemented loc what milestone = Odin's [where] clause is the same shape ([core/slice/slice.odin:289] is [where intrinsics.type_is_ordered(T)]) with forty-one predicates against - these five. The fifth, [copyable?], has no Odin counterpart at all: Odin - has no move semantics, so [$T] never has to answer the question. The prior - art there is Rust's [T: Copy], with the difference that [copyable?] is a - question the compiler answers rather than a trait a user implements. *) -let predicate_names = [ "ordered?"; "equal?"; "hashable?"; "numeric?"; "copyable?" ] + these four. There is no [copyable?] any more and no Odin counterpart + either: Odin has no move semantics, and since the repeal neither does this + language, so [$T] never has to answer the question. *) +let predicate_names = [ "ordered?"; "equal?"; "hashable?"; "numeric?" ] (* ── What a type owns, transitively ──────────────────────────────────── - spec-memory.md: "Ownership is structural, not declared." [Types.is_move_only] - answers the same question one level deep and deliberately stops there — a - [Named] is not move-only, because making it so is the transitive ownership - model that recursive teardown would need, and there is no recursive teardown. - This walk is the *other* use of the same fact, and the two must not be - collapsed: nothing here feeds the move checker, and a type this says yes - about is still copied and still tracked exactly as it was yesterday. + The one structural ownership question that survived the repeal, because it + is not about copying at all. What it decides, and the only thing it decides, is whether a container of this element type has to be built against a region allocator — see @@ -438,12 +432,11 @@ let predicate_names = [ "ordered?"; "equal?"; "hashable?"; "numeric?"; "copyable contain itself by value anyway — [check_finite] refuses that — only through a container, which is an arm that answers for itself. - [env.unions], the untagged ones, are deliberately not consulted: a move-only - member in one is refused outright, and that refusal is not waiting on - teardown the way these were — nothing anywhere records which member is - live, so there is no fact a release could read. A region removes the - teardown question and leaves that one exactly where it was, so an untagged - union owns nothing and there is nothing here to walk. *) + [env.unions], the untagged ones, are deliberately not consulted: nothing + anywhere records which member of one is live, so there is no fact this + walk could read — an untagged union is treated as owning nothing, and what + its members point at is the program's, through whatever tag it keeps + beside the union. *) let owning_fields env n = match Hashtbl.find_opt env.structs n with | Some s -> [ s.Tast.fields ] @@ -488,23 +481,20 @@ let pred_holds p (t : Types.t) = [key_pair]. *) | "hashable?" -> Types.keyable t | "numeric?" -> Types.is_numeric t - | "copyable?" -> not (Types.is_move_only t) | _ -> false (* What one declared predicate *also* gives you. These are entailments over the type system as it stands, not conveniences: every type [is_comparable] - admits is a number or an enum, so it is equatable and it is not move-only. - The table is only sound while that is true — an ordered move-only type, or - an ordered type with no [=], would make it wrong — so it lives in one place - and says so. The gain is real ergonomics: [{:where (ordered? $t)}] is - enough for a [sort!] that also compares and reads its elements twice, - rather than three predicates on one line. *) + admits is a number or an enum, so it is equatable. The table is only sound + while that is true — an ordered type with no [=] would make it wrong — so + it lives in one place and says so. The gain is real ergonomics: + [{:where (ordered? $t)}] is enough for a [sort!] that also compares, + rather than two predicates on one line. *) let pred_entails ~declared ~wanted = String.equal declared wanted || match wanted, declared with | "ordered?", "numeric?" -> true | "equal?", ("numeric?" | "ordered?") -> true - | "copyable?", ("numeric?" | "ordered?" | "equal?" | "hashable?") -> true | _ -> false let declares preds v wanted = @@ -518,27 +508,6 @@ let declares preds v wanted = properties are the Vec's. *) let tyvar_of (t : Types.t) = match t with Types.Var v -> Some v | _ -> None -(* ── Move-only, with a type variable defaulting to move ──────────────── - [Types.is_move_only (Var _)] is [false] and cannot be anything else: the - same variable is [i32] at one instantiation and [(Vec i32)] at the next, so - the property is not decidable abstractly. The author's decision is to - default to **move**, because move is the *stricter* rule: assuming it can - only refuse a program that would have been fine, never admit one that - double-frees. [copyable?] is the opt-out, exactly as Rust's [T: Copy] is. - - In the body this means a generic may not use a parameter twice without - declaring [copyable?]. Since the repeal this gates the structural rules - only — what a struct or union may own — not any use of a binding. - - A [Var] only ever survives the abstract pass. Inside an instantiation - [env.subst] has made everything concrete, so this is [Types.is_move_only] - there and the strictness costs nothing at a call site. *) -let rec move_only preds (t : Types.t) = - match t with - | Types.Var v -> not (declares preds v "copyable?") - | Types.Option e | Types.Array (_, e) -> move_only preds e - | t -> Types.is_move_only t - (* ── (Map K V), spec-memory.md ────────────────────────────────────────── Both halves are checked where the type is written, not where an operation is, so that a map nothing ever uses is still refused if it cannot work. @@ -567,8 +536,8 @@ let map_type ?(preds = []) loc (k : Types.t) (v : Types.t) = (* The key, as far as the type alone can say. A struct passes here and is decided at the operation, by [key_pair], which walks its fields — the struct table is not necessarily complete while a type is being resolved, - and every map that exists reaches an operation anyway, because a global of - move-only type is refused and a local needs (map-new). *) + and every map that exists reaches an operation anyway, because a global + map starts zeroed and a local needs (map-new). *) (* A type variable is a map key exactly when the [where] clause says it is hashable. Nothing else about it is knowable here, and falling through to [Types.keyable] would answer no for a variable that is about to be @@ -1944,16 +1913,17 @@ and var ctx loc ~want name = | None -> captured ctx loc name; Loc.failk "check/unknown-name" loc "unknown name %s" name) -(* What remains of spec-memory.md's ownership section after the repeal of - 2026-09-18 is entirely in the types: move-only decides what may be copied, - the struct/union rules below decide what may own what, and the - allocator's capability decides what a free means at run time. Which frees - run, and in what order, is the program's own business — the same contract - Odin ships with — and the dev build's generation words are the net under - it. The flow analysis that used to live here (a per-function dead set, a - borrow flag over container reads, a loop-iteration diff) tracked use-after- - move and double-free statically; it was repealed rather than repaired when - its holes proved structural. See spec-memory.md, "The repeal". *) +(* What remains of spec-memory.md's ownership section after the repeals of + 2026-09-18 is the allocator's side alone: the region rule decides where a + container of owning elements may be built, and the allocator's capability + decides what a free means at run time. Everything copies — a container as + its header, the copies aliasing one buffer — and which frees run, and in + what order, is the program's own business, the same contract Odin ships + with; the dev build's epoch words are the net under it. The flow analysis + that used to live here (a per-function dead set, a borrow flag, a + loop-iteration diff) went in the first repeal; the move-only concept + itself — copy refusals, [copyable?], the struct/union owning rules — went + in the second. See spec-memory.md, "The repeal". *) (* [defer_ok] is granted again before *every* form, not once before the block: [check] withdraws it as it starts, so granting it once would let the first @@ -3913,9 +3883,8 @@ and named_call ctx ~want loc name args = (* A field is never freed on its own: it would leave its owner partly dead with no way to say so. *) fail loc - "free takes a move-only value — a Vec, a Map, or a struct that owns \ - one — found %s. A resource type with a drop hook is step 5 and does \ - not exist yet" + "free takes an owning container — a Vec or a Map — found %s. A \ + resource type with a drop hook is step 5 and does not exist yet" (Types.to_string other)) (* (clone v) uses the current allocator, (clone v a) names one. A deep, independent copy: spec-memory.md's "copying is always explicit". *) @@ -4076,7 +4045,8 @@ and named_call ctx ~want loc name args = | _ -> assert false) (* (get m k) -> (Option V). Absence is None, not an untyped nil, and the - first implementation admits copyable values only, so this is a copy. + answer is a copy of the value's bytes — for an owning value, a copy of + its header, aliasing what the map's slot points at. There is no allocation here and therefore no guard: a lookup that finds nothing is an answer, not a failure. *) | "get" -> @@ -4582,11 +4552,10 @@ and named_call ctx ~want loc name args = and a reader who sees it has already been told where the promise comes from. - **It owns nothing.** The result is a [Types.Slice], which is not - move-only, carries no allocator, and is the same non-owning view - (as-slice v) answers — so [free] refuses it by the rule it already had - ("free takes a move-only value"), and nothing in the move analysis needed - to learn about this form. *) + **It owns nothing.** The result is a [Types.Slice], which carries no + allocator and is the same non-owning view (as-slice v) answers — so + [free] refuses it by the rule it already had ("free takes an owning + container"). *) | "slice-from-ptr" -> arity loc name 2 args; (match args with @@ -4929,8 +4898,8 @@ and named_call ctx ~want loc name args = | Some b -> (match b.bty with Types.Fn _ -> true | _ -> false) | None -> false) -> (* The binding the guard already found, read directly. Going back through - [check] would repeat the lookup and walk the move and capture paths for - a type that is neither move-only nor capturable. *) + [check] would repeat the lookup and walk the capture path for a type + that is not capturable. *) (match lookup ctx name with | Some b -> call_value ctx ~want loc (mk loc b.bty (Tast.Local b.slot)) args | None -> assert false) @@ -5035,7 +5004,7 @@ and generic_call ctx ~want loc name vars pats pret args = code the caller did not write, which is the thing the pass exists to avoid. So the caller has to declare at least what the callee asks for, and [pred_entails] means [ordered?] covers a callee wanting - [copyable?] without anyone writing both. *) + [equal?] without anyone writing both. *) (match Hashtbl.find_opt ctx.env.generics name with | None -> () | Some gfn -> @@ -5346,45 +5315,16 @@ let collect env (decls : Ast.decl list) = aborts the whole compilation, so an entry left behind by a declaration that is about to be refused is never read. *) Hashtbl.replace env.structs n { Tast.sname = n; fields }; - (* spec-memory.md: "Ownership is structural, not declared" — a struct - containing a Vec is itself move-only, and freeing one recurses into - its owning fields while (free (.items b)) is refused because it - would leave the owner partly dead. None of that transitive - machinery exists, and it is what [drop] would have brought. So the - field is still refused at the declaration, where the message can - say so, rather than accepted into a struct that copies its header - on assignment and gives two owners one buffer. + (* A struct field may own storage. Since the repeal a struct + holding a [(Vec i32)] is an ordinary value: assignment copies the + header bytes, the copies alias one buffer, and freeing through + two copies is the program's bug — Odin's contract, kept whole. - With one exception, and it is exact: a field whose container holds - *owning* elements. That container cannot exist outside a region — - the guard at its construction is what makes sure of it (see - [vec-new]) — so the struct's field is region-allocated too, - transitively and by the same guard, and the whole graph is released - by one [free-all]. There is nothing for a teardown to recurse into - because there is no teardown, and the two-owners-one-buffer problem - is not one when the owner is the region and neither copy is it. - - The plain case stays refused precisely because nothing enforces - anything there: a [(Vec i32)] field is happily built against the - heap, nothing would object, and then (free (.items b)) through two - copies of the struct is a double free with no guard between it and - the program. *) - List.iter - (fun (f : Tast.field) -> - if Types.is_move_only f.Tast.fty - && not (region_only env f.Tast.fty) then - fail loc - "%s's field %s is %s, which is move-only, and a struct that \ - owns one is move-only too — transitively, with recursive \ - teardown and with a field that cannot be freed on its own. \ - That rule does not exist; hold the %s in a local and pass \ - it. A container whose *elements* own storage is the one \ - kind admitted here, because it can only have been built \ - against a region allocator and a single (free-all) takes \ - the whole graph" - n f.Tast.fname (Types.to_string f.Tast.fty) - (Types.to_string f.Tast.fty)) - fields + The region rule is separate and survives on its own ground: a + field whose container holds *owning* elements can only have been + built against a region allocator — the guard at its construction + is what makes sure of it (see [vec-new]) — so that graph is + released by one [free-all] and no teardown recurses anywhere. *) | Ast.Defdata (n, vs) -> (* A data type with no cases has no value, so nothing could ever be given one, and a parameter of that type would be a function nothing can @@ -5419,115 +5359,23 @@ let collect env (decls : Ast.decl list) = because a data type that could hold a container where a struct could not would be a hole in the same rule. *) Hashtbl.replace env.datas n { Tast.dname = n; cases }; - (* The same refusal a struct field gets, for the same reason, in the - same words, and with the same one exception: a data type case's - fields are a struct, the data type copies bytewise on assignment, - and there is no recursive teardown to make that safe — except where - the field's container holds owning elements, which can only have - been built against a region and is therefore released whole. - - This is the arm the recursive dynamic value needs, and it is worth - naming what it buys: a [Value] with a [(Vec Value)] case and a - [(Map string Value)] case is now declarable, parsed into an arena, - walked, and released by one [free-all] with no per-element teardown - anywhere. What it costs is that a [Value] is copied bytewise like - any other data value, so two copies share the inner blocks. In a - region that is aliasing and not a double free, because neither copy - owns anything — the region does. *) - List.iter - (fun (vloc, (c : Tast.variant)) -> - List.iter - (fun (f : Tast.field) -> - if Types.is_move_only f.Tast.fty - && not (region_only env f.Tast.fty) then - fail vloc - "%s.%s's field %s is %s, which is move-only, and a \ - data type case that owns one makes the data type \ - move-only too — transitively, with recursive teardown. \ - That rule does not exist; hold the %s in a local and \ - pass it. A \ - container whose *elements* own storage is the one kind \ - admitted here, because it can only have been built \ - against a region allocator and a single (free-all) \ - takes the whole graph" - n c.Tast.vname f.Tast.fname (Types.to_string f.Tast.fty) - (Types.to_string f.Tast.fty)) - c.Tast.vfields) - cases_with_loc; + (* A case's fields are a struct and may own storage, on the struct's + terms since the repeal: copies alias, and the free is the + program's to write. The region rule still applies on its own + ground — a [(Vec Value)] case field can only have been built + against a region, so the recursive dynamic value parses into an + arena and one [free-all] releases the graph, no teardown + anywhere. *) List.iter (fun (c : Tast.variant) -> Hashtbl.replace env.cases (n ^ "." ^ c.Tast.vname) (n, c); Hashtbl.replace env.cases c.Tast.vname (n, c)) cases - (* ── The untagged union ────────────────────────────────────────── - C's semantics, deliberately and in full: the members overlay one - storage, the size is the largest of them, the alignment the - strictest, and nothing anywhere records which member was written - last. - - {2 What Flan says about reading a member that was not written} - - It reads the bytes that are there, through that member's type. Not - undefined behaviour, and not a refusal either — a *definition*, and - this is the one place in the checker that chooses bytes over safety - on purpose, so it is worth saying why. - - Refusing it was the alternative, and it would have made the feature - nothing: type punning *is* reading the member that was not written, - and both uses this type exists for are that read. Binding a C header - means holding the union the library holds and reading whichever - member the library's own tag says is live — a tag Flan cannot see, - because it is a field of the enclosing struct and the rule that - relates them is prose in a manual. Overlaying an f32 on a u32 to look - at its bits is the other use and is the same read. A checker that - refused it would be refusing the type. - - So the promise is the one C's implementations actually make and - C's standard does not: the layout is the target's, the bytes are the - bytes, and a read is a reinterpretation of them. What is *not* - promised is anything about bytes never written — a member larger - than the one last stored reads its own size, and the tail is - indeterminate exactly as a struct's padding is. That is the honest - line, and it is narrower than it sounds: the ZII rule means a union - starts all-bytes-zero unless [uninit] says otherwise, so the tail is - zero rather than garbage in every program that did not ask for - garbage. - - {2 uninit} - - Allowed, unlike on a data type. The refusal there is not about - garbage — [uninit] is garbage everywhere and says so — it is that a - data type's tag *steers*, and a tag no case names falls past every - comparison in a [match] into a block LLVM is entitled to treat as - unreachable. An untagged union steers nothing. Reading a member of - one is already a reinterpretation of whatever bytes are there, so - [uninit] makes those bytes arbitrary and changes nothing else, which - is exactly what it means on an [i64]. - - {2 Why bool is not a member} - - An [i1] loaded out of a byte that is neither 0 nor 1 is not a - [false], it is a value the optimiser is entitled to assume cannot - exist, and a union is the one type that can hand it one — write the - [u8] member 2, read the [bool] member. Nothing about that is visible - at the read, so it cannot be refused there. The alternative was to - load a union's bool as an [i8] and compare it against zero in both - backends, which is a correct answer and a real cost paid by every - bool in the language to make one type safe. Refused at the - declaration instead, where the message can name the replacement: - [u8], compared explicitly. The check below is recursive, because a - bool inside a struct member is the same byte. - - {2 Why no member may be move-only} - - Because nothing knows which member is live, so nothing can tear one - down. That is not a limitation of today's compiler, which is what - the struct and data type refusals above say about themselves; it is - a property of the type, and it does not go away when recursive - teardown lands. A [drop] of a union would have to free whichever - member is live and there is no such fact — freeing the wrong one is - a free of a pointer that was an f64 a moment ago. *) - | Ast.Defunion (n, ms) -> + (* Nothing records which member of a union is live, so nothing — the + program included — can free the right one through the union itself. + Since the repeal that is a fact about the value and not a refusal: + a member may own storage, and freeing it is done through whatever + tag the program keeps beside the union, as C does. *) | Ast.Defunion (n, ms) -> if ms = [] then fail loc "%s declares no members, so it has no size and nothing could be \ @@ -5536,20 +5384,6 @@ let collect env (decls : Ast.decl list) = if List.length (List.sort_uniq compare names) <> List.length names then fail loc "%s declares the same member twice" n; let fields = List.map field ms in - List.iter - (fun (f : Tast.field) -> - if Types.is_move_only f.Tast.fty then - fail loc - "%s's member %s is %s, which is move-only, and a union may \ - not own one: the members overlay one storage and nothing \ - records which was written, so nothing can free the right \ - one. Unlike a struct's, this is not waiting on recursive \ - teardown — there is no fact for teardown to read. Hold the \ - %s beside the union, or in a struct with a tag you check \ - yourself" - n f.Tast.fname (Types.to_string f.Tast.fty) - (Types.to_string f.Tast.fty)) - fields; Hashtbl.replace env.unions n { Tast.sname = n; fields } | Ast.Defn fn -> (* A signature that introduces a type variable is a *pattern*, not a @@ -5823,9 +5657,7 @@ let rec check_fn env (fn : Ast.fn) : Tast.fn = whichever call site happened to instantiate it at a type that worked. The holes in it are real and are the report's business: [println] is - plan.org's one compiler-provided exception and this pass rejects it, and - move-only-ness is not decidable abstractly at all — [Types.is_move_only - (Var _)] is false, but the same variable at [(Vec i32)] is move-only. *) + plan.org's one compiler-provided exception and this pass rejects it. *) and check_generic env (fn : Ast.fn) = let vars, params, ret = Hashtbl.find env.gsigs fn.Ast.name in let saved_lifted = env.lifted and saved_vars = env.tyvars @@ -5850,14 +5682,12 @@ and check_generic env (fn : Ast.fn) = checking a function. *) let () = check_fn_ref := check_fn -(* A global of move-only type is legal. Before the repeal what made it legal - was a flow rule — reading one was always a borrow, so nothing could take - or free it. That rule is gone with the rest of the flow analysis: a global - Vec may now be handed to a function, bound, or freed, and keeping its - process-long lifetime honest is the program's business, on the same terms - as every other free. +(* A container's only compile-time constant is the zeroed one: a Vec's or a + Map's real value exists at run time, behind an allocator. That is a fact + about initialisers and it survived both repeals untouched — nothing here + is about copying or moving. - What this pass still decides is how such a global may be *started*, and the + What this pass decides is how such a global may be *started*, and the answer is zeroed and nothing else. A zeroed Vec is a real empty Vec — null block, zero length, zero capacity — so the ZII value is the value a program would have written anyway, and filling it is an ordinary (set g (slurp @@ -5880,15 +5710,21 @@ let () = check_fn_ref := check_fn A global *Allocator* is not any of this — an allocator is a copyable opaque handle — which is what makes the handler-owns-the-arena shape in exhausted.flan expressible. *) -let move_only_global_init loc n (ty : Types.t) (init : Ast.init) = - if Types.is_move_only ty then +let rec zero_only (t : Types.t) = + match t with + | Types.Vec _ | Types.Map _ -> true + | Types.Option e | Types.Array (_, e) -> zero_only e + | _ -> false + +let container_global_init loc n (ty : Types.t) (init : Ast.init) = + if zero_only ty then match init with | Ast.Zeroed -> () | _ -> fail loc - "the global %s is %s, which is move-only, and a move-only global \ - starts zeroed: a global's initialiser is a compile-time constant and \ - %s is not one. Write (defvar %s %s) with no initialiser — a zeroed \ + "the global %s is %s, and such a global starts zeroed: a global's \ + initialiser is a compile-time constant, %s is not one, and a \ + container's only constant value is the empty one. Write (defvar %s %s) with no initialiser — a zeroed \ %s is an empty one, and that is a value, not a placeholder — then \ load it with (set %s ...) in the function that loads it, which runs \ once and whose result outlives every call to main" @@ -5896,19 +5732,21 @@ let move_only_global_init loc n (ty : Types.t) (init : Ast.init) = (match init with Ast.Uninit -> "uninit" | _ -> "this initialiser") n (Types.to_string ty) (Types.to_string ty) n -(* A move-only global has to be a [defvar]. A [defconst] is not an assignable - place — [check_place] refuses one by name — so a constant Vec could only - ever hold the zeroed value it was declared with, and nothing could ever put - the file's bytes in it. Refused here, where the fix is one keyword, rather - than at the (set ...) that discovers it three forms later. *) -let no_move_only_defconst loc n (ty : Types.t) = - if Types.is_move_only ty then +(* A container global has to be a [defvar]. A [defconst] is not an assignable + place — [check_place] refuses one by name — and a container's only constant + is the zeroed one, so a constant Vec could only ever hold the empty value + it was declared with: nothing could ever put the file's bytes in it. + Refused here, where the fix is one keyword, rather than at the (set ...) + that discovers it three forms later. *) +let no_container_defconst loc n (ty : Types.t) = + if zero_only ty then fail loc - "the global %s is %s, which is move-only, and a move-only global is a \ - defvar and not a defconst: a constant is not an assignable place, so \ - nothing could ever load this one — it would stay the empty %s it was \ - declared as. Write (defvar %s %s) and fill it in a function" - n (Types.to_string ty) (Types.to_string ty) n (Types.to_string ty) + "the global %s is %s, and a %s global is a defvar and not a defconst: \ + a constant is not an assignable place, so nothing could ever load \ + this one — it would stay the empty %s it was declared as. Write \ + (defvar %s %s) and fill it in a function" + n (Types.to_string ty) (Types.to_string ty) (Types.to_string ty) + n (Types.to_string ty) (* A union member written into a global would have to be encoded into the blob at link time, which is the byte-level encoder a data type case does not have @@ -5939,7 +5777,7 @@ let check_global env (d : Ast.decl) : Tast.global option = | Ast.Defvar (n, _, init) -> let ty, _ = Hashtbl.find env.globals n in no_zeroed_fn d.Ast.dloc (Printf.sprintf "the global %s" n) ty; - move_only_global_init d.Ast.dloc n ty init; + container_global_init d.Ast.dloc n ty init; let ginit = match init with | Ast.Zeroed -> { Tast.e = Tast.Zero ty; ty; loc = d.Ast.dloc } @@ -5972,7 +5810,7 @@ let check_global env (d : Ast.decl) : Tast.global option = | Ast.Defconst (n, _, v) -> let ty, _ = Hashtbl.find env.globals n in no_zeroed_fn d.Ast.dloc (Printf.sprintf "the global %s" n) ty; - no_move_only_defconst d.Ast.dloc n ty; + no_container_defconst d.Ast.dloc n ty; (* [collect] already folded the integer constants, because an array length has to be known before any type resolves. Use that value here rather than the expression it came from: a global's initialiser has to be a diff --git a/lib/prelude.ml b/lib/prelude.ml index 78482b7..4eb5d96 100644 --- a/lib/prelude.ml +++ b/lib/prelude.ml @@ -228,29 +228,16 @@ let source = {flan| ;; variable supports only what it is declared to support — an unconstrained ;; one is refused at the *definition*, not at some later call site — and ;; [ordered?] is the predicate that admits [<], [<=], [>], [>=], [min] and -;; [max]. It admits [=] and [copyable?] too: every type the language orders is -;; a number or an enum, so it is equatable and it is not move-only. +;; [max]. It admits [=] too: every type the language orders is a number or an +;; enum, so it is equatable. ;; -;; [{:where (copyable? $t)}] is the opt-out from the other default. A type -;; variable is **move-only** until it says otherwise, because move is the -;; stricter rule and assuming it can only refuse a valid program rather than -;; admit a broken one: [reduce]'s accumulator is read into [f] and then -;; assigned again, which is correct at [i32] and a double move at [(Vec i32)], -;; and the checker cannot tell which until it substitutes. -;; -;; **Two of these ten are forced and the rest are convention, and the -;; difference is worth knowing.** [filter] and [reduce] do not check without -;; [copyable?]: the first returns a [(Vec $t)], and a Vec of an owning element -;; is refused, and the second holds its accumulator in a local and reads it -;; twice. [swap!], [reverse!], [map!] and [sort-by!] check *without* it, -;; because the move analysis tracks locals and parameters and does not track a -;; read out of a slice — so [(let [t (at s i)] ... (set (at s j) t))] is not -;; seen as a move even when the element owns storage. They declare it anyway, -;; and should: at [[(Vec i32)]] those bodies would duplicate a header. It is -;; the one place move-by-default is not conservative, and until element-level -;; moves are tracked, a [copyable?] on a body that moves elements between -;; slots is a convention the reader has to keep rather than a fact the checker -;; enforces. +;; There is no [copyable?] any more. Since the repeal every value copies — +;; a container copies as its header, the copies alias one buffer, and what +;; the copies then do is the program's business, as it is in Odin. A body +;; that reads an element into a local and writes it into another slot is +;; duplicating a header when the element owns storage, and nothing here +;; says otherwise any more: that sentence moved from a predicate into this +;; comment, which is where Odin keeps it too. ;; ;; **What did not collapse, and why it should not.** [sum-i32] and [sum-f32] ;; widen their element into [i64] and [f64]; "the wider type $t accumulates @@ -263,13 +250,11 @@ let source = {flan| ;; keeping attached to something. (defn swap! [s [$t] i i32 j i32] () - {:where (copyable? $t)} (let [t (at s i)] (set (at s i) (at s j)) (set (at s j) t))) (defn reverse! [s [$t]] () - {:where (copyable? $t)} (let [i 0 j (- (len s) 1)] (while (< i j) @@ -317,7 +302,6 @@ let source = {flan| ;; predicates existed, and it stays because passing a comparison is a real ;; thing to want and not only a workaround. (defn sort-by! [s [$t] before? (Fn [$t $t] bool)] () - {:where (copyable? $t)} (let [i 1] (while (< i (len s)) (let [j i] @@ -369,7 +353,6 @@ let source = {flan| ;; here: it is two type variables and a second signature, and nothing has ;; wanted it. (defn map! [s [$t] f (Fn [$t] $t)] () - {:where (copyable? $t)} (dotimes [i (len s)] (set (at s i) (f (at s i))))) @@ -377,7 +360,6 @@ let source = {flan| ;; in. The accumulator comes first in the step, which is the order that reads ;; as (f acc x) and the order Odin's slice.reduce uses. (defn reduce [s [$t] init $t f (Fn [$t $t] $t)] $t - {:where (copyable? $t)} (let [acc init] (dotimes [i (len s)] (set acc (f acc (at s i)))) @@ -391,7 +373,6 @@ let source = {flan| ;; runtime needed no change at all, because SizeOf and AlignOf are computed at ;; the instantiation site, where the element type is concrete. (defn filter [s [$t] keep? (Fn [$t] bool)] (Vec $t) - {:where (copyable? $t)} (let [v (vec-new t)] (dotimes [i (len s)] (when (keep? (at s i)) diff --git a/lib/types.ml b/lib/types.ml index 62bc6f2..6c93489 100644 --- a/lib/types.ml +++ b/lib/types.ml @@ -124,17 +124,6 @@ let rec to_string = function let is_numeric = function Int _ | Float _ -> true | _ -> false -(* Move-only: binding, passing or returning one transfers ownership and the - source binding is dead afterwards (spec-memory.md, "The four container - types"). That rule is what makes a double free unrepresentable, which is why - [free] needs no analysis of its own. A struct that owns one is move-only - too; that arrives with [drop], which is the step after this one. *) -let rec is_move_only = function - | Vec _ | Map _ -> true - | Option t -> is_move_only t - | Array (_, t) -> is_move_only t - | _ -> false - (* The key types the first Map implementation admits (spec-memory.md, "Maps — first implementation"): integers, enums, strings, fixed arrays, and value structs composed recursively from those. Equality and hashing for them are diff --git a/spike/generics/prelude-shapes.flan b/spike/generics/prelude-shapes.flan index a53425e..b17b777 100644 --- a/spike/generics/prelude-shapes.flan +++ b/spike/generics/prelude-shapes.flan @@ -3,7 +3,6 @@ ;; prelude; it is the same bodies, over $t, checked and run. (defn keep [s [$t] keep? (Fn [$t] bool)] (Vec $t) - {:where (copyable? $t)} (let [v (vec-new t)] (dotimes [i (len s)] (when (keep? (at s i)) @@ -15,7 +14,6 @@ (set (at s i) (f (at s i))))) (defn fold [s [$t] init $t f (Fn [$t $t] $t)] t - {:where (copyable? $t)} (let [acc init] (dotimes [i (len s)] (set acc (f acc (at s i)))) diff --git a/test/programs/generic-runaway.flan b/test/programs/generic-runaway.flan index a124b36..16bbe9f 100644 --- a/test/programs/generic-runaway.flan +++ b/test/programs/generic-runaway.flan @@ -5,6 +5,6 @@ ;;;; Session.eval runs the same code the thing that hung was C-c C-c with the ;;;; dev daemon wedged behind it. The refusal names the chain of ;;;; instantiations rather than a depth it gave up at. -(defn grow [x $t] () {:where (copyable? $t)} (grow [x x])) +(defn grow [x $t] () (grow [x x])) (defn main [] () (grow 1)) diff --git a/test/programs/generics.flan b/test/programs/generics.flan index 14b1466..c16c704 100644 --- a/test/programs/generics.flan +++ b/test/programs/generics.flan @@ -21,13 +21,11 @@ ;; The variable is bound *inside* a type constructor, which is a structural ;; walk rather than a name match. (defn first-or [s [$t] d $t] $t - {:where (copyable? $t)} (if (= (len s) 0) d (at s 0))) ;; A generic calling a generic at its own variable: the copy of [swap!] is ;; generated when [rotate!] is instantiated and not before. (defn rotate! [s [$t]] () - {:where (copyable? $t)} (dotimes [i (- (len s) 1)] (swap! s i (+ i 1)))) @@ -37,7 +35,7 @@ (+ x x)) ;; equal? admits = and !=; ordered? admits < <= > >= min max, and entails -;; equal? and copyable?. +;; equal?. (defn count-of [s [$t] x $t] i32 {:where (equal? $t)} (let [n 0] @@ -52,14 +50,12 @@ ;; Two variables, and the second is determined by its own argument. (defn fst [a $t b $u] $t - {:where [(copyable? $t) (copyable? $u)]} (do b a)) ;; println over a type variable is the one form the abstract pass defers to ;; the instantiation, because its legality is only decidable after ;; substituting. The structural printer is selected per copy. (defn show [x $t] () - {:where (copyable? $t)} (println x)) ;; A cast to a type variable. [(t x)] is not a name [is_cast] knows — [t] is @@ -73,7 +69,6 @@ ;; The builtins that take a *type name* as an argument, over a variable. Each ;; reaches the one list of what names a type; (map-new t i32) is the other. (defn one-of [x $t] (Vec $t) - {:where (copyable? $t)} (let [v (vec-new t)] (push v x) v)) @@ -81,7 +76,6 @@ ;; (zeroed) takes its type from the position it is written in, so a variable ;; in that position is answered by the instantiation like any other type. (defn zero-of [x $t] $t - {:where (copyable? $t)} (do x (zeroed))) ;; The map operations over a key that is a type variable. The hash and the diff --git a/test/programs/reload-generic.flan b/test/programs/reload-generic.flan index 3e7db4a..c3131fb 100644 --- a/test/programs/reload-generic.flan +++ b/test/programs/reload-generic.flan @@ -11,13 +11,11 @@ (defvar counter i64) (defn put! [xs [$t] i i32 v $t] () - {:where (copyable? $t)} (set (at xs i) v)) ;;; Calls [put!] at its own variable, so the copy of [put!] is generated when ;;; [hold!] is instantiated and not before. (defn hold! [xs [$t] v $t] () - {:where (copyable? $t)} (put! xs 0 v)) (defn pick [xs [$t]] $t diff --git a/test/programs/vec-in-struct.flan b/test/programs/vec-in-struct.flan index e0a5a08..72b72b2 100644 --- a/test/programs/vec-in-struct.flan +++ b/test/programs/vec-in-struct.flan @@ -1,9 +1,7 @@ -;;;; spec-memory.md: "Ownership is structural, not declared" — a struct -;;;; containing a Vec is itself move-only, transitively, with recursive -;;;; teardown, and with a field that cannot be freed on its own. None of that -;;;; machinery exists: it is the same recursive teardown `drop` brings, and it -;;;; lands with it. Accepting the field meanwhile would give a struct that -;;;; copies its header on assignment two owners of one buffer. +;;;; A struct may own a Vec since the second repeal: the field is header +;;;; bytes, assignment copies them, and the two copies alias one buffer. +;;;; Which copy's free runs is the program's business — Odin's contract. +;;;; This used to be a negative fixture; now it pins the admission. (defstruct Builder [buf (Vec u8)]) (defn main [] i32 0) diff --git a/test/test_acceptance.ml b/test/test_acceptance.ml index 3fa5aa5..8d7fe44 100644 --- a/test/test_acceptance.ml +++ b/test/test_acceptance.ml @@ -1992,13 +1992,10 @@ let () = the Vec of a Vec is a run-time question about the allocator instead, so its program runs rather than being refused (programs/arena-region.flan). - This one stays, and the narrowing is exactly why: a [(Vec u8)] field - holds elements that own nothing, so nothing forces it into a region, - and two copies of the struct would be two headers over one heap buffer. - A container whose *elements* own storage is the case that is admitted, - because that one can only have been built against a region. *) - refuses "a struct field that owns a Vec" "programs/vec-in-struct.flan" - "a struct that owns one is move-only too"; + Since the second repeal the plain field is admitted: two copies of + the struct are two headers over one buffer, and that is the program's + to manage — Odin's contract. The program compiles and runs. *) + outputs "a struct field that owns a Vec" "programs/vec-in-struct.flan" ""; (* And it does not cross to C: the shim would flatten a header that owns storage. Refused by the shim generator, where the message can say what to pass instead. *) @@ -2789,9 +2786,6 @@ ERR@7 unexpected token: not the kind the caller was reading refuses_src "a data type with no cases" "(defdata U [])\n(defn f [u U] () 0)" "declares no cases"; - refuses_src "a data type case that owns a Vec" - "(defdata U [(A [v (Vec i32)])])\n(defn f [u U] () 0)" - "which is move-only"; (* At the operation, not at the type: a struct key is decided by walking its fields and the struct table is not necessarily complete while a type is resolving, so both are answered where the hash and equality diff --git a/test/test_flan.ml b/test/test_flan.ml index 969e00e..4c6c92d 100644 --- a/test/test_flan.ml +++ b/test/test_flan.ml @@ -896,12 +896,12 @@ let () = rejects_check "slice-from-ptr with a negative literal length" "(defn f [p (Ptr i32)] i32 (len (slice-from-ptr p -1)))" ~needle:"is negative"; - (* The storage stays C's. A slice is not move-only and carries no allocator, - so free refuses one by the rule it already had — this pins that the new - form did not become a thing anybody could hand to free. *) + (* The storage stays C's. A slice carries no allocator, so free refuses one + by the rule it already had — this pins that the new form did not become + a thing anybody could hand to free. *) rejects_check "free of a slice made from a pointer" "(defn f [p (Ptr i32)] () (free (slice-from-ptr p 3)))" - ~needle:"free takes a move-only value"; + ~needle:"free takes an owning container"; (* ── Structs, fields and auto-deref ────────────────────────────── *) let cursor = "(defstruct Cursor [src [u8] pos i32]) " in @@ -1040,17 +1040,14 @@ let () = "(defdata Value [Nil (List [items (Vec Value)])])"; accepts "a data type case holding a Map of itself" "(defdata Value [Nil (Table [entries (Map string Value)])])"; - (* And the narrowing is exact, which is what these two are for. A container - whose elements own *nothing* is not forced into a region by anything, so - it would sit in a copyable aggregate on the heap with two headers and one - buffer between them — the double free the original refusal existed to - prevent. It stays refused, in a struct and in a union alike. *) - rejects_check "a data type case holding a plain Vec" - "(defdata Value [Nil (Bytes [bs (Vec u8)])])" - ~needle:"makes the data type move-only"; - rejects_check "a struct field holding a plain Vec" - "(defstruct B [buf (Vec u8)])" - ~needle:"a struct that owns one is move-only too"; + (* Since the second repeal the plain case is admitted too: a struct or a + case holding a heap-backed Vec copies as bytes, the copies alias one + buffer, and a free through two copies is the program's bug — Odin's + contract exactly. These pin the admission. *) + accepts "a data type case holding a plain Vec" + "(defdata Value [Nil (Bytes [bs (Vec u8)])])"; + accepts "a struct field holding a plain Vec" + "(defstruct B [buf (Vec u8)])"; (* free does not recurse and does not quietly release the outer block: it names free-all, which is the operation that actually releases the graph. *) rejects_check "free on a container of owning elements" @@ -1622,12 +1619,11 @@ let () = rejects_check "a union that contains itself by value" "(defunion U [a i32 b U])\n(defn f [u U] i32 0)" ~needle:"contains itself by value"; - (* Not waiting on drop, unlike the struct and data type refusals: nothing - records which member is live, so there is no fact recursive teardown - could read. *) - rejects_check "a union member that is move-only" - "(defunion U [n i64 v (Vec i32)])\n(defn f [u U] i32 0)" - ~needle:"nothing records which was written"; + (* Nothing records which member is live, and since the second repeal that + is the program's fact to keep rather than a refusal: a union member may + own storage, C's way. *) + accepts "a union member that owns storage" + "(defunion U [n i64 v (Vec i32)])\n(defn f [u U] i32 0)"; (* And the one the optimiser would otherwise be handed: a byte that is neither 0 nor 1 read as an i1. Refused at any depth, which is why the second row goes through a struct. *) @@ -2604,7 +2600,7 @@ let () = accepts "a map return type, written the one way there is" "(defn f [] (Map string i32) (map-new string i32))"; accepts "a map return type followed by a constraint map" - "(defn f [x $t] (Map string i32) {:where (copyable? $t)} \ + "(defn f [x $t] (Map string i32) {:where (equal? $t)} \ (do x (map-new string i32)))"; rejects_check "braces in type position say where the spelling went" ~needle:"written (Map K V)" @@ -2621,13 +2617,13 @@ let () = ~needle:"nothing here says t is ordered?" "(defn less [a $t b $t] bool {:where (equal? $t)} (< a b))"; (* The entailments, which are the reason a signature is one predicate long - rather than three. Every type the language orders is a number or an enum, - so it is equatable and it is not move-only. *) + rather than two. Every type the language orders is a number or an enum, + so it is equatable. *) accepts "ordered? entails equal?" "(defn same [a $t b $t] bool {:where (ordered? $t)} (= a b))"; accepts "numeric? entails ordered?" "(defn less [a $t b $t] bool {:where (numeric? $t)} (< a b))"; - accepts "ordered? entails copyable?" + accepts "a variable read twice under one predicate" "(defn twice [a $t] bool {:where (ordered? $t)} (< a a))"; rejects_check "a predicate nobody has heard of" ~needle:"is not a type predicate" @@ -2636,12 +2632,13 @@ let () = ~needle:"is not a type variable of f" "(defn f [a i32] i32 {:where (ordered? $t)} a)"; - (* Move-only by default still decides the structural rules for a $t — what - may own one — but since the repeal a double use of a binding is not - checked, so both of these are accepted with and without the clause. *) - accepts "a type variable is usable twice without copyable?" + (* Everything copies since the second repeal, so a double use of a binding + needs no clause at all — and [copyable?] itself is gone, refused the way + any unknown predicate is, which is this pin's job to remember. *) + accepts "a type variable is usable twice with no clause" "(defn twice [a $t b (Fn [$t $t] $t)] $t (b a a))"; - accepts "and copyable? is still a clause a signature may state" + rejects_check "copyable? is no longer a predicate" + ~needle:"is not a type predicate" "(defn twice [a $t b (Fn [$t $t] $t)] $t {:where (copyable? $t)} (b a a))"; (* The allow-list, and it has two members. println over a type variable is @@ -2649,16 +2646,16 @@ let () = after substituting — which is the one thing the abstract pass otherwise refuses to do. *) accepts "println over a type variable is deferred" - "(defn show [x $t] () {:where (copyable? $t)} (println x))"; + "(defn show [x $t] () {:where (equal? $t)} (println x))"; accepts "and so is print" - "(defn show [x $t] () {:where (copyable? $t)} (print x))"; + "(defn show [x $t] () {:where (equal? $t)} (print x))"; (* A predicate a body relies on has to be carried by every signature between it and the call site, or the refusal moves into code the caller did not write. *) rejects_check "a predicate is not carried through a generic call" ~needle:"has to be carried by every signature" - "(defn outer [s [$t]] () {:where (copyable? $t)} (sort! s))"; + "(defn outer [s [$t]] () {:where (equal? $t)} (sort! s))"; accepts "and is accepted when it is" "(defn outer [s [$t]] () {:where (ordered? $t)} (sort! s))"; @@ -2670,7 +2667,7 @@ let () = itself is refused where it is written, at the definition. *) rejects_check "a map keyed by a type variable that is not hashable?" ~needle:"is not a map key" - "(defn f [m (Map $t i32)] i32 {:where (copyable? $t)} (len m))"; + "(defn f [m (Map $t i32)] i32 {:where (numeric? $t)} (len m))"; accepts "and hashable? is what says it is" "(defn f [m (Map $t i32)] i32 {:where (hashable? $t)} (len m))"; accepts "and under it the operations are deferred, not refused" diff --git a/test/test_session.ml b/test/test_session.ml index cc7e2c5..0962cbb 100644 --- a/test/test_session.ml +++ b/test/test_session.ml @@ -791,7 +791,7 @@ let () = installed nothing and did not say anything had gone wrong. Both copies have to be named, and the copy of [put!] that [hold!] pulls in has to be there too, which is transitivity. *) - (match Session.eval (gen ()) "(defn hold! [xs [$t] v $t] () {:where (copyable? $t)} (put! xs 0 v) (put! xs 0 v))" with + (match Session.eval (gen ()) "(defn hold! [xs [$t] v $t] () (put! xs 0 v) (put! xs 0 v))" with | c -> if not c.Session.installs then fail "redefining a generic installed nothing"; @@ -814,7 +814,7 @@ let () = instantiation that generated them was transitive, and finding them again is one table lookup rather than a walk, because a whole-program check has already regenerated all of them. *) - (match Session.eval (gen ()) "(defn put! [xs [$t] i i32 v $t] () {:where (copyable? $t)} (set (at xs i) v))" with + (match Session.eval (gen ()) "(defn put! [xs [$t] i i32 v $t] () (set (at xs i) v))" with | c -> List.iter (fun want -> @@ -884,7 +884,7 @@ let () = caller. *) (match Session.eval (gen ()) - "(defn put! [xs [$t] i i64 v $t] () {:where (copyable? $t)} \ + "(defn put! [xs [$t] i i64 v $t] () \ (set (at xs (i32 i)) v))" with | _ -> fail "a generic's changed parameter type was accepted" @@ -902,7 +902,7 @@ let () = long before the session is asked anything. *) (match Session.eval (gen ()) - "(defn pick [xs [$t]] $t {:where [(ordered? $t) (copyable? $t)]} (at xs 0))" + "(defn pick [xs [$t]] $t {:where (ordered? $t)} (at xs 0))" with | c -> if not (List.mem "pick-i32" c.Session.fns) then diff --git a/web/index.html b/web/index.html index 8860532..1af28df 100644 --- a/web/index.html +++ b/web/index.html @@ -886,11 +886,10 @@ type as an argument — (vec-new t), (map-new t i32), (min (max x lo) hi)) (defn first-or [s [$t] d $t] $t ; the variable inside a slice type - {:where (copyable? $t)} + {:where (equal? $t)} (if (= (len s) 0) d (at s 0))) (defn one-of [x $t] (Vec $t) ; bare t is the type-name argument - {:where (copyable? $t)} (let [v (vec-new t)] (push v x) v)) @@ -927,8 +926,8 @@ $t)} at the head of the body, or take the operation as a parameter — a

What makes that liveable is a where clause, written as a Clojure-style map at the head of the body — {:where (ordered? $t)}, or a vector when -there is more than one: {:where [(copyable? $t) (copyable? $u)]}. There -are five predicates, and each gates builtins the compiler already has:

+there is more than one: {:where [(ordered? $t) (hashable? $u)]}. There +are four predicates, and each gates builtins the compiler already has:

@@ -937,30 +936,19 @@ are five predicates, and each gates builtins the compiler already has:

-
ordered?< <= > >= min max
equal?= and !=
hashable?the variable as a Map key — (map-new t V), get, put, has-key?
copyable?reading the value more than once; Pool and Vec element positions

They entail each other in one direction, so one clause usually does: -numeric? gives ordered?, ordered? gives -equal?, and any of the four gives copyable?. A -sort! that compares its elements and reads them twice declares +numeric? gives ordered?, and ordered? gives +equal?. A sort! that compares its elements declares ordered? and nothing else.

-

A type variable is move-only by default, and -copyable? is the opt-out. Types.is_move_only of a variable is -not decidable abstractly — the same variable is i32 at one instantiation -and (Vec i32) at the next — so the checker assumes the stricter rule, -which can only refuse a program that would have been fine and never admit one that -double-frees. It is Rust's T: Copy, with the difference that the compiler -answers the question rather than a user implementing a trait. So -(defn twice [x $t] $t (+ x x)) does not merely want -numeric?; reading x a second time is a use after move:

- -
x was moved at twice.flan:1:26 and cannot be used again — t is move-only, so
-binding, passing or returning one transfers ownership and the source binding is
-dead afterwards (spec-memory.md). That rule is what makes a double free
-unrepresentable; (clone x) if you wanted a second one
+

Every value copies. There used to be a fifth predicate, +copyable?, gating a second read of a move-only variable; the move +concept was repealed on 2026-09-18 — a container copies as its header, the +copies alias one buffer, and which free runs is the program's business, as it +is in Odin — so the predicate went with it.

Each instantiation then checks the concrete type against what the signature declared, and refuses the call site when it does not answer:

From bb2471f7a1bb0a529978760539bee24e92cfc9fb Mon Sep 17 00:00:00 2001 From: Joseph Ferano Date: Fri, 18 Sep 2026 12:23:39 +0700 Subject: [PATCH 3/4] The gen word leaves both headers: a check nothing runs is weight, and Odin carries none of it --- lib/check.ml | 6 +++--- lib/emit.ml | 19 +++++++++-------- runtime/flan_rt.c | 45 +++++++++++++++-------------------------- test/test_acceptance.ml | 2 +- 4 files changed, 29 insertions(+), 43 deletions(-) diff --git a/lib/check.ml b/lib/check.ml index 99c1675..b8caf6f 100644 --- a/lib/check.ml +++ b/lib/check.ml @@ -3831,9 +3831,9 @@ and named_call ctx ~want loc name args = (* spec-memory.md's first release point. Since the repeal, what it consumes it consumes at run time only: nothing marks the binding dead, so a second [free] or a read after this one type-checks and misbehaves at run time — - the allocator aborts on a double free it can see, and the dev build's - generation word traps a stale read. That is the Odin contract: free is a - thing you write, and writing it twice is yours to not do. *) + the allocator aborts on a double free it can see, and the epoch word + traps a read through a released region. That is the Odin contract: free + is a thing you write, and writing it twice is yours to not do. *) | "free" -> arity loc name 1 args; let target = check ctx (List.hd args) in diff --git a/lib/emit.ml b/lib/emit.ml index 86d2f81..083da71 100644 --- a/lib/emit.ml +++ b/lib/emit.ml @@ -287,7 +287,7 @@ let rec lay m (t : Types.t) : int * int = | Types.Ptr _ -> 8, 8 | Types.Alloc -> 8, 8 | Types.Fn _ -> 8, 8 - | Types.Vec _ | Types.Map _ -> 48, 8 + | Types.Vec _ | Types.Map _ -> 40, 8 (* [n x T] adds no padding of its own: T's size already carries its tail. *) | Types.Array (n, e) -> let s, a = lay m e in Int64.to_int n * s, a | Types.Option e -> let s, a, _ = lay_fields m [ Types.Int Types.I8; e ] in s, a @@ -512,15 +512,15 @@ let rec dty m d (t : Types.t) : int = | Types.Alloc -> dnode d "!DIDerivedType(tag: DW_TAG_pointer_type, name: \"Allocator\", baseType: null, size: 64)" - (* Shown as what it is. The two dev words are in the layout and so they - are here too: a debugger that showed four fields of a six-field struct - would put the reader's offsets out by two. *) + (* Shown as what it is. The epoch word is in the layout and so it is + here too: a debugger that showed four fields of a five-field struct + would put the reader's offsets out by one. *) | Types.Vec e -> composite (Types.to_string t) [ ("ptr", Types.Ptr e); ("len", Types.Int Types.I64); ("cap", Types.Int Types.I64); ("allocator", Types.Alloc); - ("gen", Types.Int Types.I64); ("epoch", Types.Int Types.I64) ] - (* Six fields again, and shown as six for the same reason: a debugger + ("epoch", Types.Int Types.I64) ] + (* Five fields again, and shown as five for the same reason: a debugger that showed fewer would put the reader's offsets out. [log2cap] is shown rather than a capacity because that is what is stored — the capacity is 1 << it, and a debugger that invented the shift would be @@ -529,8 +529,7 @@ let rec dty m d (t : Types.t) : int = composite (Types.to_string t) [ ("data", Types.Ptr (Types.Int Types.U8)); ("len", Types.Int Types.I64); ("log2cap", Types.Int Types.I64); - ("allocator", Types.Alloc); ("gen", Types.Int Types.I64); - ("epoch", Types.Int Types.I64) ] + ("allocator", Types.Alloc); ("epoch", Types.Int Types.I64) ] |> fun n -> ignore k; ignore v; n (* A pointer to code, and lldb is told exactly that and no more. DWARF has DW_TAG_subroutine_type for the signature behind it, and spelling @@ -2668,11 +2667,11 @@ let header = {|; Generated by flan. The layout is C's: no object headers anywher %slice = type { ptr, i64 } ; (Vec T), spec-memory.md. The element type is nowhere in it: the runtime is ; type-erased and every operation is handed size and align at its call site. -%vec = type { ptr, i64, i64, ptr, i64, i64 } +%vec = type { ptr, i64, i64, ptr, i64 } ; (Map K V), spec-memory.md — Odin's open-addressed Robin Hood map. Neither key ; nor value type appears in it, for the same reason: one type-erased runtime, ; handed the two sizes and a hash/equality pair at each call site. -%map = type { ptr, i64, i64, ptr, i64, i64 } +%map = type { ptr, i64, i64, ptr, i64 } ; A handler frame: the one it displaced, the condition type it matches, and ; the lifted function that runs. Allocated on the establishing frame's stack. %handler = type { ptr, i32, ptr } diff --git a/runtime/flan_rt.c b/runtime/flan_rt.c index 492dc02..4267dbb 100644 --- a/runtime/flan_rt.c +++ b/runtime/flan_rt.c @@ -906,8 +906,7 @@ struct flan_allocator { void *data; uint32_t caps; /* Bumped on every free-all. A container records it and traps if it moved: - * spec-memory.md, "Dev builds detect a released region". Separate from the - * per-Vec generation word, which answers a different question. */ + * spec-memory.md, "Dev builds detect a released region". */ uint64_t epoch; /* Dev accounting for the general-purpose tier: "did you forget to free" is * an allocator-tier question and this is the allocator's answer. */ @@ -1392,30 +1391,26 @@ _Noreturn void flan_region_only_fail(const uint8_t *loc, int64_t loclen) { * produce the numbers, and it passes them in. There are no generics here and * none are needed. * - * Header, and it is six words rather than the spec's four: + * Header, and it is five words rather than the spec's four: * * ptr len cap allocator the release layout spec-memory.md fixes - * gen bumped on every reallocation — the stale-slice - * word spec-memory.md asks for. It has no reader - * and cannot have one as things stand, which is - * the part "not yet" used to hide: a slice is - * ptr+len, so it carries neither the Vec it came - * from nor the generation it was taken at, and - * the check has nothing to compare. Giving it a - * reader is a third word on every slice in the - * language, not a change to this file. Nothing - * here or anywhere else reads it; do not write - * code that trusts it. See docs/BUILT.md. * epoch the allocator's epoch when this Vec last * touched it. Any operation on a container whose * recorded epoch has moved traps. * - * The two dev words are present in every build, not only a dev one, and that + * There used to be a sixth word, gen, the stale-slice generation + * spec-memory.md once asked for. It was bumped on every reallocation and + * consulted by nothing — a slice is ptr+len and carries neither the Vec it + * came from nor the generation it was taken at, so the check it promised had + * nothing to compare — and Odin's header (data, len, cap, allocator, and + * nothing else) is the model this one follows. Deleted 2026-09-18 with the + * ownership repeal; see docs/BUILT.md. + * + * The epoch word is present in every build, not only a dev one, and that * is not laziness: a redefinition module is built by llc and ld against a host * that was built separately, and nothing makes the two agree on a struct size. * A layout that changes with a build flag is a layout that can disagree across - * that boundary silently. Dropping them in release is deferred and docs/BUILT.md - * says what it is blocked on. + * that boundary silently. * * Every entry point returns int8_t 1/0 for "did it fit", and never reports * failure any other way: the condition, the restart and the message are the @@ -1426,7 +1421,6 @@ typedef struct flan_vec { int64_t len; int64_t cap; flan_allocator *alloc; - int64_t gen; int64_t epoch; } flan_vec; @@ -1546,7 +1540,6 @@ static int8_t flan_vec_grow(flan_vec *v, int64_t want, int64_t size, v->cap = cap; /* Any slice taken before this points at storage that may have moved. The * word is bumped here and read nowhere yet; see docs/BUILT.md. */ - v->gen++; return 1; } @@ -1565,7 +1558,6 @@ int8_t flan_vec_init(flan_vec *v, flan_allocator *a, int64_t cap, int64_t size, v->ptr = NULL; v->len = 0; v->cap = 0; - v->gen = 0; v->alloc = a; v->epoch = (int64_t)v->alloc->epoch; if (cap <= 0) return 1; @@ -1649,7 +1641,6 @@ void flan_vec_free(flan_vec *v, int64_t size, int64_t align, v->len = 0; v->cap = 0; v->alloc = NULL; - v->gen++; v->epoch = 0; } @@ -1701,11 +1692,11 @@ int8_t flan_vec_clone(flan_vec *dst, flan_vec *src, flan_allocator *a, * data one allocation: keys | values | hashes | scratch * len live entries * log2cap 0 until something is allocated; never 1 or 2 after - * allocator gen epoch as on a Vec, and checked the same way + * allocator epoch as on a Vec, and checked the same way * * Odin stuffs log2cap into the low six bits of the data pointer because its - * Raw_Map must be three words. This header already carries an allocator, a - * generation and an epoch, so the bit-stuffing would buy nothing and cost a + * Raw_Map must be three words. This header already carries an allocator and + * an epoch, so the bit-stuffing would buy nothing and cost a * mask on every access — and, more usefully, not tagging means correctness * never depends on the block being 64-byte aligned. It is requested as 64, and * cell packing pays off when the request is honoured, but an arena whose base @@ -1757,7 +1748,6 @@ typedef struct flan_map { int64_t len; int64_t log2cap; flan_allocator *alloc; - int64_t gen; int64_t epoch; } flan_map; @@ -2274,7 +2264,7 @@ static int8_t flan_map_grow(flan_map *m, int64_t want, int64_t ksize, if (log2cap <= m->log2cap && m->data) return 1; fresh.data = NULL; fresh.len = 0; fresh.log2cap = 0; - fresh.alloc = a; fresh.gen = 0; fresh.epoch = (int64_t)a->epoch; + fresh.alloc = a; fresh.epoch = (int64_t)a->epoch; if (!flan_map_alloc(&fresh, a, log2cap, ksize, vsize)) return 0; if (m->data) { @@ -2302,7 +2292,6 @@ static int8_t flan_map_grow(flan_map *m, int64_t want, int64_t ksize, m->len = fresh.len; /* Every key and value moved, so any pointer into the old block is stale — * the same word, bumped for the same reason, as a Vec's reallocation. */ - m->gen++; return 1; } @@ -2313,7 +2302,6 @@ int8_t flan_map_init(flan_map *m, flan_allocator *a, int64_t ksize, m->data = NULL; m->len = 0; m->log2cap = 0; - m->gen = 0; m->alloc = a; m->epoch = (int64_t)a->epoch; /* No block until something is put in it: an empty map that is never written @@ -2529,7 +2517,6 @@ void flan_map_free(flan_map *m, int64_t ksize, int64_t vsize, m->len = 0; m->log2cap = 0; m->alloc = NULL; - m->gen++; m->epoch = 0; } diff --git a/test/test_acceptance.ml b/test/test_acceptance.ml index 8d7fe44..46baa50 100644 --- a/test/test_acceptance.ml +++ b/test/test_acceptance.ml @@ -762,7 +762,7 @@ let () = let dbg = Emit.program ~debug:true (Check.program (Parse.program (Reader.read_file "programs/vec.flan"))) in if not (contains dbg "name: \"Allocator\"") - || not (contains dbg "name: \"(Vec i32)\", size: 384") + || not (contains dbg "name: \"(Vec i32)\", size: 320") then begin incr failures; print_endline "FAIL debug info for Allocator and (Vec T)" From 0faacb3e57599785c0150161dc957b89b9827cf5 Mon Sep 17 00:00:00 2001 From: Joseph Ferano Date: Fri, 18 Sep 2026 12:38:26 +0700 Subject: [PATCH 4/4] The spec records the second round: two containers, everything copies, five words in a header --- FIX.org | 27 ++++++++++ NEXT.md | 4 +- docs/BUILT.md | 10 ++++ docs/REVIEW-production-readiness.md | 4 +- spec-memory.md | 80 +++++++++++++++++++---------- 5 files changed, 93 insertions(+), 32 deletions(-) diff --git a/FIX.org b/FIX.org index 2d001f2..9bae6c5 100644 --- a/FIX.org +++ b/FIX.org @@ -256,3 +256,30 @@ NEXT.md are annotated at their live claims. Two of the day's fix lanes were cancelled with this (borrowed-flag, region element); the while-condition fix merged in the morning is deleted again by the repeal, and its pin with it. + +* The second round, 2026-09-18 — Pool, move-only, and the gen word + +Ordered by the author after the ownership repeal, on the same argument: the +Odin position, full stop. + +- Pool and (Handle T) are gone — types, checker arms, runtime section, + fixtures. Two containers are enough; a slab with generational handles is a + library over a Vec when a program wants one. +- The move-only concept is gone: everything copies as its header, copyable? + left the predicate list (four remain), and the struct/defdata/defunion + owning-field refusals are lifted. The region rule stands untouched — a + container of owning elements is still built against a region and released + by one free-all. +- The gen word left both container headers (read by nothing since it was + written). A Vec is ptr len cap allocator epoch; the epoch trap stays. +- Container globals keep both declaration rules, reworded: they start zeroed + (a global initialiser is a compile-time constant, and a container's only + constant is the empty one), and a defconst container is refused since a + constant is not an assignable place. sand.flan's experiment line would now + be refused with the reworded sentence. + +Everything verified together: dune test --force 232/0 with zero suite FAILs, +@x86 122 MATCH / 0 DIFFER, @sanitize clean, and the whole-repo check sweep +against the parent differs only where it should: the two negative fixtures +now accepted (vec-in-struct, the clause-less generics corpus), the two pool +fixtures deleted. diff --git a/NEXT.md b/NEXT.md index f033eb8..b032bcd 100644 --- a/NEXT.md +++ b/NEXT.md @@ -195,7 +195,7 @@ Worth stating because the notes elsewhere may still read the old way: an `Int`, a `Ptr`, an `Alloc` or a `Handle`, with aggregates leaving through an out-pointer, and `crossable` refuses an aggregate return from a `declare` outright. The refusal in `call_native` is unreachable and building sret behind it would have been *wrong* — that path is the C boundary, where - SysV returns a 16-byte slice in `rax:rdx` rather than by hidden pointer. `Vec`, `Map` and `Pool` all + SysV returns a 16-byte slice in `rax:rdx` rather than by hidden pointer. `Vec`, `Map` and `Pool` (since removed) all match; item 16's "unexercised" line was stale. - **The header check is not opt-in.** `vendor/raylib/raylib-5.5.h` is committed and `vendor/raylib/headers` names it directly. There is no `FLAN_RAYLIB_H`. @@ -321,7 +321,7 @@ the easy half. What is left is conditions, and the measurement moved them from ' doing first. Do that before item 1, not after. 3. **`Rt` with an aggregate return**, and with it most of the container runtime. `Vec`, `Map` and - `Pool` have not been exercised through this backend at all. + `Pool` (since removed) have not been exercised through this backend at all. 4. **`Fnval`'s indirection cell.** `FnAddr (Fnval n)` emits the symbol, which is right for a whole-program build and wrong the instant anything is redefined into it. There are no cells and no diff --git a/docs/BUILT.md b/docs/BUILT.md index 7521e67..410baff 100644 --- a/docs/BUILT.md +++ b/docs/BUILT.md @@ -2910,6 +2910,16 @@ is still right: a union has a C layout and still may not cross to C by value, be ## `(Handle T)` and the pool, which is what a stale reference answers with +**Removed 2026-09-18**, in the second round of the repeal: two containers are +enough, the corpus's only pools were its own fixtures, and a slab behind +generational handles is a library over a `Vec` when a program wants one — +which is where Odin keeps it. The `gen` word on `Vec` and `Map` went the same +day (maintained, read by nothing; the header is `ptr len cap allocator +epoch` now), and so did the move-only concept itself — everything copies, and +`copyable?` left the predicate list. spec-memory.md, "The repeal", carries +all three amendments. The section below is kept as the record of what was +built. + A handle is a reference to something that can die, which reports that it died rather than silently resolving to whatever reused its slot. `check.ml` refused `(Handle T)` by name as milestone 6; this is what it stood for, and the pool came with it because the pool is what makes the report possible. diff --git a/docs/REVIEW-production-readiness.md b/docs/REVIEW-production-readiness.md index e71c50d..e744b6d 100644 --- a/docs/REVIEW-production-readiness.md +++ b/docs/REVIEW-production-readiness.md @@ -144,8 +144,8 @@ The containers, strings/UTF-8, sequences, random, and printing layers are decent `flan_transfer_fail`, `flan_null_alloc_fail`, `flan_free_all_fail` → `rt_die`). Bounds and arithmetic already park via the break-loop hook; these should too. - **Unchecked `malloc` in `flan_argv`** (`flan_rt.c:162`) — the one in the file. -- **`v->gen` stale-slice word is maintained and never consulted** (`flan_rt.c:1347`) — - either implement the check or delete the field before someone trusts it. +- ~~**`v->gen` stale-slice word is maintained and never consulted**~~ — deleted + 2026-09-18 with the second round of the repeal; the header is five words now. - **`flan_slurp_into` conflates elements and bytes and skips `flan_vec_check`** (`flan_rt.c:2746`) — safe only because check.ml pins slurp to `(Vec u8)`; a latent trap. - **`flan run` swallows build flags as program arguments** (`bin/main.ml:634-651`) — diff --git a/spec-memory.md b/spec-memory.md index ad960e0..e3dfa8d 100644 --- a/spec-memory.md +++ b/spec-memory.md @@ -29,11 +29,10 @@ facility (see plan.org, "Managed classes"). or a literal in read-only memory. Copying a slice copies ptr+len, never the elements. A slice may be `const`-qualified; freeing through one is not possible because a slice has no allocator and no `cap`. -- `(Vec T)` and `(Map K V)` are **move-only**. Assignment hands over the one - header rather than copying it — there is no implicit shallow copy, so two - owners never arise from an assignment; `(clone x)` is the only spelling of a - second, independent one. Since the repeal, using the source binding again is - not a compile error: the header is still there, and a program that frees +- `(Vec T)` and `(Map K V)` **were move-only**; the second repeal removed the + concept. Assignment copies the header, the copies alias one buffer, and + `(clone x)` is the spelling of an independent one. Using a binding after + assigning it away is ordinary: the header is still there, and a program that frees through it twice or reads through it after a free misbehaves at run time, where the allocator and the dev build's generation word are the net. @@ -78,7 +77,10 @@ points at. allocator; `(clone x alloc)` names one. Value types (`[n T]`, structs of value types, primitives) need no `clone` — assignment already copies them. -A struct containing a `Vec` field is itself move-only. Ownership is structural, +A struct containing a `Vec` field was itself move-only until the second +repeal; since it, the field is admitted and the struct copies like any other +(see "The repeal"). The paragraphs below record the rule as designed. +Ownership is structural, not declared: a type is a value type iff all of its fields are **and it declares no `drop` hook** (see Allocators). A `drop` hook makes a type move-only for the same reason a `Vec` field does — exactly one owner, so the hook fires exactly @@ -106,12 +108,13 @@ region" for the rule that stands in its place and for what it costs. - A future lightweight provenance pass may reject the obvious mistakes (a borrow of a local escaping, use after an owner moves, and reallocation with a live borrow). It must not require Rust-style lifetime annotations or dictate - an ECS-shaped object model. Long-lived graph links use `(Handle a)`; temporary - graphs may use explicitly managed, stable region storage. -- Cross-referencing long-lived objects uses `(Handle a)` into a pool, never a - raw pointer or slice. A stale handle is detectable. + an ECS-shaped object model. +- Cross-referencing long-lived objects used `(Handle a)` into a `Pool` until + the second repeal (below) removed both: two containers proved enough, and a + program that wants generational indirection builds it over a `Vec`, as an + Odin program does. -## Globals of move-only type +## Container globals A global may be a `Vec` or a `Map`. Its intended lifetime is the process's — it is loaded once and never released — and before the repeal a flow rule enforced @@ -127,10 +130,9 @@ take their target as a borrow, so a global `(Vec u8)` is filled and grown where it stands. The aliasing contract is the one above and nothing more — a push that reallocates invalidates a slice taken before it, and that is the programmer's whether the owner is a local or a global. Globals get no borrow rule locals do -not have; the dev build's generation word lives on the `Vec`, so the stale-slice -trap works the same either way. +not have. -A move-only global **starts zeroed** — a zeroed `Vec` is an empty `Vec` — and is +A container global **starts zeroed** — a zeroed `Vec` is an empty `Vec` — and is loaded by whichever function loads it, with an ordinary assignment: ``` @@ -147,6 +149,9 @@ first block and leaks it; there is no `drop`, and freeing is a thing you write. ## The repeal — 2026-09-18 +(Extended the same day by a second round; see the amendments at the end of +this section.) + The first implementation carried a static flow analysis: a per-function dead set recording moved-out bindings, a borrow flag over the container-reading operations, an iteration diff for loops, and a borrowed-never-moved rule for @@ -162,17 +167,31 @@ believed. What the language promises after the repeal is Odin's contract, which is the model this memory design was built from in the first place: -- **The types** still decide what may be copied and what may own what: move-only - assignment hands over the header, `clone` is the only copy, and the - struct/union/pool ownership rules all stand. -- **The allocator** still decides what a free means: `can-free`, regions, +- **The allocator** decides what a free means: `can-free`, regions, `free-all`, and the region-only rules for containers of owning elements all stand. - **Which frees run, and when, is the program's.** `defer` is the tool, and a double free or use-after-free is a run-time misbehaviour, not a compile error. -- **The dev build detects.** The generation word on `Vec`, the region epoch - trap, and the block registry are the net, where a game is actually run. +- **The dev build detects.** The region epoch trap and the block registry are + the net, where a game is actually run. + +The same day, the rest of the concept followed, on the same argument carried +to its end: + +- **The move-only concept itself is gone.** Everything copies — a container as + its header, the copies aliasing one buffer. The `copyable?` predicate went + with it (four predicates remain), as did the struct, data-type and union + owning-field refusals: a struct may hold a `Vec`, and the two-headers-one- + buffer aliasing that buys is the program's, exactly as it is in Odin. +- **`Pool` and `(Handle a)` are gone.** Two containers are enough; a slab with + generational handles is a library a program writes over a `Vec` when it + wants one, which is where Odin keeps it too. +- **The `gen` word is gone from both headers.** It was bumped on every + reallocation and read by nothing — the stale-slice check it promised needs a + third word on every slice, not a word here. A `Vec` is now + `ptr len cap allocator epoch`; the epoch word stays because free-all + detection reads it on every operation. A future provenance pass (the "Open" section at the end of this document, and plan.org #3) remains the door back to static checking. It is additive: nothing @@ -235,13 +254,13 @@ instantiates it: > field-free storage. It does **not** support `=`, `<`, `+`, or `hash`. What makes that liveable is a `where` clause of compile-time type predicates, -written as a map at the head of the body. There are five — `ordered?`, `equal?`, -`hashable?`, `numeric?`, `copyable?` — they are not type classes because a +written as a map at the head of the body. There are four — `ordered?`, +`equal?`, `hashable?`, `numeric?` — they are not type classes because a predicate carries no implementations and merely gates a builtin the compiler -already has, and they entail one another in one direction, so one clause usually -does. A variable is move-only by default and `copyable?` is the opt-out, because -whether a variable moves is not decidable abstractly. plan.org's Types section -has the full account. +already has, and they entail one another in one direction, so one clause +usually does. (`copyable?` was the fifth until the second repeal removed the +move concept it opted out of.) plan.org's Types section has the full +account. ``` (defn sort! [s [$t]] () @@ -480,7 +499,8 @@ a reason that is not teardown — nothing records which member is live, so there is no fact a release could read — and a region answers the teardown question without touching that one. -A `Pool` is admitted with the others, and it is the one where the trade is not +A `Pool` was admitted with the others while it existed (the second repeal +removed the type), and it was the one where the trade is not identical, because `(release p h)` recycles a slot while the pool lives on. Whatever the dead element owned stays allocated until `free-all`. That is a region leak bounded by the region, which is what a region already is; it is not @@ -611,7 +631,11 @@ practice: a union is all-bytes-zero unless `uninit` says otherwise. Three things a union may not do, and each for a reason that does not expire: -- **No move-only member.** Nothing knows which member is live, so nothing can +- **No owning member** — until the second repeal, which admits one: nothing + records which member is live, and since nothing (the program included) can + free the right one through the union itself, the tag the program keeps + beside it is the way, C's way. The rest of this entry records the rule as + designed. Nothing knows which member is live, so nothing can tear one down. Unlike the struct and `defdata` refusals, this is not waiting on recursive teardown — there is no fact for teardown to read, and freeing the wrong member is a free of a pointer that was an `f64` a moment ago.