dev-chatty.flan outlives the surveys' twenty seconds by design, and unlike
dev-repl it prints while it does -- so the two backends stop at different
lines and the diff reports on scheduling rather than on lowering. It joins
dev-loop and dev-watch in the excluded-by-name list in both sweeps, with the
distinction written down.
rt_flush_out is guarded on __wasm__: the pipe it is careful about belongs to a
merged flan dev, which is only ever a native host, and wasm32 need not answer
for a descriptor mode its runtime may model differently.
And three comments that went false with the _exit: the atexit registration in
the merged entry point is no longer there for rt_die, which unlinks the socket
for itself now, so both places that said so say what it is actually left
covering.
Retrying immediately looked like eight chances and was one: a walk that bails
at the epoch check costs almost nothing, so all eight fit inside the single
compaction they were all losing to, and the listing refused having waited for
nothing. A quarter of a millisecond between attempts -- the agent's break-loop
idiom, legal here because the waiter is the listener thread and never the game
loop -- bounds the whole refusal at two milliseconds. Measured with a writer
noting and freeing on top of three thousand live blocks: 8 right answers in 200
without the pause, 200 in 200 with it. It is not magic, and the comment says
so: a writer that spends most of its time rearranging the table still gets
refused, which is the honest answer and used to be a zero-row lie.
The two cases the last commit left unwired are wired now, and a third joins
them: a listing taken while the table really is being compacted, which nothing
covered -- the full-of-live case never compacts and the churn case is
single-threaded, so the retry itself was exercised by nothing. It asserts only
what a slower machine cannot change: never zero rows, never a count that is
neither right nor a refusal. How the rest divides is printed, not pinned.
It ended "send it again once the program is running", which reads as a
withdrawal of what eval promises a parked program on every other evaluation:
that a body redefined while parked installs when the program is run again.
What is true is narrower — this module was not taken, and the run that drains
the sixty-four already queued is what makes room for it.
The three named arms are not every way a step after the check can fail.
write_file makes the daemon's copy of the module's text before llc is called at
all, and a Sys_error from it went out through serve's guard with the session
already holding the declaration — the same stranded declaration under a
different exception. Dev.eval now restores on the way past anything that
escapes, and carries an accepted flag so that a module the agent has already
taken is never rolled back out from under the process.
That is also the seam the crash can be reproduced through. test_dev takes the
daemon's working directory away from it — its own, not the macro cache the two
failures above use, which cannot fail a build with no macro in it — evaluates a
defn, and then calls it. Without the restore the daemon lists probe-two in
describe and the call closes the socket: the null cell, the game thread, and
address 0.
Two seconds was measured on one warm machine and has no margin against the
6.8s cold build listening already records. The status and the absence of the
frame-boundary sentence are what discriminate; this bound exists only so a
timeout cannot be read as an answer, so it moves to 4.5 and says so.
The unreadable-frame case wrote both frames as one string, where `(:a14' reads
as a typo rather than as the end of one frame and the start of the next; they
are two inserts now, with a line saying which is which. And the check that a
request after a daemon restart does not wait out a reply the old connection
owed was asserting against the same number it had bound the timeout to -- the
one arrangement that cannot tell "fast" from "timed out a moment ago". The
timeout is ten seconds and the assertion is three, which is the gap the claim
is actually about.
The registry compacted whenever the table was three quarters full, and a
compaction reclaims dead entries and nothing else. A program holding more than
three quarters of the table in live blocks therefore compacted on every
allocation for the rest of its life, reclaiming nothing each time and holding
the table-wide epoch odd while it did. A listing racing that loop lost all
eight of its attempts and answered with zero rows -- "nothing is held", about a
program holding three thousand blocks, from the verb that exists to find a
leak. Measured at 199 wrong answers in 200.
The trigger now also asks whether there is an eighth of a table's worth of dead
to reclaim, which is a count four places maintain: a death, an arena's
free-all, a note written over a dead slot, and the sweep itself. That bounds
the cost from the other side too, since a sweep that runs reclaims at least 512
slots and so cannot run twice in 512 allocations.
Separately, flan_dev_reg_by_type answered a walk it could not take with zero
rows, which is the same number a program that had freed everything gets, and
stepped past slots flan_reg_snap could not copy while still calling the walk
whole. It now counts those slots and returns -1 with the count, the agent
refuses in a sentence the daemon already renders, and the snap contract says
which caller keeps it and why reg_at is allowed not to.
A note that finds no slot is still dropped -- dying because a diagnostic ran out
of room would be the diagnostic shooting the patient -- and now says so on
stderr once, quoting how many entries were dead rather than claiming the table
is all live.
test/dev_limits.c gains three modes, driven from test_reload: 3100 live blocks
read under a writer thread (1 right in 200 before, 200 after), 3000 live with
600 churned on top of them to prove the sweep still runs, and a genuinely full
table that must say so exactly once.
rt_die began with fflush(stdout) and ended with exit(134), and under a merged
flan dev both could hang. The flush waits on a 64K pipe whose reader is busy;
exit runs the atexit chain and the ELF destructors, which want the loader lock
a dlopening listener thread may be holding, and in that build the chain also
holds OCaml's shutdown. A bounds failure that hangs is worse than one that
kills the process, because nothing is printed and nothing exits.
So the flush every trap does first goes through rt_flush_out, which puts fd 1
into non-blocking mode and accepts a truncated tail, and rt_die takes _exit
and unlinks FLAN_DEV_SOCK by hand -- the same shape as die_now in
flan_agent.c, which argued all of this first and is quoted rather than
diverged from. On a terminal, a file, or a pipe with room, O_NONBLOCK changes
nothing, and the acceptance corpus diffs that output.
One consequence worth knowing: _exit skips ASan's exit-time leak report, so a
trapping program under @sanitize no longer reports leaks.
`flan-dev-quit' promises to stop the daemon this Emacs started. It sent `close'
down the current connection as well, on the assumption that the two are the
same program -- and `flan-connect' is the command for attaching to one that is
not, so the assumption was one keystroke from being false. Connect to a daemon
running in a terminal, quit, and two programs ended: the one Emacs owned, and
somebody else's.
The daemon's socket is now kept apart from the connection's, which is what lets
one be told from the other. `flan-connect' names both programs before it
abandons a connection belonging to a daemon this Emacs started, and refuses
outright for a Lisp caller, as `flan-dev' already did for a running program.
`flan-dev-quit' on a connection that is not the daemon's closes that connection
and says what it left running. `flan-dev-restart-program' restarts on the
daemon's own socket, and refuses while the connection is elsewhere: there is no
reading of "build it again" that leaves one session where there was one.
Closing the window of a printing program left the pipe full, and the flushes
on the way out blocked on a compiler thread that was busy answering the very
request asking to run it again. program_state still said RUNNING, so rerun
refused a finished program as "the program is already running".
Two flushes moved. flan_exit no longer flushes before the hook -- exit(3)
flushes for itself, so that call only ever ran on the merged path, and there
it was the first thing to block. flan_merged_park flips the state under the
lock first and flushes after, because a state flip is two stores and cannot
wait on anything.
What widens is the window in which the program is parked and not yet on the
condvar. Nothing is lost there: program_asked is the fact and a signal
delivered to nobody is discarded. Two re-runs in that window are both
answered ok for one run, which is the trade against a refusal that was false.
`backward-sexp' does not signal when there is no form before point; it goes to
the beginning of the buffer and stays there. At point-min that is no movement,
so the form the dispatch then looked at was the one *after* point -- whose head
is very often a declaration -- and the region between start and end was empty.
The key installed the file's first declaration by name with no body, which the
daemon accepts, and the echo area reported it as a change. Both paths check for
movement now: the predicate refuses, and the expression arm refuses in words
rather than asking the daemon to evaluate the empty string.
The same predicate asked only for the depth at the open delimiter, and a form
written at column 1 inside a comment or a string is at depth 0 like any other.
A `defvar' in a comment is prose; it is not offered as a declaration any more.
Depth in a narrowed buffer still means depth within the narrowing, which is
noted where it is read rather than changed.
The merged build's stdout is a 64K pipe back into the daemon's own process,
and the accept loop is the only thing reading it -- which it is not doing
while serve is answering a request. The two five-second waits for a frame
boundary now drain the pipe on every tick, so a program stopped inside fwrite
is one the daemon lets go rather than one it waits out and then accuses of
not calling agent/poll.
drain and not take: the text stays in the buffer until with_output puts it on
the reply, which is where the output an evaluation caused belongs. And the
drain sits beside the sleep rather than inside the select, because a readable
pipe would make the tick free and count the timeout out in a fraction of it.
dev-chatty.flan prints 4K a frame, which is the only fixture here that fills
the pipe at all; without the drain it fails in 5.1s with the old sentence.
The members of a defenum are i32 at run time, but the reader hands the parser
an int64, so a value too large for the type arrived looking ordinary: truncated
by the x86 backend, malformed in the LLVM IR, and -- the reason this is a
correctness hole and not a nicety -- invisible to the duplicate-value rule
sitting right below it. That rule compares int64s, so (defenum E [A 0
B 4294967296]) passed it: the two differ as int64 and are both 0 as i32, and
the one check written to catch two names for one number waved through exactly
the case it exists for.
Each value is now checked where it is resolved, which is before the collision
scan runs, so the scan compares the numbers the program will actually have. A
value that does not fit is refused rather than quietly made to fit, naming the
member, its enum, and the value, with a different sentence for a value that was
written and one autoincrement walked into -- nothing in the source wrote
2147483648, so the refusal has to say where it came from before it can say it
is wrong.
The check is bound with a let rather than inlined into the cons, and that is
load-bearing: OCaml leaves :: operand order unspecified and takes the tail
first, so an inlined check would run after the recursive Int64.add and let
(defenum E [A 9223372036854775807 B]) wrap to min_int and refuse B for a number
in no one's source. Bound first, A is refused and the wrap is unreachable.
The parser is the only place this needs to happen: Parse.decl is the sole
constructor of Ast.Defenum's member values, and Load only re-qualifies the
enum's name.
Explicit-duplicate aliasing is untouched; that rule is deliberate.
`flan-dev--poll' guarded on `flan-dev--busy' and nothing else, and the watch
timer is precisely the sender that does not bind it: it sends without waiting,
so it has nothing to hold. A poll landing in that gap sent `describe' down a
connection that already owed a reply, read the watch's answer as its own, and
left its own for the watch to read a tick later -- after which the two
consumers stayed swapped for the session, each of them answering the other's
question. It runs `flan-dev-settle-hook' now, which is the invariant the hook's
docstring already claimed.
And the hook runs before `flan-dev--live-connection' rather than after. An
outstanding reply belongs to the connection it was asked on; when a daemon has
been restarted the old connection is gone and no reply is coming on the new
one, but the hook was being asked about the new one and blocked a full
`flan-dev-reply-timeout' -- a frozen Emacs on the first key pressed after a
restart, with the watch armed. `flan-dev--busy' now covers the reconnect too,
which asks the new daemon what it defines and so must not be interrupted by a
poll either.
Two orderings in the reply reader, and both of them were permanent. A frame
whose header arrived and whose body did not fell through the wait loop into
`flan-dev--extract-reply', where `byte-to-position' signalled a wrong-type
error on a position past the end of the buffer -- so the timeout message the
function goes to some trouble to word was never the one anybody read, and the
header stayed at the front of the buffer, where the next request took it as
its own and every request after that was answered by the one before it. The
body deadline is tested again now rather than trusted, and the dead frame is
erased: the timeout is said in the words meant for it, and the connection is
back in step. The header deadline still erases nothing, because a partial
header is a valid prefix of a reply that is merely slow.
The other is `flan-dev--extract-reply' reading the payload before deleting it,
so a payload that would not read was never consumed and the same bytes
signalled again on every later request. It is deleted first now. That makes
the frame gone whether or not the read succeeded, which `flan-watch--tick' has
to know: it cleared its pending flag only on a reply it got back, and would
otherwise wait for ever for one no longer in the buffer.
The condition was checked before in_loop, outside the diff that catches a
loop giving away what the next iteration needs. Emit puts the condition in
the loop header, so it runs again every trip: a condition that frees a
local freed it once per trip. It is now diffed against the same dead set,
with its own reason. A dotimes count and a loop's initial values stay
outside: those are evaluated exactly once.
The agent refuses a module it has no room to queue with "the program is not
calling agent/poll". For a running program that is the cause. For a parked one
it is confidently wrong: there is no game thread left to poll with, nothing
drains the ring until somebody runs the program again, and the ring is full
precisely because Dev.eval accepts evaluations while parked and promises they
install at the next run. At install sixty-five that promise breaks, and the
reply sent the reader to inspect a loop that is not running.
The agent cannot know this — parking is the merged shim's state — so the
daemon, which has just asked liveness, rewrites that one reply the way
abi_mismatch rewrites dlerror's. Every other refusal is still quoted in the
agent's own words, and a running program's is unchanged.
Pinned on Dev.refusal rather than end to end: filling the ring is sixty-four
real clang runs, and what the daemon does with the agent's words is the whole
of the change.
Session.eval committed the checked program the moment a form checked, and the
two steps that can still refuse it — the build, and the agent taking the
module — come after that, in the daemon. Either one left the editor holding an
error and the session holding a declaration the process has no body for. The
next module built for that session lists the name in its install prologue,
which interns a cell for it and never stores anything into it, and a dev
build's call through a cell has no null test in front of it: the game thread
jumps to address 0 at the next C-x C-e, locals render or globals refresh.
Session.held takes the four fields eval commits as one unit and Session.restore
puts them back. Dev.eval and Dev.eval_expr take one before checking and restore
it on every arm where nothing was accepted — a failed build, a refused
delivery, an unreachable agent. eval_expr needed it for the generic instances
it keeps, whose own comment already claimed the invariant: "the session must
not come to believe it holds a body that no module was ever written for."
A delivered module that then times out is not a refusal and does not roll back:
the agent has it and will install it at a frame boundary.
The arm was written with the others and through the same deferral, and neither
the generics row in test_flan.ml nor the paragraph in BUILT.md that enumerates
what defers had it. Its placeholder is get's, for get's reason: it answers an
(Option V), so the match around it still has to check while the key is a
variable.
FIX.org carried Addr(Pfield ...) on an Option as a hole in both backends. It is
not reachable from the language: a field access goes through struct_target,
which admits a struct or a pointer to one and refuses everything else by name
with a location, so (addr (.x o)) is refused at the field and never reaches a
place. The node that failed was one the compiler built for itself.
The refusal is pinned on the bare field and on the address of one, and FIX.org
now records the finding, including the asymmetry that stays: the x86 backend
lays out an Option's tag and value as fields and the LLVM backend does not.
Neither path is reachable, so matching them would be untestable code written to
balance a road nobody drives on.
Every number-to-text conversion wrote into one file-static in the runtime and
answered a slice over it, and nothing copied. Two of them in one expression
printed the second number twice — no crash, no diagnostic, and nothing a
sanitizer could find, because every byte read was inside an object that was
alive. The wrong object.
The buffer is now the caller's, one frame slot per call site. The slot is
allocated in the checker rather than in either backend: a slot is a
function-lifetime location in both of them, where an x86 backend temporary is
bump-allocated and reclaimed at the end of the expression that made it — which
is the one lifetime a returned slice must outlive. Each backend gains one
pointer argument and no reasoning of its own, which is what keeps them
symmetric.
The static is gone rather than left unused, since a buffer with nothing but a
comment beside it is a loaded gun. What remains is the ordinary lifetime a
pointer into a frame has: storing one of these slices in a container that
outlives the frame, or returning it, is still a copy the caller has to make.
NEXT.md's sharp edge now says that instead of what it used to say.
The writer is the game thread, in every allocation and every free; the reader
is the agent's listener, on a program that is running. Nothing stood between
them. The consequence is not a slightly wrong count: a row's type pointer and
its length mean nothing apart, and a reader that takes the new pointer with the
old length reads off the end of a string literal.
Each entry now carries the watch table's seqlock, odd while it is written, and
a reader copies the entry and re-reads the counter before believing it. The
compaction bumps a table-wide counter around itself, because it moves entries
between slots and no per-slot counter can describe that; a scan that sees that
counter move walks again. It clears the table slot by slot rather than with one
memset, since the memset would zero the counters a reader was holding.
The breakdown and the leak report stay answerable while the program runs, which
is the moment they are for. reg at does not: whether one address is still live
is exactly what a running program is changing, so it is refused the way every
break verb is refused, which is what the daemon already did on its own side.
(map-remove! m k) answers the value that was there, or None, which is the
answer get already gives and for the same reason: a key that is not in the map
is an answer, not a failure. Handing the value back rather than dropping it
makes "take this out and use it" one call instead of two that hash the key
twice.
The removal shifts the probe run back over the hole. A Robin Hood lookup stops
at the first empty slot, so a hole left in the middle of a run hides every
entry after it — and the hidden ones are precisely what a test that only asks
after what it removed never looks at, which is why the program removes a
thousand of two thousand keys and then asks for the other thousand.
Odin was read rather than recalled here, and it does the opposite: its erase
marks a tombstone and its insert carries the repair loop. Staying tombstone-
free keeps the shape the rest of the file already assumed, and the lookups —
which outnumber the removals — pay nothing for it. The note in the runtime and
the two in BUILT.md that said Odin deletes by backward shift were describing
Odin's insert, and now say which is which.
It allocates nothing and releases nothing, so there is no guard around it and
it means the same thing on a map in an arena as on one in the heap: a key and a
value live inside the one block the map allocated, and there was never anything
per entry to hand back.
The argument vector's malloc was unchecked, and a failure there would have
published a null pointer with a length beside it. It now dies naming what it
was building, because argv has no allocation site for a condition to hang on.
flan_slurp_into read a capacity of elements as a capacity of bytes and skipped
the epoch check every other container operation runs. The element size is now
a parameter and the length it publishes counts whole elements, so the day slurp
answers something other than (Vec u8) it does not answer with bytes nobody
wrote.
A string with a NUL in it is refused at the C boundary, which is the policy
flan_path_cstr has always had for a path: C reads to the first NUL, so what
crosses is a prefix of what was passed, and a window title is no different from
a filename in that respect. The refusal names the declare-c, which is the name
the program's author wrote.
The runtime's two translation units are compiled with -Wall -Wextra. They were
already clean under both; the flag is there so the next one is caught rather
than read.
The generation word keeps its place and loses its "yet": a reader for it is a
third word on every slice in the language, which is a spec amendment rather
than a runtime patch, and the comment now says so where someone deciding to
trust the word would read it.
--dev builds a program whose call sites go through indirection cells so
something can attach and redefine through them. Nothing can attach to a
process this command builds, execs, waits for and deletes, so the flag had no
meaning here -- and an --x86 --dev route through run would have falsified
Build's own statement that flan dev never reaches that fork because --x86 is
read only by flan build. It falls into the refusal arm with a sentence
instead.
A GitHub Actions workflow on push: dune build, dune test --force, dune build
@checks. @x86 parity is not under dune test, so the routine suite never
protected it; both of this repository's silent failures would have been caught
by one person typing one command, and the problem was never the command.
The suite step keeps its log and greps it for Fatal error, because a suite
that passes while leaving an unhandled exception on stderr is one that is
telling you something and being ignored.
FLAN_LLC is pinned to the llc matching clang's version rather than left to
PATH order: the live loop goes llc + ld -shared + dlopen and never calls the
clang driver, so a mismatch breaks every reload test while flan build keeps
working, which is a bad failure to debug from a log.
What an Ubuntu runner cannot cover -- raylib by exact Fedora soname,
emscripten, a wasi sysroot, lldb -- is written in the workflow with the skip
path each one already takes, so the tick does not read as more than it is.
README.md and test/dune both said there was no CI; both now say what there is
and what it misses.
The tagged sum is Tast.data now and Tast.unions is C's untagged union, which
arrives as a structure whose every field sits at offset zero. That is a
layout, and a layout is the one thing an object has none of here -- two
properties cannot share a run of bytes -- so it is refused with the type's own
name rather than met as "not a struct".
Two hardenings the sweep could not have found. $str built a view onto node's
Buffer pool, where small Buffers share one ArrayBuffer, so a write through one
string literal's slice could have reached another's bytes; native puts a
literal in .rodata where that write is a fault. And copy_of's Option arm named
its argument three times, which evaluates it three times.
SURVEY_FLAGS reaches both sides now, as it does in the x86 sweep, so the
unchecked indexing path -- a bare a[i] with no $at around it, which nothing
had ever run -- is swept too: 23 match, 0 differ.
web/examples/ffi.flan opened with (declare cos-f64 [x f64] f64 "cos"), which
was a fine one-liner until the prelude grew cos-f64 an hour ago. @page caught
it: "cos-f64 is defined twice", with the prelude line named as the other site.
It is cosh now. Same shape, same answer, and the collision is worth keeping in
the page rather than editing around silently -- a reader reaching for a libm
function needs to know the common ones are already there and that a second
declaration of a name is refused, not shadowed. The example says so in one
sentence.
This is the cost of filling out the prelude, and it is the whole of it: a
program that declared one of the new names for itself stops compiling, with
both sites named. Nothing in the corpus or in examples/ hit it; this page did.
The alias is @x86's shape and deps: one rule over spike/js/survey.sh, FLAN
passed so the script does not start a dune inside dune's own lock. It is not
in the default run and node is probed rather than assumed.
spike/js/survey.sh is the x86 sweep's shape with one deliberate difference in
what it counts. That backend is behind, so a refusal there is a regression and
its strict mode fails on one. This is a dialect, so a refusal is the design
working -- a pointer, an allocator, a Map, the FFI and conditions are refused
permanently and correctly. What fails the @js alias is a DIFFER, which is a
wrong answer, and a CRASH, which is JS this backend emitted and node would not
run.
Two probes carry the decisions the corpus does not reach. p1-int-semantics
prints wrapping at all eight widths, a multiply past 2^53, truncating division
with a negative operand, shifts whose count is out of range, bitwise over a
u32, f32 that is not a double, and the conversions both ways -- 35 lines, all
identical to the LLVM build. It found two real bugs: >>> binds tighter than &
in JavaScript, so a bit-and on a u32 answered -1; and a 64-bit value through
Number() rounds to 53 bits before it can be truncated, so (i32 i64hi) answered
0 where it must answer -1.
p2-value-copies goes past values.flan to the cases a shallow copy would pass:
a struct inside a struct, a struct returned out of a function, an element read
out of an array of structs, and a global.
Also fixed, and all three were found by the sweep rather than by reading: a
unit-typed call in statement position was compiled to an expression nobody
emitted, so (load-xs) silently did not happen; an arrow body that starts with
a brace is a block, so a zeroed array of structs was a syntax error; and a
bounds message must carry the index expression's location, not the form's,
because that is the one emit.ml passes to check_at.
Render reads an Option's tag as field 0 and a union's as field 0, which is the
LLVM layout and not this one, so both are answered here rather than refused.
fdefers is dropped rather than refused: nothing in the dialect can start a
transfer, so the transfer exit path is unreachable, and refusing it would have
refused every program that writes a plain defer.
lib/js.ml lowers the same checked Tast the other two backends take to one
CommonJS file, by object mapping rather than linear memory: docs/DISCUSS.md
item 5 settled that fork before this was written, and item 5's consequence is
the whole shape of the file. Object mapping means the host's collector owns
every value, so there is no (Ptr T), no free, no arena and no allocator, and a
program that uses one is refused by name with a location rather than compiled
badly.
flan build --target=js leaves Build.executable through its own two lines,
before anything that assumes a clang: there is no object to compile and no
linker to run. --dev, --debug, --sanitize and --x86 are refused there rather
than swallowed. Js.Unsupported exits 3 beside X86.Unsupported, so a sweep can
count refused-by-name apart from did-not-compile.
What runs end to end: integer and float arithmetic with the normalisation each
width needs, let, if, while with break and continue, calls, function values,
structs, fixed arrays, slices, unions, options, match, and println through the
same structural printer the other backends walk.
Value semantics is the trap the object mapping sets and the reason the header
carries a section on it. A Flan struct and a fixed array copy on assignment and
a JS object does not, so every site emit.ml memcpys emits a generated
Point$copy here. Fable's JS backend faces the same question for F# structs and
answers it the other way -- it inserts no clone, and its Rust backend does --
so the divergence is deliberate and the survey pins it.
