Joseph Ferano
bd981ff87a
A defer is in the typed IR twice -- spliced into the body for the normal path, and again in fdefers for the path a transfer leaves through -- so a dyn temporary inside one is emitted twice. dyn_roots counted only the body's, and the second copy went into slots nothing had rooted. Nothing failed, and that is the whole reason this is worth a commit of its own. dyn_tmp falls back to a plain slot rather than unbalancing the stack, so the pushes and the pops still matched, the program ran and printed the right answer, and the values were simply invisible. Against a stub that never collects there is no symptom to find -- no leak, no crash, no wrong number. It would have become a symptom the week the real collector landed, in a defer reached only on a handled condition, which is close to the worst place to start looking. What found it was the IR: a rooted slot is spelled %dr and the fallback %dx, and the assertion is that no dyn program in the corpus emits one of the latter. That is now a test over all five dyn programs, and it is the only check in the lane that can see a missing root while there is still nothing to lose one by. When the collector arrives it is the thing to extend rather than replace. Also checked, both clean: flan dev --llvm builds and runs a dyn program, which is the route the x86 refusal sends people to and would have been a link error in the worst possible place; and the daemon's own refusal already names the flag.
What is in here, and what is still true
These are the documents that are written once and read occasionally: the reasons behind the code, the
reports from finished investigations, and the record of individual work sessions. The documents that are
edited every day stay at the repository root, because source comments cite them by bare filename from
dozens of places and a path that moves is a path that rots. So plan.org, NEXT.md, spec-memory.md
and spec-conditions.md are one directory up, and everything here points back at them.
A note on how to read the citations below: a document in this directory that says plan.org means the
one at the repository root. Nothing in docs/ is named for a file at the root, so there is no ambiguity,
and rewriting a hundred prose mentions into ../plan.org would have cost more in readability than it
bought in precision.
If you have thirty seconds
Read BUILT.md. It is by far the largest document here and it is the one that pays: it holds the
reason behind every part of the compiler that exists, from why nothing is ever dlclosed to why the
printer is a compile-time walk over a type rather than a runtime function. It is current, it is
maintained, and deleting it would mean deriving all of it again. If you want to know why a thing is the
shape it is, the answer is in here.
After that, ../NEXT.md at the root for what is actually in flight, and REFERENCES.md here for
where the evidence comes from — the reference clones on this machine, what each one answers, and the
standing rule that a claim in these notes was read out of a clone rather than recalled.
The current documents
| File | What it is |
|---|---|
BUILT.md |
Why the parts that exist are shaped the way they are. The longest and the most load-bearing document in the repository. Current. |
DISCUSS.md |
Open questions, raised and deliberately not answered. Nothing in it is a decision or a task; entries that have since been answered say so and point at where the answer landed. Current, though it is half archive by now. |
PORTING.md |
What the author's game, siam-farmer, needs from Flan that Flan does not have yet, measured against the code that exists rather than against a plan. It is the requirements document the language is actually steering by. Current. |
REFERENCES.md |
The reference clones under ~/Repositories, what each one is consulted for, and the specific files and lines already cited from them. Current. |
The reports
| File | What it is |
|---|---|
SPIKE-GENERICS.md |
Milestone 5's parametric polymorphism, run early and out of order as a spike. The spike succeeded and generics landed, so this is the report of finished work rather than a live plan — but its findings about where the cost falls are still the reason the implementation looks the way it does. Historical, findings still stand. |
overview.md |
The first brainstorm, from before the language had S-expressions. It says in its own first line that it is superseded and no longer accurate. Kept for history only; its table of what changed is the only part worth reading. Superseded. |
handoffs/
One report per work session, each written by whoever held the branch at the time. They are the
operational record: what was attempted, what was measured, what was decided without being able to ask,
and what was left open for the next lane. They are all historical the moment they are written — a handoff
describes a session that has ended — but they are cited by name from source comments and from NEXT.md,
because the reasoning behind a guard or a calling convention is often only written down once and this is
where it was written.
Six of them are the hand-written x86-64 backend, read in the order the work happened:
handoffs/HANDOFF-x86-rt.md set the remaining-items list that the four after it close, handoffs/HANDOFF-x86-redef.md
built the redefinition emitter, handoffs/HANDOFF-x86-aggregates.md took that across the struct boundary,
handoffs/HANDOFF-x86-guards.md settled the two guards nothing reaches, handoffs/HANDOFF-x86-debug.md added debug
information, and handoffs/HANDOFF-x86-cost.md measured what the backend costs and set the survey running on its
own so a refusal cannot sit unnoticed again.
The other six sessions are unrelated to each other. handoffs/HANDOFF-arith.md is why a divide by zero is a condition
rather than a SIGFPE. handoffs/HANDOFF-raylib-ports.md is the running record of the last two raylib example
ports, whose lasting findings were folded into PORTING.md, and handoffs/HANDOFF-cimport-ptr.md is the arm
cimport.ml's header check had been promising in a comment and not implementing — which is what those two ports
found, worked around and wrote up. handoffs/HANDOFF-devtest-noise.md is the linker
error dune test used to print on every run. handoffs/HANDOFF-emacs-flake.md is the test_emacs flake that
turned out to be SIGPIPE killing the daemon mid-reply, and it is worth reading for the two mechanisms it
rules out as much as for the one it found. handoffs/HANDOFF-tidy.md is this reorganisation.