Item 12 asked five questions. All five come back clean, and the answer is
feasible with no obstacle that argues for porting the compiler.
The one that mattered most was signals, and it turned out to be a non-question:
OCaml 5.2 on Linux/amd64 installs no signal handlers at all -- fifteen swept at
four moments, every one SIG_DFL, and a plain ocamlopt executable behaves the
same, so embedding changes nothing. OCaml 5 checks the stack limit explicitly
instead of arming a guard page, so the SIGSEGV the break loop wants was never
taken. The break loop can have it outright and Stack_overflow still works. That
is measured on one platform only, and the entry says so: macOS/arm64 is the one
claim here that must be re-run rather than trusted.
The rest: -output-complete-obj links with dune uninvolved and the existing C
stubs intact, no symbol collides across the four .c files and libasmrun, the
game keeps the main thread while a C-created listener calls into OCaml after
caml_c_thread_register, and a compaction left an 8 MiB arena byte-for-byte
untouched. Startup is 0.6ms and the compiler adds 4.14MB -- which makes the
merged dev build smaller than today's daemon alone, and there is one of it
rather than two.
Written as item 14 with the numbers, the three ways the GC assumption would
break, what the spike does not cover, and the order the real work goes in. The
backend is left exactly where item 13 put it.
BUILT.md gains "The header is read now", directly under the section whose last
paragraph promised that reading a header was what would convert the trusted
half into a checked one and that it was not built. That sentence is replaced by
a pointer to the one below it, in BUILT.md and in shim.ml's docstring both.
It records the things worth not re-deriving: why the dump and not libclang (and
that Zig left libclang too, which strengthens the argument rather than weakening
it), why the import is bounded by the package's own defstructs, why generating
defstructs would make the check circular in exactly the way a _Static_assert
was rejected for, refusal-by-demotion from Zig's failDecl, the naming rule and
what it must actually guarantee, and both const-vs-non-const char * and the
target-varying widths.
The diff and the costs are stated as measurements, with the table: 16 of 16
defstructs and 172 of 172 declare-c agree against 5.5, ten real differences
against 5.1-dev, release +4ms warm, redefinition 31.0 -> 46.5ms.
DISCUSS.md item 6 is rewritten rather than removed. The mechanism question is
settled and is now in BUILT.md; what is left is narrower and is two decisions
that are the author's — whether the header stays a build-time read or becomes a
committed generator, and whether the 172 hand-written lines migrate. Both have
the argument on each side written out, including what migration would lose:
key-pressed? is a better name than is-key-pressed, and an enum parameter
imports as i32 because nothing tells the importer the package calls KeyboardKey
"Key".
