# Session save — 2026-09-22 (m2compiler-V3, step 4 complete)

## Where we are

HEAD: `abc41a7` — tag `v3-step4.3`, milestone tag `v3-step4`.
Suite **87/87** (44 run — incl. 4 trap-aborts + 4 sessions — +
43 reject). Build is warning-free (only the known-benign Coco
TypeBlock LL(1) advisory). Tree clean except untracked `git.txt`
(push recipe, intentional). No remote configured.

## Step 4 in three landings (all green at each tag)

- `v3-step4.1` (79/79) — **calls**: value/`VAR` params, function
  results, recursion, `FORWARD`, open-array `VAR` formals,
  int→real argument conversion; frames with entry copies and
  stack-slot locals; 233 `invalid call`. Two backend bugs fixed:
  nested-call state clobber (16-deep call stack) and uninitialized
  stack slots (zero-init locals).
- `v3-step4.2` (82/82) — **nested procedures**: static-link display
  (`alloc8` link records, chain walking for up-level load/store/
  address), lexical `ProcDepthOf`; bare `P;` parameterless calls.
  QBE can't nest definitions, so nested bodies hoist via
  per-nesting-depth buffers (`nestBufs`).
- `v3-step4.3` (87/87) — **separate compilation**: single-image
  sessions (`lib.def lib.mod prog.mod` → one `<Prog>.ssa`),
  module registry + scopes, `FROM`/`IMPORT`, qualified `L.x` via
  materialization, opaque `TYPE T;` completion, module `BEGIN` as
  `<mod>_init` called from `main`, whole-image buffering written
  under the program module's name.

## Locked decisions from this session (do not relitigate)

- Whole-program single-image separate compilation (V1/V2 lineage),
  not per-file objects; program module is last in the session.
- Unknown modules import as silent stubs; a known module's missing
  export is 201; a session with no program module is an error.
- Opaque types complete via `SetTarget` on the definition's alias;
  clients use them behind pointers only.
- Mangled symbols are `<proc>_<uid>` (uid per compilation);
  definitions and implementations agree because the implementation
  resumes the definition's proc node (`ResumeProc`).
- `DISPOSE` nils and is shallow; nil-deref raw; classic idents.

## Step 4 deferred (carry forward)

Strict 231 signature checking for impl-vs-def headings (arity is
checked; parameter/result types are not), procedure-type variables
and indirect calls, `HIGH`/`LEN`, variant records, import cycles,
class lowering (vtable/`THIS`), enum literals, `F()^` result
suffixes, >64 locals, recursive `DISPOSE`.

## Next: step 5 — Benjamin stdlib

Per `docs/plan.md` and the Blaise map (`docs/blaise-phases-map.md`):
`stdlib/` with classic `DEFINITION`/`IMPLEMENTATION` + `OPAQUE`
forms (no R10 `INTERFACE`/blueprints/operator-procedures), semantics
from `Benjamin/Actual/m2bsk-master/r10/stdlib/*.if`:
`Strings`, `TextIO` (+ `UWrite*`), `WholeIO`, `Math`, `Files`, over
`runtime/syslib` (`SysIO`/`Storage`). This is the first phase that
exercises the new separate-compilation machinery with real
libraries.

## Resume commands

```sh
cd /home/eric/Projets/Projets-Modula2/MyWork/m2compiler-V3/compiler
./build.sh && ./run_tests.sh   # expect 87/87, zero gm2 warnings
```