Session summary — 2026-10-04 (c): L3 attempted to completion; parked green

Branch ast-stage-c. HEAD e8956b2. Suite 182/182; self-hosting fixpoint OK (3,147,849 bytes). Working tree clean except the user's compiler/toto.mod.

L3 (procedures) is not enabled — Lower.CanLower still rejects procedure-bodied units, so the tree stays green. L0–L2 remain byte-verified.

What was achieved (then reverted, because it broke self-hosting)

The L3 physics were solved during this session and did byte-compare:

Durable symbol resolution. SymTab.PopScope keeps symbol nodes allocated (they just become unreachable), so a new read-only LookupAny/FindAny plus ProcNParAny/ParamTypeAny/ ParamIsVarAny/ProcUidAny/ProcDepthOfAny/ProcResAny/ ParamNameAny/IsExternalAny could resolve a name (and a procedure's formals) after its scope closed — exactly what an end-of-unit Lower needs.
Two real bugs fixed (also reverted with the rest):
- NkProcDecl op defaulted to -1; CanProc requires 0 for a normal body → every PROCEDURE was rejected. (Fix: set 0 at node creation.)
- NkCall child 0 is an NkDesignator, not a bare NkIdent; calls were mangling as $_0. (Fix: CalleeName unwraps it.)
With those, candiag and t_lower3 byte-compared MATCH and the suite reached 183/183.

Why it was parked

The SymTab additions broke self-hosting and could not be stabilized within the session:

NthParam was used before its declaration (line ~2258) by the new accessors → invalid call / not a RECORD type cascades under the V3-built compiler. Inlining the plink walk fixed that error, but:
stage 3 of the fixpoint still failed (M2S.mod:46 not supported yet).
Compounding this, an ASTDUMP debug statement was accidentally committed into M2.atg in v3-lower3-wip, corrupting later builds and wasting diagnosis time (now removed on HEAD).

Option 1 (concurrent legacy+L emit) is also ruled out: QbeGen shares one buffer and one counter set, so interleaved emitters corrupt the legacy path (docs/summary_two-phase-lower3-finding.md).

The path forward (recommended)

L3 does not need SymTab changes. Do option 2 via grammar hooks with zero SymTab surface:

while each scope is open, have the grammar stash (name, kind, ty) for locals/params (and procedure signature info) into a Lower-owned table;
Lower resolves through that table, so it works at unit end without touching SymTab and without concurrent emit.

This reuses all the AST/call/header work already committed in v3-lower3-wip and avoids the self-host fragility that the SymTab additions triggered.

State / tags

Tags: v3-lower0, v3-lower1, v3-lower2, v3-lower3-wip, v3-lower-eod-2026-10-04, and this summary's tag.
L0–L2 byte-compare tests: t_exit, t_arith, t_lower1, t_lower2.

Resume

cd ~/Projets/Projets-Modula2/MyWork/m2compiler-V3
git checkout ast-stage-c
cd compiler && ./build.sh && ./run_tests.sh   # 182/182
cd .. && ./bootstrap/fixpoint.sh              # FIXPOINT OK

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