# Next session — handoff (2026-10-18)

State: branch **`resolve-check`**, tree clean.  Suite **239/239**,
fixpoint **OK (3,812,771 bytes)**, corpus **405/612, 0 crashes**.
Tags include `v3-enum-import`, `v3-ordl`, `v3-showcase24`,
`v3-convert`, `v3-set-word`, `v3-strict-decl-order`, `v3-m2-conformance`,
`v3-gap-examples`.

## Policy (decided)

Follow **Modula-2**, not gm2 degradation: declaration before use (only a
`POINTER`'s base may forward-reference).  `docs/gaps/` classifies every
remaining case; **`decl-order` and `gm2-ext` are not targets** (gm2
accepts non-conforming code; V3 correctly rejects it).  The corpus is
gm2's testsuite, so its number mixes both; the **`undeclared identifier`
bucket (44) is now inflated by the decl-order files** — don't chase it
blindly.

The corpus harness now resolves **transitive** imports (2026-10-18); that
is the measurement method from here.

## P0 — generics: two instantiations of one generic (a real bug)

`analysis_gaps.md` §10: instantiating one generic twice with arguments
from different families fails on the second instantiation
(`GStack(INTEGER)` + `GStack(CHAR)` → `incompatible assignment` at
`n^.val := v`); `INTEGER`+`CARDINAL` passes only because the wrong
binding still type-checks.  Each type argument alone works.

**Likely culprit:** `SymTab.EnterTypeParamBound` (SymTab.mod ~line 675):

```mod
IF Lookup(name) AND (SymKind(name) = KindType) THEN RETURN TRUE END;
```

During an instantiation re-parse the formal is already visible, so it
returns **without rebinding** to the new actual — the first
instantiation's binding sticks.

*First steps:* reproduce with a five-file session (`GBox(T)` generic
def/mod + two instantiations + a program); check how the driver
establishes the scope for each re-parse (`InstBegin`/`Reenter`, compiler
frame); make the formal binding per-instantiation (fresh alias), then
add a regression test (two instantiations, distinct scalar families) and
re-run fixpoint (generics are used in the compiler's own generics
tests, not its source).

## P1 — quick, bounded corpus wins

- **`gap22` `__FILE__`/`__LINE__`** (`packed`): gm2 predefined
  constants; `__`/`_` are not legal identifier chars in V3.  Either add
  the two pseudo-constants or leave as `gm2-ext` (+1 file).
- **`gap09` scalar actual into `ARRAY OF BYTE`** (gm2's untyped byte
  buffer; `aochar`, `arrayofbyte`, `bytearray`): accept a scalar/
  `ADDRESS` actual for an `ARRAY OF BYTE`/`VAR ARRAY OF BYTE` formal by
  passing its address (+ ~3 files).
- **`gap16`/`gap17` set span**: raise the cap / handle `SET OF CARDINAL`
  (low value).

## P2 — structural (parser / semantics)

- **`gap12` variant records**: empty variant arms, `ELSE`, untagged
  inner `CASE` (`varient2/3/8`, `tsize`/`2`).
- **`gap11` bare procedure value as a statement** (`tinyproc2/4`).
- **`gap10` `VAR` actual type leniency** (gm2 same-size rule;
  `testparam2/3`) — decide whether to adopt it (non-standard).
- **`gap13` remainder**: the *standard* built-ins (`ORD`, `CHR`, `VAL`,
  `MOD`, …) are still Coco/R keyword tokens; de-reserving them needs
  contextual-keyword parsing (predeclared identifiers).  `ORDL` (the
  corpus case) is done.
- **`gap18` set-typed `CASE` labels** (`bitset5`).

## P3 — conformance remainder (architectural)

Forward references to module-level **variables/procedures** from a
procedure body still work (the two-phase parse defers bodies).  Strict
declaration-before-use would require order-aware body checking; decide
whether to pursue (high risk, touches self-hosting).  The declaration
part itself is already strict.

## P4 — latent correctness

The **size-sensitive V3 miscompile** (historical "removing `ASTDUMP`
breaks the fixpoint") is still unroot-caused.  Worth a dedicated
bisection session: it is a correctness landmine, unlike the remaining
language gaps.

## P5 — housekeeping

- Consolidate `docs/summary_*.md` (see `docs/INDEX.md`).
- Decide merge/push of `resolve-check` (no pushes so far).

## Gates for every step

`./build.sh`, `./run_tests.sh` (must stay 100%), `bootstrap/fixpoint.sh`
(**byte-identical**), `corpusx.sh` (record OK/CRASH + note), update
`docs/gaps/` + `STATUS`/`README`, commit with a `v3-*` tag.

## Resume

```sh
cd .../m2compiler-V3
git checkout resolve-check
cd compiler && ./build.sh && ./run_tests.sh   # 239/239
cd .. && TMP="$PWD/.scratch/fixpoint" ./bootstrap/fixpoint.sh
M2FLAGS="" ./.scratch/corpusx.sh              # 405 OK, 0 crash
```