# Step: V3 compiler corpus run (gm2 testsuite)

Tag `v3-corpus-run`. V3 suite **151/151**, fixpoint OK (unchanged —
this only adds a harness and a doc).

## Why

The TopSpeed corpus validated the *sidecar grammar*, not V3 the
compiler (the sidecar is a separate `TSM2` binary built from
`TopSpeed-V3-M2.atg`; it reuses V3's `SymTab`/`QbeGen`/`FileIO` sources
but never runs `compiler/M2`).  So this step runs **V3 itself** over a
real standard-Modula-2 corpus: the gm2 testsuite
`testsuite/gm2/pim/pass` and `testsuite/gm2/iso/run/pass`.

Harness: `tools/v3-corpus/corpus.sh` (copies each file to a scratch
tree, compiles alone, splits failures into CRASH / LIB / LANG — see its
README).

## Baseline

| | files |
| --- | --- |
| total | **612** |
| **compile-OK** (0 errors) | **219** |
| CRASH (M2 died, rc ≥ 128) | **7** |
| LIB (imports a gm2 library V3 lacks) | **182** |
| LANG (real V3 gap) | **204** |

So ~182 of the 393 failures are simply **missing gm2 libraries**
(`StrIO`, `NumberIO`, `STextIO`, `SWholeIO`, `FpuIO`, `WholeStr`,
`StdIO`, `M2RTS`, `DynamicStrings`, `Processes`, …) — expected, not
language gaps.  The signal is the **204 LANG** files.

## Top LANG gaps (from the corpus)

- **7 crashes** — all set-related: `largeset`, `program2`, `set9`,
  `sets3`, `smallset4/5/6`.  Real bugs (segfaults), highest priority.
- **48 `not supported yet`** — deliberate V3 `230`s; the corpus shows
  which constructs matter, e.g. **array constructors**
  (`array {'h','e','l','l','o'}` in `arrayconst1`).
- **79 `undeclared identifier`** — mostly **`SYSTEM` facilities** V3
  does not expose (`FROM SYSTEM IMPORT BYTE;` → `BYTE`), plus small
  library holes.
- **Anchored subranges** `INTEGER [-1 .. 24]` (`array2`, `array3`) —
  PIM form V3's `Subrange` does not parse (`';' expected` at `[`).
- **Unnamed parameters in procedure types**
  (`PROCEDURE (VAR ARRAY OF REAL)` in `another.mod`) — PIM allows
  them; V3 requires a name (`ident expected`).
- Assorted: `incompatible assignment`/`comparison` on char arrays,
  `invalid ArrayType`, `invalid call`, `FOR … BY`, etc.

## Reproduce

```sh
cd tools/v3-corpus
./corpus.sh            # -> 219 compile-OK / 7 CRASH / 182 LIB / 204 LANG
```

## Suggested next steps

1. **Fix the 7 set crashes** (a correctness bug — a compiler must not
   segfault on valid input).
2. **`SYSTEM` facilities**: expose at least `BYTE` / `WORD` /
   `SHORTADDR` etc. so `FROM SYSTEM IMPORT …` works.
3. **Anchored subranges** `T[lo..hi]` (small grammar addition).
4. **Unnamed proc-type parameters** (small grammar addition).
5. **Array constructors** `array{…}` (bigger: codegen).

## Files

`tools/v3-corpus/{corpus.sh,README.md}`, this doc.