# Step: V3 compiler corpus runs

Tag `v3-corpus-run`. V3 suite **152/152**, fixpoint OK.

## 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 work runs **V3 itself** over two
real Modula-2 corpora.

Harness: `tools/v3-corpus/corpus.sh` — compiles each file with
`compiler/M2` alone (pairing an IMPLEMENTATION with its sibling
DEFINITION), in a scratch tree, and splits failures into CRASH (M2
died) / LIB (imports a module outside V3's known stdlib) / LANG (real
gap).

## Corpora and results

**1. gm2 testsuite** — `testsuite/gm2/pim/pass` + `iso/run/pass`
(612 files):

| | files |
| --- | --- |
| **compile-OK** | **242** |
| CRASH | 0 |
| LIB (missing gm2 library) | 185 |
| LANG (real V3 gap) | 185 |

**2. gm2 standard libraries** — `$HOME/bin/Modula2/Gm2/lib/gcc/…/m2/`
(`m2pim`/`m2iso`/`m2log`/`m2cor`/`m2min`, 336 files, `.def`+`.mod`):

| | files |
| --- | --- |
| **compile-OK** | **78** |
| CRASH | 0 |
| LIB | 176 |
| LANG | 82 |

(LIB is high in both because each file is compiled alone — cross-module
imports are not resolved; the real signal is LANG.)

## Fixes landed

### A. Long-line buffer overflow (the 7 "set" crashes) — `v3-fix-longline-crash`

`PrintListing`'s line buffer was `ARRAY [0 .. 255]` and `GetLine` wrote
without bounding to `HIGH(line)`, so a source line > 255 chars (an
860-char enum line in the gm2 set tests) overflowed the stack.  Fixed
in `compiler/src/compiler.frm` (truncate in `GetLine`, buffer →
4096, bounded caret loop); regression `t_longline.mod`; CRASH → 0.

### B. `EXPORT QUALIFIED` in DEFINITION modules — this step

gm2/PIM definition modules carry an export list
(`EXPORT QUALIFIED ReadString, WriteString, …;`).  V3's `DefUnit` did
not accept it → `'END' expected` on the first such file.  Added the
clause (parsed; the names are already exported by the module scope).
This raised **both** corpora: testsuite compile-OK **219 → 242**, gm2
libs **42 → 78**.

## Remaining LANG gaps

- Tests suite: **185** files, mostly gm2-specific libraries' call sites
  and deliberate V3 `230`s (array constructors, …).
- gm2 libs: **82** files, dominated by **gm2-specific syntax** —
  `PROCEDURE __BUILTIN__ name(...)` (`Builtins`/`libc`/`libm`/…),
  C-name pragmas, ISO module attributes — which are *not* V3's dialect.
- Genuine V3 gaps still seen: **`SYSTEM` facilities** (`FROM SYSTEM
  IMPORT BYTE`), **anchored subranges** `T[lo..hi]`, **unnamed
  procedure-type parameters**.

## Reproduce

```sh
cd tools/v3-corpus
./corpus.sh                       # gm2 testsuite -> 242 OK / 185 LANG
G=$HOME/bin/Modula2/Gm2/lib/gcc/x86_64-pc-linux-gnu/16.0.1/m2
./corpus.sh $G/m2pim $G/m2iso $G/m2log $G/m2cor $G/m2min   # 78 OK
```

## Suggested next steps

1. **`SYSTEM` facilities**: expose `BYTE`/`WORD`/`SHORTADDR` etc.
2. **Anchored subranges** `T[lo..hi]` (small grammar addition).
3. **Unnamed proc-type parameters** (small grammar addition).
4. Resolve cross-module imports in the harness (pass each file's
   imported `.def`s) to remove the LIB noise and isolate LANG.

## Files

`tools/v3-corpus/{corpus.sh,README.md}`, `compiler/src/compiler.frm`
(long-line fix), `compiler/src/M2.atg` (`EXPORT QUALIFIED`),
`compiler/tests/t_longline.mod`, `compiler/run_tests.sh`, this doc.