# 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 and fixes what it finds.

Harness: `tools/v3-corpus/corpus.sh` — compiles each file with
`compiler/M2` in a scratch tree, together with its sibling DEFINITION
and the DEFINITION of every module it imports (`$V3_LIBS` search path),
and splits failures into CRASH / LIB (unresolved import) / LANG (real
gap).

## Corpora and results

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

| | no libs | with `$V3_LIBS` |
| --- | --- | --- |
| **compile-OK** | 242 | **272** |
| CRASH | 0 | 0 |
| LIB | 185 | **9** |
| LANG | 185 | **331** |

**2. gm2 standard libraries** (`m2pim`/`m2iso`/`m2log`/`m2cor`/`m2min`,
336 files):

| | no libs | with `$V3_LIBS` |
| --- | --- | --- |
| **compile-OK** | 78 | **115** |
| LIB | 176 | **0** |
| LANG | 82 | **221** |

(With the import path set, LIB noise is gone and the true LANG counts
are visible.)

## Fixes landed

1. **Long-line buffer overflow** (`v3-fix-longline-crash`) — `GetLine`
   wrote past a 256-byte listing buffer; a long line (an 860-char enum)
   overflowed the stack.  Fixed (`GetLine` truncates, buffer 4096,
   bounded caret loop); CRASH → 0.
2. **`EXPORT QUALIFIED`** in DEFINITION modules (`v3-export-qualified`).
3. **`SYSTEM` facilities** — predefine `BYTE`/`SBYTE`/`WORD`/`SWORD`/
   `LONGWORD`/`SHORTADDR`/`LONGADDR`/`PROC`/`LOC` (mapped onto V3's
   integer family / `ADDRESS`) so `FROM SYSTEM IMPORT BYTE;` and
   `ARRAY OF BYTE` resolve.
4. **Anchored subranges** `T[lo..hi]` (`INTEGER [-1 .. 24]`).
5. **Unnamed procedure-type parameters** (`PROCEDURE (VAR ARRAY OF
   REAL)`) plus **open arrays in procedure types** and structural
   proc-type formal compatibility (`ParamTypesOk`), so assigning a
   procedure with an open-array parameter to a procedure variable works.
6. **Harness import resolution** — `corpus.sh` now finds and passes the
   `.def` of each imported module (`$V3_LIBS`), removing the LIB noise.

## Remaining LANG gaps

- **`ARRAY <ordinalType> OF T`** (index-type arrays, e.g.
  `ARRAY btype OF INTEGER` in `array2`/`array3`) — V3 only has
  `ARRAY [lo..hi] OF` / `ARRAY OF`.  The big one.
- **`undeclared identifier`** — SYSTEM facilities beyond the set
  above, and small library holes.
- **gm2-specific syntax** — `PROCEDURE __BUILTIN__ name(…)`, C-name
  pragmas, ISO module attributes (not V3's dialect; skip).
- **`not supported yet`** — deliberate `230`s (array constructors, …).

## Reproduce

```sh
cd tools/v3-corpus
./corpus.sh                       # testsuite, no libs
G=$HOME/bin/Modula2/Gm2/lib/gcc/x86_64-pc-linux-gnu/16.0.1/m2
V3_LIBS="$G/m2pim:$G/m2iso:$G/m2log:$G/m2cor:$G/m2min" ./corpus.sh
V3_LIBS="$G/m2pim:$G/m2iso:$G/m2log:$G/m2cor:$G/m2min" \
  ./corpus.sh "$G/m2pim" "$G/m2iso" "$G/m2log" "$G/m2cor" "$G/m2min"
```

## Suggested next steps

1. **`ARRAY <type> OF T`** (index-type arrays) — a real PIM feature.
2. More `SYSTEM` facilities / library holes.
3. Array constructors `array{…}` (codegen).

## Files

`tools/v3-corpus/{corpus.sh,README.md}`, `compiler/src/compiler.frm`
(long-line), `compiler/src/M2.atg` (`EXPORT QUALIFIED`, anchored
subranges, unnamed proc-type params), `compiler/src/SymTab.def`/`.mod`
(SYSTEM predefs, `ParamTypesOk`), `compiler/tests/t_longline.mod`,
`compiler/run_tests.sh`, this doc.