# m2compiler-V3 — feature status (at `v3-step4`, 87/87 green)

Pipeline: Coco/R `M2.atg` (1748 lines, 73 productions) → `gm2`-built
`M2` → QBE `.ssa` → `qbe` → `cc` → run. `SymTab.mod` 1623 lines,
`QbeGen.mod` 2193 lines. Regenerate with
`cd compiler && ./build.sh && ./run_tests.sh`.

Legend: ✅ done · 🔄 partial · ⏸ not started / deferred.

## Lexical / syntax
- ✅ Classic idents (no `_`), `0x`/`0X` hex (no `H`), reals with `E`
  exponents, `#` `<` `<=` `>` `>=` `=`, `//` + nested `(* *)`,
  strings `'…'`/`"…"`, `0x` array bounds.
- ✅ `NOT`/`AND`/`OR` (no `~`/`&`), unary minus at expr start,
  no octal `B`/`C` suffixes.

## Types
- ✅ `INTEGER`/`CARDINAL`/`SHORTINT`/`LONGINT` (one family, QBE `w`),
  `REAL`/`LONGREAL` (`d`, widened), `BOOLEAN`, `CHAR`.
- ✅ Named types, aliases, integer/char subranges (folded bounds),
  enumerations declared (literal *use* is 230).
- ✅ `ARRAY [lo..hi,…]` (multi-dim) and open `ARRAY OF` formals.
- ✅ `RECORD` (flat blobs, nested inline, array fields as pointers).
- ✅ `SET OF` bool/char/subrange (multi-word masks).
- ✅ `POINTER TO`, `NIL` as a real type.
- ✅ Opaque `TYPE T;` + completion in the implementation.
- ⏸ Enums in expressions/CASE labels, variant records, procedure
  types, `LONGINT` quads.

## Declarations
- ✅ `CONST` (integer/char/real literals, folded), `VAR`, `TYPE`,
  `PROCEDURE` headings + bodies, `FORWARD`.
- ✅ `DEFINITION`/`IMPLEMENTATION` modules, `IMPORT`/`FROM … IMPORT`,
  `EXPORT` (parsed), nested local `MODULE` (parsed; lowering pending).
- ✅ Opaque completion; module `BEGIN` init bodies.
- ⏸ Strict 231 impl-vs-def signature checks (arity checked, types not).

## Statements
- ✅ Assignment, `IF/ELSIF/ELSE`, `CASE` (labels, ranges, `ELSE`),
  `WHILE`, `REPEAT/UNTIL`, `LOOP/EXIT`, `FOR/TO/BY` (static sign),
  `WITH` (single/multi/nested), `RETURN` (232-checked),
  `NEW`/`DISPOSE` (builtins), bare and parenthesized calls.
- ⏸ `HIGH`/`LEN`, `GOTO`/labels.

## Expressions
- ✅ Full precedence, `+ - * / DIV MOD`, comparisons, eager
  `AND`/`OR`/`NOT`, `IN`, set ops (`+ - * /` = union/diff/inter/symdiff),
  pointer `=`/`#`, int→real conversion, `^` deref, indexing, field
  access, qualified `L.x`/`L.P`.
- ✅ `NIL` comparisons/assignment.
- ⏸ String `=`/`+`, `VAL`/`ADR`/`TSIZE`/`SIZE` builtins, result
  suffixes (`F()^`).

## Procedures & modules
- ✅ Value + `VAR` params, function results, recursion, mutual
  recursion (`FORWARD`), nested procedures with static-link display
  (any depth), array/record/set/pointer params, open-array `VAR`
  formals.
- ✅ Separate compilation: `lib.def lib.mod prog.mod` → one image;
  module init functions; opaque completion.
- ⏸ Procedure-type variables / indirect calls, per-file object
  emission, import cycles.

## Backend (QBE)
- ✅ Length-prefixed arrays (count + elements), deep record copy,
  count-checked whole-array assign, runtime bounds/span traps
  (`$abort`, rc 134), multi-word sets, `alloc8` heap
  (`malloc`/`free`), static-link frames, deterministic `%tN`/`@LN`,
  whole-image buffering.
- ✅ `REAL` runtime const flush, string literals as descriptors.
- ⏸ `runtime/syslib/Trap` (traps are `$abort` for now), recursive
  `DISPOSE`.

## Error codes
- ✅ 200/201/202, 210–222, 223 (declared), 230, 231, 232,
  **233 `invalid call`**, plus `file:line:col` console format.

## Not started
- ⏸ Clarion `CLASS` lowering (declared + checked only), Unicode
  `UCHAR`/`UString` (locked design, no lexer/backing), `stdlib` /
  `runtime/syslib` libraries, self-hosting fixpoint. The TopSpeed
  legacy grammar (`TopSpeed-V3-M2.atg`) is a separate sidecar, not
  merged.

Next: step 5 — Benjamin stdlib (first real use of separate
compilation). Roadmap: `docs/plan.md`, `docs/blaise-phases-map.md`.