# m2compiler-V3 — feature status (at `v3-charcat-convresults`, 139/139 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 (literals carry ordinals; usable in expressions,
  `CASE` labels, `CONST` and as parameter/value types).
- ✅ `ARRAY [lo..hi,…]` (multi-dim) and open `ARRAY OF` formals.
- ✅ `RECORD` (flat blobs, nested inline, array fields as pointers),
  including variant records (`RECORD … ; CASE tag : T OF … END`): plain
  fields pack before the tag, each branch's fields overlay after it.
- ✅ `SET OF` bool/char/subrange (multi-word masks).
- ✅ `POINTER TO`, `NIL` as a real type.
- ✅ `UCHAR` (32-bit codepoint) + `U'a'`/`U"…"` literals (strict
  RFC3629 decode → 234 on bad bytes), `UCHR`/`CHR8`/`UORD`, `U"…"`
  whole-string assignment to a 1-D `ARRAY OF UCHAR`, `+`
  concatenation of `U"…"` (and single-codepoint operands), and
  `LEN`/`LENGTH`/`HIGH` of a UString.
- ✅ Opaque `TYPE T;` + completion in the implementation.
- ✅ Variant records (`RECORD CASE … OF … END`); ⏸ whole-record
  equality/assignment for variants is 236 (overlapping storage).

## 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 impl-vs-def signature checks (error **235**): result type,
  formal count, formal types and `VAR`-ness are compared against the
  `DEFINITION` (was arity-only).

## 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`.
- ✅ String `=`/`#` (content), string `+` (concatenation for literals,
  `CHAR` arrays and `CHAR` operands), string assignment (content copy,
  truncated to the array capacity, NUL-terminated), `LEN`/`LENGTH` of
  arrays and string literals. UString `+`/`LEN` likewise.
- ✅ `NIL` comparisons/assignment.
- ✅ `VAL`/`ADR`/`TSIZE`/`SIZE`/`HIGH`/`LEN` work. ⏸ 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; strict 235 signature
  checks between a definition and its implementation.
- ⏸ 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`**, **234 `invalid UTF-8 in U-literal`**,
  **235 `implementation does not match definition`**, plus
  `file:line:col` console format.

## Library
- ✅ `runtime/syslib`: `SysShim`, `FileIO`, `Utf8` (UTF-8 codec).
- ✅ `stdlib`: `SysIO`, `TextIO` (+ UTF-8 `U*`), `WholeIO`, `Math`,
  `Strings`, `CharClass`, `Files` (layered on `IOChan`),
  `Conversions` (ISO `ConvResults` statuses + BOOLEAN shortcuts),
  `RealIO`, `ProgramArgs`,
  `IOChan` (streams + files; `Position`/`Seek`/`Rewind`), `Storage`.

## Not started
- ⏸ Clarion `CLASS` lowering — declared and checked only (fields,
  methods, single inheritance, `VIRTUAL`); bodies/dispatch need a
  receiver-passing design (see `docs/summary_class-lowering.md`).
  ⏸ `VAL(LONGINT|REAL, x)` and long→int narrowing (V3 has no 64→32
  conversion; `Conversions` works around it). The TopSpeed legacy
  grammar (`TopSpeed-V3-M2.atg`) is a separate sidecar, not merged.

(Self-hosting is reached: `bootstrap/fixpoint.sh` builds a
byte-identical compiler image; `stdlib/` + `runtime/syslib` are in
use. See `docs/summary_selfhosting.md`.)

Next: variant records, `UString` assignment, `Files` on `IOChan`.
Roadmap: `docs/plan.md`, `docs/blaise-phases-map.md`.