M2compiler-V3/docs/summary_step1.12.md

V3 step 1.12 — complete TopSpeed V3 grammar: full 662-file corpus parse-clean (done 2026-09-20)

Deliverable: compiler/src/TopSpeed-V3-M2.atg — the complete historical TopSpeed/Clarion Modula-2 V3 dialect as a Coco/R grammar, reconstructed from the real V3 distribution and validated to parse the whole thing.

The modern-subset frontend (compiler/src/M2.atg) is untouched; the two grammars coexist (see docs/grammar.md). The scratch compiler used for validation is /tmp/opencode/buildv3/M2 (corpus area /home/eric/bin/Dos/M2/TS-V3).

Validation numbers

• CR: 25 benign LL(1) advisories (all "start & successor of a deletable structure" + a couple "start of several alternatives"), 0 attribute errors, 0 undefined/unreachable/circular nonterminals.
• Full 662-file corpus: 0 syntax errors. Every remaining sweep row is a semantic not a type (parse-clean), e.g. GWINC2M/GRAPH/WINDOW DEFs, COMPDEMO, LIB.MOD, WINDOW.MOD. LIB.MOD:1224 (was 'FOR' expected), WINDOW.MOD, GRAPH.MOD all clean.
• Scratch regression suite: 35 passed, 0 failed.

Dialect coverage added vs. the modern subset

Identifiers _/@; &=AND, ~=NOT, <>=#; literal suffixes H/C/B

• 0x hex; ::= constant aliases; anchored subranges (SHORTINT[-1..1]); qualified type/designator idents; ARRAY (fixed + open), RECORD with variants, SET OF, POINTER TO, PROCEDURE types; WITH, IN, IS, set constructors {}, shifts <</>>, calls; Clarion-class CLASS ... (decl+single inheritance+IMPLEMENTATION blocks, CLAUSE extra parent = 230); LABEL/GOTO; INLINE; enum TYPEs; mapped-array constructors (VarDecl nil slots + factors).

Constructs the scalar backend cannot lower yet parse fully and end with standard SemError(230) — the parse-now/lower-later discipline.

Fence policy (scanner, M2S.mod manual patch)

(*%F flag*) regions are skipped (level-matched, nested %T/%E balance); (*%T tag*) is whitespace but its region is compiled; standalone (*%E*) is an empty comment. All flags off in default build.

• Required for the shipped corpus: DEMO/OMAIN/COMPDEMO doc banners, WINDOW.MOD's OS/2 alternate body, LIB.MOD variant blocks.
• The alternative "%T also skip" policy was tested and rejected: it strands LIB's IsOfClass common loop body (the %T/%F markers each supply a WHILE header; skipping both leaves the shared IF…; ThisObject:=…; END; dangling → LIB.MOD:126:9 ident expected).
• Re-apply after every CR regeneration (regeneration garbles M2S.def too — restore from repo; never copy an older patched M2S.mod over a fresh scan — token tables renumber when literals change).

The LIB.MOD:1224 bug — root cause and fix

Not a fence issue. WHILE [seg:ofs bp]^ # 0 DO failed 'FOR' expected at the ^: the mapped-array constructor [Expr : Expr [ TypeIdent ]] was a Factor with no designator-suffix chain, so ^/.id/subscript/call after it was unparsable. Confirmed by minimal repro (tt.mod failed identically at 8:21); ST@ trace showed WHILE dispatched then died inside its expression. Earlier line-bisection results were marker-pairing artifacts.

Fix: new MapTail production (suffix chain { "." ident | "^" | "[" Expr "]" | "(" [ params ] ")" }, each SemError(230)), called after the mapped branch of Fact.

Other grammar bugs fixed along the way

• Empty-ELSE: [ "ELSE" [ StatSeq ] ] in IF and CASE (was mandatory StatSeq) — closed the MODBASE/REP16/ELSE cascade errors.
• lqn not lxq in Statement's GOTO attribute (compile error).
• This session's earlier 4/35 regression came from a stale token table (patched M2S.mod copied over a fresh regen after LABEL/GOTO renumbered literals) — re-patching the fresh file restored 35/35.

SymTab / QbeGen (in repo)

SHORTCARD predefined (SymTab); QbeGen.NormLit handling 0x/hex/ octal-B/C-character literal forms. Committed with the ATG.

Next

Composites in the modern subset (step 3: ARRAY/RECORD/SET/POINTER, WITH, IN) can cross-check against TopSpeed-V3-M2.atg. Decide how the recovered dialect rules relate to the R10-clean M2.atg (the corpus grammar is the deliverable; merging is a separate decision). Scratch tooling/tests live under /tmp/opencode (not committed); the canonical patched scanner is /tmp/opencode/M2S.mod.patched.