C11 _Generic selection

• Type: feature (cparser). Track C. Low priority (C11, rare in target corpus).
• Found: 2026-07-06 c-testsuite run.

Failing test

• 00219: #define gen_sw(a) _Generic(a, const char *: 1, default: 8, int: 123) plus assorted controlling-expression type checks. "expected C expression". Compile-time type dispatch: pick assoc whose type matches the controlling expr (after lvalue conversion), else default.

Gate

Drop 00219.c from test/c-conformance/pxx.skip; runner green.

RESOLVED 2026-07-09 (A+B+C agent) — dedicated on-demand CGType descriptor

Implemented without the feared full type-model overhaul. The 2026-07-07 triage overstated it: most distinctions _Generic needs already live in TTypeKind — int/long split as tyInt32/tyInt64, char/signed char/unsigned char as tyChar/tyInt8/tyUInt8, struct via rec id. The only genuinely-missing bits were long vs long long (both collapse to tyInt64 on LP64) and pointee-const (int* vs const int*).

Approach — a compact structural descriptor (cgXxx, defs.inc) built ON DEMAND only inside _Generic (pool resets per call, ~10 slots), never persisted per symbol:

• _Generic desugars at parse time to the selected association's expression; the controlling expr and unchosen assocs are parsed then discarded (never lowered), so no codegen. (cparser.inc ParseCPrimary + CGAlloc/CExprCG/CGConvControlling/ ParseCGAssocType/CGMatch helpers.)
• Controlling type = lvalue conversion (strip top const) + array/function decay to pointer, then structural match vs each association type-name.
• Two minimal additions: SymPtrPointeeConst (per C pointer symbol) captured in CAllocDeclVar from a new CTypeBaseConst flag; and an l/L/ll integer-literal suffix (CAttrFlags bit 16/32) so 17L types as long (was silently dropped — the lexer ate the suffix). long long distinguished on the association side via CTypeLongLong.

All C-mode-gated + additive; the Pascal self-host source never reaches it, so self-host stayed byte-identical (one-step converge). 00219 byte-identical, dropped from pxx.skip; conformance 219/0/1; whole-corpus reran with no regression from the literal-suffix change; test/cgeneric_selection_b209.c -> exit 42, wired into test-core; stable re-pinned v178->v179. Commit: see resolve.

Triage note 2026-07-07

Not bounded: 00219 distinguishes types with full C precision — const char * vs int, int * vs int * const (const-qualified pointer), struct a vs struct b, int[4], int **, long vs long long vs int, function-pointer types, signed/const int variants. pxx does not track const-qualification, pointer-const, or full integer-width distinctions in its type model, so real _Generic dispatch needs a much richer C type representation + a type-compatibility matcher. Large feature, not a parser-only add.