UPDATE 2026-07-18 (85c233a2)

Single-dim pointer-to-array params int (*q)[N] are FIXED — the param path now records SymPtrElemArrLen/NDims/dims onto the param symbol (test test/cptr_to_array_param.c, at(m[1],2,3)=123, was 110). What REMAINS is only the multi-dim param int (*q)[A][B]: it now parses (declarator dim capture landed with the local fix) but fails at IR lowering with IR_UNSUPPORTED: AST node kind 5 (AN_BINOP) on the q[i][j][k] flatten in the param body — a deeper lowering gap distinct from the shape capture. Clean compile error, no miscompile, never worked. Retargeted to that residual.

C: pointer-to-array function parameters mis-stride / don't lower

• Type: bug (Track C — C frontend param declarators, cparser.inc). Wrong value (single-dim) / compile fail (multi-dim). Valid C.
• Found: 2026-07-18, while fixing [[bug-c-pointer-to-multidim-array-declarator]] (which fixed the LOCAL-variable form).

Repro

int m[3][4][5];
int f1(int (*q)[5])   { return q[2][3]; }    /* single-dim ptr-to-array param */
int f2(int (*q)[4][5]){ return q[0][2][3]; } /* multi-dim ptr-to-array param  */
int main(void){ /* fill m ... */ return f1(m[1]) + f2(&m[1]); }

• gcc: both correct (q strides by the row size).
• pxx: f1 returns the wrong value — q[2][3] mis-strides because the PARAMETER symbol never gets SymPtrElemArrLen set (unlike a local int (*q)[5]), so the pointer-to-array p[i][j] flatten in ParseCPostfixTail doesn't fire and it strides as a plain pointer. f2 (multi-dim) fails with IR_UNSUPPORTED at lowering.

Root

Local pointer-to-array declarators set SymPtrElemArrLen (and, since 77fb51df, SymPtrElemNDims + SymArrDimSpan for multi-dim) in ParseCLocalDeclAST. The function-parameter declarator path does NOT — it parses (*q)[N] without recording the pointee array shape on the param symbol.

Fix direction

In the C parameter parser, when a param declarator is a pointer-to-array (CTypePtrElemArrLen > 0 after ParseCDeclType), copy the same fields onto the param symbol that the local path sets: SymPtrElemArrLen, SymPtrElemNDims, and the per-dim spans into SymArrDimSpan[idx*MAX_ARR_DIMS+d]. Then the existing ParseCPostfixTail flatten (single- and multi-dim) works for params unchanged.

Acceptance

• f1/f2 match gcc; C-conformance 220/220 + self-host byte-identical.
• A test/*.c regression (single- and multi-dim ptr-to-array params).

Log

• 2026-07-18 — resolved, commit 27cb6404.