C: uninitialized local named same as an in-scope typedef mis-parses

• Type: bug (cfront parser — declaration vs typedef disambiguation). Track C.
• Priority: HIGH — blocks the entire zlib bring-up; a common real-world C shadow (gcc/clang accept it silently).
• Found: 2026-07-06, zlib bring-up (feature-c-corpus-expansion step 2).

Minimal repro (gcc exit 0; pxx pascal26:2: error: expected C expression)

typedef struct { unsigned char op, bits; unsigned short val; } code;
static int h(void){ int code; int n=0; for(code=0;code<16;code++){ n+=code; } return n; }
int main(void){ return h()-120; }

Exact trigger

A local variable declaration T code; with NO initializer, where code is an in-scope typedef name, in an inner (block) scope. Legal C: the declarator code reintroduces the identifier as an ordinary object, shadowing the typedef for the rest of the block. pxx's C parser, after the type-specifier int, sees the typedef-name code and treats it as (part of) the type / a non-declarator, then hits ; and reports "expected C expression".

Disambiguating cases that ALREADY parse (narrow the fix):

• int code = 7; (WITH initializer) — parses fine.
• unsigned code as a function PARAMETER — parses fine.
• code global; (using code AS the type) — parses fine. So only the bare, initializer-less block-scope declaration is broken. Fix likely in the C statement/declaration parser: when a type-specifier is already in hand, an identifier that happens to be a typedef-name must be accepted as the declarator (object name), same as the initialized path does.

How it surfaced (real code)

zlib inftrees.h: typedef struct {...} code;. zlib trees.c (pulled after inftrees.h in the amalgam) declares int code; and loops for(code=0; ...). Whole zlib runner fails to compile. See [[feature-c-corpus-zlib]].

Gate

Repro compiles + runs exit 0 under pxx; zlib runner advances past trees.c.

Log

• 2026-07-06 — resolved, commit 0e2740ee.

Log

• 2026-07-06 — followup (commit 098e5b94): the shadow check wrongly fired on any same-name symbol, breaking c-testsuite 00022 (typedef int x; suppressed by a builtin x). Restricted to skLocal/skParam. Missed originally because c-conformance is not in make test.