https://gcc.gnu.org/bugzilla/show_bug.cgi?id=36941
Eric Gallager <egallager at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|UNCONFIRMED |NEW Last reconfirmed| |2017-07-25 CC| |egallager at gcc dot gnu.org Ever confirmed|0 |1 --- Comment #7 from Eric Gallager <egallager at gcc dot gnu.org> --- (In reply to Chris Lattner from comment #0) > GCC accepts: > extern struct S x; > void foo() { (void)x; } > > But correctly rejects: > > extern struct S x; > void foo() { x; } > Confirmed. Note that clang diagnoses the first one like this: $ /sw/opt/llvm-3.1/bin/clang-3.1 -c 36941.c 36941.c:2:20: error: incomplete type 'struct S' where a complete type is required void foo() { (void)x; } ^ 36941.c:1:15: note: forward declaration of 'struct S' extern struct S x; ^