https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87435
Bug ID: 87435
Summary: "Duplicate const" warning NOT emitted from typedef in
-std=c90
Product: gcc
Version: 8.2.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: ndesaulniers at google dot com
Target Milestone: ---
Forked from https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80868.
Test case: https://godbolt.org/z/jjstcx
typedef const int t;
const t x;
It seems that for -std=c90 (non pedantic, non GNU), GCC does not warn for a
duplicate type specifier. That seems to violate C90 6.5.3 constraints: "The
same type qualifier shall not appear more than once in the same specifier-list
or qualifier-list, either directly or via one or more typedefs."
I found this while trying to match GCC's behavior for warning about duplicate
type qualifiers from `typeof` expressions in Clang:
https://reviews.llvm.org/D52248#1243898
