https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63943
Bug ID: 63943 Summary: -Wmaybe-uninitialized pragma mishandled in inlined function Product: gcc Version: 4.9.2 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c Assignee: unassigned at gcc dot gnu.org Reporter: eggert at gnu dot org Created attachment 34031 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=34031&action=edit Program with -Wmaybe-uninitialized problem Compile the attached program t.c with "gcc -Wmaybe-uninitialized -O2 -c t.c" on x86-64 with GCC 4.9.2, and the output will be: t.c: In function 'main': t.c:17:3: warning: '*((void *)&v+4)' may be used uninitialized in this function [-Wmaybe-uninitialized] return argc < 1 ? !argv : dereference (v + 1); ^ '#pragma GCC diagnostic ignored "-Wmaybe-uninitialized"' is in effect when the possibly-uninitialized variable is used, but this use is in a function that GCC inlined, and GCC is incorrectly warning based on the pragma setting in the calling function, not based on the pragma setting where the dereferencing actually occurs. The problem does not occur with GCC 4.8.3 so this appears to be a regression. The problem also goes away if I add '__attribute__((noinline))' to the 'dereference' function, so this appears to be related to inlining. I ran into this problem while thinking about enabling -Werror when compiling glibc; my first cut at this ran into the above problem.