https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78915
Bug ID: 78915 Summary: missing -Wuninitialized accessing allocated memory Product: gcc Version: 7.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: middle-end Assignee: unassigned at gcc dot gnu.org Reporter: msebor at gcc dot gnu.org Target Milestone: --- All three functions in the test case below read uninitialized memory but only f0 is diagnosed with the -Wuninitialized warning. All three should be. $ cat z.c && gcc -O2 -S -Wall -Wextra -Wpedantic z.c int f0 (void) { int i; ++i; return i; } int f1 (unsigned n) { int *p = (int*)__builtin_alloca (n); ++*p; return *p; } int f2 (unsigned n) { int *p = (int*)__builtin_malloc (n); if (!p) return -1; ++*p; return *p; } z.c: In function āf0ā: z.c:5:3: warning: āiā is used uninitialized in this function [-Wuninitialized] ++i; ^~~