https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98484
Bug ID: 98484 Summary: missing -Wstringop-overflow on a multiply inlined calls from system header Product: gcc Version: 11.0 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: --- GCC 11 diagnoses invalid accesses by built-in functions like memcpy made in inlined calls to functions defined in system headers, but apparently only for a single level of inlining. When the function that does the invalid access is itself called from another inline function it isn't diagnosed. (I noticed this while looking into pr98465.) $ cat b.c && gcc -O2 -S -Wall -fdump-tree-optimized=/dev/stdout b.c # 1 "a.h" 1 3 4 # 2 "a.h" 3 4 static inline void f0 (void *p) { __builtin_memcpy (p, "12345678", 8); } static inline void f1 (void *p) { f0 (p); } # 1 "b.c" 1 static inline void f2 (void *p) { f0 (p); } extern char a[8]; void g0 (void) { f0 (a + 4); // missing warning } void g1 (void) { f1 (a + 4); // missing warning } void g2 (void) { f2 (a + 4); // missing warning } ;; Function g0 (g0, funcdef_no=3, decl_uid=1953, cgraph_uid=4, symbol_order=3) void g0 () { <bb 2> [local count: 1073741824]: __builtin_memcpy (&MEM <char[8]> [(void *)&a + 4B], "12345678", 8); [tail call] return; } In file included from b.c:1: In function ‘f0’, inlined from ‘g0’ at b.c:11:3: a.h:4:3: warning: ‘__builtin_memcpy’ writing 8 bytes into a region of size 4 overflows the destination [-Wstringop-overflow=] 4 | | ^ In file included from a.h:12, from b.c:1: a.h: In function ‘g0’: b.c:7:13: note: at offset 4 into destination object ‘a’ of size 8 7 | | ^ ;; Function g1 (g1, funcdef_no=7, decl_uid=1956, cgraph_uid=5, symbol_order=4) void g1 () { <bb 2> [local count: 1073741824]: __builtin_memcpy (&MEM <char[8]> [(void *)&a + 4B], "12345678", 8); [tail call] return; } ;; Function g2 (g2, funcdef_no=9, decl_uid=1959, cgraph_uid=6, symbol_order=5) void g2 () { <bb 2> [local count: 1073741824]: __builtin_memcpy (&MEM <char[8]> [(void *)&a + 4B], "12345678", 8); [tail call] return; }