https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109956
Alexander Monakov <amonakov at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |amonakov at gcc dot gnu.org --- Comment #8 from Alexander Monakov <amonakov at gcc dot gnu.org> --- (In reply to jos...@codesourcery.com from comment #6) > For the standard, dynamically allocated case, you should only need to > allocate enough memory to contain the initial part of the struct and the > array members being accessed - not any padding after that array. (There > were wording problems before C99 TC2; see DR#282.) I think the following testcase indicates that GCC assumes that tail padding is accessible: struct S { int i; char c; char fam[]; }; void f(struct S *p, struct S *q) { *p = *q; } f: movq (%rsi), %rax movq %rax, (%rdi) ret Sorry for the tangential remark, but there seems to be a contradiction.