https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114493
--- Comment #15 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The releases/gcc-12 branch has been updated by Jakub Jelinek <ja...@gcc.gnu.org>: https://gcc.gnu.org/g:d4126b329b2ae4f2b60efa1c7ad51b576de168bd commit r12-10534-gd4126b329b2ae4f2b60efa1c7ad51b576de168bd Author: Jakub Jelinek <ja...@redhat.com> Date: Thu Jun 6 22:12:11 2024 +0200 c: Fix up pointer types to may_alias structures [PR114493] The following testcase ICEs in ipa-free-lang, because the fld_incomplete_type_of gcc_assert (TYPE_CANONICAL (t2) != t2 && TYPE_CANONICAL (t2) == TYPE_CANONICAL (TREE_TYPE (t))); assertion doesn't hold. This is because t is a struct S * type which was created while struct S was still incomplete and without the may_alias attribute (and TYPE_CANONICAL of a pointer type is a type created with can_alias_all = false argument), while later on on the struct definition may_alias attribute was used. fld_incomplete_type_of then creates an incomplete distinct copy of the structure (but with the original attributes) but pointers created for it are because of the "may_alias" attribute TYPE_REF_CAN_ALIAS_ALL, including their TYPE_CANONICAL, because while that is created with !can_alias_all argument, we later set it because of the "may_alias" attribute on the to_type. This doesn't ICE with C++ since PR70512 fix because the C++ FE sets TYPE_REF_CAN_ALIAS_ALL on all pointer types to the class type (and its variants) when the may_alias is added. The following patch does that in the C FE as well. 2024-06-06 Jakub Jelinek <ja...@redhat.com> PR c/114493 * c-decl.cc (c_fixup_may_alias): New function. (finish_struct): Call it if "may_alias" attribute is specified. * gcc.dg/pr114493-1.c: New test. * gcc.dg/pr114493-2.c: New test. (cherry picked from commit d5a3c6d43acb8b2211d9fb59d59482d74c010f01)
