On Sun, 26 May 2024, Martin Uecker wrote: > This is the patch I sent previously, but I tried to improve the > description and added a long comment. This patch is needed so > that we do not have to update TYPE_CANONICAL of structures / unions > when a tagged type is completed that is (recursively) pointed to > by a member of the structure / union. > > Bootstrapped and regression tested on x86_64. > > > C23: fix aliasing for structures/unions with incomplete types > > When incomplete structure/union types are completed later, compatibility > of struct types that contain pointers to such types changes. When forming > equivalence classes for TYPE_CANONICAL, we therefor need to be > conservative > and treat all structs with the same tag which are pointer targets as > equivalent for purposed of determining equivalency of structure/union > types which contain such types as member. This avoids having to update > TYPE_CANONICAL of such structure/unions recursively. The pointer types > themselves are updated in c_update_type_canonical. > > gcc/c/ > * c-typeck.cc (comptypes_internal): Add flag to track > whether a struct is the target of a pointer. > (tagged_types_tu_compatible): When forming equivalence > classes, treat nested pointed-to structs as equivalent. > > gcc/testsuite/ > * gcc.dg/c23-tag-incomplete-alias-1.c: New test.
This patch is OK. -- Joseph S. Myers josmy...@redhat.com
