https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113599
Bug ID: 113599
Summary: Wrong computation of member offset through
pointer-to-member
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: simon.marchi at polymtl dot ca
Target Milestone: ---
This commit:
c++: non-dependent .* operand folding [PR112427]
https://gitlab.com/gnutools/gcc/-/commit/d3f48f68227
seems to cause a regression in some cases when computing the address of a
member using a pointer-to-member.
Origin: https://sourceware.org/bugzilla/show_bug.cgi?id=31281
I made this reproducer, which was then made more minimal by Tom de Vries. We
get the address of the thread_info::node field in two different ways. One
using through a pointer-to-member, the other is getting its address directly.
We expect both to be equal. gcc 14/trunk gets it wrong.
...
struct intrusive_list_node {
void *next;
};
struct dummy {
void *base;
};
struct thread_info : public dummy, public intrusive_list_node {
intrusive_list_node node;
};
static thread_info ti;
int main (void) {
auto thread_info::*MemberNode = &thread_info::node;
auto node_ptr_1 = &(ti.*MemberNode);
auto node_ptr_2 = &ti.node;
return !(node_ptr_1 == node_ptr_2);
}
...
gcc-13:
...
$ g++ test.cpp; ./a.out; echo $?
0
...
gcc-14:
...
$ g++ test.cpp; ./a.out; echo $?
1
...
