https://gcc.gnu.org/bugzilla/show_bug.cgi?id=120576
Bug ID: 120576
Summary: Wsubobject-linkage warning on lambda as a template
parameter in header
Product: gcc
Version: 14.2.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: stsp at users dot sourceforge.net
Target Milestone: ---
Certain versions of gcc emit
this warning when lambda template
parameter is found in a header:
https://godbolt.org/z/fxa95eKvh
It is probably fixed in gcc-15,
but I don't have it locally and
can't find the relevant ticket.
All tickets I could find, say it
was fixed in gcc-14, which seems
to be not the case.
If it is actually fixed in 15,
then please consider back-porting
fix to 14.
If the godbolt URL is not a
way of sharing test-cases, then
here is it too.
off.cpp:
#include <cstdio>
#include "off.hpp"
int main()
{
A a;
printf("%i\n", a.b.off);
return 0;
}
off.hpp:
#include <cstddef>
template <auto O>
struct B {
static constexpr int off = O();
};
struct A {
char a;
B<[]<typename T = A>() constexpr { return offsetof(T, b); }> b;
};
error msg:
off.hpp:8:8: warning: ‘A’ has a field ‘B<<lambda closure
object>A::<lambda()>()> A::b’ whose type has internal linkage
[-Wsubobject-linkage]
8 | struct A {
