https://gcc.gnu.org/bugzilla/show_bug.cgi?id=127321
Bug ID: 127321
Summary: -Wsfinae-incomplete not reverted by `#pragma GCC
diagnostic pop`
Product: gcc
Version: 17.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: ivan.lazaric.gcc at gmail dot com
Target Milestone: ---
```cpp
template<int n>
struct registry {
friend consteval auto injected(registry);
};
template<int n, typename T>
struct inject {
friend consteval auto injected(registry<n>) { return T{}; }
};
template<int n, typename = decltype([]{})>
consteval int query1() {
if constexpr (requires (registry<n> r) { injected(r); }) {
return sizeof(injected(registry<n>{}));
} else {
return 0;
}
}
#pragma GCC diagnostic push
#pragma GCC diagnostic warning "-Wsfinae-incomplete=0"
template<int n, typename = decltype([]{})>
consteval int query2() {
if constexpr (requires (registry<n> r) { injected(r); }) {
return sizeof(injected(registry<n>{}));
} else {
return 0;
}
}
#pragma GCC diagnostic pop
template<int n, typename = decltype([]{})>
consteval int query3() {
if constexpr (requires (registry<n> r) { injected(r); }) {
return sizeof(injected(registry<n>{}));
} else {
return 0;
}
}
static_assert(query1<0>() == 0);
static_assert(query2<0>() == 0);
static_assert(query3<0>() == 0);
inject<0, int> i;
static_assert(query1<0>() == 4);
static_assert(query2<0>() == 4);
static_assert(query3<0>() == 4);
```
Flags: "-std=c++26 -Wno-non-template-friend"
Compiling this produces no warnings
Godbolt: https://godbolt.org/z/v3WGqhP7e
If we comment out the `pragma diagnostic warning` line,
we get a warning related to `query1`.
Godbolt: https://godbolt.org/z/nzMqc3oaY
