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* [Bug c++/113272] New: Wrong specialization of class template selected
@ 2024-01-08 13:23 fchelnokov at gmail dot com
2024-01-08 15:52 ` [Bug c++/113272] " pinskia at gcc dot gnu.org
` (3 more replies)
0 siblings, 4 replies; 5+ messages in thread
From: fchelnokov at gmail dot com @ 2024-01-08 13:23 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113272
Bug ID: 113272
Summary: Wrong specialization of class template selected
Product: gcc
Version: 13.2.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: fchelnokov at gmail dot com
Target Milestone: ---
This program
#include <concepts>
template <auto>
struct A;
template <auto p>
requires std::same_as<decltype(p), const int*>
struct A<p> : std::false_type {};
template <auto p>
requires std::same_as<decltype(p), int*>
struct A<p> : std::true_type {};
int x = 0;
static_assert( A<&x>::value ); ///< try to comment this line
static_assert( !A<(const int *)&x>::value ); ///< GCC fails here
is accepted by Clang and MSVC, but GCC erroneously evaluates the last line.
Online demo: https://godbolt.org/z/5Pqx6TG3W
But if one comments the previous static_assert, then it starts working.
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug c++/113272] Wrong specialization of class template selected
2024-01-08 13:23 [Bug c++/113272] New: Wrong specialization of class template selected fchelnokov at gmail dot com
@ 2024-01-08 15:52 ` pinskia at gcc dot gnu.org
2024-01-09 14:41 ` mpolacek at gcc dot gnu.org
` (2 subsequent siblings)
3 siblings, 0 replies; 5+ messages in thread
From: pinskia at gcc dot gnu.org @ 2024-01-08 15:52 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113272
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |janschultke at googlemail dot com
--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
*** Bug 113274 has been marked as a duplicate of this bug. ***
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug c++/113272] Wrong specialization of class template selected
2024-01-08 13:23 [Bug c++/113272] New: Wrong specialization of class template selected fchelnokov at gmail dot com
2024-01-08 15:52 ` [Bug c++/113272] " pinskia at gcc dot gnu.org
@ 2024-01-09 14:41 ` mpolacek at gcc dot gnu.org
2024-01-09 14:56 ` fchelnokov at gmail dot com
2024-01-10 0:12 ` pinskia at gcc dot gnu.org
3 siblings, 0 replies; 5+ messages in thread
From: mpolacek at gcc dot gnu.org @ 2024-01-09 14:41 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113272
Marek Polacek <mpolacek at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Last reconfirmed| |2024-01-09
CC| |mpolacek at gcc dot gnu.org
Ever confirmed|0 |1
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug c++/113272] Wrong specialization of class template selected
2024-01-08 13:23 [Bug c++/113272] New: Wrong specialization of class template selected fchelnokov at gmail dot com
2024-01-08 15:52 ` [Bug c++/113272] " pinskia at gcc dot gnu.org
2024-01-09 14:41 ` mpolacek at gcc dot gnu.org
@ 2024-01-09 14:56 ` fchelnokov at gmail dot com
2024-01-10 0:12 ` pinskia at gcc dot gnu.org
3 siblings, 0 replies; 5+ messages in thread
From: fchelnokov at gmail dot com @ 2024-01-09 14:56 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113272
--- Comment #2 from Fedor Chelnokov <fchelnokov at gmail dot com> ---
Here is simplified program without #include <concepts>:
template <auto>
struct A {};
template <auto p> requires requires(){ *p = 0; }
struct A<p> {};
int x = 0;
struct B : A<&x>, A<(const int *)&x> {};
GCC fails here because of
error: duplicate base type 'A<(& x)>' invalid
Online demo: https://godbolt.org/z/aan59E6WE
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug c++/113272] Wrong specialization of class template selected
2024-01-08 13:23 [Bug c++/113272] New: Wrong specialization of class template selected fchelnokov at gmail dot com
` (2 preceding siblings ...)
2024-01-09 14:56 ` fchelnokov at gmail dot com
@ 2024-01-10 0:12 ` pinskia at gcc dot gnu.org
3 siblings, 0 replies; 5+ messages in thread
From: pinskia at gcc dot gnu.org @ 2024-01-10 0:12 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113272
--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Ok, this behavior is interesting:
```
int g = 0;
int g1 = 0;
template <auto *a>
struct A {
void f() { g++; }
};
template < const auto * a>
struct A<a>{
void f(){ g1++; }
};
int x = 0;
const int x1 = 0;
int main()
{
{
int t = 0;
A<&x> a;
t++;
a.f();
if (g != t)
return 1;
}
int t = 0;
if (0){
A<(const int *)&x> a1;
a1.f();
t++;
if (g1 != t)
return 1;
}
{
A<&x1> a1;
a1.f();
t++;
if (g1 != t)
return 1;
}
return 0;
}
```
The above passes like expected but if we enable the case for `A<(const int
*)&x>`, we get a failure in that g is incremented and not g1.
Note MSVC has the same behavior for the above testcase. Though clang rejects it
with an error:
```
<source>:9:8: error: class template partial specialization is not more
specialized than the primary template [-Winvalid-partial-specialization]
9 | struct A<a>{
| ^
<source>:4:8: note: template is declared here
4 | struct A {
| ^
```
Which I find even more interesting ...
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2024-01-10 0:12 UTC | newest]
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2024-01-08 13:23 [Bug c++/113272] New: Wrong specialization of class template selected fchelnokov at gmail dot com
2024-01-08 15:52 ` [Bug c++/113272] " pinskia at gcc dot gnu.org
2024-01-09 14:41 ` mpolacek at gcc dot gnu.org
2024-01-09 14:56 ` fchelnokov at gmail dot com
2024-01-10 0:12 ` pinskia at gcc dot gnu.org
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