https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89300
Bug ID: 89300
Summary: C++ requires statement does not fail silently for
const void *
Product: gcc
Version: 8.2.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: svenja.mehringer at gmail dot com
Target Milestone: ---
The following code snippet fails to compile with GCC 8.1/8.2/latest trunk on
Godbolt because of the requires clause. From my understanding, the requires
should just evaluate to false and remove the second foo overload from the list
of possible candidates.
```cpp
#include <type_traits>
template <typename t>
void foo()
{}
template <typename t>
requires requires { std::is_integral_v<decltype(std::declval<t>() -
std::declval<t>())>; }
void foo()
{}
int main()
{
foo<const void *>();
}
```
see https://godbolt.org/z/iFW2MO
The same code compiles fine with the clang experimental concept branch.
The error message:
```
<source>: In function 'int main()':
<source>:8:71: error: invalid use of 'const void'
requires requires { std::is_integral_v<decltype(std::declval<t>() -
std::declval<t>())>; }
~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~
Compiler returned: 1
```
Locally reproduced on :
Using built-in specs.
COLLECT_GCC=/import/GCC//8.2.0/bin/g++
COLLECT_LTO_WRAPPER=/import/GCC/8.2.0/bin/../libexec/gcc/x86_64-pc-linux-gnu/8.2.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ./configure --prefix=/data/scratch/skillen1105/gcc8.2/dest
Thread model: posix
gcc version 8.2.0 (GCC)
