https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97399
Bug ID: 97399
Summary: g++ 9.3 cannot compile SFINAE code with separated
declaration and definition, g++ 7.3 compiles
Product: gcc
Version: 9.3.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: renlin at gcc dot gnu.org
Target Milestone: ---
Created attachment 49362
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=49362&action=edit
test case 1
For gcc_1.c++
gcc 7.3 compiles for this code
clang 7 compiles for this code
gcc 9.3 fails to compile with following message
Not sure if this is gcc's issue or clang.
```
<source>:29:16: error: no declaration matches 'constexpr
enable_if_t<((tmp*)this)->is_integral<E>(), bool> tmp::func(E, E) const'
29 | constexpr auto tmp::func(E f_lhs, E f_rhs)
| ^~~
<source>:18:27: note: candidate is: 'template<class E> static constexpr
enable_if_t<((tmp*)this)->is_integral<E>(), bool> tmp::func(E, E)'
18 | static constexpr auto func(E f_lhs, E f_rhs)
| ^~~~
<source>:12:8: note: 'struct tmp' defined here
12 | struct tmp
```
Meanwhile for gcc_2.c++
gcc compiles without any issue.
clang gives the following error message
```
<source>:27:28: error: template parameter redefines default argument
template <class E, class = enable_if_t<tmp::is_integral<E>(), bool>>
^
<source>:17:32: note: previous default template argument defined here
template <class E, class = enable_if_t<tmp::is_integral<E>(), bool>>
```
It seems this is not an new issue, and might be duplicated.
