https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88355
--- Comment #2 from Emmanuel Le Trong <emmanuel.le-tr...@cnrs-orleans.fr> ---
Ok I got this new snippet showing what is very probably the same bug, although
the diagnostic message is not the same at all. (And quite frankly I don't
understand it.)
$ cat bug_5.cpp
struct T {};
template <T>
struct U {};
template <T t>
void f (U<t>) {}
int main ()
{
constexpr T t;
f (U<t>{});
}
$ g++-9 -std=c++2a -Wall -Wextra bug_5.cpp
bug_5.cpp: In function ‘int main()’:
bug_5.cpp:12:18: error: no matching function for call to ‘f(U<T()>)’
12 | f (U<t>{});
| ^
bug_5.cpp:7:10: note: candidate: ‘template<T t> void
f(U<((T*)(void)0)->T::__ct_comp (((const T)t))>)’
7 | void f (U<t>) {}
| ^
bug_5.cpp:7:10: note: template argument deduction/substitution failed:
bug_5.cpp:12:18: note: couldn't deduce template parameter ‘t’
12 | f (U<t>{});
| ^
$ g++-9 --verbose
Using built-in specs.
COLLECT_GCC=g++-9
COLLECT_LTO_WRAPPER=/home/manu/system/opt/gcc-9/libexec/gcc/x86_64-pc-linux-gnu/9.0.1/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ../gcc-9/configure --prefix=/home/manu/system/opt/gcc-9
--program-suffix=-9 : (reconfigured) ../gcc-9/configure
--prefix=/home/manu/system/opt/gcc-9 --program-suffix=-9 : (reconfigured)
../gcc-9/configure --prefix=/home/manu/system/opt/gcc-9 --program-suffix=-9
--enable-languages=c,c++,fortran,lto,objc --no-create --no-recursion
Thread model: posix
gcc version 9.0.1 20190227 (experimental) (GCC)
