Clang++ compiler error about static constexpr member function

[akr-akari]

The code is as follows.

struct Test
{
    static constexpr void foo1() noexcept
    {
        fooImpl(2022);
    }

    static constexpr void foo2() noexcept
    {
        fooImpl(3.14);
    }

    template<class T>
    static constexpr void fooImpl(T value) noexcept
    {
    }
};

int main()
{
    Test t;
    t.foo1();
    t.foo2();
}

In gcc, it compiles successfully. But in clang, the compilation fails and the output is as follows.

> clang++ main.cc -omain.exe
main.cc:19:27: warning: inline function 'Test::fooImpl<int>' is not defined
      [-Wundefined-inline]
    static constexpr void fooImpl(T value) noexcept
                          ^
main.cc:10:9: note: used here
        fooImpl(2022);
        ^
main.cc:19:27: warning: inline function 'Test::fooImpl<double>' is not defined
      [-Wundefined-inline]
    static constexpr void fooImpl(T value) noexcept
                          ^
main.cc:15:9: note: used here
        fooImpl(3.14);
        ^
2 warnings generated.
C:/Users/XIANG/winlibs/mingw64/bin/ld: C:/Users/XIANG/AppData/Local/Temp/main-640e60.o:main.cc:(.text$_ZN4Test4foo1Ev[_ZN4Test4foo1Ev]+0xa): undefined reference to `void Test::fooImpl<int>(int)'
C:/Users/XIANG/winlibs/mingw64/bin/ld: C:/Users/XIANG/AppData/Local/Temp/main-640e60.o:main.cc:(.text$_ZN4Test4foo2Ev[_ZN4Test4foo2Ev]+0xd): undefined reference to `void Test::fooImpl<double>(double)'
clang++: error: linker command failed with exit code 1 (use -v to see invocation)

But I put fooImpl() at the top and it compiles successfully.

The code is as follows.

struct Test
{
    template<class T>
    static constexpr void fooImpl(T value) noexcept
    {
    }

    static constexpr void foo1() noexcept
    {
        fooImpl(2022);
    }

    static constexpr void foo2() noexcept
    {
        fooImpl(3.14);
    }
};

int main()
{
    Test t;
    t.foo1();
    t.foo2();
}

[llvmbot]

@llvm/issue-subscribers-clang-frontend

[serge-sans-paille]

https://reviews.llvm.org/D128119 seems to fix the issue

[serge-sans-paille]

https://reviews.llvm.org/D128119 got merged and this now compilers with top-of-tree clang, closing