warning: inline function '(...)' is not defined (even though it is)

[banach-space]

Bugzilla Link	38174
Version	trunk
OS	Linux
CC	@dwblaikie,@DougGregor

Extended Description

Hello,

class A {
  template <char N>
  struct Foo {
    static constexpr char Bar() { return 0; }
  };

  using Constants = Foo<1>;

  char var = Constants::Bar();
};

$ clang++ -std=c++17 -c bug.cpp 
bug.cpp:4:27: warning: inline function 'A::Foo<'\x01'>::Bar' is not defined [-Wundefined-inline]
    static constexpr char Bar() { return 0; }
                          ^
bug.cpp:9:25: note: used here
  char var = Constants::Bar();
                        ^
1 warning generated.

This warning shouldn't be here, should it? Originally discovered with clang-6, but I've also checked ToT and that also issues a warning. Could be somewhat related to 18781, but that particular problem seems to be fixed.

[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 compiles without warning.

[llvmbot]

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