Link to the "auto" function as a template parameter

Question

Here is the minimal (C ++ 14) code to reproduce the problem:

template <void (&a)()> struct Foo { static auto value() {} }; void bar() {} template struct Foo<Foo<bar>::value>; 

GNU C ++ "g ++ (Ubuntu 5.1.0-0ubuntu11 ~ 14.04.1) 5.1.0" The compiler emits:

 error: could not convert template argument 'Foo<a>::value<bar>' to 'void (&)()' template struct Foo<Foo<bar>::value>; ^ 

The first strange thing I notice is Foo<a>::value<bar> - a not substituted, but value somehow becomes a template?

The following pointless corrections reinforce my impression that this is a compiler error:

• Declaring value() as returning void instead of its output
• "Dereferencing" value : template struct Foo<*Foo<bar>::value>;
• Parenthesizing value : template struct Foo<(Foo<bar>::value)>;
• Creating a pointer: template <void (*a)()> struct Foo ...

Finally, Clang compiles my fragment in order.

So, is there an obscure standard sentence somewhere that forbids the first fragment, or did GCC just die on me?

Answer 1

This behavior was recognized as a bug and was filed by GCC Bugzilla .