https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86747
François-R Boyer <Francois-R.Boyer at PolyMtl dot ca> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |Francois-R.Boyer at PolyMtl
dot ca
--- Comment #3 from François-R Boyer <Francois-R.Boyer at PolyMtl dot ca> ---
I'm not sure if this bug is related or if I should post it as a separate bug
report. I have the same error messages, with a friend class, but in my case it
is not redundant, and happens in a much more complicated case. Here is the
code:
template <class> struct A {
template <template <class> class> struct B {
template <template <class> class> friend struct B;
};
};
template <class> struct C { };
A<int>::B<C> b;
The above compiles on latest MSVC, clang, and most other compilers on godbolt,
including g++ 7.3. The error with g++ 8.1, 8.2 and 9.0.0 20181007 on godbolt
is:
<source>: In instantiation of 'struct A<int>::B<C>':
<source>:9:14: required from here
<source>:2:32: error: template parameter 'template<class> template<class>
class<template-parameter-2-1>'
2 | template <template <class> class> struct B {
| ^~~~~
<source>:3:57: error: redeclared here as 'template<class>
class<template-parameter-1-1>'
3 | template <template <class> class> friend struct B;
| ^
Note that if struct A is not a template, of if struct B has a simple type
parameter instead of a template template, it compiles.
