[clang] Bug with constraints when using nested classes and sizeof causing compilation failure of GNU ranges library

[elizabethandrews]

Newer versions of the library compile due to a workaround in the library for clang. I think the issue described below is still a bug though.

Short reproducer - https://godbolt.org/z/1qzac3vEj

template<typename T=int>
class bg {
public:
  template <int... h>
      requires (sizeof...(h) > 0) friend class l;
};
template <int... h>
    requires (sizeof...(h) > 0) class l;
void m() { bg v; } 

You need the nested class in a template (https://godbolt.org/z/1qzac3vEj) and sizeof (https://godbolt.org/z/3exhT3ahh) to reproduce this.

It might be related to #61763

[shafik]

CC @erichkeane

[BenBrock]

This bug appears to prevent Clang trunk from compiling certain parts of ranges (zip_view and zip_transform_view) with libstdc++ versions earlier than 13.3.0.

13.3.0 includes a workaround that avoids triggering this bug. (Some Linux repos' distributions of GCC, such as Ubuntu's 13.2.0-23 and OpenSUSE's 13.2.1 include the workaround as well.)

[llvmbot]

@llvm/issue-subscribers-clang-frontend

Author: None (elizabethandrews)

Newer versions of the library compile due to a workaround in the library for clang. I think the issue described below is still a bug though.

Short reproducer - https://godbolt.org/z/1qzac3vEj

template<typename T=int>
class bg {
public:
  template <int... h>
      requires (sizeof...(h) > 0) friend class l;
};
template <int... h>
    requires (sizeof...(h) > 0) class l;
void m() { bg v; } 

You need the nested class in a template (https://godbolt.org/z/1qzac3vEj) and sizeof (https://godbolt.org/z/3exhT3ahh) to reproduce this.

It might be related to #61763

[zyn0217]

@sdkrystian Is this something your patch would fix?

[sdkrystian]

@zyn0217 I think this is an issue with sizeof... itself