[clang] Crash instantiating static variable template specialization member of class template

[katzdm]

The following program crashes during codegen, and looks to have done so since Clang 9.

template <typename>
struct TCls {
  template <typename T>
  static auto var = T::smem;
};

struct S { static constexpr int smem = 1; };

int main() {
  (void) TCls<int>::var<S>;
}

https://godbolt.org/z/x9eYMKfrv

[llvmbot]

@llvm/issue-subscribers-clang-codegen

Author: Daniel M. Katz (katzdm)

The following program crashes during codegen, and looks to have done so since Clang 9.

template <typename>
struct TCls {
  template <typename T>
  static auto var = T::smem;
};

struct S { static constexpr int smem = 1; };

int main() {
  (void) TCls<int>::var<S>;
}

https://godbolt.org/z/x9eYMKfrv

[shafik]

edg rejects your original version: https://godbolt.org/z/3Y6eT17T7 b/c var is not constant.

Note edg accepts this version, clang still crashes https://godbolt.org/z/accxTdhE3

template <typename T1>
struct TCls {
  template <typename T2>
  const static auto var = T1::smem;
};

struct S { static constexpr int smem = 1; };

int main() {
  (void) TCls<S>::var<S>;
}

[dty2]

Hi, I'd like to take ownership of this issue and work on a fix. I'll investigate the root cause and provide updates here as I progress. Thanks!

[dty2]

Sorry for the long wait. The pr is #138122