[clang-tidy] modernize-type-traits false positive

[vient]

https://godbolt.org/z/b537zPjo9

namespace std {

template <class a>
struct disjunction : a {};

struct b {
  static int value;
};

template <class>
using c = disjunction<b>;

auto c_v = c<b>::value;

} // namespace std

clang-tidy-17 and current trunk with --checks=modernize-type-traits --extra-arg=-std=c++17 args produce

<source>:13:12: warning: use c++17 style variable templates [modernize-type-traits]
   13 | auto c_v = c<b>::value;
      |            ^   ~~~~~~~
      |             _v
1 warning generated.

In other words, it advises to use c_v in definition of c_v. Renaming std namespace or disjunction struct or value field make the warning go away.

This is problematic if --warnings-as-errors is used, I did not manage to think of a way to bypass this bug other than copying the std::disjunction implementation to my namespace.

[xgupta]

You can temporarily bypass this warning by adding // NOLINT.
auto c_v = c<b>::value; // NOLINT

But thanks for reporting the issue.

[njames93]

Seems like the check is incorrectly using the desugared type