[clang-format] Incorrect method body when combining trailing return type & `decltype` in `requires` clause

[helmesjo]

Continuation of #56176 (@HazardyKnusperkeks).

Tweaking the original example in that issue by adding & to the trailing return and using decltype(...) in the requires clause breaks it:

  template<typename T>
  struct Foo
  {
    auto bar(T in) -> int& requires (is_integral_v<decltype(in)>) {
                             call_something();
                             return 0;
                           }
  };

Changing one of the following fixes the formatting again:

• -> int& to -> int
• decltype(in) to T
• requires (...) to requires ...

You need parens if you negate ((!...)), but I guess a (highly arbitrary looking) workaround is to change from
requires (is_integral_v<decltype(in)>)
to
requires is_integral_v<decltype(in)> || true
works (tested).

$ clang++ --version
Homebrew clang version 17.0.6

[llvmbot]

@llvm/issue-subscribers-bug

Author: Fred Helmesjö (helmesjo)

Continuation of #56176 (@HazardyKnusperkeks).

Tweaking the original example in that issue by adding & to the trailing return and using decltype(...) in the requires statement breaks it:

  template<typename T>
  struct Foo
  {
    auto bar(T in) -> int& requires (is_integral_v<decltype(in)>) {
                             call_something();
                             return 0;
                           }
  };

Changing one of the following fixes the formatting again:

• -> int& to -> int
• decltype(in) to T
• requires (...) to requires ...

You need parens if you negate ((!...)), but I guess a (highly arbitrary looking) workaround is to change from
requires (is_integral_v<decltype(in)>)
to
requires is_integral_v<decltype(in)> || true
works (tested).

$ clang++ --version
Homebrew clang version 17.0.6

[rymiel]

Note that this can only be reproduced if using the option RequiresExpressionIndentation: Keyword (please provide the configuration in the future so it can be reproduced better)

The requires keyword is annotated as TT_RequiresExpression, instead of TT_RequiresClause as expected