[clang-format] version 17 trips up on templated base class uniform initialization.

[joeatodd]

Running clang-format test.cpp (i.e. default style rules) with version 17 on the following reproducer:

template <int Dim>
struct Base{};

template <int Dim>
struct Derived : public Base<Dim>{

  Derived() : Base<Dim>{} {
    // Derived ctor impl
  }
};

produces:

template <int Dim> struct Base {};

template <int Dim> struct Derived : public Base<Dim> {

  Derived() : Base<Dim> {}
  {
    // Derived ctor impl
  }
};

but it ought to produce:

template <int Dim> struct Base {};

template <int Dim> struct Derived : public Base<Dim> {

  Derived() : Base<Dim>{} {
    // Derived ctor impl
  }
};

Version 16 produces this correct output.

I played around with this reproducer a little. I think its the combination of the <Dim> template argument and the {} uniform initialization of the derived class which is confusing clang-format. Removing the former or replacing the latter with () produces expected output.

Both the versions mentioned here are from the downstream DPC++ project:
Working: clang-format version 17.0.0 (https://github.com/intel/llvm.git 21ca00fb1cc5408b2428e3c386aa5137ed551fdb)
Broken: clang-format version 16.0.0 (https://github.com/intel/llvm.git 751acf357ed192a2f9de5171ccdf4a69510cff37)

[llvmbot]

@llvm/issue-subscribers-clang-format

[rymiel]

I've bisected this to 6dcde65

[galenelias]

I've submitted a fix for review here: https://reviews.llvm.org/D156705

Sorry for the regression!

[owenca]

/cherry-pick

[tru]

/cherry-pick 0a6c271

@owenca for next time - you need to specify the sha or multiple sha's with the command.