[clang-format] Wrong formatting when template variable is last thing before closing parenthesis

[vient]

auto t1 = a<int> + b;
auto t2 = (b) + b;
auto t3 = (a<int>) + b;
auto t4 = (a<int> + 1) + b;

is formatted as

auto t1 = a<int> + b;
auto t2 = (b) + b;
auto t3 = (a<int>)+b;  // wrong, no spaces around +
auto t4 = (a<int> + 1) + b;

https://godbolt.org/z/9K11MrPz9 clang-format version 20.0.0git (https://github.com/llvm/llvm-project.git 8daf4f16fa08b5d876e98108721dd1743a360326)

[dty2]

Hi, I guess the problem you mentioned comes from this part of the code. The below code in llvm-project/clang/lib/Format/TokenAnnotator.cpp. To verify this, you can add " SpaceAfterCStyleCast : true
" to your .clang-format file. Then you will find the "auto r2 = (c)+b;" will change to "auto r2 = (c) +b;"
And I will try to fix it. (:

  // If the next token is a binary operator or a selector name, we have
  // incorrectly classified the parenthesis as a cast. FIXME: Detect correctly.
  if (Left.is(TT_CastRParen)) {
    return Style.SpaceAfterCStyleCast ||
           Right.isOneOf(TT_BinaryOperator, TT_SelectorName);
  }

[leijurv]

Probably the issue is earlier. Why is this being treated as a cast? Given that the next token is a TT_BinaryOperator, the code says "fixme: detect correctly".

[owenca]

We probably need to add a new option, e.g. VariableTemplates:

$ echo 'auto t3 = (a<int>) + b;' | clang-format -style='{VariableTemplates: [a]}'
auto t3 = (a<int>) + b;