[clang] [clang-format] Fix a bug in annotating angles containing FatArrow (PR #108671)

[kadir çetinkaya via cfe-commits]

================
@@ -243,14 +244,16 @@ class AnnotatingParser {
       // operator that was misinterpreted because we are parsing template
       // parameters.
       // FIXME: This is getting out of hand, write a decent parser.
-      if (InExpr && !Line.startsWith(tok::kw_template) &&
+      if (InExpr && !SeenFatArrow && !Line.startsWith(tok::kw_template) &&
           Prev.is(TT_BinaryOperator)) {
         const auto Precedence = Prev.getPrecedence();
         if (Precedence > prec::Conditional && Precedence < prec::Relational)
           return false;
       }
       if (Prev.isOneOf(tok::question, tok::colon) && !Style.isProto())
         SeenTernaryOperator = true;
+      else if (Prev.is(TT_FatArrow))
----------------
kadircet wrote:

i don't think new or empty parantheses are a must either, the logic around here is just checking that `<>` are inside an expression, hence that kind of code pattern is likely quite common as people tend to do arithmetic via metaprogramming using these patterns. e.g:
```cpp
constexpr auto foo() { return FixedInt<N | M>(foo); }
```

this will be formatted as the following now:
```cpp
constexpr auto foo() { return FixedInt < N | M > (foo); }
```

https://github.com/llvm/llvm-project/pull/108671