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

[Owen Pan via cfe-commits]

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@@ -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))
----------------
owenca wrote:

How realistic is your C++ example? In general, I don't think we can really tell if the angle brackets are template opener/closer or comparison operators without checking more (and very specific) contexts, e.g. the `new` keyword before `Bar` and the empty parentheses after `>`. In absence of that, it seems more likely that the angles are comparison operators. See e.g. this [test case](https://github.com/llvm/llvm-project/blob/95a0b4f729310d95d89f01f4d92ab7d2bf09941c/clang/unittests/Format/TokenAnnotatorTest.cpp#L645).

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