[clang-format] Defer formatting of operator< to honor paren spacing

[rymiel]

Summary

I'm not exactly sure what the intent of that section of
spaceRequiredBetween is doing, it seems to handle templates and <<,
but the part which adds spaces before parens is way later, as part
of spaceRequiredBeforeParens.

Fixes https://github.com/llvm/llvm-project/issues/58821

[owenpan]

clang/unittests/Format/FormatTest.cpp

15476

Drop it as it doesn't test the patch?

clang/lib/Format/TokenAnnotator.cpp

if (Left.is(tok::less) || Right.isOneOf(tok::greater, tok::less)) {
     if (Style.Language == FormatStyle::LK_TextProto ||
         (Style.Language == FormatStyle::LK_Proto &&
          (Left.is(TT_DictLiteral) || Right.is(TT_DictLiteral)))) {
       // Format empty list as `<>`.
       if (Left.is(tok::less) && Right.is(tok::greater))
         return false;
       return !Style.Cpp11BracedListStyle;
     }
+    // Don't attempt to format operator<(), as it is handled later.
+    if (Right.isNot(TT_OverloadedOperatorLParen))
       return false;
   }
   if (Right.is(tok::ellipsis)) {
     return Left.Tok.isLiteral() || (Left.is(tok::identifier) && Left.Previous &&
                                     Left.Previous->is(tok::kw_case));
   }
   if (Left.is(tok::l_square) && Right.is(tok::amp))
     return Style.SpacesInSquareBrackets;
   if (Right.is(TT_PointerOrReference)) {

clang/unittests/Format/FormatTest.cpp

TEST_F(FormatTest, ConfigurableSpaceBeforeParens) {
   verifyFormat("T A::operator()();", NoSpace);
   verifyFormat("X A::operator++(T);", NoSpace);
   verifyFormat("auto lambda = []() { return 0; };", NoSpace);
 
   FormatStyle Space = getLLVMStyle();
   Space.SpaceBeforeParens = FormatStyle::SBPO_Always;
 
   verifyFormat("int f ();", Space);
+  verifyFormat("bool operator< ();", Space);
+  verifyFormat("bool operator> ();", Space);
   verifyFormat("void f (int a, T b) {\n"
                "  while (true)\n"
                "    continue;\n"
                "}",
                Space);
   verifyFormat("if (true)\n"
                "  f ();\n"
                "else if (true)\n"