[clang-format] Make some binary operations imply requires clause

This patch adjusts the requires clause/expression lookahead heuristic to
assume that some binary operation mean that the requires keyword refers
to a clause.

This partially reverts the removed case clauses from
9b68c09, with an additional check that
we're not in a type parameter.

This is quite a band-aid fix, it may be worth it to rewrite that whole
heuristic to track more state in the future, instead of just blindly
marching forward across multiple unrelated definitions, since right now,
the definition following the one with the requires clause can influence
whether the heuristic chooses clause or expression.

Fixes #110485

Author: rymiel

clang/lib/Format/UnwrappedLineParser.cpp

@@ -3528,6 +3528,17 @@ bool UnwrappedLineParser::parseRequires() {
         return false;
       }
       break;
+    case tok::equalequal:
+    case tok::greaterequal:
+    case tok::lessequal:
+    case tok::r_paren:
+    case tok::pipepipe:
+      if (OpenAngles == 0) {
+        FormatTok = Tokens->setPosition(StoredPosition);
+        parseRequiresClause(RequiresToken);
+        return true;
+      }
+      break;
     case tok::eof:
       // Break out of the loop.
       Lookahead = 50;

clang/unittests/Format/TokenAnnotatorTest.cpp

@@ -1296,6 +1296,21 @@ TEST_F(TokenAnnotatorTest, UnderstandsRequiresClausesAndConcepts) {
   Tokens = annotate("bool x = t && requires(Foo<C1 || C2> x) { x.foo(); };");
   ASSERT_EQ(Tokens.size(), 25u) << Tokens;
   EXPECT_TOKEN(Tokens[5], tok::kw_requires, TT_RequiresExpression);
+
+  // Second function definition is required due to lookahead
+  Tokens = annotate("void f() & requires(n == 1) {}\nvoid g();");
+  ASSERT_EQ(Tokens.size(), 19u) << Tokens;
+  EXPECT_TOKEN(Tokens[4], tok::amp, TT_PointerOrReference);
+  EXPECT_TOKEN(Tokens[5], tok::kw_requires, TT_RequiresClause);
+
+  Tokens = annotate("void f() & requires(n || h) {}\nvoid g();");
+  ASSERT_EQ(Tokens.size(), 19u) << Tokens;
+  EXPECT_TOKEN(Tokens[4], tok::amp, TT_PointerOrReference);
+  EXPECT_TOKEN(Tokens[5], tok::kw_requires, TT_RequiresClause);
+
+  Tokens = annotate("bool x = t && requires(F<n == 1> x) { x.foo(); };");
+  ASSERT_EQ(Tokens.size(), 25u) << Tokens;
+  EXPECT_TOKEN(Tokens[5], tok::kw_requires, TT_RequiresExpression);
 }
 
 TEST_F(TokenAnnotatorTest, UnderstandsRequiresExpressions) {