[clang-format] Fix requires misannotation with comma (#65908)

clang-format uses a heuristic to determine if a requires() is either a
requires clause or requires expression, based on what is in the
parentheses. Part of this heuristic assumed that a requires clause can
never contain a comma, however this is not the case if said comma is in
the template argument of a type.

This patch allows commas to appear in a requires clause if an angle
bracket `<` has been opened.

Fixes #65904

clang/lib/Format/UnwrappedLineParser.cpp

@@ -3362,9 +3362,12 @@ bool clang::format::UnwrappedLineParser::parseRequires() {
     case tok::kw_volatile:
     case tok::kw_const:
     case tok::comma:
-      FormatTok = Tokens->setPosition(StoredPosition);
-      parseRequiresExpression(RequiresToken);
-      return false;
+      if (OpenAngles == 0) {
+        FormatTok = Tokens->setPosition(StoredPosition);
+        parseRequiresExpression(RequiresToken);
+        return false;
+      }
+      break;
     case tok::r_paren:
     case tok::pipepipe:
       FormatTok = Tokens->setPosition(StoredPosition);

clang/unittests/Format/TokenAnnotatorTest.cpp

@@ -1032,6 +1032,16 @@ TEST_F(TokenAnnotatorTest, UnderstandsRequiresClausesAndConcepts) {
   ASSERT_EQ(Tokens.size(), 22u) << Tokens;
   EXPECT_TOKEN(Tokens[4], tok::kw_requires, TT_RequiresClause);
   EXPECT_TOKEN(Tokens[10], tok::ampamp, TT_PointerOrReference);
+
+  Tokens = annotate("void f() & requires(true) {}");
+  EXPECT_EQ(Tokens.size(), 12u) << Tokens;
+  EXPECT_TOKEN(Tokens[4], tok::amp, TT_PointerOrReference);
+  EXPECT_TOKEN(Tokens[5], tok::kw_requires, TT_RequiresClause);
+
+  Tokens = annotate("void f() & requires(C<true, true>) {}");
+  EXPECT_EQ(Tokens.size(), 17u) << Tokens;
+  EXPECT_TOKEN(Tokens[4], tok::amp, TT_PointerOrReference);
+  EXPECT_TOKEN(Tokens[5], tok::kw_requires, TT_RequiresClause);
 }
 
 TEST_F(TokenAnnotatorTest, UnderstandsRequiresExpressions) {
@@ -1151,6 +1161,14 @@ TEST_F(TokenAnnotatorTest, UnderstandsRequiresExpressions) {
   EXPECT_TOKEN(Tokens[3], tok::kw_requires, TT_RequiresExpression);
   EXPECT_TOKEN(Tokens[4], tok::l_paren, TT_RequiresExpressionLParen);
   EXPECT_TOKEN(Tokens[14], tok::l_brace, TT_RequiresExpressionLBrace);
+
+  Tokens = annotate("bool foo = requires(C<true, true> c) {\n"
+                    "  { c.foo(); }\n"
+                    "};");
+  ASSERT_EQ(Tokens.size(), 25u) << Tokens;
+  EXPECT_TOKEN(Tokens[3], tok::kw_requires, TT_RequiresExpression);
+  EXPECT_TOKEN(Tokens[4], tok::l_paren, TT_RequiresExpressionLParen);
+  EXPECT_TOKEN(Tokens[13], tok::l_brace, TT_RequiresExpressionLBrace);
 }
 
 TEST_F(TokenAnnotatorTest, UnderstandsPragmaRegion) {