[clang-format] Fix formatting of requires expressions in braced initializers (#163005)

`UnwrappedLineParser::parseBracedList` had no
explicit handling for the `requires` keyword, so it would just call
`nextToken()` instead of properly parsing the `requires` expression.

This fix adds a case for `tok::kw_requires` in `parseBracedList`,
calling `parseRequiresExpression` to handle it correctly, matching the
existing behavior in `parseParens`.

Fixes #162984.

Author: ZhongRuoyu

clang/lib/Format/UnwrappedLineParser.cpp

@@ -2569,6 +2569,12 @@ bool UnwrappedLineParser::parseBracedList(bool IsAngleBracket, bool IsEnum) {
       if (IsEnum && !Style.AllowShortEnumsOnASingleLine)
         addUnwrappedLine();
       break;
+    case tok::kw_requires: {
+      auto *RequiresToken = FormatTok;
+      nextToken();
+      parseRequiresExpression(RequiresToken);
+      break;
+    }
     default:
       nextToken();
       break;

clang/unittests/Format/TokenAnnotatorTest.cpp

@@ -1490,6 +1490,11 @@ TEST_F(TokenAnnotatorTest, UnderstandsRequiresExpressions) {
   EXPECT_TOKEN(Tokens[4], tok::l_paren, TT_RequiresExpressionLParen);
   EXPECT_TOKEN(Tokens[8], tok::l_brace, TT_RequiresExpressionLBrace);
 
+  Tokens = annotate("bool foo{requires { 0; }};");
+  ASSERT_EQ(Tokens.size(), 11u) << Tokens;
+  EXPECT_TOKEN(Tokens[3], tok::kw_requires, TT_RequiresExpression);
+  EXPECT_TOKEN(Tokens[4], tok::l_brace, TT_RequiresExpressionLBrace);
+
   Tokens = annotate("if (requires(int i) { i + 5; }) return;");
   ASSERT_EQ(Tokens.size(), 17u) << Tokens;
   EXPECT_TOKEN(Tokens[2], tok::kw_requires, TT_RequiresExpression);