[clang-format] Fix formatting of requires expressions in braced initializers

[ZhongRuoyu]

When clang-format encountered a requires expression inside a braced initializer (e.g., bool foo{requires { 0; }};), it would incorrectly format the code to the following:

bool bar{requires {0;
}
}
;

The issue was that 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:

llvm-project/clang/lib/Format/UnwrappedLineParser.cpp

Lines 2713 to 2718 in 7eee672

	case tok::kw_requires: {
	auto RequiresToken = FormatTok;
	nextToken();
	parseRequiresExpression(RequiresToken);
	break;
	}

Fixes #162984.

[llvmbot]

@llvm/pr-subscribers-clang-format

Author: Ruoyu Zhong (ZhongRuoyu)

Changes

When clang-format encountered a requires expression inside a braced initializer (e.g., bool foo{requires { 0; }};), it would incorrectly format the code to the following:

bool bar{requires {0;
}
}
;

The issue was that 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:

llvm-project/clang/lib/Format/UnwrappedLineParser.cpp

Lines 2713 to 2718 in 7eee672

	case tok::kw_requires: {
	auto RequiresToken = FormatTok;
	nextToken();
	parseRequiresExpression(RequiresToken);
	break;
	}

Fixes #162984.

---

Full diff: https://github.com/llvm/llvm-project/pull/163005.diff

2 Files Affected:

• (modified) clang/lib/Format/UnwrappedLineParser.cpp (+6)
• (modified) clang/unittests/Format/FormatTest.cpp (+6)

diff --git a/clang/lib/Format/UnwrappedLineParser.cpp b/clang/lib/Format/UnwrappedLineParser.cpp
index 28797433e06e3..dec71191d7356 100644
--- a/clang/lib/Format/UnwrappedLineParser.cpp
+++ b/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;
diff --git a/clang/unittests/Format/FormatTest.cpp b/clang/unittests/Format/FormatTest.cpp
index fef70365b5e18..5a8056e310d45 100644
--- a/clang/unittests/Format/FormatTest.cpp
+++ b/clang/unittests/Format/FormatTest.cpp
@@ -26973,6 +26973,12 @@ TEST_F(FormatTest, RequiresExpressionIndentation) {
                Style);
 }
 
+TEST_F(FormatTest, RequiresExpressionInBracedInitializer) {
+  verifyFormat("bool foo{requires { 0; }};");
+  verifyFormat("int bar{requires(T t) { t.f(); }};");
+  verifyFormat("auto baz{requires { typename T::type; } && true};");
+}
+
 TEST_F(FormatTest, StatementAttributeLikeMacros) {
   FormatStyle Style = getLLVMStyle();
   StringRef Source = "void Foo::slot() {\n"