[clang-format] Add TT_CompoundRequirementLBrace for better annotation (#121539)

Also, add `ST_CompoundRequirement` to help annotating */&/&& in compound
requirement expressions as `TT_BinaryOperator`.

Fixes #121471.

Author: owenca

clang/lib/Format/FormatToken.h

@@ -45,6 +45,7 @@ namespace format {
   TYPE(CastRParen)                                                             \
   TYPE(ClassLBrace)                                                            \
   TYPE(ClassRBrace)                                                            \
+  TYPE(CompoundRequirementLBrace)                                              \
   /* ternary ?: expression */                                                  \
   TYPE(ConditionalExpr)                                                        \
   /* the condition in an if statement */                                       \

clang/lib/Format/TokenAnnotator.cpp

@@ -143,6 +143,8 @@ class AnnotatingParser {
     case TT_StructLBrace:
     case TT_UnionLBrace:
       return ST_Class;
+    case TT_CompoundRequirementLBrace:
+      return ST_CompoundRequirement;
     default:
       return ST_Other;
     }
@@ -2076,7 +2078,7 @@ class AnnotatingParser {
             TT_RecordLBrace, TT_StructLBrace, TT_UnionLBrace, TT_RequiresClause,
             TT_RequiresClauseInARequiresExpression, TT_RequiresExpression,
             TT_RequiresExpressionLParen, TT_RequiresExpressionLBrace,
-            TT_BracedListLBrace)) {
+            TT_CompoundRequirementLBrace, TT_BracedListLBrace)) {
       CurrentToken->setType(TT_Unknown);
     }
     CurrentToken->Role.reset();
@@ -3100,6 +3102,9 @@ class AnnotatingParser {
       }
     }
 
+    if (!Scopes.empty() && Scopes.back() == ST_CompoundRequirement)
+      return TT_BinaryOperator;
+
     return TT_PointerOrReference;
   }
 

clang/lib/Format/TokenAnnotator.h

@@ -40,6 +40,8 @@ enum ScopeType {
   ST_ChildBlock,
   // Contained in class declaration/definition.
   ST_Class,
+  // Contained in compound requirement.
+  ST_CompoundRequirement,
   // Contained within other scope block (function, loop, if/else, etc).
   ST_Other,
 };

clang/lib/Format/UnwrappedLineFormatter.cpp

@@ -535,7 +535,7 @@ class LineJoiner {
       // Try to merge records.
       if (TheLine->Last->is(TT_EnumLBrace)) {
         ShouldMerge = Style.AllowShortEnumsOnASingleLine;
-      } else if (TheLine->Last->is(TT_RequiresExpressionLBrace)) {
+      } else if (TheLine->Last->is(TT_CompoundRequirementLBrace)) {
         ShouldMerge = Style.AllowShortCompoundRequirementOnASingleLine;
       } else if (TheLine->Last->isOneOf(TT_ClassLBrace, TT_StructLBrace)) {
         // NOTE: We use AfterClass (whereas AfterStruct exists) for both classes

clang/lib/Format/UnwrappedLineParser.cpp

@@ -392,7 +392,7 @@ bool UnwrappedLineParser::parseLevel(const FormatToken *OpeningBrace,
       break;
     case tok::l_brace:
       if (InRequiresExpression) {
-        FormatTok->setFinalizedType(TT_RequiresExpressionLBrace);
+        FormatTok->setFinalizedType(TT_CompoundRequirementLBrace);
       } else if (FormatTok->Previous &&
                  FormatTok->Previous->ClosesRequiresClause) {
         // We need the 'default' case here to correctly parse a function
@@ -1705,7 +1705,8 @@ void UnwrappedLineParser::parseStructuralElement(
   }
 
   for (const bool InRequiresExpression =
-           OpeningBrace && OpeningBrace->is(TT_RequiresExpressionLBrace);
+           OpeningBrace && OpeningBrace->isOneOf(TT_RequiresExpressionLBrace,
+                                                 TT_CompoundRequirementLBrace);
        !eof();) {
     if (IsCpp && FormatTok->isCppAlternativeOperatorKeyword()) {
       if (auto *Next = Tokens->peekNextToken(/*SkipComment=*/true);

clang/unittests/Format/TokenAnnotatorTest.cpp

@@ -1456,6 +1456,18 @@ TEST_F(TokenAnnotatorTest, UnderstandsRequiresExpressions) {
   EXPECT_TOKEN(Tokens[13], tok::l_brace, TT_RequiresExpressionLBrace);
 }
 
+TEST_F(TokenAnnotatorTest, CompoundRequirement) {
+  auto Tokens = annotate("template <typename T, typename V>\n"
+                         "concept CheckMultiplicableBy = requires(T a, V b) {\n"
+                         "  { a * b } -> std::same_as<T>;\n"
+                         "};");
+  ASSERT_EQ(Tokens.size(), 36u) << Tokens;
+
+  EXPECT_TOKEN(Tokens[19], tok::l_brace, TT_RequiresExpressionLBrace);
+  EXPECT_TOKEN(Tokens[20], tok::l_brace, TT_CompoundRequirementLBrace);
+  EXPECT_TOKEN(Tokens[22], tok::star, TT_BinaryOperator);
+}
+
 TEST_F(TokenAnnotatorTest, UnderstandsPragmaRegion) {
   // Everything after #pragma region should be ImplicitStringLiteral
   auto Tokens = annotate("#pragma region Foo(Bar: Hello)");