[clang] reflection operator parsing for global namespace and primitive types #164685

changkhothuychung · 2025-10-22T19:00:36Z

First step in adding support for reflection, will add reflection operator parsing for the remaining cases in upcoming subsequent PRs.

llvmbot · 2025-10-22T19:01:24Z

@llvm/pr-subscribers-clang

Author: Nhat Nguyen (changkhothuychung)

Changes

First step in adding support for reflection, will add reflection operator parsing for the remaining cases in upcoming subsequent PRs.

Patch is 22.24 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/164685.diff

27 Files Affected:

(modified) clang/include/clang/AST/ExprCXX.h (+50)
(modified) clang/include/clang/AST/RecursiveASTVisitor.h (+4)
(modified) clang/include/clang/Basic/DiagnosticParseKinds.td (+5)
(modified) clang/include/clang/Basic/Features.def (+2)
(modified) clang/include/clang/Basic/LangOptions.def (+1)
(modified) clang/include/clang/Basic/StmtNodes.td (+3)
(modified) clang/include/clang/Basic/TokenKinds.def (+1)
(modified) clang/include/clang/Driver/Options.td (+6-1)
(modified) clang/include/clang/Parse/Parser.h (+6)
(modified) clang/include/clang/Sema/Sema.h (+11)
(modified) clang/include/clang/Serialization/ASTBitCodes.h (+3)
(modified) clang/lib/AST/ExprCXX.cpp (+34)
(modified) clang/lib/AST/ExprClassification.cpp (+1)
(modified) clang/lib/AST/ExprConstant.cpp (+1)
(modified) clang/lib/AST/StmtPrinter.cpp (+6)
(modified) clang/lib/AST/StmtProfile.cpp (+5)
(modified) clang/lib/Lex/Lexer.cpp (+3)
(modified) clang/lib/Parse/CMakeLists.txt (+1)
(modified) clang/lib/Parse/ParseExpr.cpp (+10)
(added) clang/lib/Parse/ParseReflect.cpp (+54)
(modified) clang/lib/Parse/ParseTentative.cpp (+3)
(modified) clang/lib/Sema/SemaExceptionSpec.cpp (+1)
(modified) clang/lib/Sema/SemaExpr.cpp (+19)
(modified) clang/lib/Sema/TreeTransform.h (+6)
(modified) clang/lib/Serialization/ASTReaderStmt.cpp (+9)
(modified) clang/lib/Serialization/ASTWriterStmt.cpp (+6)
(added) clang/test/Reflection/parsing-reflection.pass.cpp (+21)

diff --git a/clang/include/clang/AST/ExprCXX.h b/clang/include/clang/AST/ExprCXX.h
index 5f16bac94d5e6..5c8b2209d5364 100644
--- a/clang/include/clang/AST/ExprCXX.h
+++ b/clang/include/clang/AST/ExprCXX.h
@@ -5493,6 +5493,56 @@ class BuiltinBitCastExpr final
   }
 };
 
+/// Represents a C++2c reflect expression (P2996).
+class CXXReflectExpr : public Expr {
+
+  // Source locations.
+  SourceLocation OperatorLoc;
+  SourceRange OperandRange;
+
+  CXXReflectExpr(const ASTContext &C, QualType T, QualType Ty);
+  CXXReflectExpr(const ASTContext &C, QualType T, Decl *Arg, bool IsNamespace);
+  CXXReflectExpr(EmptyShell Empty);
+
+public:
+
+  static CXXReflectExpr *Create(ASTContext &C, SourceLocation OperatorLoc,
+                                SourceLocation ArgLoc, QualType Operand);
+
+  static CXXReflectExpr *Create(ASTContext &C, SourceLocation OperatorLoc,
+                                SourceLocation OperandLoc, Decl *Operand);
+
+  static CXXReflectExpr *CreateEmpty(ASTContext& C);
+
+  SourceLocation getBeginLoc() const LLVM_READONLY { return OperatorLoc; }
+  SourceLocation getEndLoc() const LLVM_READONLY {
+    return OperandRange.getEnd();
+  }
+  SourceRange getSourceRange() const {
+    return SourceRange(getBeginLoc(), getEndLoc());
+  }
+
+  /// Returns location of the '^^'-operator.
+  SourceLocation getOperatorLoc() const { return OperatorLoc; }
+  SourceRange getOperandRange() const { return OperandRange; }
+
+  /// Sets the location of the '^^'-operator.
+  void setOperatorLoc(SourceLocation L) { OperatorLoc = L; }
+  void setOperandRange(SourceRange R) { OperandRange = R; }
+
+  child_range children() {
+    return child_range(child_iterator(), child_iterator());
+  }
+
+  const_child_range children() const {
+    return const_child_range(const_child_iterator(), const_child_iterator());
+  }
+
+  static bool classof(const Stmt *T) {
+    return T->getStmtClass() == CXXReflectExprClass;
+  }
+};
+
 } // namespace clang
 
 #endif // LLVM_CLANG_AST_EXPRCXX_H
diff --git a/clang/include/clang/AST/RecursiveASTVisitor.h b/clang/include/clang/AST/RecursiveASTVisitor.h
index 7a2881f6124f3..7b8a678ffb861 100644
--- a/clang/include/clang/AST/RecursiveASTVisitor.h
+++ b/clang/include/clang/AST/RecursiveASTVisitor.h
@@ -2883,6 +2883,10 @@ DEF_TRAVERSE_STMT(CXXUnresolvedConstructExpr, {
   TRY_TO(TraverseTypeLoc(S->getTypeSourceInfo()->getTypeLoc()));
 })
 
+DEF_TRAVERSE_STMT(CXXReflectExpr, {
+  // TODO
+})
+
 // These expressions all might take explicit template arguments.
 // We traverse those if so.  FIXME: implement these.
 DEF_TRAVERSE_STMT(CXXConstructExpr, {})
diff --git a/clang/include/clang/Basic/DiagnosticParseKinds.td b/clang/include/clang/Basic/DiagnosticParseKinds.td
index c724136a7fdaf..ea81a2332cd50 100644
--- a/clang/include/clang/Basic/DiagnosticParseKinds.td
+++ b/clang/include/clang/Basic/DiagnosticParseKinds.td
@@ -1848,6 +1848,11 @@ def err_placeholder_expected_auto_or_decltype_auto : Error<
   "expected 'auto' or 'decltype(auto)' after concept name">;
 }
 
+let CategoryName = "Reflection Issue" in {
+def err_cannot_reflect_operand : Error<
+  "cannot reflect the provided operand">;
+}
+
 def warn_max_tokens : Warning<
   "the number of preprocessor source tokens (%0) exceeds this token limit (%1)">,
   InGroup<MaxTokens>, DefaultIgnore;
diff --git a/clang/include/clang/Basic/Features.def b/clang/include/clang/Basic/Features.def
index 0e91b42a132c1..c9d24430326ff 100644
--- a/clang/include/clang/Basic/Features.def
+++ b/clang/include/clang/Basic/Features.def
@@ -380,6 +380,8 @@ FEATURE(cxx_abi_relative_vtable, LangOpts.CPlusPlus && LangOpts.RelativeCXXABIVT
 
 FEATURE(clang_atomic_attributes, true)
 
+FEATURE(reflection, LangOpts.Reflection)
+
 // CUDA/HIP Features
 FEATURE(cuda_noinline_keyword, LangOpts.CUDA)
 EXTENSION(cuda_implicit_host_device_templates, LangOpts.CUDA && LangOpts.OffloadImplicitHostDeviceTemplates)
diff --git a/clang/include/clang/Basic/LangOptions.def b/clang/include/clang/Basic/LangOptions.def
index 84f5ab3443a59..b2051fb536432 100644
--- a/clang/include/clang/Basic/LangOptions.def
+++ b/clang/include/clang/Basic/LangOptions.def
@@ -498,6 +498,7 @@ LANGOPT(BoundsSafety, 1, 0, NotCompatible, "Bounds safety extension for C")
 LANGOPT(EnableLifetimeSafety, 1, 0, NotCompatible, "Experimental lifetime safety analysis for C++")
 
 LANGOPT(PreserveVec3Type, 1, 0, NotCompatible, "Preserve 3-component vector type")
+LANGOPT(Reflection      , 1, 0, NotCompatible, "C++26 Reflection")
 
 #undef LANGOPT
 #undef ENUM_LANGOPT
diff --git a/clang/include/clang/Basic/StmtNodes.td b/clang/include/clang/Basic/StmtNodes.td
index bf3686bb372d5..987e1d1408e06 100644
--- a/clang/include/clang/Basic/StmtNodes.td
+++ b/clang/include/clang/Basic/StmtNodes.td
@@ -177,6 +177,9 @@ def CoyieldExpr : StmtNode<CoroutineSuspendExpr>;
 def ConceptSpecializationExpr : StmtNode<Expr>;
 def RequiresExpr : StmtNode<Expr>;
 
+// c++ 26 reflection
+def CXXReflectExpr : StmtNode<Expr>;
+
 // Obj-C Expressions.
 def ObjCStringLiteral : StmtNode<Expr>;
 def ObjCBoxedExpr : StmtNode<Expr>;
diff --git a/clang/include/clang/Basic/TokenKinds.def b/clang/include/clang/Basic/TokenKinds.def
index 564d6010181cc..b7fef8b2de739 100644
--- a/clang/include/clang/Basic/TokenKinds.def
+++ b/clang/include/clang/Basic/TokenKinds.def
@@ -233,6 +233,7 @@ PUNCTUATOR(greatergreater,      ">>")
 PUNCTUATOR(greaterequal,        ">=")
 PUNCTUATOR(greatergreaterequal, ">>=")
 PUNCTUATOR(caret,               "^")
+PUNCTUATOR(caretcaret,          "^^")
 PUNCTUATOR(caretequal,          "^=")
 PUNCTUATOR(pipe,                "|")
 PUNCTUATOR(pipepipe,            "||")
diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
index 6245cf33a0719..1880459fab52f 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -3663,6 +3663,11 @@ defm application_extension : BoolFOption<"application-extension",
   PosFlag<SetTrue, [], [ClangOption, CC1Option],
           "Restrict code to those available for App Extensions">,
   NegFlag<SetFalse>>;
+defm reflection : BoolFOption<"reflection",
+  LangOpts<"Reflection">, DefaultFalse,
+  PosFlag<SetTrue, [], [ClangOption, CC1Option],
+          "Enable C++26 reflection">,
+  NegFlag<SetFalse>>;
 defm sized_deallocation : BoolFOption<"sized-deallocation",
   LangOpts<"SizedDeallocation">, Default<cpp14.KeyPath>,
   PosFlag<SetTrue, [], [], "Enable C++14 sized global deallocation functions">,
@@ -7153,7 +7158,7 @@ defm android_pad_segment : BooleanFFlag<"android-pad-segment">, Group<f_Group>;
 def shared_libflangrt : Flag<["-"], "shared-libflangrt">,
   HelpText<"Link the flang-rt shared library">, Group<Link_Group>,
   Visibility<[FlangOption]>, Flags<[NoArgumentUnused]>;
-def static_libflangrt : Flag<["-"], "static-libflangrt">, 
+def static_libflangrt : Flag<["-"], "static-libflangrt">,
   HelpText<"Link the flang-rt static library">, Group<Link_Group>,
   Visibility<[FlangOption]>, Flags<[NoArgumentUnused]>;
 
diff --git a/clang/include/clang/Parse/Parser.h b/clang/include/clang/Parse/Parser.h
index e301cf1080977..9b8d8f7633f4d 100644
--- a/clang/include/clang/Parse/Parser.h
+++ b/clang/include/clang/Parse/Parser.h
@@ -150,6 +150,7 @@ enum class TentativeCXXTypeIdContext {
   AsTemplateArgument,
   InTrailingReturnType,
   AsGenericSelectionArgument,
+  AsReflectionOperand
 };
 
 /// The kind of attribute specifier we have found.
@@ -5167,6 +5168,11 @@ class Parser : public CodeCompletionHandler {
   /// Implementations are in ParseHLSL.cpp
   ///@{
 
+
+    //===--------------------------------------------------------------------===//
+    // C++2c: Reflection [P2996]
+    ExprResult ParseCXXReflectExpression(SourceLocation OpLoc);
+
 private:
   bool MaybeParseHLSLAnnotations(Declarator &D,
                                  SourceLocation *EndLoc = nullptr,
diff --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h
index f53aafdeb4f36..d07c1160023b3 100644
--- a/clang/include/clang/Sema/Sema.h
+++ b/clang/include/clang/Sema/Sema.h
@@ -14663,6 +14663,17 @@ class Sema final : public SemaBase {
   /// Implementations are in SemaConcept.cpp
   ///@{
 
+public:
+
+    ExprResult ActOnCXXReflectExpr(SourceLocation OpLoc, TypeSourceInfo* T);
+    ExprResult ActOnCXXReflectExpr(SourceLocation OpLoc,
+                                 SourceLocation ArgLoc, Decl *D);
+
+    ExprResult BuildCXXReflectExpr(SourceLocation OperatorLoc,
+                                 SourceLocation OperandLoc, QualType T);
+    ExprResult BuildCXXReflectExpr(SourceLocation OperatorLoc,
+                                  SourceLocation OperandLoc, Decl *D);
+
 public:
   void PushSatisfactionStackEntry(const NamedDecl *D,
                                   const llvm::FoldingSetNodeID &ID) {
diff --git a/clang/include/clang/Serialization/ASTBitCodes.h b/clang/include/clang/Serialization/ASTBitCodes.h
index 5d09d5536e5ab..b950c444d9aa2 100644
--- a/clang/include/clang/Serialization/ASTBitCodes.h
+++ b/clang/include/clang/Serialization/ASTBitCodes.h
@@ -1925,6 +1925,9 @@ enum StmtCode {
   EXPR_CONCEPT_SPECIALIZATION,            // ConceptSpecializationExpr
   EXPR_REQUIRES,                          // RequiresExpr
 
+  // Reflection
+  EXPR_REFLECT,
+
   // CUDA
   EXPR_CUDA_KERNEL_CALL, // CUDAKernelCallExpr
 
diff --git a/clang/lib/AST/ExprCXX.cpp b/clang/lib/AST/ExprCXX.cpp
index 95de6a82a5270..b4758465f669a 100644
--- a/clang/lib/AST/ExprCXX.cpp
+++ b/clang/lib/AST/ExprCXX.cpp
@@ -1939,6 +1939,40 @@ TypeTraitExpr *TypeTraitExpr::CreateDeserialized(const ASTContext &C,
   return new (Mem) TypeTraitExpr(EmptyShell(), IsStoredAsBool);
 }
 
+CXXReflectExpr::CXXReflectExpr(const ASTContext &C, QualType T, QualType Ty)
+: Expr(CXXReflectExprClass, T, VK_PRValue, OK_Ordinary) {}
+
+CXXReflectExpr::CXXReflectExpr(const ASTContext &C, QualType T, Decl *Arg, bool IsNamespace)
+: Expr(CXXReflectExprClass, T, VK_PRValue, OK_Ordinary) {}
+
+CXXReflectExpr::CXXReflectExpr(EmptyShell Empty)
+: Expr(CXXReflectExprClass, Empty) {}
+
+CXXReflectExpr *CXXReflectExpr::Create(ASTContext &C, SourceLocation OperatorLoc,
+                                SourceLocation OperandLoc, QualType Operand) {
+  CXXReflectExpr *E = new (C) CXXReflectExpr(C, C.DependentTy, Operand);
+  E->setOperatorLoc(OperatorLoc);
+  E->setOperandRange(OperandLoc);
+  return E;
+}
+
+CXXReflectExpr *CXXReflectExpr::Create(ASTContext &C,
+                                       SourceLocation OperatorLoc,
+                                       SourceLocation OperandLoc,
+                                       Decl *Operand) {
+  bool IsNamespace = isa<TranslationUnitDecl>(Operand);
+
+  CXXReflectExpr *E = new (C) CXXReflectExpr(C, C.DependentTy, Operand,
+                                             IsNamespace);
+  E->setOperatorLoc(OperatorLoc);
+  E->setOperandRange(OperandLoc);
+  return E;
+}
+
+CXXReflectExpr *CXXReflectExpr::CreateEmpty(ASTContext &C) {
+  return new (C) CXXReflectExpr(EmptyShell());
+}
+
 CUDAKernelCallExpr::CUDAKernelCallExpr(Expr *Fn, CallExpr *Config,
                                        ArrayRef<Expr *> Args, QualType Ty,
                                        ExprValueKind VK, SourceLocation RP,
diff --git a/clang/lib/AST/ExprClassification.cpp b/clang/lib/AST/ExprClassification.cpp
index aeacd0dc765ef..4c53c316e989a 100644
--- a/clang/lib/AST/ExprClassification.cpp
+++ b/clang/lib/AST/ExprClassification.cpp
@@ -216,6 +216,7 @@ static Cl::Kinds ClassifyInternal(ASTContext &Ctx, const Expr *E) {
   case Expr::SourceLocExprClass:
   case Expr::ConceptSpecializationExprClass:
   case Expr::RequiresExprClass:
+  case Expr::CXXReflectExprClass:
     return Cl::CL_PRValue;
 
   case Expr::EmbedExprClass:
diff --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp
index b706b14945b6d..0f14aa3c7258f 100644
--- a/clang/lib/AST/ExprConstant.cpp
+++ b/clang/lib/AST/ExprConstant.cpp
@@ -18295,6 +18295,7 @@ static ICEDiag CheckICE(const Expr* E, const ASTContext &Ctx) {
   case Expr::ArrayTypeTraitExprClass:
   case Expr::ExpressionTraitExprClass:
   case Expr::CXXNoexceptExprClass:
+  case Expr::CXXReflectExprClass:
     return NoDiag();
   case Expr::CallExprClass:
   case Expr::CXXOperatorCallExprClass: {
diff --git a/clang/lib/AST/StmtPrinter.cpp b/clang/lib/AST/StmtPrinter.cpp
index 586c3000f105c..8e5bab721e8e4 100644
--- a/clang/lib/AST/StmtPrinter.cpp
+++ b/clang/lib/AST/StmtPrinter.cpp
@@ -2566,6 +2566,12 @@ void StmtPrinter::VisitCXXUnresolvedConstructExpr(
     OS << ')';
 }
 
+
+void StmtPrinter::VisitCXXReflectExpr(CXXReflectExpr *S) {
+  // TODO: Make this better.
+  OS << "^(...)";
+}
+
 void StmtPrinter::VisitCXXDependentScopeMemberExpr(
                                          CXXDependentScopeMemberExpr *Node) {
   if (!Node->isImplicitAccess()) {
diff --git a/clang/lib/AST/StmtProfile.cpp b/clang/lib/AST/StmtProfile.cpp
index 589a156a2b6ea..ad37b5e71472e 100644
--- a/clang/lib/AST/StmtProfile.cpp
+++ b/clang/lib/AST/StmtProfile.cpp
@@ -2164,6 +2164,11 @@ StmtProfiler::VisitLambdaExpr(const LambdaExpr *S) {
   ID.AddInteger(Hasher.CalculateHash());
 }
 
+void StmtProfiler::VisitCXXReflectExpr(const CXXReflectExpr *E) {
+  VisitExpr(E);
+  // TODO: 
+}
+
 void
 StmtProfiler::VisitCXXScalarValueInitExpr(const CXXScalarValueInitExpr *S) {
   VisitExpr(S);
diff --git a/clang/lib/Lex/Lexer.cpp b/clang/lib/Lex/Lexer.cpp
index b282a600c0e56..5df36d041d0c1 100644
--- a/clang/lib/Lex/Lexer.cpp
+++ b/clang/lib/Lex/Lexer.cpp
@@ -4348,6 +4348,9 @@ bool Lexer::LexTokenInternal(Token &Result, bool TokAtPhysicalStartOfLine) {
     if (Char == '=') {
       CurPtr = ConsumeChar(CurPtr, SizeTmp, Result);
       Kind = tok::caretequal;
+    } else if (LangOpts.Reflection && Char == '^') {
+      CurPtr = ConsumeChar(CurPtr, SizeTmp, Result);
+      Kind = tok::caretcaret;
     } else {
       if (LangOpts.OpenCL && Char == '^')
         Diag(CurPtr, diag::err_opencl_logical_exclusive_or);
diff --git a/clang/lib/Parse/CMakeLists.txt b/clang/lib/Parse/CMakeLists.txt
index e6cbf3b868b7d..8dd120f529b13 100644
--- a/clang/lib/Parse/CMakeLists.txt
+++ b/clang/lib/Parse/CMakeLists.txt
@@ -26,6 +26,7 @@ add_clang_library(clangParse
   ParseTentative.cpp
   Parser.cpp
   ParseOpenACC.cpp
+  ParseReflect.cpp
 
   LINK_LIBS
   clangAST
diff --git a/clang/lib/Parse/ParseExpr.cpp b/clang/lib/Parse/ParseExpr.cpp
index 3515343202de1..22963d985b01b 100644
--- a/clang/lib/Parse/ParseExpr.cpp
+++ b/clang/lib/Parse/ParseExpr.cpp
@@ -1208,6 +1208,13 @@ Parser::ParseCastExpression(CastParseKind ParseKind, bool isAddressOfOperand,
     AllowSuffix = false;
     Res = ParseUnaryExprOrTypeTraitExpression();
     break;
+  case tok::caretcaret: {
+    if (getLangOpts().Reflection) {
+      SourceLocation FirstCaret = ConsumeToken(); // eat first '^'
+      Res = ParseCXXReflectExpression(/*OpLoc=*/FirstCaret);
+    }
+    break;
+  }
   case tok::ampamp: {      // unary-expression: '&&' identifier
     if (NotPrimaryExpression)
       *NotPrimaryExpression = true;
@@ -2249,6 +2256,9 @@ ExprResult Parser::ParseUnaryExprOrTypeTraitExpression() {
   else if (getLangOpts().C2y && OpTok.is(tok::kw__Countof))
     Diag(OpTok, diag::warn_c2y_compat_keyword) << OpTok.getName();
 
+  if (OpTok.is(tok::caretcaret))
+    return ParseCXXReflectExpression(OpTok.getLocation());
+
   EnterExpressionEvaluationContext Unevaluated(
       Actions, Sema::ExpressionEvaluationContext::Unevaluated,
       Sema::ReuseLambdaContextDecl);
diff --git a/clang/lib/Parse/ParseReflect.cpp b/clang/lib/Parse/ParseReflect.cpp
new file mode 100644
index 0000000000000..817c885ab2804
--- /dev/null
+++ b/clang/lib/Parse/ParseReflect.cpp
@@ -0,0 +1,54 @@
+
+
+
+
+#include "clang/AST/LocInfoType.h"
+#include "clang/Basic/DiagnosticParse.h"
+#include "clang/Parse/Parser.h"
+#include "clang/Parse/RAIIObjectsForParser.h"
+#include "clang/Sema/EnterExpressionEvaluationContext.h"
+using namespace clang;
+
+ExprResult Parser::ParseCXXReflectExpression(SourceLocation OpLoc) {
+  assert(Tok.is(tok::caretcaret) && "expected '^^'");
+  EnterExpressionEvaluationContext Unevaluated(
+      Actions, Sema::ExpressionEvaluationContext::Unevaluated);
+
+  SourceLocation OperandLoc = Tok.getLocation();
+
+  // Parse a leading nested-name-specifier
+  CXXScopeSpec SS;
+  if (ParseOptionalCXXScopeSpecifier(SS, /*ObjectType=*/nullptr,
+                                     /*ObjectHasErrors=*/false,
+                                     /*EnteringContext=*/false)) {
+    SkipUntil(tok::semi, StopAtSemi | StopBeforeMatch);
+    return ExprError();
+  }
+
+  {
+    TentativeParsingAction TPA(*this);
+
+    if (SS.isValid() &&
+               SS.getScopeRep().getKind() == NestedNameSpecifier::Kind::Global) {
+      // Check for global namespace '^^::'
+      TPA.Commit();
+      Decl *TUDecl = Actions.getASTContext().getTranslationUnitDecl();
+      return Actions.ActOnCXXReflectExpr(OpLoc, SourceLocation(), TUDecl);
+    }
+    TPA.Revert();
+  }
+
+  if (isCXXTypeId(TentativeCXXTypeIdContext::AsReflectionOperand)) {
+    TypeResult TR = ParseTypeName(/*TypeOf=*/nullptr);
+    if (TR.isInvalid())
+      return ExprError();
+
+    TypeSourceInfo *TSI = nullptr;
+    QualType QT = Actions.GetTypeFromParser(TR.get(), &TSI);
+
+    return Actions.ActOnCXXReflectExpr(OpLoc, TSI);
+  }
+
+  Diag(OperandLoc, diag::err_cannot_reflect_operand);
+  return ExprError();
+}
diff --git a/clang/lib/Parse/ParseTentative.cpp b/clang/lib/Parse/ParseTentative.cpp
index 82f2294ff5bb7..8a3ae2232767e 100644
--- a/clang/lib/Parse/ParseTentative.cpp
+++ b/clang/lib/Parse/ParseTentative.cpp
@@ -574,6 +574,9 @@ bool Parser::isCXXTypeId(TentativeCXXTypeIdContext Context, bool &isAmbiguous) {
     } else if (Context == TentativeCXXTypeIdContext::InTrailingReturnType) {
       TPR = TPResult::True;
       isAmbiguous = true;
+    } else if (Context == TentativeCXXTypeIdContext::AsReflectionOperand) {
+      TPR = TPResult::True;
+      isAmbiguous = true;
     } else
       TPR = TPResult::False;
   }
diff --git a/clang/lib/Sema/SemaExceptionSpec.cpp b/clang/lib/Sema/SemaExceptionSpec.cpp
index a0483c3027199..ff8d2139289a3 100644
--- a/clang/lib/Sema/SemaExceptionSpec.cpp
+++ b/clang/lib/Sema/SemaExceptionSpec.cpp
@@ -1379,6 +1379,7 @@ CanThrowResult Sema::canThrow(const Stmt *S) {
   case Expr::CXXNoexceptExprClass:
   case Expr::CXXNullPtrLiteralExprClass:
   case Expr::CXXPseudoDestructorExprClass:
+  case Expr::CXXReflectExprClass:
   case Expr::CXXScalarValueInitExprClass:
   case Expr::CXXThisExprClass:
   case Expr::CXXUuidofExprClass:
diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index 06b2529011c74..95bc91ab29f90 100644
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -17760,6 +17760,25 @@ void Sema::PushExpressionEvaluationContextForFunction(
   }
 }
 
+ExprResult Sema::ActOnCXXReflectExpr(SourceLocation OpLoc, TypeSourceInfo* TSI) {
+  return BuildCXXReflectExpr(OpLoc, TSI->getTypeLoc().getBeginLoc(), TSI->getType());
+}
+
+ExprResult Sema::ActOnCXXReflectExpr(SourceLocation OpLoc,
+                                     SourceLocation ArgLoc, Decl *D) {
+  return BuildCXXReflectExpr(OpLoc, ArgLoc, D);
+}
+
+ExprResult Sema::BuildCXXReflectExpr(SourceLocation OperatorLoc,
+                                     SourceLocation OperandLoc, QualType T) {
+  return CXXReflectExpr::Create(Context, OperatorLoc, OperandLoc, T);
+}
+
+ExprResult Sema::BuildCXXReflectExpr(SourceLocation OperatorLoc,
+                                     SourceLocation OperandLoc, Decl *D) {
+  return CXXReflectExpr::Create(Context, OperatorLoc, OperandLoc, D);
+}
+
 namespace {
 
 const DeclRefExpr *CheckPossibleDeref(Sema &S, const Expr *PossibleDeref) {
diff --git a/clang/lib/Sema/TreeTransform.h b/clang/lib/Sema/TreeTransform.h
index 6967301483361..6620c422331e4 100644
--- a/clang/lib/Sema/TreeTransform.h
+++ b/clang/lib/Sema/TreeTransform.h
@@ -12873,6 +12873,12 @@ ExprResult TreeTransform<Derived>::TransformSYCLUniqueStableNameExpr(
       E->getLocation(), E->getLParenLocation(), E->getRParenLocation(), NewT);
 }
 
+template <typename Derived>
+ExprResult TreeTransform<Derived>::TransformCXXReflectExpr(CXXReflectExpr *E) {
+  // No subexpressions to recurse over in PR1.
+  return E;
+}
+
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformPredefinedExpr(PredefinedExp...
[truncated]

llvmbot · 2025-10-22T19:01:25Z

@llvm/pr-subscribers-clang-modules

Author: Nhat Nguyen (changkhothuychung)

Changes

First step in adding support for reflection, will add reflection operator parsing for the remaining cases in upcoming subsequent PRs.

Patch is 22.24 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/164685.diff

27 Files Affected:

(modified) clang/include/clang/AST/ExprCXX.h (+50)
(modified) clang/include/clang/AST/RecursiveASTVisitor.h (+4)
(modified) clang/include/clang/Basic/DiagnosticParseKinds.td (+5)
(modified) clang/include/clang/Basic/Features.def (+2)
(modified) clang/include/clang/Basic/LangOptions.def (+1)
(modified) clang/include/clang/Basic/StmtNodes.td (+3)
(modified) clang/include/clang/Basic/TokenKinds.def (+1)
(modified) clang/include/clang/Driver/Options.td (+6-1)
(modified) clang/include/clang/Parse/Parser.h (+6)
(modified) clang/include/clang/Sema/Sema.h (+11)
(modified) clang/include/clang/Serialization/ASTBitCodes.h (+3)
(modified) clang/lib/AST/ExprCXX.cpp (+34)
(modified) clang/lib/AST/ExprClassification.cpp (+1)
(modified) clang/lib/AST/ExprConstant.cpp (+1)
(modified) clang/lib/AST/StmtPrinter.cpp (+6)
(modified) clang/lib/AST/StmtProfile.cpp (+5)
(modified) clang/lib/Lex/Lexer.cpp (+3)
(modified) clang/lib/Parse/CMakeLists.txt (+1)
(modified) clang/lib/Parse/ParseExpr.cpp (+10)
(added) clang/lib/Parse/ParseReflect.cpp (+54)
(modified) clang/lib/Parse/ParseTentative.cpp (+3)
(modified) clang/lib/Sema/SemaExceptionSpec.cpp (+1)
(modified) clang/lib/Sema/SemaExpr.cpp (+19)
(modified) clang/lib/Sema/TreeTransform.h (+6)
(modified) clang/lib/Serialization/ASTReaderStmt.cpp (+9)
(modified) clang/lib/Serialization/ASTWriterStmt.cpp (+6)
(added) clang/test/Reflection/parsing-reflection.pass.cpp (+21)

diff --git a/clang/include/clang/AST/ExprCXX.h b/clang/include/clang/AST/ExprCXX.h
index 5f16bac94d5e6..5c8b2209d5364 100644
--- a/clang/include/clang/AST/ExprCXX.h
+++ b/clang/include/clang/AST/ExprCXX.h
@@ -5493,6 +5493,56 @@ class BuiltinBitCastExpr final
   }
 };
 
+/// Represents a C++2c reflect expression (P2996).
+class CXXReflectExpr : public Expr {
+
+  // Source locations.
+  SourceLocation OperatorLoc;
+  SourceRange OperandRange;
+
+  CXXReflectExpr(const ASTContext &C, QualType T, QualType Ty);
+  CXXReflectExpr(const ASTContext &C, QualType T, Decl *Arg, bool IsNamespace);
+  CXXReflectExpr(EmptyShell Empty);
+
+public:
+
+  static CXXReflectExpr *Create(ASTContext &C, SourceLocation OperatorLoc,
+                                SourceLocation ArgLoc, QualType Operand);
+
+  static CXXReflectExpr *Create(ASTContext &C, SourceLocation OperatorLoc,
+                                SourceLocation OperandLoc, Decl *Operand);
+
+  static CXXReflectExpr *CreateEmpty(ASTContext& C);
+
+  SourceLocation getBeginLoc() const LLVM_READONLY { return OperatorLoc; }
+  SourceLocation getEndLoc() const LLVM_READONLY {
+    return OperandRange.getEnd();
+  }
+  SourceRange getSourceRange() const {
+    return SourceRange(getBeginLoc(), getEndLoc());
+  }
+
+  /// Returns location of the '^^'-operator.
+  SourceLocation getOperatorLoc() const { return OperatorLoc; }
+  SourceRange getOperandRange() const { return OperandRange; }
+
+  /// Sets the location of the '^^'-operator.
+  void setOperatorLoc(SourceLocation L) { OperatorLoc = L; }
+  void setOperandRange(SourceRange R) { OperandRange = R; }
+
+  child_range children() {
+    return child_range(child_iterator(), child_iterator());
+  }
+
+  const_child_range children() const {
+    return const_child_range(const_child_iterator(), const_child_iterator());
+  }
+
+  static bool classof(const Stmt *T) {
+    return T->getStmtClass() == CXXReflectExprClass;
+  }
+};
+
 } // namespace clang
 
 #endif // LLVM_CLANG_AST_EXPRCXX_H
diff --git a/clang/include/clang/AST/RecursiveASTVisitor.h b/clang/include/clang/AST/RecursiveASTVisitor.h
index 7a2881f6124f3..7b8a678ffb861 100644
--- a/clang/include/clang/AST/RecursiveASTVisitor.h
+++ b/clang/include/clang/AST/RecursiveASTVisitor.h
@@ -2883,6 +2883,10 @@ DEF_TRAVERSE_STMT(CXXUnresolvedConstructExpr, {
   TRY_TO(TraverseTypeLoc(S->getTypeSourceInfo()->getTypeLoc()));
 })
 
+DEF_TRAVERSE_STMT(CXXReflectExpr, {
+  // TODO
+})
+
 // These expressions all might take explicit template arguments.
 // We traverse those if so.  FIXME: implement these.
 DEF_TRAVERSE_STMT(CXXConstructExpr, {})
diff --git a/clang/include/clang/Basic/DiagnosticParseKinds.td b/clang/include/clang/Basic/DiagnosticParseKinds.td
index c724136a7fdaf..ea81a2332cd50 100644
--- a/clang/include/clang/Basic/DiagnosticParseKinds.td
+++ b/clang/include/clang/Basic/DiagnosticParseKinds.td
@@ -1848,6 +1848,11 @@ def err_placeholder_expected_auto_or_decltype_auto : Error<
   "expected 'auto' or 'decltype(auto)' after concept name">;
 }
 
+let CategoryName = "Reflection Issue" in {
+def err_cannot_reflect_operand : Error<
+  "cannot reflect the provided operand">;
+}
+
 def warn_max_tokens : Warning<
   "the number of preprocessor source tokens (%0) exceeds this token limit (%1)">,
   InGroup<MaxTokens>, DefaultIgnore;
diff --git a/clang/include/clang/Basic/Features.def b/clang/include/clang/Basic/Features.def
index 0e91b42a132c1..c9d24430326ff 100644
--- a/clang/include/clang/Basic/Features.def
+++ b/clang/include/clang/Basic/Features.def
@@ -380,6 +380,8 @@ FEATURE(cxx_abi_relative_vtable, LangOpts.CPlusPlus && LangOpts.RelativeCXXABIVT
 
 FEATURE(clang_atomic_attributes, true)
 
+FEATURE(reflection, LangOpts.Reflection)
+
 // CUDA/HIP Features
 FEATURE(cuda_noinline_keyword, LangOpts.CUDA)
 EXTENSION(cuda_implicit_host_device_templates, LangOpts.CUDA && LangOpts.OffloadImplicitHostDeviceTemplates)
diff --git a/clang/include/clang/Basic/LangOptions.def b/clang/include/clang/Basic/LangOptions.def
index 84f5ab3443a59..b2051fb536432 100644
--- a/clang/include/clang/Basic/LangOptions.def
+++ b/clang/include/clang/Basic/LangOptions.def
@@ -498,6 +498,7 @@ LANGOPT(BoundsSafety, 1, 0, NotCompatible, "Bounds safety extension for C")
 LANGOPT(EnableLifetimeSafety, 1, 0, NotCompatible, "Experimental lifetime safety analysis for C++")
 
 LANGOPT(PreserveVec3Type, 1, 0, NotCompatible, "Preserve 3-component vector type")
+LANGOPT(Reflection      , 1, 0, NotCompatible, "C++26 Reflection")
 
 #undef LANGOPT
 #undef ENUM_LANGOPT
diff --git a/clang/include/clang/Basic/StmtNodes.td b/clang/include/clang/Basic/StmtNodes.td
index bf3686bb372d5..987e1d1408e06 100644
--- a/clang/include/clang/Basic/StmtNodes.td
+++ b/clang/include/clang/Basic/StmtNodes.td
@@ -177,6 +177,9 @@ def CoyieldExpr : StmtNode<CoroutineSuspendExpr>;
 def ConceptSpecializationExpr : StmtNode<Expr>;
 def RequiresExpr : StmtNode<Expr>;
 
+// c++ 26 reflection
+def CXXReflectExpr : StmtNode<Expr>;
+
 // Obj-C Expressions.
 def ObjCStringLiteral : StmtNode<Expr>;
 def ObjCBoxedExpr : StmtNode<Expr>;
diff --git a/clang/include/clang/Basic/TokenKinds.def b/clang/include/clang/Basic/TokenKinds.def
index 564d6010181cc..b7fef8b2de739 100644
--- a/clang/include/clang/Basic/TokenKinds.def
+++ b/clang/include/clang/Basic/TokenKinds.def
@@ -233,6 +233,7 @@ PUNCTUATOR(greatergreater,      ">>")
 PUNCTUATOR(greaterequal,        ">=")
 PUNCTUATOR(greatergreaterequal, ">>=")
 PUNCTUATOR(caret,               "^")
+PUNCTUATOR(caretcaret,          "^^")
 PUNCTUATOR(caretequal,          "^=")
 PUNCTUATOR(pipe,                "|")
 PUNCTUATOR(pipepipe,            "||")
diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
index 6245cf33a0719..1880459fab52f 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -3663,6 +3663,11 @@ defm application_extension : BoolFOption<"application-extension",
   PosFlag<SetTrue, [], [ClangOption, CC1Option],
           "Restrict code to those available for App Extensions">,
   NegFlag<SetFalse>>;
+defm reflection : BoolFOption<"reflection",
+  LangOpts<"Reflection">, DefaultFalse,
+  PosFlag<SetTrue, [], [ClangOption, CC1Option],
+          "Enable C++26 reflection">,
+  NegFlag<SetFalse>>;
 defm sized_deallocation : BoolFOption<"sized-deallocation",
   LangOpts<"SizedDeallocation">, Default<cpp14.KeyPath>,
   PosFlag<SetTrue, [], [], "Enable C++14 sized global deallocation functions">,
@@ -7153,7 +7158,7 @@ defm android_pad_segment : BooleanFFlag<"android-pad-segment">, Group<f_Group>;
 def shared_libflangrt : Flag<["-"], "shared-libflangrt">,
   HelpText<"Link the flang-rt shared library">, Group<Link_Group>,
   Visibility<[FlangOption]>, Flags<[NoArgumentUnused]>;
-def static_libflangrt : Flag<["-"], "static-libflangrt">, 
+def static_libflangrt : Flag<["-"], "static-libflangrt">,
   HelpText<"Link the flang-rt static library">, Group<Link_Group>,
   Visibility<[FlangOption]>, Flags<[NoArgumentUnused]>;
 
diff --git a/clang/include/clang/Parse/Parser.h b/clang/include/clang/Parse/Parser.h
index e301cf1080977..9b8d8f7633f4d 100644
--- a/clang/include/clang/Parse/Parser.h
+++ b/clang/include/clang/Parse/Parser.h
@@ -150,6 +150,7 @@ enum class TentativeCXXTypeIdContext {
   AsTemplateArgument,
   InTrailingReturnType,
   AsGenericSelectionArgument,
+  AsReflectionOperand
 };
 
 /// The kind of attribute specifier we have found.
@@ -5167,6 +5168,11 @@ class Parser : public CodeCompletionHandler {
   /// Implementations are in ParseHLSL.cpp
   ///@{
 
+
+    //===--------------------------------------------------------------------===//
+    // C++2c: Reflection [P2996]
+    ExprResult ParseCXXReflectExpression(SourceLocation OpLoc);
+
 private:
   bool MaybeParseHLSLAnnotations(Declarator &D,
                                  SourceLocation *EndLoc = nullptr,
diff --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h
index f53aafdeb4f36..d07c1160023b3 100644
--- a/clang/include/clang/Sema/Sema.h
+++ b/clang/include/clang/Sema/Sema.h
@@ -14663,6 +14663,17 @@ class Sema final : public SemaBase {
   /// Implementations are in SemaConcept.cpp
   ///@{
 
+public:
+
+    ExprResult ActOnCXXReflectExpr(SourceLocation OpLoc, TypeSourceInfo* T);
+    ExprResult ActOnCXXReflectExpr(SourceLocation OpLoc,
+                                 SourceLocation ArgLoc, Decl *D);
+
+    ExprResult BuildCXXReflectExpr(SourceLocation OperatorLoc,
+                                 SourceLocation OperandLoc, QualType T);
+    ExprResult BuildCXXReflectExpr(SourceLocation OperatorLoc,
+                                  SourceLocation OperandLoc, Decl *D);
+
 public:
   void PushSatisfactionStackEntry(const NamedDecl *D,
                                   const llvm::FoldingSetNodeID &ID) {
diff --git a/clang/include/clang/Serialization/ASTBitCodes.h b/clang/include/clang/Serialization/ASTBitCodes.h
index 5d09d5536e5ab..b950c444d9aa2 100644
--- a/clang/include/clang/Serialization/ASTBitCodes.h
+++ b/clang/include/clang/Serialization/ASTBitCodes.h
@@ -1925,6 +1925,9 @@ enum StmtCode {
   EXPR_CONCEPT_SPECIALIZATION,            // ConceptSpecializationExpr
   EXPR_REQUIRES,                          // RequiresExpr
 
+  // Reflection
+  EXPR_REFLECT,
+
   // CUDA
   EXPR_CUDA_KERNEL_CALL, // CUDAKernelCallExpr
 
diff --git a/clang/lib/AST/ExprCXX.cpp b/clang/lib/AST/ExprCXX.cpp
index 95de6a82a5270..b4758465f669a 100644
--- a/clang/lib/AST/ExprCXX.cpp
+++ b/clang/lib/AST/ExprCXX.cpp
@@ -1939,6 +1939,40 @@ TypeTraitExpr *TypeTraitExpr::CreateDeserialized(const ASTContext &C,
   return new (Mem) TypeTraitExpr(EmptyShell(), IsStoredAsBool);
 }
 
+CXXReflectExpr::CXXReflectExpr(const ASTContext &C, QualType T, QualType Ty)
+: Expr(CXXReflectExprClass, T, VK_PRValue, OK_Ordinary) {}
+
+CXXReflectExpr::CXXReflectExpr(const ASTContext &C, QualType T, Decl *Arg, bool IsNamespace)
+: Expr(CXXReflectExprClass, T, VK_PRValue, OK_Ordinary) {}
+
+CXXReflectExpr::CXXReflectExpr(EmptyShell Empty)
+: Expr(CXXReflectExprClass, Empty) {}
+
+CXXReflectExpr *CXXReflectExpr::Create(ASTContext &C, SourceLocation OperatorLoc,
+                                SourceLocation OperandLoc, QualType Operand) {
+  CXXReflectExpr *E = new (C) CXXReflectExpr(C, C.DependentTy, Operand);
+  E->setOperatorLoc(OperatorLoc);
+  E->setOperandRange(OperandLoc);
+  return E;
+}
+
+CXXReflectExpr *CXXReflectExpr::Create(ASTContext &C,
+                                       SourceLocation OperatorLoc,
+                                       SourceLocation OperandLoc,
+                                       Decl *Operand) {
+  bool IsNamespace = isa<TranslationUnitDecl>(Operand);
+
+  CXXReflectExpr *E = new (C) CXXReflectExpr(C, C.DependentTy, Operand,
+                                             IsNamespace);
+  E->setOperatorLoc(OperatorLoc);
+  E->setOperandRange(OperandLoc);
+  return E;
+}
+
+CXXReflectExpr *CXXReflectExpr::CreateEmpty(ASTContext &C) {
+  return new (C) CXXReflectExpr(EmptyShell());
+}
+
 CUDAKernelCallExpr::CUDAKernelCallExpr(Expr *Fn, CallExpr *Config,
                                        ArrayRef<Expr *> Args, QualType Ty,
                                        ExprValueKind VK, SourceLocation RP,
diff --git a/clang/lib/AST/ExprClassification.cpp b/clang/lib/AST/ExprClassification.cpp
index aeacd0dc765ef..4c53c316e989a 100644
--- a/clang/lib/AST/ExprClassification.cpp
+++ b/clang/lib/AST/ExprClassification.cpp
@@ -216,6 +216,7 @@ static Cl::Kinds ClassifyInternal(ASTContext &Ctx, const Expr *E) {
   case Expr::SourceLocExprClass:
   case Expr::ConceptSpecializationExprClass:
   case Expr::RequiresExprClass:
+  case Expr::CXXReflectExprClass:
     return Cl::CL_PRValue;
 
   case Expr::EmbedExprClass:
diff --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp
index b706b14945b6d..0f14aa3c7258f 100644
--- a/clang/lib/AST/ExprConstant.cpp
+++ b/clang/lib/AST/ExprConstant.cpp
@@ -18295,6 +18295,7 @@ static ICEDiag CheckICE(const Expr* E, const ASTContext &Ctx) {
   case Expr::ArrayTypeTraitExprClass:
   case Expr::ExpressionTraitExprClass:
   case Expr::CXXNoexceptExprClass:
+  case Expr::CXXReflectExprClass:
     return NoDiag();
   case Expr::CallExprClass:
   case Expr::CXXOperatorCallExprClass: {
diff --git a/clang/lib/AST/StmtPrinter.cpp b/clang/lib/AST/StmtPrinter.cpp
index 586c3000f105c..8e5bab721e8e4 100644
--- a/clang/lib/AST/StmtPrinter.cpp
+++ b/clang/lib/AST/StmtPrinter.cpp
@@ -2566,6 +2566,12 @@ void StmtPrinter::VisitCXXUnresolvedConstructExpr(
     OS << ')';
 }
 
+
+void StmtPrinter::VisitCXXReflectExpr(CXXReflectExpr *S) {
+  // TODO: Make this better.
+  OS << "^(...)";
+}
+
 void StmtPrinter::VisitCXXDependentScopeMemberExpr(
                                          CXXDependentScopeMemberExpr *Node) {
   if (!Node->isImplicitAccess()) {
diff --git a/clang/lib/AST/StmtProfile.cpp b/clang/lib/AST/StmtProfile.cpp
index 589a156a2b6ea..ad37b5e71472e 100644
--- a/clang/lib/AST/StmtProfile.cpp
+++ b/clang/lib/AST/StmtProfile.cpp
@@ -2164,6 +2164,11 @@ StmtProfiler::VisitLambdaExpr(const LambdaExpr *S) {
   ID.AddInteger(Hasher.CalculateHash());
 }
 
+void StmtProfiler::VisitCXXReflectExpr(const CXXReflectExpr *E) {
+  VisitExpr(E);
+  // TODO: 
+}
+
 void
 StmtProfiler::VisitCXXScalarValueInitExpr(const CXXScalarValueInitExpr *S) {
   VisitExpr(S);
diff --git a/clang/lib/Lex/Lexer.cpp b/clang/lib/Lex/Lexer.cpp
index b282a600c0e56..5df36d041d0c1 100644
--- a/clang/lib/Lex/Lexer.cpp
+++ b/clang/lib/Lex/Lexer.cpp
@@ -4348,6 +4348,9 @@ bool Lexer::LexTokenInternal(Token &Result, bool TokAtPhysicalStartOfLine) {
     if (Char == '=') {
       CurPtr = ConsumeChar(CurPtr, SizeTmp, Result);
       Kind = tok::caretequal;
+    } else if (LangOpts.Reflection && Char == '^') {
+      CurPtr = ConsumeChar(CurPtr, SizeTmp, Result);
+      Kind = tok::caretcaret;
     } else {
       if (LangOpts.OpenCL && Char == '^')
         Diag(CurPtr, diag::err_opencl_logical_exclusive_or);
diff --git a/clang/lib/Parse/CMakeLists.txt b/clang/lib/Parse/CMakeLists.txt
index e6cbf3b868b7d..8dd120f529b13 100644
--- a/clang/lib/Parse/CMakeLists.txt
+++ b/clang/lib/Parse/CMakeLists.txt
@@ -26,6 +26,7 @@ add_clang_library(clangParse
   ParseTentative.cpp
   Parser.cpp
   ParseOpenACC.cpp
+  ParseReflect.cpp
 
   LINK_LIBS
   clangAST
diff --git a/clang/lib/Parse/ParseExpr.cpp b/clang/lib/Parse/ParseExpr.cpp
index 3515343202de1..22963d985b01b 100644
--- a/clang/lib/Parse/ParseExpr.cpp
+++ b/clang/lib/Parse/ParseExpr.cpp
@@ -1208,6 +1208,13 @@ Parser::ParseCastExpression(CastParseKind ParseKind, bool isAddressOfOperand,
     AllowSuffix = false;
     Res = ParseUnaryExprOrTypeTraitExpression();
     break;
+  case tok::caretcaret: {
+    if (getLangOpts().Reflection) {
+      SourceLocation FirstCaret = ConsumeToken(); // eat first '^'
+      Res = ParseCXXReflectExpression(/*OpLoc=*/FirstCaret);
+    }
+    break;
+  }
   case tok::ampamp: {      // unary-expression: '&&' identifier
     if (NotPrimaryExpression)
       *NotPrimaryExpression = true;
@@ -2249,6 +2256,9 @@ ExprResult Parser::ParseUnaryExprOrTypeTraitExpression() {
   else if (getLangOpts().C2y && OpTok.is(tok::kw__Countof))
     Diag(OpTok, diag::warn_c2y_compat_keyword) << OpTok.getName();
 
+  if (OpTok.is(tok::caretcaret))
+    return ParseCXXReflectExpression(OpTok.getLocation());
+
   EnterExpressionEvaluationContext Unevaluated(
       Actions, Sema::ExpressionEvaluationContext::Unevaluated,
       Sema::ReuseLambdaContextDecl);
diff --git a/clang/lib/Parse/ParseReflect.cpp b/clang/lib/Parse/ParseReflect.cpp
new file mode 100644
index 0000000000000..817c885ab2804
--- /dev/null
+++ b/clang/lib/Parse/ParseReflect.cpp
@@ -0,0 +1,54 @@
+
+
+
+
+#include "clang/AST/LocInfoType.h"
+#include "clang/Basic/DiagnosticParse.h"
+#include "clang/Parse/Parser.h"
+#include "clang/Parse/RAIIObjectsForParser.h"
+#include "clang/Sema/EnterExpressionEvaluationContext.h"
+using namespace clang;
+
+ExprResult Parser::ParseCXXReflectExpression(SourceLocation OpLoc) {
+  assert(Tok.is(tok::caretcaret) && "expected '^^'");
+  EnterExpressionEvaluationContext Unevaluated(
+      Actions, Sema::ExpressionEvaluationContext::Unevaluated);
+
+  SourceLocation OperandLoc = Tok.getLocation();
+
+  // Parse a leading nested-name-specifier
+  CXXScopeSpec SS;
+  if (ParseOptionalCXXScopeSpecifier(SS, /*ObjectType=*/nullptr,
+                                     /*ObjectHasErrors=*/false,
+                                     /*EnteringContext=*/false)) {
+    SkipUntil(tok::semi, StopAtSemi | StopBeforeMatch);
+    return ExprError();
+  }
+
+  {
+    TentativeParsingAction TPA(*this);
+
+    if (SS.isValid() &&
+               SS.getScopeRep().getKind() == NestedNameSpecifier::Kind::Global) {
+      // Check for global namespace '^^::'
+      TPA.Commit();
+      Decl *TUDecl = Actions.getASTContext().getTranslationUnitDecl();
+      return Actions.ActOnCXXReflectExpr(OpLoc, SourceLocation(), TUDecl);
+    }
+    TPA.Revert();
+  }
+
+  if (isCXXTypeId(TentativeCXXTypeIdContext::AsReflectionOperand)) {
+    TypeResult TR = ParseTypeName(/*TypeOf=*/nullptr);
+    if (TR.isInvalid())
+      return ExprError();
+
+    TypeSourceInfo *TSI = nullptr;
+    QualType QT = Actions.GetTypeFromParser(TR.get(), &TSI);
+
+    return Actions.ActOnCXXReflectExpr(OpLoc, TSI);
+  }
+
+  Diag(OperandLoc, diag::err_cannot_reflect_operand);
+  return ExprError();
+}
diff --git a/clang/lib/Parse/ParseTentative.cpp b/clang/lib/Parse/ParseTentative.cpp
index 82f2294ff5bb7..8a3ae2232767e 100644
--- a/clang/lib/Parse/ParseTentative.cpp
+++ b/clang/lib/Parse/ParseTentative.cpp
@@ -574,6 +574,9 @@ bool Parser::isCXXTypeId(TentativeCXXTypeIdContext Context, bool &isAmbiguous) {
     } else if (Context == TentativeCXXTypeIdContext::InTrailingReturnType) {
       TPR = TPResult::True;
       isAmbiguous = true;
+    } else if (Context == TentativeCXXTypeIdContext::AsReflectionOperand) {
+      TPR = TPResult::True;
+      isAmbiguous = true;
     } else
       TPR = TPResult::False;
   }
diff --git a/clang/lib/Sema/SemaExceptionSpec.cpp b/clang/lib/Sema/SemaExceptionSpec.cpp
index a0483c3027199..ff8d2139289a3 100644
--- a/clang/lib/Sema/SemaExceptionSpec.cpp
+++ b/clang/lib/Sema/SemaExceptionSpec.cpp
@@ -1379,6 +1379,7 @@ CanThrowResult Sema::canThrow(const Stmt *S) {
   case Expr::CXXNoexceptExprClass:
   case Expr::CXXNullPtrLiteralExprClass:
   case Expr::CXXPseudoDestructorExprClass:
+  case Expr::CXXReflectExprClass:
   case Expr::CXXScalarValueInitExprClass:
   case Expr::CXXThisExprClass:
   case Expr::CXXUuidofExprClass:
diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index 06b2529011c74..95bc91ab29f90 100644
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -17760,6 +17760,25 @@ void Sema::PushExpressionEvaluationContextForFunction(
   }
 }
 
+ExprResult Sema::ActOnCXXReflectExpr(SourceLocation OpLoc, TypeSourceInfo* TSI) {
+  return BuildCXXReflectExpr(OpLoc, TSI->getTypeLoc().getBeginLoc(), TSI->getType());
+}
+
+ExprResult Sema::ActOnCXXReflectExpr(SourceLocation OpLoc,
+                                     SourceLocation ArgLoc, Decl *D) {
+  return BuildCXXReflectExpr(OpLoc, ArgLoc, D);
+}
+
+ExprResult Sema::BuildCXXReflectExpr(SourceLocation OperatorLoc,
+                                     SourceLocation OperandLoc, QualType T) {
+  return CXXReflectExpr::Create(Context, OperatorLoc, OperandLoc, T);
+}
+
+ExprResult Sema::BuildCXXReflectExpr(SourceLocation OperatorLoc,
+                                     SourceLocation OperandLoc, Decl *D) {
+  return CXXReflectExpr::Create(Context, OperatorLoc, OperandLoc, D);
+}
+
 namespace {
 
 const DeclRefExpr *CheckPossibleDeref(Sema &S, const Expr *PossibleDeref) {
diff --git a/clang/lib/Sema/TreeTransform.h b/clang/lib/Sema/TreeTransform.h
index 6967301483361..6620c422331e4 100644
--- a/clang/lib/Sema/TreeTransform.h
+++ b/clang/lib/Sema/TreeTransform.h
@@ -12873,6 +12873,12 @@ ExprResult TreeTransform<Derived>::TransformSYCLUniqueStableNameExpr(
       E->getLocation(), E->getLParenLocation(), E->getRParenLocation(), NewT);
 }
 
+template <typename Derived>
+ExprResult TreeTransform<Derived>::TransformCXXReflectExpr(CXXReflectExpr *E) {
+  // No subexpressions to recurse over in PR1.
+  return E;
+}
+
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformPredefinedExpr(PredefinedExp...
[truncated]

github-actions · 2025-10-22T19:02:40Z

⚠️ C/C++ code formatter, clang-format found issues in your code. ⚠️

You can test this locally with the following command:

git-clang-format --diff origin/main HEAD --extensions cpp,h -- clang/lib/Parse/ParseReflect.cpp clang/test/Reflection/parsing-reflection.pass.cpp clang/include/clang/AST/ExprCXX.h clang/include/clang/AST/RecursiveASTVisitor.h clang/include/clang/Parse/Parser.h clang/include/clang/Sema/Sema.h clang/include/clang/Serialization/ASTBitCodes.h clang/lib/AST/ExprCXX.cpp clang/lib/AST/ExprClassification.cpp clang/lib/AST/ExprConstant.cpp clang/lib/AST/ItaniumMangle.cpp clang/lib/AST/StmtPrinter.cpp clang/lib/AST/StmtProfile.cpp clang/lib/Lex/Lexer.cpp clang/lib/Parse/ParseExpr.cpp clang/lib/Parse/ParseTentative.cpp clang/lib/Sema/SemaExceptionSpec.cpp clang/lib/Sema/SemaExpr.cpp clang/lib/Sema/TreeTransform.h clang/lib/Serialization/ASTReaderStmt.cpp clang/lib/Serialization/ASTWriterStmt.cpp --diff_from_common_commit

⚠️
The reproduction instructions above might return results for more than one PR
in a stack if you are using a stacked PR workflow. You can limit the results by
changing origin/main to the base branch/commit you want to compare against.
⚠️

View the diff from clang-format here.

diff --git a/clang/include/clang/AST/RecursiveASTVisitor.h b/clang/include/clang/AST/RecursiveASTVisitor.h
index 126d5284a..37e9570ec 100644
--- a/clang/include/clang/AST/RecursiveASTVisitor.h
+++ b/clang/include/clang/AST/RecursiveASTVisitor.h
@@ -983,7 +983,9 @@ bool RecursiveASTVisitor<Derived>::TraverseLambdaCapture(LambdaExpr *LE,
                                                     bool TraverseQualifier) {  \
     if (!getDerived().shouldTraversePostOrder())                               \
       TRY_TO(WalkUpFrom##TYPE(T));                                             \
-    { CODE; }                                                                  \
+    {                                                                          \
+      CODE;                                                                    \
+    }                                                                          \
     if (getDerived().shouldTraversePostOrder())                                \
       TRY_TO(WalkUpFrom##TYPE(T));                                             \
     return true;                                                               \
@@ -1255,7 +1257,9 @@ DEF_TRAVERSE_TYPE(PredefinedSugarType, {})
       if (getDerived().shouldWalkTypesOfTypeLocs())                            \
         TRY_TO(WalkUpFrom##TYPE(const_cast<TYPE *>(TL.getTypePtr())));         \
     }                                                                          \
-    { CODE; }                                                                  \
+    {                                                                          \
+      CODE;                                                                    \
+    }                                                                          \
     if (getDerived().shouldTraversePostOrder()) {                              \
       TRY_TO(WalkUpFrom##TYPE##Loc(TL));                                       \
       if (getDerived().shouldWalkTypesOfTypeLocs())                            \
@@ -2523,12 +2527,11 @@ DEF_TRAVERSE_STMT(GCCAsmStmt, {
   // children() iterates over inputExpr and outputExpr.
 })
 
-DEF_TRAVERSE_STMT(
-    MSAsmStmt,
-    {
-        // FIXME: MS Asm doesn't currently parse Constraints, Clobbers, etc.
-        // Once added this needs to be implemented.
-    })
+DEF_TRAVERSE_STMT(MSAsmStmt,
+                  {
+                      // FIXME: MS Asm doesn't currently parse Constraints,
+                      // Clobbers, etc. Once added this needs to be implemented.
+                  })
 
 DEF_TRAVERSE_STMT(CXXCatchStmt, {
   TRY_TO(TraverseDecl(S->getExceptionDecl()));
@@ -2626,11 +2629,10 @@ DEF_TRAVERSE_STMT(MemberExpr, {
                                             S->getNumTemplateArgs()));
 })
 
-DEF_TRAVERSE_STMT(ImplicitCastExpr,
-                  {
-                      // We don't traverse the cast type, as it's not written in
-                      // the source code.
-                  })
+DEF_TRAVERSE_STMT(ImplicitCastExpr, {
+                                        // We don't traverse the cast type, as
+                                        // it's not written in the source code.
+                                    })
 
 DEF_TRAVERSE_STMT(CStyleCastExpr, {
   TRY_TO(TraverseTypeLoc(S->getTypeInfoAsWritten()->getTypeLoc()));
diff --git a/clang/lib/AST/StmtPrinter.cpp b/clang/lib/AST/StmtPrinter.cpp
index 37c2dd40c..24778c94f 100644
--- a/clang/lib/AST/StmtPrinter.cpp
+++ b/clang/lib/AST/StmtPrinter.cpp
@@ -152,13 +152,11 @@ public:
       StmtVisitor<StmtPrinter>::Visit(S);
   }
 
-    [[maybe_unused]] void VisitStmt(Stmt *Node) {
-      Indent() << "<<unknown stmt type>>" << NL;
-    }
+  [[maybe_unused]] void VisitStmt(Stmt *Node) {
+    Indent() << "<<unknown stmt type>>" << NL;
+  }
 
-    [[maybe_unused]] void VisitExpr(Expr *Node) {
-      OS << "<<unknown expr type>>";
-    }
+  [[maybe_unused]] void VisitExpr(Expr *Node) { OS << "<<unknown expr type>>"; }
 
   void VisitCXXNamedCastExpr(CXXNamedCastExpr *Node);

changkhothuychung · 2025-10-22T19:32:58Z

will close and create new one

changkhothuychung added 5 commits October 22, 2025 14:34

parsing global namespace and primitive types

482e25e

cleanup

c2d6d7e

cleanup

7c7ac79

cleanup

61c7f94

cleanup

78fe7c4

llvmbot added clang Clang issues not falling into any other category clang:frontend Language frontend issues, e.g. anything involving "Sema" clang:modules C++20 modules and Clang Header Modules labels Oct 22, 2025

changkhothuychung requested review from cor3ntin and shafik October 22, 2025 19:01

changkhothuychung added 4 commits October 22, 2025 15:22

add dummy mangling

5ae0873

add file description

4503b11

clang format

0820f21

Merge branch 'main' into refl-parsing

1e36903

changkhothuychung closed this Oct 22, 2025

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[clang] reflection operator parsing for global namespace and primitive types #164685

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