[WIP] P3385

clang/include/clang/AST/APValue.h

@@ -32,6 +32,7 @@ template <typename T> class BasicReaderBase;
 
   class AddrLabelExpr;
   class ASTContext;
+  class AttributeCommonInfo;
   class CharUnits;
   class CXX26AnnotationAttr;
   class CXXRecordDecl;
@@ -489,6 +490,10 @@ class APValue {
     return isReflection() && getReflectionKind() == ReflectionKind::Annotation;
   }
 
+  bool isReflectedAttribute() const {
+    return isReflection() && getReflectionKind() == ReflectionKind::Attribute;
+  }
+
   void dump() const;
   void dump(raw_ostream &OS, const ASTContext &Context) const;
 
@@ -678,6 +683,7 @@ class APValue {
   CXXBaseSpecifier *getReflectedBaseSpecifier() const;
   TagDataMemberSpec *getReflectedDataMemberSpec() const;
   CXX26AnnotationAttr *getReflectedAnnotation() const;
+  AttributeCommonInfo *getReflectedAttribute() const;
 
   void setInt(APSInt I) {
     assert(isInt() && "Invalid accessor");

clang/include/clang/AST/ExprCXX.h

@@ -5321,7 +5321,8 @@ class BuiltinBitCastExpr final
 };
 
 /// Represents a C++2c reflect expression (P2996). The operand of the expression
-/// is either a type, an expression, a template-name, or a namespace.
+/// is either a type, an expression, a template-name, an attribute or a
+/// namespace.
 class CXXReflectExpr : public Expr {
   enum class OperandKind {
     Unset,
@@ -5408,12 +5409,12 @@ class CXXReflectExpr : public Expr {
 /// reflections (P2996). Arguments vary by function.
 class CXXMetafunctionExpr : public Expr {
 public:
-  // Type of callback provided to executing metafunctinons to help evaluate an
+  // Type of callback provided to executing metafunctions to help evaluate an
   // expression in the current constant evaluation context.
   using EvaluateFn = std::function<bool(APValue &, const Expr *,
                                         bool ConvertToRValue)>;
 
-  // Type of callback provided to report a diagnistc to the evaluation context.
+  // Type of callback provided to report a diagnostic to the evaluation context.
   using DiagnoseFn = std::function<PartialDiagnostic &(SourceLocation,
                                                        unsigned)>;
 

clang/include/clang/AST/RecursiveASTVisitor.h

@@ -2991,6 +2991,7 @@ DEF_TRAVERSE_STMT(CXXReflectExpr, {
     case ReflectionKind::Namespace:
     case ReflectionKind::BaseSpecifier:
     case ReflectionKind::DataMemberSpec:
+    case ReflectionKind::Attribute: // TODO P3385 ?
       break;
     }
   }

clang/include/clang/AST/Reflection.h

@@ -48,7 +48,7 @@ enum class ReflectionKind {
   ///
   /// Corresponds to an APValue (plus a QualType).
   Object,
-  
+
   /// \brief A reflection of a value (i.e., the result of a prvalue).
   ///
   /// Corresponds to an APValue (plus a QualType).
@@ -102,8 +102,10 @@ enum class ReflectionKind {
 
   /// \brief A reflection of an annotation (P2996 ext).
   Annotation,
-};
 
+  /// \brief A reflection of a standard attribute (P3385).
+  Attribute,
+};
 
 /// \brief Representation of a hypothetical data member, which could be used to
 /// complete an incomplete class definition using the 'std::meta::define_class'

clang/include/clang/Basic/DiagnosticMetafnKinds.td

@@ -18,7 +18,7 @@ def metafn_no_associated_property : Note<
   "%0 has no %select{type|parent}1">;
 def metafn_cannot_query_property : Note<"cannot query the "
   "%select{type|object|value|size|alignment|parameters|return type|"
-           "annotations}0 of %1">;
+           "annotations|attributes}0 of %1">;
 
 // Ranges of entities.
 def metafn_cannot_introspect_type : Note<
@@ -89,6 +89,11 @@ def metafn_value_not_structural_type : Note<
 def metafn_result_not_representable : Note<
   "provided %select{value|object}0 cannot be represented by a reflection">;
 
+def metafn_p3385_trace_execution_checkpoint : Warning<
+  "(p3385-metafn) trace_execution_checkpoint %0">;
+def metafn_p3385_non_standard_attribute : Warning<
+  "(p3385-metafn) Non standard attribute discovered %0">;
+
 // Class definition.
 def metafn_name_invalid_identifier : Note<
   "provided name '%0' is not a valid identifier">;

clang/include/clang/Basic/DiagnosticParseKinds.td

@@ -1746,6 +1746,20 @@ def err_annotation_with_using : Error<
   "annotations are not permitted following an attribute-using-prefix">;
 }
 
+let CategoryName = "P3385" in {
+
+def p3385_trace_attribute_parsed : Warning<
+  "(p3385) found attribute to parse following caret operator">;
+def p3385_trace_empty_attributes_list : Warning<
+  "(p3385) reflection of an empty attribute list">;
+def p3385_trace_execution_checkpoint : Warning<
+  "(p3385) trace_execution_checkpoint %0">;
+def p3385_err_attributes_list : Error<
+  "(p3385) reflection of attribute list is not supported, found %0 attributes">;
+def p3385_err_attribute_splicing_error : Error<
+  "(p3385) splicing of attributes error: %0">;
+}
+
 let CategoryName = "Generics Issue" in {
 
 def err_objc_expected_type_parameter : Error<

clang/include/clang/Basic/DiagnosticSemaKinds.td

@@ -3173,6 +3173,9 @@ def note_dependent_splice_explicit_this_may_fix : Note<
 def err_cannot_expand_over_type : Error<
   "cannot expand over an expression of type %0">;
 
+def p3385_trace_building_attribute_reflection : Warning<
+  "(p3385) building a CXX reflection on attribute %0">;
+
 // C++11 char16_t/char32_t
 def warn_cxx98_compat_unicode_type : Warning<
   "'%0' type specifier is incompatible with C++98">,

clang/include/clang/Parse/Parser.h

@@ -316,6 +316,8 @@ class Parser : public CodeCompletionHandler {
 
   /// Factory object for creating ParsedAttr objects.
   AttributeFactory AttrFactory;
+  /// FIXNE P3385
+  ParsedAttributes Attrs;
 
   /// Gathers and cleans up TemplateIdAnnotations when parsing of a
   /// top-level declaration is finished.
@@ -3047,6 +3049,11 @@ class Parser : public CodeCompletionHandler {
     ParseCXX11AttributeSpecifierInternal(Attrs, OpenMPTokens, EndLoc);
     ReplayOpenMPAttributeTokens(OpenMPTokens);
   }
+
+  bool tryParseSpliceAttrSpecifier(ParsedAttributes &Attrs,
+                                   SourceLocation *EndLoc = nullptr);
+  /// Try parsing a splice expression when inside an attribute specifier
+
   void ParseCXX11Attributes(ParsedAttributes &attrs);
   /// Parses a C++11 (or C23)-style attribute argument list. Returns true
   /// if this results in adding an attribute to the ParsedAttributes list.

clang/include/clang/Sema/Sema.h

@@ -35,6 +35,7 @@
 #include "clang/AST/Type.h"
 #include "clang/AST/TypeLoc.h"
 #include "clang/Basic/AttrSubjectMatchRules.h"
+#include "clang/Basic/AttributeCommonInfo.h"
 #include "clang/Basic/Builtins.h"
 #include "clang/Basic/CapturedStmt.h"
 #include "clang/Basic/Cuda.h"
@@ -15173,6 +15174,7 @@ class Sema final : public SemaBase {
   ExprResult ActOnCXXReflectExpr(SourceLocation OpLoc,
                                  ParsedTemplateArgument Template);
   ExprResult ActOnCXXReflectExpr(SourceLocation OpLoc, CXXSpliceExpr *E);
+  ExprResult ActOnCXXReflectExpr(SourceLocation OpLoc, ParsedAttr *a);
 
   ExprResult ActOnCXXMetafunction(SourceLocation KwLoc,
                                   SourceLocation LParenLoc,
@@ -15222,6 +15224,7 @@ class Sema final : public SemaBase {
   ExprResult BuildCXXReflectExpr(SourceLocation OperatorLoc,
                                  SourceLocation OperandLoc,
                                  TemplateName Template);
+  ExprResult BuildCXXReflectExpr(SourceLocation OperatorLoc, ParsedAttr *A);
 
   // Reflection of expression operands.
   ExprResult BuildCXXReflectExpr(SourceLocation OperatorLoc, Expr *E);

clang/lib/AST/APValue.cpp

@@ -22,6 +22,7 @@
 #include "clang/AST/ExprCXX.h"
 #include "clang/AST/LocInfoType.h"
 #include "clang/AST/Type.h"
+#include "clang/Basic/AttributeCommonInfo.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/raw_ostream.h"
 using namespace clang;
@@ -547,6 +548,7 @@ static void profileReflection(llvm::FoldingSetNodeID &ID, APValue V) {
   case ReflectionKind::Namespace:
   case ReflectionKind::BaseSpecifier:
   case ReflectionKind::Annotation:
+  case ReflectionKind::Attribute:
     ID.AddPointer(V.getOpaqueReflectionData());
     return;
   case ReflectionKind::DataMemberSpec: {
@@ -942,6 +944,13 @@ CXX26AnnotationAttr *APValue::getReflectedAnnotation() const {
           const_cast<void *>(getOpaqueReflectionData()));
 }
 
+AttributeCommonInfo *APValue::getReflectedAttribute() const {
+  assert(getReflectionKind() == ReflectionKind::Attribute &&
+         "not a reflection of an attribute");
+  return reinterpret_cast<AttributeCommonInfo *>(
+          const_cast<void *>(getOpaqueReflectionData()));
+}
+
 static double GetApproxValue(const llvm::APFloat &F) {
   llvm::APFloat V = F;
   bool ignored;
@@ -1295,6 +1304,9 @@ void APValue::printPretty(raw_ostream &Out, const PrintingPolicy &Policy,
     case ReflectionKind::Annotation:
       Repr = "annotation";
       break;
+    case ReflectionKind::Attribute:
+      Repr = "attribute";
+      break;
     }
     Out << "^^(" << Repr << ")";
     return;
@@ -1635,6 +1647,7 @@ void APValue::setReflection(ReflectionKind RK, const void *Ptr) {
   case ReflectionKind::BaseSpecifier:
   case ReflectionKind::DataMemberSpec:
   case ReflectionKind::Annotation:
+  case ReflectionKind::Attribute:
     SelfData.Kind = RK;
     SelfData.Data = Ptr;
     return;

clang/lib/AST/ComputeDependence.cpp

@@ -986,6 +986,7 @@ ExprDependence clang::computeDependence(CXXReflectExpr *E,
   case ReflectionKind::Namespace:
   case ReflectionKind::BaseSpecifier:
   case ReflectionKind::DataMemberSpec:
+  case ReflectionKind::Attribute:
     return ExprDependence::None;
   }
   llvm_unreachable("unknown reflection kind while computing dependence");