[c++20] Implement P1009R2: allow omitting the array bound in an array

new expression.

This was voted into C++20 as a defect report resolution, so we
retroactively apply it to all prior language modes (though it can never
actually be used before C++11 mode).

llvm-svn: 360006

1 files changed, 15 insertions, 12 deletions

diff --git a/clang/lib/AST/ExprCXX.cpp b/clang/lib/AST/ExprCXX.cpp
index b1ce1674014..bbf7e044aae 100644
--- a/clang/lib/AST/ExprCXX.cpp
+++ b/clang/lib/AST/ExprCXX.cpp
@@ -97,7 +97,8 @@ CXXNewExpr::CXXNewExpr(bool IsGlobalNew, FunctionDecl *OperatorNew,
                        FunctionDecl *OperatorDelete, bool ShouldPassAlignment,
                        bool UsualArrayDeleteWantsSize,
                        ArrayRef<Expr *> PlacementArgs, SourceRange TypeIdParens,
-                       Expr *ArraySize, InitializationStyle InitializationStyle,
+                       Optional<Expr *> ArraySize,
+                       InitializationStyle InitializationStyle,
                        Expr *Initializer, QualType Ty,
                        TypeSourceInfo *AllocatedTypeInfo, SourceRange Range,
                        SourceRange DirectInitRange)
@@ -112,7 +113,7 @@ CXXNewExpr::CXXNewExpr(bool IsGlobalNew, FunctionDecl *OperatorNew,
          "Only NoInit can have no initializer!");
 
   CXXNewExprBits.IsGlobalNew = IsGlobalNew;
-  CXXNewExprBits.IsArray = ArraySize != nullptr;
+  CXXNewExprBits.IsArray = ArraySize.hasValue();
   CXXNewExprBits.ShouldPassAlignment = ShouldPassAlignment;
   CXXNewExprBits.UsualArrayDeleteWantsSize = UsualArrayDeleteWantsSize;
   CXXNewExprBits.StoredInitializationStyle =
@@ -122,12 +123,14 @@ CXXNewExpr::CXXNewExpr(bool IsGlobalNew, FunctionDecl *OperatorNew,
   CXXNewExprBits.NumPlacementArgs = PlacementArgs.size();
 
   if (ArraySize) {
-    if (ArraySize->isInstantiationDependent())
-      ExprBits.InstantiationDependent = true;
-    if (ArraySize->containsUnexpandedParameterPack())
-      ExprBits.ContainsUnexpandedParameterPack = true;
+    if (Expr *SizeExpr = *ArraySize) {
+      if (SizeExpr->isInstantiationDependent())
+        ExprBits.InstantiationDependent = true;
+      if (SizeExpr->containsUnexpandedParameterPack())
+        ExprBits.ContainsUnexpandedParameterPack = true;
+    }
 
-    getTrailingObjects<Stmt *>()[arraySizeOffset()] = ArraySize;
+    getTrailingObjects<Stmt *>()[arraySizeOffset()] = *ArraySize;
   }
 
   if (Initializer) {
@@ -179,11 +182,11 @@ CXXNewExpr::Create(const ASTContext &Ctx, bool IsGlobalNew,
                    FunctionDecl *OperatorNew, FunctionDecl *OperatorDelete,
                    bool ShouldPassAlignment, bool UsualArrayDeleteWantsSize,
                    ArrayRef<Expr *> PlacementArgs, SourceRange TypeIdParens,
-                   Expr *ArraySize, InitializationStyle InitializationStyle,
-                   Expr *Initializer, QualType Ty,
-                   TypeSourceInfo *AllocatedTypeInfo, SourceRange Range,
-                   SourceRange DirectInitRange) {
-  bool IsArray = ArraySize != nullptr;
+                   Optional<Expr *> ArraySize,
+                   InitializationStyle InitializationStyle, Expr *Initializer,
+                   QualType Ty, TypeSourceInfo *AllocatedTypeInfo,
+                   SourceRange Range, SourceRange DirectInitRange) {
+  bool IsArray = ArraySize.hasValue();
   bool HasInit = Initializer != nullptr;
   unsigned NumPlacementArgs = PlacementArgs.size();
   bool IsParenTypeId = TypeIdParens.isValid();