[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).

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@360006 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 14 insertions, 7 deletions

diff --git a/lib/Sema/TreeTransform.h b/lib/Sema/TreeTransform.h
index a8ea6b01d1..b1b2a911c2 100644
--- a/lib/Sema/TreeTransform.h
+++ b/lib/Sema/TreeTransform.h
@@ -2745,7 +2745,7 @@ public:
                                SourceRange TypeIdParens,
                                QualType AllocatedType,
                                TypeSourceInfo *AllocatedTypeInfo,
-                               Expr *ArraySize,
+                               Optional<Expr *> ArraySize,
                                SourceRange DirectInitRange,
                                Expr *Initializer) {
     return getSema().BuildCXXNew(StartLoc, UseGlobal,
@@ -10378,9 +10378,16 @@ TreeTransform<Derived>::TransformCXXNewExpr(CXXNewExpr *E) {
     return ExprError();
 
   // Transform the size of the array we're allocating (if any).
-  ExprResult ArraySize = getDerived().TransformExpr(E->getArraySize());
-  if (ArraySize.isInvalid())
-    return ExprError();
+  Optional<Expr *> ArraySize;
+  if (Optional<Expr *> OldArraySize = E->getArraySize()) {
+    ExprResult NewArraySize;
+    if (*OldArraySize) {
+      NewArraySize = getDerived().TransformExpr(*OldArraySize);
+      if (NewArraySize.isInvalid())
+        return ExprError();
+    }
+    ArraySize = NewArraySize.get();
+  }
 
   // Transform the placement arguments (if any).
   bool ArgumentChanged = false;
@@ -10417,7 +10424,7 @@ TreeTransform<Derived>::TransformCXXNewExpr(CXXNewExpr *E) {
 
   if (!getDerived().AlwaysRebuild() &&
       AllocTypeInfo == E->getAllocatedTypeSourceInfo() &&
-      ArraySize.get() == E->getArraySize() &&
+      ArraySize == E->getArraySize() &&
       NewInit.get() == OldInit &&
       OperatorNew == E->getOperatorNew() &&
       OperatorDelete == E->getOperatorDelete() &&
@@ -10444,7 +10451,7 @@ TreeTransform<Derived>::TransformCXXNewExpr(CXXNewExpr *E) {
   }
 
   QualType AllocType = AllocTypeInfo->getType();
-  if (!ArraySize.get()) {
+  if (!ArraySize) {
     // If no array size was specified, but the new expression was
     // instantiated with an array type (e.g., "new T" where T is
     // instantiated with "int[4]"), extract the outer bound from the
@@ -10472,7 +10479,7 @@ TreeTransform<Derived>::TransformCXXNewExpr(CXXNewExpr *E) {
       E->getBeginLoc(), E->isGlobalNew(),
       /*FIXME:*/ E->getBeginLoc(), PlacementArgs,
       /*FIXME:*/ E->getBeginLoc(), E->getTypeIdParens(), AllocType,
-      AllocTypeInfo, ArraySize.get(), E->getDirectInitRange(), NewInit.get());
+      AllocTypeInfo, ArraySize, E->getDirectInitRange(), NewInit.get());
 }
 
 template<typename Derived>