PR11594: Don't blindly build a UnaryOperator UO_Minus on an expression which

might not be an rvalue when checking array accesses. Instead, pass through a
flag indicating the array index is negated.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@146753 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 5 insertions, 5 deletions

diff --git a/lib/Sema/SemaChecking.cpp b/lib/Sema/SemaChecking.cpp
index c8f2d05e0d..9bb532b532 100644
--- a/lib/Sema/SemaChecking.cpp
+++ b/lib/Sema/SemaChecking.cpp
@@ -4277,7 +4277,7 @@ static bool IsTailPaddedMemberArray(Sema &S, llvm::APInt Size,
 
 void Sema::CheckArrayAccess(const Expr *BaseExpr, const Expr *IndexExpr,
                             const ArraySubscriptExpr *ASE,
-                            bool AllowOnePastEnd) {
+                            bool AllowOnePastEnd, bool IndexNegated) {
   IndexExpr = IndexExpr->IgnoreParenCasts();
   if (IndexExpr->isValueDependent())
     return;
@@ -4292,6 +4292,8 @@ void Sema::CheckArrayAccess(const Expr *BaseExpr, const Expr *IndexExpr,
   llvm::APSInt index;
   if (!IndexExpr->EvaluateAsInt(index, Context))
     return;
+  if (IndexNegated)
+    index = -index;
 
   const NamedDecl *ND = NULL;
   if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(BaseExpr))
diff --git a/lib/Sema/SemaExpr.cpp b/lib/Sema/SemaExpr.cpp
index c18d37df5f..552d0e7f21 100644
--- a/lib/Sema/SemaExpr.cpp
+++ b/lib/Sema/SemaExpr.cpp
@@ -6203,11 +6203,9 @@ QualType Sema::CheckSubtractionOperands(ExprResult &LHS, ExprResult &RHS,
       if (!checkArithmeticOpPointerOperand(*this, Loc, LHS.get()))
         return QualType();
 
-      Expr *IExpr = RHS.get()->IgnoreParenCasts();
-      UnaryOperator negRex(IExpr, UO_Minus, IExpr->getType(), VK_RValue,
-                           OK_Ordinary, IExpr->getExprLoc());
       // Check array bounds for pointer arithemtic
-      CheckArrayAccess(LHS.get()->IgnoreParenCasts(), &negRex);
+      CheckArrayAccess(LHS.get(), RHS.get(), /*ArraySubscriptExpr*/0,
+                       /*AllowOnePastEnd*/true, /*IndexNegated*/true);
 
       if (CompLHSTy) *CompLHSTy = LHS.get()->getType();
       return LHS.get()->getType();