Dead stores checker: Don't flag dead stores for self-assignments (common escape hatch for 'unused variable' warnings).
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@62010 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/CheckDeadStores.cpp b/lib/Analysis/CheckDeadStores.cpp
index 51943d50..cad19f4 100644
--- a/lib/Analysis/CheckDeadStores.cpp
+++ b/lib/Analysis/CheckDeadStores.cpp
@@ -128,16 +128,23 @@
if (DeclRefExpr* DR = dyn_cast<DeclRefExpr>(B->getLHS()))
if (VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl())) {
+ Expr* RHS = B->getRHS()->IgnoreParenCasts();
+
// Special case: check for assigning null to a pointer.
// This is a common form of defensive programming.
if (VD->getType()->isPointerType()) {
- if (IntegerLiteral* L =
- dyn_cast<IntegerLiteral>(B->getRHS()->IgnoreParenCasts()))
+ if (IntegerLiteral* L = dyn_cast<IntegerLiteral>(RHS))
// FIXME: Probably should have an Expr::isNullPointerConstant.
if (L->getValue() == 0)
return;
}
-
+ // Special case: self-assignments. These are often used to shut up
+ // "unused variable" compiler warnings.
+ if (DeclRefExpr* RhsDR = dyn_cast<DeclRefExpr>(RHS))
+ if (VD == dyn_cast<VarDecl>(RhsDR->getDecl()))
+ return;
+
+ // Otherwise, issue a warning.
DeadStoreKind dsk =
Parents.isSubExpr(B)
? Enclosing