Don't emit a dead store for '++' operations unless it occurs with a return statement. We've never seen any other cases that were real bugs.
Fixes <rdar://problem/6962292>.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@125419 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/StaticAnalyzer/Checkers/DeadStoresChecker.cpp b/lib/StaticAnalyzer/Checkers/DeadStoresChecker.cpp
index 442e1b3..a6c0ea3 100644
--- a/lib/StaticAnalyzer/Checkers/DeadStoresChecker.cpp
+++ b/lib/StaticAnalyzer/Checkers/DeadStoresChecker.cpp
@@ -191,6 +191,8 @@
if (S->getLocStart().isMacroID())
return;
+ // Only cover dead stores from regular assignments. ++/-- dead stores
+ // have never flagged a real bug.
if (BinaryOperator* B = dyn_cast<BinaryOperator>(S)) {
if (!B->isAssignmentOp()) return; // Skip non-assignments.
@@ -221,14 +223,11 @@
}
}
else if (UnaryOperator* U = dyn_cast<UnaryOperator>(S)) {
- if (!U->isIncrementOp())
+ if (!U->isIncrementOp() || U->isPrefix())
return;
- // Handle: ++x within a subexpression. The solution is not warn
- // about preincrements to dead variables when the preincrement occurs
- // as a subexpression. This can lead to false negatives, e.g. "(++x);"
- // A generalized dead code checker should find such issues.
- if (U->isPrefix() && Parents.isConsumedExpr(U))
+ Stmt *parent = Parents.getParentIgnoreParenCasts(U);
+ if (!parent || !isa<ReturnStmt>(parent))
return;
Expr *Ex = U->getSubExpr()->IgnoreParenCasts();