[analyzer] Make analyzer less aggressive when dealing with [self init].
With inlining, retain count checker starts tracking 'self' through the
init methods. The analyser results were too noisy if the developer
did not follow 'self = [super init]' pattern (which is common
especially in older code bases) - we reported self init anti-pattern AND
possible use-after-free. This patch teaches the retain count
checker to assume that [super init] does not fail when it's not consumed
by another expression. This silences the retain count warning that warns
about possibility of use-after-free when init fails, while preserving
all the other checking on 'self'.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@162508 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/StaticAnalyzer/Checkers/RetainCountChecker.cpp b/lib/StaticAnalyzer/Checkers/RetainCountChecker.cpp
index 03956bb..ab8acb1 100644
--- a/lib/StaticAnalyzer/Checkers/RetainCountChecker.cpp
+++ b/lib/StaticAnalyzer/Checkers/RetainCountChecker.cpp
@@ -930,6 +930,35 @@
S = getPersistentSummary(RE, RecEffect, DefEffect);
}
+
+ // Special case '[super init];' and '[self init];'
+ //
+ // Even though calling '[super init]' without assigning the result to self
+ // and checking if the parent returns 'nil' is a bad pattern, it is common.
+ // Additionally, our Self Init checker already warns about it. To avoid
+ // overwhelming the user with messages from both checkers, we model the case
+ // of '[super init]' in cases when it is not consumed by another expression
+ // as if the call preserves the value of 'self'; essentially, assuming it can
+ // never fail and return 'nil'.
+ // Note, we don't want to just stop tracking the value since we want the
+ // RetainCount checker to report leaks and use-after-free if SelfInit checker
+ // is turned off.
+ if (const ObjCMethodCall *MC = dyn_cast<ObjCMethodCall>(&Call)) {
+ if (MC->getMethodFamily() == OMF_init && MC->isReceiverSelfOrSuper()) {
+
+ // Check if the message is not consumed, we know it will not be used in
+ // an assignment, ex: "self = [super init]".
+ const Expr *ME = MC->getOriginExpr();
+ const LocationContext *LCtx = MC->getLocationContext();
+ ParentMap &PM = LCtx->getAnalysisDeclContext()->getParentMap();
+ if (!PM.isConsumedExpr(ME)) {
+ RetainSummaryTemplate ModifiableSummaryTemplate(S, *this);
+ ModifiableSummaryTemplate->setReceiverEffect(DoNothing);
+ ModifiableSummaryTemplate->setRetEffect(RetEffect::MakeNoRet());
+ }
+ }
+
+ }
}
const RetainSummary *