From: Devin Coughlin <dcoughlin@apple.com>
Date: Tue, 26 Jan 2016 23:58:48 +0000 (+0000)
Subject: [analyzer] Body farm: Look for property ivar in shadowing readwrite property.
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=609444fdf26450fc530f2fcc72b2c1a743e03bfd;p=clang

[analyzer] Body farm: Look for property ivar in shadowing readwrite property.

After r251874, readonly properties that are shadowed by a readwrite property
in a class extension no longer have an instance variable, which caused the body
farm to not synthesize getters. Now, if a readonly property does not have an
instance variable look for a shadowing property and try to get the instance
variable from there.

rdar://problem/24060091

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@258886 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Analysis/BodyFarm.cpp b/lib/Analysis/BodyFarm.cpp
index 09904369ba..325c326137 100644
--- a/lib/Analysis/BodyFarm.cpp
+++ b/lib/Analysis/BodyFarm.cpp
@@ -383,10 +383,49 @@ Stmt *BodyFarm::getBody(const FunctionDecl *D) {
   return Val.getValue();
 }
 
+static const ObjCIvarDecl *findBackingIvar(const ObjCPropertyDecl *Prop) {
+  const ObjCIvarDecl *IVar = Prop->getPropertyIvarDecl();
+
+  if (IVar)
+    return IVar;
+
+  // When a readonly property is shadowed in a class extensions with a
+  // a readwrite property, the instance variable belongs to the shadowing
+  // property rather than the shadowed property. If there is no instance
+  // variable on a readonly property, check to see whether the property is
+  // shadowed and if so try to get the instance variable from shadowing
+  // property.
+  if (!Prop->isReadOnly())
+    return nullptr;
+
+  auto *Container = cast<ObjCContainerDecl>(Prop->getDeclContext());
+  const ObjCInterfaceDecl *PrimaryInterface = nullptr;
+  if (auto *InterfaceDecl = dyn_cast<ObjCInterfaceDecl>(Container)) {
+    PrimaryInterface = InterfaceDecl;
+  } else if (auto *CategoryDecl = dyn_cast<ObjCCategoryDecl>(Container)) {
+    PrimaryInterface = CategoryDecl->getClassInterface();
+  } else if (auto *ImplDecl = dyn_cast<ObjCImplDecl>(Container)) {
+    PrimaryInterface = ImplDecl->getClassInterface();
+  } else {
+    return nullptr;
+  }
+
+  // FindPropertyVisibleInPrimaryClass() looks first in class extensions, so it
+  // is guaranteed to find the shadowing property, if it exists, rather than
+  // the shadowed property.
+  auto *ShadowingProp = PrimaryInterface->FindPropertyVisibleInPrimaryClass(
+      Prop->getIdentifier());
+  if (ShadowingProp && ShadowingProp != Prop) {
+    IVar = ShadowingProp->getPropertyIvarDecl();
+  }
+
+  return IVar;
+}
+
 static Stmt *createObjCPropertyGetter(ASTContext &Ctx,
                                       const ObjCPropertyDecl *Prop) {
   // First, find the backing ivar.
-  const ObjCIvarDecl *IVar = Prop->getPropertyIvarDecl();
+  const ObjCIvarDecl *IVar = findBackingIvar(Prop);
   if (!IVar)
     return nullptr;
 
diff --git a/test/Analysis/properties.m b/test/Analysis/properties.m
index bf9424c8c2..4fdbb69d87 100644
--- a/test/Analysis/properties.m
+++ b/test/Analysis/properties.m
@@ -211,6 +211,33 @@ void testConsistencyAssign(Person *p) {
   clang_analyzer_eval(p.friend == origFriend); // expected-warning{{UNKNOWN}}
 }
 
+@interface ClassWithShadowedReadWriteProperty {
+  int _f;
+}
+@property (readonly) int someProp;
+@end
+
+@interface ClassWithShadowedReadWriteProperty ()
+@property (readwrite) int someProp;
+@end
+
+@implementation ClassWithShadowedReadWriteProperty
+- (void)testSynthesisForShadowedReadWriteProperties; {
+  clang_analyzer_eval(self.someProp == self.someProp); // expected-warning{{TRUE}}
+
+  _f = 1;
+
+  // Read of shadowed property should not invalidate receiver.
+  (void)self.someProp;
+  clang_analyzer_eval(_f == 1); // expected-warning{{TRUE}}
+
+  _f = 2;
+  // Call to getter of shadowed property should not invalidate receiver.
+  (void)[self someProp];
+  clang_analyzer_eval(_f == 2); // expected-warning{{TRUE}}
+}
+@end
+
 #if !__has_feature(objc_arc)
 void testOverrelease(Person *p, int coin) {
   switch (coin) {