[analyzer] Do not try to body-farm Objective-C properties with custom accessors.

If a property is defined with a custom getter, we should not behave as if
the getter simply returns an instance variable. We don't support setters,
so they aren't affected.

On top of being the right thing to do, this also fixes a crash on
the newly added test - in which a property and its getter are defined
in two separate categories.

rdar://problem/47051544

Differential Revision: https://reviews.llvm.org/D56823

llvm-svn: 351609

2 files changed, 40 insertions, 0 deletions

diff --git a/clang/lib/Analysis/BodyFarm.cpp b/clang/lib/Analysis/BodyFarm.cpp
index 35f04640676..2a682a8ba42 100644
--- a/clang/lib/Analysis/BodyFarm.cpp
+++ b/clang/lib/Analysis/BodyFarm.cpp
@@ -807,6 +807,11 @@ Stmt *BodyFarm::getBody(const ObjCMethodDecl *D) {
 
   D = D->getCanonicalDecl();
 
+  // We should not try to synthesize explicitly redefined accessors.
+  // We do not know for sure how they behave.
+  if (!D->isImplicit())
+    return nullptr;
+
   Optional<Stmt *> &Val = Bodies[D];
   if (Val.hasValue())
     return Val.getValue();
diff --git a/clang/test/Analysis/properties.m b/clang/test/Analysis/properties.m
index 461639f4c2b..17b156035a3 100644
--- a/clang/test/Analysis/properties.m
+++ b/clang/test/Analysis/properties.m
@@ -1005,3 +1005,38 @@ void testNoCrashWhenAccessPropertyAndThereAreNoDirectBindingsAtAll() {
 
 #endif // non-ARC
 
+@interface ExplicitAccessorInCategory : NSObject
+@property(readonly) int normal;
+- (int)normal;
+@property(readonly) int no_custom_accessor;
+@end
+
+@interface ExplicitAccessorInCategory ()
+@property(readonly) int in_category;
+
+@property(readonly) int still_no_custom_accessor;
+// This is an ordinary method, not a getter.
+- (int)still_no_custom_accessor;
+@end
+
+@interface ExplicitAccessorInCategory ()
+- (int)in_category;
+
+// This is an ordinary method, not a getter.
+- (int)no_custom_accessor;
+@end
+
+@implementation ExplicitAccessorInCategory
+- (void)foo {
+	// Make sure we don't farm bodies for explicit accessors: in particular,
+	// we're not sure that the accessor always returns the same value.
+	clang_analyzer_eval(self.normal == self.normal); // expected-warning{{UNKNOWN}}
+	// Also this used to crash.
+	clang_analyzer_eval(self.in_category == self.in_category); // expected-warning{{UNKNOWN}}
+
+	// When there is no explicit accessor defined (even if it looks like there is),
+	// farm the getter body and see if it does actually always yield the same value.
+	clang_analyzer_eval(self.no_custom_accessor == self.no_custom_accessor); // expected-warning{{TRUE}}
+	clang_analyzer_eval(self.still_no_custom_accessor == self.still_no_custom_accessor); // expected-warning{{TRUE}}
+}
+@end