[PATCH] D31538: [analyzer] MisusedMovedObjectChecker: Fix a false positive on state-resetting a base-class sub-object.

[Artem Dergachev via Phabricator via cfe-commits]

NoQ created this revision.

If a state reset method is defined in a parent class, but called over an object 
of a child class, then the checker doesn't treat this as a state reset, at 
least for the sake of "Copying a 'moved-from' object" warning class.

The patch fixes it, but Peter may have a better fix in mind :)


https://reviews.llvm.org/D31538

Files:
  lib/StaticAnalyzer/Checkers/MisusedMovedObjectChecker.cpp
  test/Analysis/MisusedMovedObject.cpp


Index: test/Analysis/MisusedMovedObject.cpp
===================================================================
--- test/Analysis/MisusedMovedObject.cpp
+++ test/Analysis/MisusedMovedObject.cpp
@@ -617,3 +617,11 @@
     a.b.foo();           // no-warning
   }
 }
+
+class C: public A {};
+void resetSuperClass() {
+  C c;
+  C c1 = std::move(c);
+  c.clear();
+  C c2 = c; // no-warning
+}
Index: lib/StaticAnalyzer/Checkers/MisusedMovedObjectChecker.cpp
===================================================================
--- lib/StaticAnalyzer/Checkers/MisusedMovedObjectChecker.cpp
+++ lib/StaticAnalyzer/Checkers/MisusedMovedObjectChecker.cpp
@@ -416,7 +416,14 @@
     return;
 
   if (isStateResetMethod(MethodDecl)) {
-    State = State->remove<TrackedRegionMap>(ThisRegion);
+    // A state reset method resets the whole object, not only sub-object
+    // of a parent class in which it is defined.
+    const MemRegion *WholeObjectRegion = ThisRegion;
+    while (const CXXBaseObjectRegion *BR =
+               dyn_cast<CXXBaseObjectRegion>(WholeObjectRegion))
+      WholeObjectRegion = BR->getSuperRegion();
+
+    State = State->remove<TrackedRegionMap>(WholeObjectRegion);
     C.addTransition(State);
     return;
   }



Index: test/Analysis/MisusedMovedObject.cpp
===================================================================
--- test/Analysis/MisusedMovedObject.cpp
+++ test/Analysis/MisusedMovedObject.cpp
@@ -617,3 +617,11 @@
     a.b.foo();           // no-warning
   }
 }
+
+class C: public A {};
+void resetSuperClass() {
+  C c;
+  C c1 = std::move(c);
+  c.clear();
+  C c2 = c; // no-warning
+}
Index: lib/StaticAnalyzer/Checkers/MisusedMovedObjectChecker.cpp
===================================================================
--- lib/StaticAnalyzer/Checkers/MisusedMovedObjectChecker.cpp
+++ lib/StaticAnalyzer/Checkers/MisusedMovedObjectChecker.cpp
@@ -416,7 +416,14 @@
     return;
 
   if (isStateResetMethod(MethodDecl)) {
-    State = State->remove<TrackedRegionMap>(ThisRegion);
+    // A state reset method resets the whole object, not only sub-object
+    // of a parent class in which it is defined.
+    const MemRegion *WholeObjectRegion = ThisRegion;
+    while (const CXXBaseObjectRegion *BR =
+               dyn_cast<CXXBaseObjectRegion>(WholeObjectRegion))
+      WholeObjectRegion = BR->getSuperRegion();
+
+    State = State->remove<TrackedRegionMap>(WholeObjectRegion);
     C.addTransition(State);
     return;
   }

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