[PATCH] Fix static analyzer crash when casting from an incomplete type

[Pavel Labath]

  Fix static analyzer crash when casting from an incomplete type

  Update comment and use hasDefinition() instead of isCompleteDefinition().

http://llvm-reviews.chandlerc.com/D1006

CHANGE SINCE LAST DIFF
  http://llvm-reviews.chandlerc.com/D1006?vs=2478&id=2499#toc

Files:
  lib/StaticAnalyzer/Core/Store.cpp
  test/Analysis/derived-to-base.cpp

Index: lib/StaticAnalyzer/Core/Store.cpp
===================================================================
--- lib/StaticAnalyzer/Core/Store.cpp
+++ lib/StaticAnalyzer/Core/Store.cpp
@@ -325,7 +325,10 @@
     if (MRClass == TargetClass)
       return loc::MemRegionVal(MR);
 
-    if (!TargetType->isVoidType()) {
+    // We skip over incomplete types. They must be the result of an earlier
+    // reinterpret_cast, as one can only dynamic_cast between types in the same
+    // class hierarchy.
+    if (!TargetType->isVoidType() && MRClass->hasDefinition()) {
       // Static upcasts are marked as DerivedToBase casts by Sema, so this will
       // only happen when multiple or virtual inheritance is involved.
       CXXBasePaths Paths(/*FindAmbiguities=*/false, /*RecordPaths=*/true,
Index: test/Analysis/derived-to-base.cpp
===================================================================
--- test/Analysis/derived-to-base.cpp
+++ test/Analysis/derived-to-base.cpp
@@ -450,3 +450,28 @@
   }
 };
 
+namespace Bug16309 {
+  struct Incomplete;
+
+  struct Base { virtual ~Base(); };
+
+  struct Derived : public Base { int x; };
+
+  void* f(Incomplete *i) {
+    Base *b = reinterpret_cast<Base *>(i);
+    // This used to crash because of the reinterpret_cast above.
+    Derived *d = dynamic_cast<Derived *>(b);
+    return d;
+  }
+
+  // And check that reinterpret+dynamic casts work correctly after the fix.
+  void g() {
+    Derived d;
+    d.x = 47;
+    Base *b = &d;
+    Incomplete *i = reinterpret_cast<Incomplete *>(b);
+    Base *b2 = reinterpret_cast<Base *>(i);
+    Derived *d2 = dynamic_cast<Derived *>(b2);
+    clang_analyzer_eval(d2->x == 47); // expected-warning{{TRUE}}
+  }
+}
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