From: Jordan Rose <jordan_rose@apple.com>
Date: Sat, 8 Sep 2012 01:24:38 +0000 (+0000)
Subject: [analyzer] Cast the result of a placement new-expression to the correct type.
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=9874f597ef5d5748695c88daaa9a3208f95c2032;p=clang

[analyzer] Cast the result of a placement new-expression to the correct type.

This is necessary because further analysis will assume that the SVal's
type matches the AST type. This caused a crash when trying to perform
a derived-to-base cast on a C++ object that had been new'd to be another
object type.

Yet another crash in PR13763.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@163442 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/StaticAnalyzer/Core/ExprEngineCXX.cpp b/lib/StaticAnalyzer/Core/ExprEngineCXX.cpp
index 10ecb3b9a9..60c73c6296 100644
--- a/lib/StaticAnalyzer/Core/ExprEngineCXX.cpp
+++ b/lib/StaticAnalyzer/Core/ExprEngineCXX.cpp
@@ -250,7 +250,9 @@ void ExprEngine::VisitCXXNewExpr(const CXXNewExpr *CNE, ExplodedNode *Pred,
   if (FD && FD->isReservedGlobalPlacementOperator()) {
     // Non-array placement new should always return the placement location.
     SVal PlacementLoc = State->getSVal(CNE->getPlacementArg(0), LCtx);
-    State = State->BindExpr(CNE, LCtx, PlacementLoc);
+    SVal Result = svalBuilder.evalCast(PlacementLoc, CNE->getType(),
+                                       CNE->getPlacementArg(0)->getType());
+    State = State->BindExpr(CNE, LCtx, Result);
   } else {
     State = State->BindExpr(CNE, LCtx, symVal);
   }
diff --git a/test/Analysis/inline.cpp b/test/Analysis/inline.cpp
index 6491b12c58..6c7cfc14e8 100644
--- a/test/Analysis/inline.cpp
+++ b/test/Analysis/inline.cpp
@@ -270,8 +270,13 @@ namespace OperatorNew {
 
 
 namespace VirtualWithSisterCasts {
+  // This entire set of tests exercises casts from sister classes and
+  // from classes outside the hierarchy, which can very much confuse
+  // code that uses DynamicTypeInfo or needs to construct CXXBaseObjectRegions.
+  // These examples used to cause crashes in +Asserts builds.
   struct Parent {
     virtual int foo();
+    int x;
   };
 
   struct A : Parent {
@@ -282,20 +287,41 @@ namespace VirtualWithSisterCasts {
     virtual int foo();
   };
 
+  struct Grandchild : public A {};
+
   struct Unrelated {};
 
   void testDowncast(Parent *b) {
     A *a = (A *)(void *)b;
     clang_analyzer_eval(a->foo() == 42); // expected-warning{{UNKNOWN}}
+
+    a->x = 42;
+    clang_analyzer_eval(a->x == 42); // expected-warning{{TRUE}}
   }
 
   void testRelated(B *b) {
     A *a = (A *)(void *)b;
     clang_analyzer_eval(a->foo() == 42); // expected-warning{{UNKNOWN}}
+
+    a->x = 42;
+    clang_analyzer_eval(a->x == 42); // expected-warning{{TRUE}}
   }
 
   void testUnrelated(Unrelated *b) {
     A *a = (A *)(void *)b;
     clang_analyzer_eval(a->foo() == 42); // expected-warning{{UNKNOWN}}
+
+    a->x = 42;
+    clang_analyzer_eval(a->x == 42); // expected-warning{{TRUE}}
+  }
+
+  void testCastViaNew(B *b) {
+    Grandchild *g = new (b) Grandchild();
+    // FIXME: We actually now have perfect type info because of 'new'.
+    // This should be TRUE.
+    clang_analyzer_eval(g->foo() == 42); // expected-warning{{UNKNOWN}}
+
+    g->x = 42;
+    clang_analyzer_eval(g->x == 42); // expected-warning{{TRUE}}
   }
 }