3 files changed, 49 insertions, 9 deletions

diff --git a/lib/StaticAnalyzer/Core/ExprEngineC.cpp b/lib/StaticAnalyzer/Core/ExprEngineC.cpp
index 7a53fccf2e..2d52c01e1d 100644
--- a/lib/StaticAnalyzer/Core/ExprEngineC.cpp
+++ b/lib/StaticAnalyzer/Core/ExprEngineC.cpp
@@ -617,11 +617,15 @@ void ExprEngine::VisitGuardedExpr(const Expr *Ex,
                                   const Expr *R,
                                   ExplodedNode *Pred,
                                   ExplodedNodeSet &Dst) {
+  assert(L && R);
+
   StmtNodeBuilder B(Pred, Dst, *currBldrCtx);
   ProgramStateRef state = Pred->getState();
   const LocationContext *LCtx = Pred->getLocationContext();
   const CFGBlock *SrcBlock = 0;
 
+  // Find the predecessor block.
+  ProgramStateRef SrcState = state;
   for (const ExplodedNode *N = Pred ; N ; N = *N->pred_begin()) {
     ProgramPoint PP = N->getLocation();
     if (PP.getAs<PreStmtPurgeDeadSymbols>() || PP.getAs<BlockEntrance>()) {
@@ -629,6 +633,7 @@ void ExprEngine::VisitGuardedExpr(const Expr *Ex,
       continue;
     }
     SrcBlock = PP.castAs<BlockEdge>().getSrc();
+    SrcState = N->getState();
     break;
   }
 
@@ -644,14 +649,25 @@ void ExprEngine::VisitGuardedExpr(const Expr *Ex,
     CFGElement CE = *I;
     if (Optional<CFGStmt> CS = CE.getAs<CFGStmt>()) {
       const Expr *ValEx = cast<Expr>(CS->getStmt());
-      hasValue = true;
-      V = state->getSVal(ValEx, LCtx);
+      ValEx = ValEx->IgnoreParens();
+
+      // For GNU extension '?:' operator, the left hand side will be an
+      // OpaqueValueExpr, so get the underlying expression.
+      if (const OpaqueValueExpr *OpaqueEx = dyn_cast<OpaqueValueExpr>(L))
+        L = OpaqueEx->getSourceExpr();
+
+      // If the last expression in the predecessor block matches true or false
+      // subexpression, get its the value.
+      if (ValEx == L->IgnoreParens() || ValEx == R->IgnoreParens()) {
+        hasValue = true;
+        V = SrcState->getSVal(ValEx, LCtx);
+      }
       break;
     }
   }
 
-  assert(hasValue);
-  (void) hasValue;
+  if (!hasValue)
+    V = svalBuilder.conjureSymbolVal(0, Ex, LCtx, currBldrCtx->blockCount());
 
   // Generate a new node with the binding from the appropriate path.
   B.generateNode(Ex, Pred, state->BindExpr(Ex, LCtx, V, true));
diff --git a/lib/StaticAnalyzer/Core/SValBuilder.cpp b/lib/StaticAnalyzer/Core/SValBuilder.cpp
index 19a4353ffc..309230ebed 100644
--- a/lib/StaticAnalyzer/Core/SValBuilder.cpp
+++ b/lib/StaticAnalyzer/Core/SValBuilder.cpp
@@ -106,12 +106,19 @@ SValBuilder::getRegionValueSymbolVal(const TypedValueRegion* region) {
   return nonloc::SymbolVal(sym);
 }
 
-DefinedOrUnknownSVal SValBuilder::conjureSymbolVal(const void *symbolTag,
-                                                   const Expr *expr,
+DefinedOrUnknownSVal SValBuilder::conjureSymbolVal(const void *SymbolTag,
+                                                   const Expr *Ex,
                                                    const LocationContext *LCtx,
-                                                   unsigned count) {
-  QualType T = expr->getType();
-  return conjureSymbolVal(symbolTag, expr, LCtx, T, count);
+                                                   unsigned Count) {
+  QualType T = Ex->getType();
+
+  // Compute the type of the result. If the expression is not an R-value, the
+  // result should be a location.
+  QualType ExType = Ex->getType();
+  if (Ex->isGLValue())
+    T = LCtx->getAnalysisDeclContext()->getASTContext().getPointerType(ExType);
+
+  return conjureSymbolVal(SymbolTag, Ex, LCtx, T, Count);
 }
 
 DefinedOrUnknownSVal SValBuilder::conjureSymbolVal(const void *symbolTag,
diff --git a/test/Analysis/conditional-operator.cpp b/test/Analysis/conditional-operator.cpp
new file mode 100644
index 0000000000..5a3c325b91
--- /dev/null
+++ b/test/Analysis/conditional-operator.cpp
@@ -0,0 +1,17 @@
+// RUN: %clang -cc1 -analyze -analyzer-checker=core,debug.ExprInspection %s -analyzer-output=text -verify
+
+void clang_analyzer_eval(bool);
+
+// Test that the analyzer does not crash on GNU extension operator "?:".
+void NoCrashTest(int x, int y) {
+	int w = x ?: y;
+}
+
+void OperatorEvaluationTest(int y) {
+  int x = 1;
+	int w = x ?: y;  // expected-note {{'?' condition is true}}
+	
+	// TODO: We are not precise when processing the "?:" operator in C++.
+  clang_analyzer_eval(w == 1); // expected-warning{{UNKNOWN}}
+                               // expected-note@-1{{UNKNOWN}}
+}
\ No newline at end of file