[analyzer] Handle reference parameters with default values.

r175026 added support for default values, but didn't take reference
parameters into account, which expect the default argument to be an
lvalue. Use createTemporaryRegionIfNeeded if we can evaluate the default
expr as an rvalue but the expected result is an lvalue.

Fixes the most recent report of PR12915. The original report predates
default argument support, so that can't be it.

llvm-svn: 176042

2 files changed, 6 insertions, 3 deletions

diff --git a/clang/lib/StaticAnalyzer/Core/ExprEngine.cpp b/clang/lib/StaticAnalyzer/Core/ExprEngine.cpp
index eb83e202b77..8b6de132497 100644
--- a/clang/lib/StaticAnalyzer/Core/ExprEngine.cpp
+++ b/clang/lib/StaticAnalyzer/Core/ExprEngine.cpp
@@ -685,7 +685,8 @@ void ExprEngine::Visit(const Stmt *S, ExplodedNode *Pred,
       StmtNodeBuilder Bldr2(PreVisit, Tmp, *currBldrCtx);
 
       const LocationContext *LCtx = Pred->getLocationContext();
-      const Expr *ArgE = cast<CXXDefaultArgExpr>(S)->getExpr();
+      const CXXDefaultArgExpr *DefaultE = cast<CXXDefaultArgExpr>(S);
+      const Expr *ArgE = DefaultE->getExpr();
 
       // Avoid creating and destroying a lot of APSInts.
       SVal V;
@@ -700,7 +701,9 @@ void ExprEngine::Visit(const Stmt *S, ExplodedNode *Pred,
         else
           V = State->getSVal(ArgE, LCtx);
 
-        State = State->BindExpr(S, LCtx, V);
+        State = State->BindExpr(DefaultE, LCtx, V);
+        if (DefaultE->isGLValue())
+          State = createTemporaryRegionIfNeeded(State, LCtx, DefaultE);
         Bldr2.generateNode(S, *I, State);
       }
 
diff --git a/clang/lib/StaticAnalyzer/Core/RegionStore.cpp b/clang/lib/StaticAnalyzer/Core/RegionStore.cpp
index 310c080fafb..acda9e0af32 100644
--- a/clang/lib/StaticAnalyzer/Core/RegionStore.cpp
+++ b/clang/lib/StaticAnalyzer/Core/RegionStore.cpp
@@ -1578,7 +1578,7 @@ static Optional<SVal> getConstValue(SValBuilder &SVB, const VarDecl *VD) {
     return None;
 
   llvm::APSInt Result;
-  if (Init->EvaluateAsInt(Result, Ctx))
+  if (!Init->isGLValue() && Init->EvaluateAsInt(Result, Ctx))
     return SVB.makeIntVal(Result);
 
   if (Init->isNullPointerConstant(Ctx, Expr::NPC_ValueDependentIsNotNull))