Move if-stmt invariant code outside, fix a compiler warning. NFC

lib/Differentiator/ReverseModeVisitor.cpp

@@ -1304,24 +1304,18 @@ Expr* getArraySizeExpr(const ArrayType* AT, ASTContext& context,
   }
 
   StmtDiff ReverseModeVisitor::VisitDeclRefExpr(const DeclRefExpr* DRE) {
-    DeclRefExpr* clonedDRE = nullptr;
+    DeclRefExpr* clonedDRE = cast<DeclRefExpr>(Clone(DRE));
     // Check if referenced Decl was "replaced" with another identifier inside
     // the derivative
-    if (const auto* VD = dyn_cast<VarDecl>(DRE->getDecl())) {
-      clonedDRE = cast<DeclRefExpr>(Clone(DRE));
+    if (const auto* VD = dyn_cast<VarDecl>(clonedDRE->getDecl())) {
       // If current context is different than the context of the original
       // declaration (e.g. we are inside lambda), rebuild the DeclRefExpr
       // with Sema::BuildDeclRefExpr. This is required in some cases, e.g.
       // Sema::BuildDeclRefExpr is responsible for adding captured fields
       // to the underlying struct of a lambda.
-      if (clonedDRE->getDecl()->getDeclContext() != m_Sema.CurContext) {
-        auto* referencedDecl = cast<VarDecl>(clonedDRE->getDecl());
-        clonedDRE = cast<DeclRefExpr>(BuildDeclRef(referencedDecl));
-      }
-    } else
-      clonedDRE = cast<DeclRefExpr>(Clone(DRE));
+      if (VD->getDeclContext() != m_Sema.CurContext)
+        clonedDRE = cast<DeclRefExpr>(BuildDeclRef(VD));
 
-    if (auto* decl = dyn_cast<VarDecl>(clonedDRE->getDecl())) {
       if (isVectorValued) {
         if (m_VectorOutput.size() <= outputArrayCursor)
           return StmtDiff(clonedDRE);