From 84dd0c961f517e606dddbcd12249f7ea488beb60 Mon Sep 17 00:00:00 2001
From: shaneasd <thatguyiknow5@hotmail.com>
Date: Fri, 4 Sep 2020 13:06:26 +0800
Subject: [PATCH] False positive dynamic_cast auto variable which has been
 checked against null (#2769)

---
 lib/valueflow.cpp      |  2 +-
 test/testcondition.cpp | 11 +++++++++++
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/lib/valueflow.cpp b/lib/valueflow.cpp
index 746ed1f35..bec2614aa 100644
--- a/lib/valueflow.cpp
+++ b/lib/valueflow.cpp
@@ -488,7 +488,7 @@ static void setTokenValue(Token* tok, const ValueFlow::Value &value, const Setti
 
     // cast..
     if (const Token *castType = getCastTypeStartToken(parent)) {
-        if (astIsPointer(tok) && value.valueType == ValueFlow::Value::INT &&
+        if (((tok->valueType() == nullptr && value.isImpossible()) || astIsPointer(tok)) && value.valueType == ValueFlow::Value::INT &&
             Token::simpleMatch(parent->astOperand1(), "dynamic_cast"))
             return;
         const ValueType &valueType = ValueType::parseDecl(castType, settings);
diff --git a/test/testcondition.cpp b/test/testcondition.cpp
index 2364be80f..188cc7cb0 100644
--- a/test/testcondition.cpp
+++ b/test/testcondition.cpp
@@ -3306,6 +3306,17 @@ private:
               "}\n");
         ASSERT_EQUALS("", errout.str());
 
+        check("int foo() {\n"
+            "    auto x = getX();\n"
+            "    if (x == nullptr)\n"
+            "        return 1;\n"
+            "    auto y = dynamic_cast<Y*>(x)\n"
+            "    if (y == nullptr)\n"
+            "        return 2;\n"
+            "    return 3;\n"
+            "}\n");
+        ASSERT_EQUALS("", errout.str());
+
         // handleKnownValuesInLoop
         check("bool g();\n"
               "void f(bool x) {\n"