4 files changed, 35 insertions, 19 deletions
diff --git a/src/analysis/analysis.cpp b/src/analysis/analysis.cpp
index bb6b93e..45abe97 100644
--- a/src/analysis/analysis.cpp
+++ b/src/analysis/analysis.cpp
@@ -217,6 +217,15 @@ bool checkForReport(Node *node,
         wi.checkNullVars.find(node->label) != wi.checkNullVars.end();
 }
 
+// report about useless check for null pointer
+void reportUselessCheck(Node *node,
+                        const std::string &var)
+{
+    Log::warn(findBackLocation(node),
+        "Useless variable check '%s'. It already was checked before",
+        var);
+}
+
 // report about null pointer if need for node
 void reportParmDeclNullPointer(Node *mainNode,
                                Node *node,
diff --git a/src/analysis/analysis.h b/src/analysis/analysis.h
index b371ab3..0c4e10f 100644
--- a/src/analysis/analysis.h
+++ b/src/analysis/analysis.h
@@ -46,6 +46,9 @@ namespace Analysis
                                        Node *node,
                                        const WalkItem &wi);
 
+    void reportUselessCheck(Node *node,
+                            const std::string &var);
+
     bool checkForReport(Node *node,
                         const WalkItem &wi);
 
diff --git a/src/analysis/expression.cpp b/src/analysis/expression.cpp
index e521615..4683dee 100644
--- a/src/analysis/expression.cpp
+++ b/src/analysis/expression.cpp
@@ -193,18 +193,22 @@ void analyseNeExpr(NeExprNode *node, const WalkItem &wi, WalkItem &wo)
     // if (var != 0)
     if (!var.empty() &&
         node2 == INTEGER_CST &&
-        wi.checkNullVars.find(var) != wi.checkNullVars.end() &&
         node2->label == "0")
     {
-        wo.checkedNonNullVars.insert(var);
-        wo.cleanExpr = true;
-        wo.uselessExpr = false;
-    }
-    else
-    {
-        wo.cleanExpr = false;
-        wo.uselessExpr = true;
+        if (wi.checkNullVars.find(var) != wi.checkNullVars.end())
+        {
+            wo.checkedNonNullVars.insert(var);
+            wo.cleanExpr = true;
+            wo.uselessExpr = false;
+            return;
+        }
+        else if (wi.knownVars.find(var) != wi.knownVars.end())
+        {
+            reportUselessCheck(node, var);
+        }
     }
+    wo.cleanExpr = false;
+    wo.uselessExpr = true;
 }
 
 void analyseEqExpr(EqExprNode *node, const WalkItem &wi, WalkItem &wo)
@@ -221,18 +225,18 @@ void analyseEqExpr(EqExprNode *node, const WalkItem &wi, WalkItem &wo)
     // if (var == 0)
     if (!var.empty() &&
         node2 == INTEGER_CST &&
-        wi.checkNullVars.find(var) != wi.checkNullVars.end() &&
         node2->label == "0")
     {
-        wo.checkedNullVars.insert(var);
-        wo.cleanExpr = true;
-        wo.uselessExpr = false;
-    }
-    else
-    {
-        wo.cleanExpr = false;
-        wo.uselessExpr = true;
+        if (wi.checkNullVars.find(var) != wi.checkNullVars.end())
+        {
+            wo.checkedNullVars.insert(var);
+            wo.cleanExpr = true;
+            wo.uselessExpr = false;
+            return;
+        }
     }
+    wo.cleanExpr = false;
+    wo.uselessExpr = true;
 }
 
 void analyseOrCondition(Node *node, Node *node1, Node *node2, const WalkItem &wi, WalkItem &wo)
diff --git a/src/analysis/function.cpp b/src/analysis/function.cpp
index 6197e0a..20ead8f 100644
--- a/src/analysis/function.cpp
+++ b/src/analysis/function.cpp
@@ -147,8 +147,8 @@ void analyseFunction(FunctionDeclNode *node, const WalkItem &wi, WalkItem &wo)
         WalkItem wi2 = wi;
         getPossibleNullParameters(node, wi2);
         walkTree(node->code, wi2, wo);
-        wo.stopWalking = true;
     }
+    wo.stopWalking = true;
 }
 
 }