Fix 11296: FN: knownConditionTrueFalse ( a !=0 && b != 0 && a == 0) (#4444)

lib/valueflow.cpp

@@ -1984,9 +1984,12 @@ static bool isConditionKnown(const Token* tok, bool then)
     if (then)
         op = "&&";
     const Token* parent = tok->astParent();
-    while (parent && (parent->str() == op || parent->str() == "!"))
+    while (parent && (parent->str() == op || parent->str() == "!" || parent->isCast()))
         parent = parent->astParent();
-    return Token::Match(parent, "(|;");
+    const Token* top = tok->astTop();
+    if (top && Token::Match(top->previous(), "if|while|for ("))
+        return parent == top || Token::simpleMatch(parent, ";");
+    return parent && parent->str() != op;
 }
 
 static const std::string& invertAssign(const std::string& assign)
@@ -6353,12 +6356,16 @@ static bool isIntegralOnlyOperator(const Token* tok) {
     return Token::Match(tok, "%|<<|>>|&|^|~|%or%");
 }
 
-static bool isIntegral(const Token* tok)
+static bool isIntegralOrPointer(const Token* tok)
 {
     if (!tok)
         return false;
     if (astIsIntegral(tok, false))
         return true;
+    if (astIsPointer(tok))
+        return true;
+    if (Token::Match(tok, "NULL|nullptr"))
+        return true;
     if (tok->valueType())
         return false;
     // These operators only work on integers
@@ -6367,7 +6374,7 @@ static bool isIntegral(const Token* tok)
     if (isIntegralOnlyOperator(tok->astParent()))
         return true;
     if (Token::Match(tok, "+|-|*|/") && tok->isBinaryOp())
-        return isIntegral(tok->astOperand1()) && isIntegral(tok->astOperand2());
+        return isIntegralOrPointer(tok->astOperand1()) && isIntegralOrPointer(tok->astOperand2());
     return false;
 }
 
@@ -6400,7 +6407,7 @@ static void valueFlowInferCondition(TokenList* tokenlist,
                         setTokenValue(tok, value, settings);
                     }
                 }
-            } else if (isIntegral(tok->astOperand1()) && isIntegral(tok->astOperand2())) {
+            } else if (isIntegralOrPointer(tok->astOperand1()) && isIntegralOrPointer(tok->astOperand2())) {
                 std::vector<ValueFlow::Value> result =
                     infer(IntegralInferModel{}, tok->str(), tok->astOperand1()->values(), tok->astOperand2()->values());
                 for (const ValueFlow::Value& value : result) {

test/testcondition.cpp

@@ -1309,7 +1309,7 @@ private:
         check("int f(char c) {\n"
               "  return (c <= 'a' && c >= 'z');\n"
               "}", "test.cpp", false);
-        ASSERT_EQUALS("", errout.str());
+        ASSERT_EQUALS("[test.cpp:2] -> [test.cpp:2]: (style) Condition 'c>='z'' is always false\n", errout.str());
     }
 
     void incorrectLogicOperator7() { // opposite expressions
@@ -4714,6 +4714,11 @@ private:
         // #11098
         check("void f(unsigned int x) { if (x == -1u) {} }\n");
         ASSERT_EQUALS("", errout.str());
+
+        check("bool f(const int *p, const int *q) {\n"
+              "    return p != NULL && q != NULL && p == NULL;\n"
+              "}\n");
+        ASSERT_EQUALS("[test.cpp:2]: (style) Condition 'p==NULL' is always false\n", errout.str());
     }
 
     void alwaysTrueContainer() {

test/testvalueflow.cpp

@@ -5089,6 +5089,7 @@ private:
                "  return((n=42) && *n == 'A');\n"
                "}";
         values = tokenValues(code, "n ==");
+        values.remove_if(&isNotUninitValue);
         ASSERT_EQUALS(true, values.empty());
 
         // #8233