Fix #13717 FN multiCondition with NULL pointer check / #13716 FN duplicateCondition (regression) (danmar#8142)

Co-authored-by: chrchr-github <noreply@github.com>

Author: chrchr-github

lib/astutils.cpp

@@ -1546,8 +1546,8 @@ bool isUsedAsBool(const Token* const tok, const Settings& settings)
         return !Token::simpleMatch(parent->astOperand1(), "dynamic_cast") && isUsedAsBool(parent, settings);
     if (parent->isUnaryOp("*"))
         return isUsedAsBool(parent, settings);
-    if (Token::Match(parent, "==|!=") && (tok->astSibling()->isNumber() || tok->astSibling()->isKeyword()) && tok->astSibling()->hasKnownIntValue() &&
-        tok->astSibling()->getKnownIntValue() == 0)
+    if (Token::Match(parent, "==|!=") && tok->valueType() && tok->valueType()->pointer &&
+        tok->astSibling()->hasKnownIntValue() && tok->astSibling()->getKnownIntValue() == 0)
         return true;
     if (parent->str() == "(" && astIsRHS(tok) && Token::Match(parent->astOperand1(), "if|while"))
         return true;

test/testcondition.cpp

@@ -3640,6 +3640,24 @@ class TestCondition : public TestFixture {
               "}");
         ASSERT_EQUALS("[test.cpp:2:16] -> [test.cpp:3:9]: (warning) Identical condition 'handle!=nullptr', second condition is always false [identicalConditionAfterEarlyExit]\n", errout_str());
 
+        check("void f(const char* p) {\n" // #13716
+              "    if (!p) {}\n"
+              "    if (p == NULL) {}\n"
+              "    if (p == nullptr) {}\n"
+              "    if (p == 0) {}\n"
+              "}");
+        ASSERT_EQUALS("[test.cpp:2:9] -> [test.cpp:3:11]: (style) The if condition is the same as the previous if condition [duplicateCondition]\n",
+                      errout_str());
+
+        check("int f(const char* p) {\n" // #13717
+              "    if (p) {}\n"
+              "    else if (!p) {}\n"
+              "    else if (p == NULL) {}\n"
+              "}");
+        ASSERT_EQUALS("[test.cpp:2:9] -> [test.cpp:3:14]: (style) Expression is always true because 'else if' condition is opposite to previous condition at line 2. [multiCondition]\n"
+                      "[test.cpp:4:16]: (style) Expression is always false because 'else if' condition matches previous condition at line 3. [multiCondition]\n",
+                      errout_str());
+
         check("void f(void* x, void* y) {\n"
               "    if (x == nullptr && y == nullptr)\n"
               "        return;\n"