Fix #13220 FN nullPointerRedundantCheck with constructor (regression) (danmar#8132)

Author: chrchr-github

lib/checknullpointer.cpp

@@ -310,7 +310,8 @@ void CheckNullPointer::nullPointerByDeRefAndCheck()
 
             return true;
         };
-        std::vector<const Token *> tokens = findTokensSkipDeadAndUnevaluatedCode(mSettings->library, scope->bodyStart, scope->bodyEnd, pred);
+        const Token* const start = (scope->function && scope->function->isConstructor()) ? scope->function->token : scope->bodyStart; // Check initialization list
+        std::vector<const Token *> tokens = findTokensSkipDeadAndUnevaluatedCode(mSettings->library, start, scope->bodyEnd, pred);
         for (const Token *tok : tokens) {
             const ValueFlow::Value *value = tok->getValue(0);
 

test/testnullpointer.cpp

@@ -3742,6 +3742,15 @@ class TestNullPointer : public TestFixture {
                "    return 1 ? 1 : *(int*)0 = 1;\n"
                "}\n");
         ASSERT_EQUALS("", errout_str());
+
+        check ("struct S {\n" // #13220
+               "    explicit S(int* p) : i(*p) {\n"
+               "        if (p) {}\n"
+               "    }\n"
+               "    int i;\n"
+               "};\n");
+        ASSERT_EQUALS("[test.cpp:3:13] -> [test.cpp:2:29]: (warning) Either the condition 'p' is redundant or there is possible null pointer dereference: p. [nullPointerRedundantCheck]\n",
+                      errout_str());
     }
 
     void nullpointerDelete() {