Partial fix for #6710 FN nullPointerRedundantCheck after pointer usage in for init statement (#8471)

Author: chrchr-github

lib/reverseanalyzer.cpp

@@ -110,8 +110,11 @@ namespace {
         {
             if (Token::simpleMatch(tok->tokAt(-2), "} else {"))
                 tok = tok->linkAt(-2);
-            if (Token::simpleMatch(tok->previous(), ") {"))
+            if (Token::simpleMatch(tok->previous(), ") {")) {
+                if (Token::simpleMatch(tok->linkAt(-1)->astOperand2(), ";"))
+                    return tok->linkAt(-1)->astOperand2();
                 return tok->linkAt(-1);
+            }
             if (Token::simpleMatch(tok->previous(), "do {"))
                 return tok->previous();
             return tok;
@@ -232,7 +235,7 @@ namespace {
                         if (!Token::Match(assignTop->astOperand1(), "%assign%")) {
                             continueB &= updateRecursive(assignTop->astOperand1());
                         }
-                        if (!assignTop->astParent())
+                        if (!assignTop->astParent() || Token::simpleMatch(assignTop->astParent(), ";"))
                             break;
                         assignTop = assignTop->astParent();
                     }

test/testnullpointer.cpp

@@ -3710,6 +3710,19 @@ class TestNullPointer : public TestFixture {
               "            i++;\n"
               "}\n");
         ASSERT_EQUALS("", errout_str());
+
+        check("void f(const int* p) {\n" // #6710
+              "    for (int i = *p; i < 5; ++i) {}\n"
+              "    if (p) {}\n"
+              "}\n"
+              "struct S { int a; };\n"
+              "void g(const S* s) {\n"
+              "    for (int i = s->a; i < 5; ++i) {}\n"
+              "    if (s) {}\n"
+              "}\n");
+        ASSERT_EQUALS("[test.cpp:3:9] -> [test.cpp:2:19]: (warning) Either the condition 'p' is redundant or there is possible null pointer dereference: p. [nullPointerRedundantCheck]\n"
+                      "[test.cpp:8:9] -> [test.cpp:7:18]: (warning) Either the condition 's' is redundant or there is possible null pointer dereference: s. [nullPointerRedundantCheck]\n",
+                      errout_str());
     }
 
     void nullpointerDeadCode() {