Fix #14544 FP nullPointerRedundantCheck (array argument) (cppcheck-opensource#8271)

Author: chrchr-github

lib/astutils.cpp

@@ -2499,7 +2499,7 @@ bool isMutableExpression(const Token* tok)
     if (const Variable* var = tok->variable()) {
         if (var->nameToken() == tok)
             return false;
-        if (!var->isPointer() && var->isConst())
+        if (var->isConst() && !var->isPointer() && (!var->isArray() || !var->isArgument()))
             return false;
     }
     return true;

test/testnullpointer.cpp

@@ -995,6 +995,14 @@ class TestNullPointer : public TestFixture {
               "char f(S* s) { return s->p ? 'a' : s->p->c; }\n");
         ASSERT_EQUALS("[test.cpp:2:24] -> [test.cpp:2:37]: (warning) Either the condition 's->p' is redundant or there is possible null pointer dereference: s->p. [nullPointerRedundantCheck]\n",
                       errout_str());
+
+        check("int f(const int a[]) {\n" // #14544
+              "    int i = 0;\n"
+              "    if (!a)\n"
+              "        a = &i;\n"
+              "    return *a;\n"
+              "}\n");
+        ASSERT_EQUALS("", errout_str());
     }
 
     void nullpointer5() {