Partial fix for #12162 false negative: functionConst (danmar#7729)

Author: chrchr-github

lib/checkclass.cpp

@@ -2596,7 +2596,7 @@ bool CheckClass::checkConstFunc(const Scope *scope, const Function *func, Member
                 if (!vt || !vt->container)
                     return false;
                 const auto yield = vt->container->getYield(end->str());
-                if (yield == Library::Container::Yield::START_ITERATOR || yield == Library::Container::Yield::END_ITERATOR) {
+                if (contains({Library::Container::Yield::START_ITERATOR, Library::Container::Yield::END_ITERATOR, Library::Container::Yield::ITERATOR}, yield)) {
                     const Token* parent = tok1->astParent();
                     while (Token::Match(parent, "(|.|::"))
                         parent = parent->astParent();

test/testclass.cpp

@@ -6821,6 +6821,13 @@ class TestClass : public TestFixture {
                    "};\n");
         ASSERT_EQUALS("[test.cpp:3:10]: (style, inconclusive) Technically the member function 'D::f' can be const. [functionConst]\n",
                       errout_str());
+
+        checkConst("struct S {\n" // #12162
+                   "    bool has(int i) { return m.find(i) != m.end(); }\n"
+                   "    std::map<int, int> m;\n"
+                   "};\n");
+        ASSERT_EQUALS("[test.cpp:2:10]: (style, inconclusive) Technically the member function 'S::has' can be const. [functionConst]\n",
+                      errout_str());
     }
 
     void const98() { // #13642