Refs #12913: Fix FN redundantCopyLocalConst with auto (#6584)

Author: chrchr-github

lib/checkother.cpp

@@ -2913,7 +2913,7 @@ void CheckOther::checkRedundantCopy()
 
     for (const Variable* var : symbolDatabase->variableList()) {
         if (!var || var->isReference() || var->isPointer() ||
-            (!var->type() && !var->isStlType()) || // bailout if var is of standard type, if it is a pointer or non-const
+            (!var->type() && !var->isStlType() && !(var->valueType() && var->valueType()->container)) || // bailout if var is of standard type, if it is a pointer or non-const
             (!var->isConst() && isVariableChanged(var, *mSettings)))
             continue;
 

test/testother.cpp

@@ -9046,6 +9046,16 @@ class TestOther : public TestFixture {
         TODO_ASSERT_EQUALS("",
                            "[test.cpp:16] -> [test.cpp:18]: (style) The comparison 'c == m->get()' is always true because 'c' and 'm->get()' represent the same value.\n",
                            errout_str());
+
+        check("struct T {\n"
+              "    std::string s;\n"
+              "    const std::string& get() const { return s; }\n"
+              "};\n"
+              "void f(const T& t) {\n"
+              "    const auto s = t.get();\n"
+              "    if (s.empty()) {}\n"
+              "}\n");
+        ASSERT_EQUALS("[test.cpp:6]: (performance, inconclusive) Use const reference for 's' to avoid unnecessary data copying.\n", errout_str());
     }
 
     void checkNegativeShift() {