Fixed #3195 (operator() from a functor-struct is never used)

lib/checkunusedfunctions.cpp

@@ -147,7 +147,11 @@ void CheckUnusedFunctions::check(ErrorLogger * const errorLogger)
         const FunctionUsage &func = it->second;
         if (func.usedOtherFile || func.filename.empty())
             continue;
-        if (it->first == "main" || it->first == "WinMain" || it->first == "_tmain" || it->first == "if")
+        if (it->first == "main" ||
+            it->first == "WinMain" ||
+            it->first == "_tmain" ||
+            it->first == "if" ||
+            (it->first.compare(0, 8, "operator") == 0 && it->first.size() > 8 && !std::isalnum(it->first[8])))
             continue;
         if (! func.usedSameFile) {
             std::string filename;

test/testunusedfunctions.cpp

@@ -44,6 +44,7 @@ private:
         TEST_CASE(unusedError);
         TEST_CASE(unusedMain);
         TEST_CASE(initializationIsNotAFunction);
+        TEST_CASE(operator1);   // #3195
 
         TEST_CASE(multipleFiles);   // same function name in multiple files
 
@@ -186,6 +187,11 @@ private:
         ASSERT_EQUALS("", errout.str());
     }
 
+    void operator1() {
+        check("struct Foo { void operator()(int a) {} };");
+        ASSERT_EQUALS("", errout.str());
+    }
+
     void multipleFiles() {
         CheckUnusedFunctions c;