Partial fix for #9602 False positives with function pointers (cppcheck-opensource#5042)

* Partial fix for #9602 False positives with function pointers

* Add test for #9222

Author: chrchr-github

lib/checkunusedfunctions.cpp

@@ -223,7 +223,7 @@ void CheckUnusedFunctions::parseTokens(const Tokenizer &tokenizer, const char Fi
             funcname = tok->next();
             while (Token::Match(funcname, "%name% :: %name%"))
                 funcname = funcname->tokAt(2);
-        } else if (tok->scope()->type != Scope::ScopeType::eEnum && Token::Match(tok, "[;{}.,()[=+-/|!?:]")) {
+        } else if (tok->scope()->type != Scope::ScopeType::eEnum && (Token::Match(tok, "[;{}.,()[=+-/|!?:]") || Token::Match(tok, "return|throw"))) {
             funcname = tok->next();
             if (funcname && funcname->str() == "&")
                 funcname = funcname->next();

test/testunusedfunctions.cpp

@@ -37,6 +37,7 @@ class TestUnusedFunctions : public TestFixture {
         TEST_CASE(incondition);
         TEST_CASE(return1);
         TEST_CASE(return2);
+        TEST_CASE(return3);
         TEST_CASE(callback1);
         TEST_CASE(callback2);
         TEST_CASE(else1);
@@ -124,6 +125,24 @@ class TestUnusedFunctions : public TestFixture {
         ASSERT_EQUALS("", errout.str());
     }
 
+    void return3() {
+        check("typedef void (*VoidFunc)();\n" // #9602
+              "void sayHello() {\n"
+              "  printf(\"Hello World\\n\");\n"
+              "}\n"
+              "VoidFunc getEventHandler() {\n"
+              "  return sayHello;\n"
+              "}\n"
+              "void indirectHello() {\n"
+              "  VoidFunc handler = getEventHandler();\n"
+              "  handler();\n"
+              "}\n"
+              "int main() {\n"
+              "  indirectHello();\n"
+              "}");
+        ASSERT_EQUALS("", errout.str());
+    }
+
     void callback1() {
         check("void f1()\n"
               "{\n"
@@ -314,8 +333,8 @@ class TestUnusedFunctions : public TestFixture {
         ASSERT_EQUALS("", errout.str());
     }
 
-    void template9() { // #7739
-        check("template<class T>\n"
+    void template9() {
+        check("template<class T>\n" // #7739
               "void f(T const& t) {}\n"
               "template<class T>\n"
               "void g(T const& t) {\n"
@@ -328,6 +347,12 @@ class TestUnusedFunctions : public TestFixture {
               "    g(3.14);\n"
               "}\n");
         ASSERT_EQUALS("", errout.str());
+
+        check("template <typename T> T f(T);\n" // #9222
+              "template <typename T> T f(T i) { return i; }\n"
+              "template int f<int>(int);\n"
+              "int main() { return f(int(2)); }\n");
+        ASSERT_EQUALS("", errout.str());
     }
 
     void throwIsNotAFunction() {