Fixed #9220 (False positive: Unused function check for template parameter)

Author: danmar

lib/checkunusedfunctions.cpp

@@ -197,6 +197,10 @@ void CheckUnusedFunctions::parseTokens(const Tokenizer &tokenizer, const char Fi
             funcname = tok;
         } else if ((lambdaEndToken || tok->scope()->isExecutable()) && Token::Match(tok, "%name% <") && Token::simpleMatch(tok->linkAt(1), "> (")) {
             funcname = tok;
+        } else if (Token::Match(tok, "< %name%") && tok->link()) {
+            funcname = tok->next();
+            while (Token::Match(funcname, "%name% :: %name%"))
+                funcname = funcname->tokAt(2);
         } else if (Token::Match(tok, "[;{}.,()[=+-/|!?:]")) {
             funcname = tok->next();
             if (funcname && funcname->str() == "&")

test/testunusedfunctions.cpp

@@ -45,6 +45,7 @@ class TestUnusedFunctions : public TestFixture {
         TEST_CASE(template2);
         TEST_CASE(template3);
         TEST_CASE(template4); // #9805
+        TEST_CASE(template5);
         TEST_CASE(throwIsNotAFunction);
         TEST_CASE(unusedError);
         TEST_CASE(unusedMain);
@@ -248,6 +249,18 @@ class TestUnusedFunctions : public TestFixture {
         ASSERT_EQUALS("", errout.str());
     }
 
+    void template5() { // #9220
+        check("void f(){}\n"
+              "\n"
+              "typedef void(*Filter)();\n"
+              "\n"
+              "template <Filter fun>\n"
+              "void g() { fun(); }\n"
+              "\n"
+              "int main() { g<f>(); return 0;}");
+        ASSERT_EQUALS("", errout.str());
+    }
+
     void throwIsNotAFunction() {
         check("struct A {void f() const throw () {}}; int main() {A a; a.f();}");
         ASSERT_EQUALS("", errout.str());