Fix #12904 FN unusedFunction with function named like unknown type (#8417)

Author: chrchr-github

lib/checkunusedfunctions.cpp

@@ -261,6 +261,9 @@ void CheckUnusedFunctions::parseTokens(const Tokenizer &tokenizer, const Setting
             while (Token::Match(funcname, "%name% :: %name%"))
                 funcname = funcname->tokAt(2);
 
+            if (funcname && funcname->isName() && !funcname->function() && !tok->astParent() && Token::Match(tok, "[(,]")) // unknown type in parameter list
+                continue;
+
             if (!Token::Match(funcname, "%name% [(),;]:}<>]"))
                 continue;
         }

test/testunusedfunctions.cpp

@@ -86,6 +86,7 @@ class TestUnusedFunctions : public TestFixture {
         TEST_CASE(attributeUnused);
         TEST_CASE(attributeMaybeUnused);
         TEST_CASE(staticFunction);
+        TEST_CASE(unnamedArg);
     }
 
     struct CheckOptions
@@ -827,6 +828,16 @@ class TestUnusedFunctions : public TestFixture {
               "}\n", dinit(CheckOptions, $.cpp = false));
         ASSERT_EQUALS("[test.c:1:6]: (style) The function 'f' should have static linkage since it is not used outside of its translation unit. [staticFunction]\n", errout_str());
     }
+
+    void unnamedArg()
+    {
+        check("struct S {\n" // #12904
+              "    void Type() {}\n"
+              "};\n"
+              "[[unused]] void f(Type) {}\n"
+              "[[unused]] void g(Type, Type) {}\n");
+        ASSERT_EQUALS("[test.cpp:2:10]: (style) The function 'Type' is never used. [unusedFunction]\n", errout_str());
+    }
 };
 
 REGISTER_TEST(TestUnusedFunctions)