Fix #10660 FP: overridden member functions of unknown abstract base c…

…lasses reported as unused (#6564)

.selfcheck_unused_suppressions

@@ -1,15 +1,8 @@
 # we are not using all methods of their interfaces
 unusedFunction:externals/*/*
 
-# TODO: fix these
-# false positive - # 10660
-unusedFunction:gui/mainwindow.cpp
-unusedFunction:gui/resultstree.cpp
-unusedFunction:gui/codeeditor.*
 # usage is disabled
 unusedFunction:lib/symboldatabase.cpp
-# false positive - #10661
-unusedFunction:oss-fuzz/main.cpp
 
 # Q_OBJECT functions which are not called in our code
-unusedFunction:cmake.output.notest/gui/cppcheck-gui_autogen/*/moc_aboutdialog.cpp
+unusedFunction:cmake.output.notest/gui/cppcheck-gui_autogen/*/moc_aboutdialog.cpp

lib/checkunusedfunctions.cpp

@@ -85,6 +85,15 @@ void CheckUnusedFunctions::parseTokens(const Tokenizer &tokenizer, const Setting
             if (func->isExtern())
                 continue;
 
+            bool foundAllBaseClasses{};
+            if (const Function* ofunc = func->getOverriddenFunction(&foundAllBaseClasses)) {
+                if (!foundAllBaseClasses || ofunc->isPure())
+                    continue;
+            }
+            else if (func->isImplicitlyVirtual()) {
+                continue;
+            }
+
             mFunctionDecl.emplace_back(func);
 
             FunctionUsage &usage = mFunctions[stripTemplateParameters(func->name())];

lib/symboldatabase.cpp

@@ -4554,9 +4554,7 @@ void Function::addArguments(const SymbolDatabase *symbolDatabase, const Scope *s
 
 bool Function::isImplicitlyVirtual(bool defaultVal) const
 {
-    if (hasVirtualSpecifier()) //If it has the virtual specifier it's definitely virtual
-        return true;
-    if (hasOverrideSpecifier()) //If it has the override specifier then it's either virtual or not going to compile
+    if (hasVirtualSpecifier() || hasOverrideSpecifier() || hasFinalSpecifier())
         return true;
     bool foundAllBaseClasses = true;
     if (getOverriddenFunction(&foundAllBaseClasses)) //If it overrides a base class's method then it's virtual

test/cli/other_test.py

@@ -831,7 +831,7 @@ def test_showtime_top5_file(tmpdir):
         elif lines[i].startswith('valueFlowEnumValue'):
             assert lines[i].endswith(' - 2 result(s))')
         else:
-            assert lines[i].endswith(' - 1 result(s))')
+            assert lines[i].endswith(' result(s))')
     assert lines[6].startswith('Overall time:')
     assert stderr == ''
 

test/testunusedfunctions.cpp

@@ -82,6 +82,7 @@ class TestUnusedFunctions : public TestFixture {
         TEST_CASE(entrypointsUnix);
 
         TEST_CASE(includes);
+        TEST_CASE(virtualFunc);
     }
 
 #define check(...) check_(__FILE__, __LINE__, __VA_ARGS__)
@@ -711,6 +712,29 @@ class TestUnusedFunctions : public TestFixture {
         check(processed);
         TODO_ASSERT_EQUALS("[test.h:3]: (style) The function 'f' is never used.\n", "[test.cpp:3]: (style) The function 'f' is never used.\n", errout_str());
     }
+
+    void virtualFunc()
+    {
+        check("struct D : public B {\n" // #10660
+              "    virtual void f() {}\n"
+              "    void g() override {}\n"
+              "    void h() final {}\n"
+              "};\n");
+        ASSERT_EQUALS("", errout_str());
+
+        check("struct B {\n"
+              "    virtual void f() = 0;\n"
+              "    void g();\n"
+              "};\n"
+              "struct D : B {\n"
+              "    void f() override {}\n"
+              "};\n"
+              "int main() {\n"
+              "    D d;\n"
+              "    d.g();\n"
+              "}\n");
+        ASSERT_EQUALS("", errout_str());
+    }
 };
 
 REGISTER_TEST(TestUnusedFunctions)