Fix #11485 FN unusedFunction / Fix #7739 FP unusedFunction (#4707)

Author: chrchr-github

lib/checkunusedfunctions.cpp

@@ -55,6 +55,13 @@ CheckUnusedFunctions CheckUnusedFunctions::instance;
 
 static const struct CWE CWE561(561U);   // Dead Code
 
+static std::string stripTemplateParameters(const std::string& funcName) {
+    std::string name = funcName;
+    const auto pos = name.find('<');
+    if (pos > 0 && pos != std::string::npos)
+        name.erase(pos - 1);
+    return name;
+}
 
 //---------------------------------------------------------------------------
 // FUNCTION USAGE - Check for unused functions etc
@@ -78,13 +85,9 @@ void CheckUnusedFunctions::parseTokens(const Tokenizer &tokenizer, const char Fi
         if (func->isExtern())
             continue;
 
-        // Don't care about templates
-        if (tokenizer.isCPP() && func->templateDef != nullptr)
-            continue;
-
         mFunctionDecl.emplace_back(func);
 
-        FunctionUsage &usage = mFunctions[func->name()];
+        FunctionUsage &usage = mFunctions[stripTemplateParameters(func->name())];
 
         if (!usage.lineNumber)
             usage.lineNumber = func->token->linenr();
@@ -223,11 +226,11 @@ void CheckUnusedFunctions::parseTokens(const Tokenizer &tokenizer, const char Fi
             while (Token::Match(funcname, "%name% :: %name%"))
                 funcname = funcname->tokAt(2);
 
-            if (!Token::Match(funcname, "%name% [(),;]:}>]"))
+            if (!Token::Match(funcname, "%name% [(),;]:}>]") || funcname->varId())
                 continue;
         }
 
-        if (!funcname)
+        if (!funcname || funcname->isKeyword() || funcname->isStandardType())
             continue;
 
         // funcname ( => Assert that the end parentheses isn't followed by {
@@ -240,15 +243,16 @@ void CheckUnusedFunctions::parseTokens(const Tokenizer &tokenizer, const char Fi
         }
 
         if (funcname) {
-            FunctionUsage &func = mFunctions[funcname->str()];
+            const auto baseName = stripTemplateParameters(funcname->str());
+            FunctionUsage &func = mFunctions[baseName];
             const std::string& called_from_file = tokenizer.list.getSourceFilePath();
 
             if (func.filename.empty() || func.filename == "+" || func.filename != called_from_file)
                 func.usedOtherFile = true;
             else
                 func.usedSameFile = true;
 
-            mFunctionCalls.insert(funcname->str());
+            mFunctionCalls.insert(baseName);
         }
     }
 }

lib/forwardanalyzer.cpp

@@ -255,16 +255,6 @@ struct ForwardTraversal {
         return traverseRecursive(tok, f, false);
     }
 
-    template<class T, class F>
-    T* findRange(T* start, const Token* end, F pred) {
-        for (T* tok = start; tok && tok != end; tok = tok->next()) {
-            Analyzer::Action action = analyzer->analyze(tok, Analyzer::Direction::Forward);
-            if (pred(action))
-                return tok;
-        }
-        return nullptr;
-    }
-
     Analyzer::Action analyzeRecursive(const Token* start) {
         Analyzer::Action result = Analyzer::Action::None;
         auto f = [&](const Token* tok) {

lib/token.cpp

@@ -68,6 +68,7 @@ Token::~Token()
  * e.g. for the sequence of tokens A B C D E, C.until(E) would yield the Range C D
  * note t can be nullptr to iterate all the way to the end.
  */
+// cppcheck-suppress unusedFunction // only used in testtokenrange.cpp
 ConstTokenRange Token::until(const Token* t) const
 {
     return ConstTokenRange(this, t);

test/testunusedfunctions.cpp

@@ -50,6 +50,8 @@ class TestUnusedFunctions : public TestFixture {
         TEST_CASE(template5);
         TEST_CASE(template6); // #10475 crash
         TEST_CASE(template7); // #9766 crash
+        TEST_CASE(template8);
+        TEST_CASE(template9);
         TEST_CASE(throwIsNotAFunction);
         TEST_CASE(unusedError);
         TEST_CASE(unusedMain);
@@ -282,6 +284,50 @@ class TestUnusedFunctions : public TestFixture {
         ASSERT_EQUALS("[test.cpp:1]: (style) The function 'f' is never used.\n", errout.str());
     }
 
+    void template8() { // #11485
+        check("struct S {\n"
+              "    template<typename T>\n"
+              "    void tf(const T&) { }\n"
+              "};\n");
+        ASSERT_EQUALS("[test.cpp:3]: (style) The function 'tf' is never used.\n", errout.str());
+
+        check("struct S {\n"
+              "    template<typename T>\n"
+              "    void tf(const T&) { }\n"
+              "};\n"
+              "int main() {\n"
+              "    C c;\n"
+              "    c.tf(1.5);\n"
+              "}\n");
+        ASSERT_EQUALS("", errout.str());
+
+        check("struct S {\n"
+              "    template<typename T>\n"
+              "    void tf(const T&) { }\n"
+              "};\n"
+              "int main() {\n"
+              "    C c;\n"
+              "    c.tf<int>(1);\n"
+              "}\n");
+        ASSERT_EQUALS("", errout.str());
+    }
+
+    void template9() { // #7739
+        check("template<class T>\n"
+              "void f(T const& t) {}\n"
+              "template<class T>\n"
+              "void g(T const& t) {\n"
+              "    f(t);\n"
+              "}\n"
+              "template<>\n"
+              "void f<double>(double const& d) {}\n"
+              "int main() {\n"
+              "    g(2);\n"
+              "    g(3.14);\n"
+              "}\n");
+        ASSERT_EQUALS("", errout.str());
+    }
+
     void throwIsNotAFunction() {
         check("struct A {void f() const throw () {}}; int main() {A a; a.f();}");
         ASSERT_EQUALS("", errout.str());