Fix #551 Detect unused Private member variables (#4973)

Author: chrchr-github

lib/checkunusedvar.cpp

@@ -1437,7 +1437,7 @@ void CheckUnusedVar::checkStructMemberUsage()
     const SymbolDatabase *symbolDatabase = mTokenizer->getSymbolDatabase();
 
     for (const Scope &scope : symbolDatabase->scopeList) {
-        if (scope.type != Scope::eStruct && scope.type != Scope::eUnion)
+        if (scope.type != Scope::eStruct && scope.type != Scope::eClass && scope.type != Scope::eUnion)
             continue;
 
         if (scope.bodyStart->fileIndex() != 0 || scope.className.empty())
@@ -1521,16 +1521,21 @@ void CheckUnusedVar::checkStructMemberUsage()
                     break;
                 }
             }
-            if (!use)
-                unusedStructMemberError(var.nameToken(), scope.className, var.name(), scope.type == Scope::eUnion);
+            if (!use) {
+                std::string prefix = "struct";
+                if (scope.type == Scope::ScopeType::eClass)
+                    prefix = "class";
+                else if (scope.type == Scope::ScopeType::eUnion)
+                    prefix = "union";
+                unusedStructMemberError(var.nameToken(), scope.className, var.name(), prefix);
+            }
         }
     }
 }
 
-void CheckUnusedVar::unusedStructMemberError(const Token *tok, const std::string &structname, const std::string &varname, bool isUnion)
+void CheckUnusedVar::unusedStructMemberError(const Token* tok, const std::string& structname, const std::string& varname, const std::string& prefix)
 {
-    const std::string prefix = isUnion ? "union member " : "struct member ";
-    reportError(tok, Severity::style, "unusedStructMember", "$symbol:" + structname + "::" + varname + '\n' + prefix + "'$symbol' is never used.", CWE563, Certainty::normal);
+    reportError(tok, Severity::style, "unusedStructMember", "$symbol:" + structname + "::" + varname + '\n' + prefix + " member '$symbol' is never used.", CWE563, Certainty::normal);
 }
 
 bool CheckUnusedVar::isRecordTypeWithoutSideEffects(const Type* type)

lib/checkunusedvar.h

@@ -77,7 +77,7 @@ class CPPCHECKLIB CheckUnusedVar : public Check {
                                       std::list<const Function*> checkedFuncs);
 
     // Error messages..
-    void unusedStructMemberError(const Token *tok, const std::string &structname, const std::string &varname, bool isUnion = false);
+    void unusedStructMemberError(const Token *tok, const std::string &structname, const std::string &varname, const std::string& prefix = "struct");
     void unusedVariableError(const Token *tok, const std::string &varname);
     void allocatedButUnusedVariableError(const Token *tok, const std::string &varname);
     void unreadVariableError(const Token *tok, const std::string &varname, bool modified);

test/testunusedvar.cpp

@@ -75,6 +75,7 @@ class TestUnusedVar : public TestFixture {
         TEST_CASE(structmember21); // #4759
         TEST_CASE(structmember22); // #11016
         TEST_CASE(structmember23);
+        TEST_CASE(classmember);
 
         TEST_CASE(localvar1);
         TEST_CASE(localvar2);
@@ -1870,6 +1871,13 @@ class TestUnusedVar : public TestFixture {
         ASSERT_EQUALS("", errout.str());
     }
 
+    void classmember() {
+        checkStructMemberUsage("class C {\n"
+                               "    int i{};\n"
+                               "};\n");
+        ASSERT_EQUALS("[test.cpp:2]: (style) class member 'C::i' is never used.\n", errout.str());
+    }
+
     void functionVariableUsage_(const char* file, int line, const char code[], const char filename[] = "test.cpp") {
         // Clear the error buffer..
         errout.str("");