checkunusedvar: handle initialization list (#2836)

lib/checkunusedvar.cpp

@@ -1135,6 +1135,12 @@ void CheckUnusedVar::checkFunctionVariableUsage_iterateScopes(const Scope* const
                 }
             }
         }
+        else if (tok->variable() && tok->variable()->isClass() && tok->variable()->type() && 
+            (tok->variable()->type()->needInitialization == Type::NeedInitialization::False) && 
+            tok->next()->str() == ";")
+        {
+            variables.write(tok->varId(), tok);
+        }
     }
 }
 
@@ -1471,7 +1477,6 @@ bool CheckUnusedVar::isRecordTypeWithoutSideEffects(const Type* type)
 {
     // a type that has no side effects (no constructors and no members with constructors)
     /** @todo false negative: check constructors for side effects */
-
     const std::pair<std::map<const Type *,bool>::iterator,bool> found=mIsRecordTypeWithoutSideEffectsMap.insert(
                 std::pair<const Type *,bool>(type,false)); //Initialize with side effects for possible recursions
     bool & withoutSideEffects = found.first->second;
@@ -1489,8 +1494,40 @@ bool CheckUnusedVar::isRecordTypeWithoutSideEffects(const Type* type)
         if (f.argDef && Token::simpleMatch(f.argDef->link(), ") ="))
             continue; // ignore default/deleted constructors
         const bool emptyBody = (f.functionScope && Token::simpleMatch(f.functionScope->bodyStart, "{ }"));
-        const bool hasInitList = f.argDef && Token::simpleMatch(f.argDef->link(), ") :");
+
-        if (!emptyBody || hasInitList)
+        Token* nextToken = f.argDef->link();
+        if (Token::simpleMatch(nextToken, ") :")) {
+            // validating initialization list
+            nextToken = nextToken->next(); // goto ":"
+
+            for (const Token *initListToken = nextToken; Token::Match(initListToken, "[:,] %var% [({]"); initListToken = initListToken->linkAt(2)->next())
+            {
+                const Token* varToken = initListToken->next();
+                const Variable* variable = varToken->variable();
+                if (variable && !isVariableWithoutSideEffects(*variable))
+                {
+                    return withoutSideEffects = false;
+                }
+
+                const Token* valueEnd = initListToken->linkAt(2);
+                for (const Token* valueToken = initListToken->tokAt(3); valueToken != valueEnd; valueToken = valueToken->next()) {
+                    const Variable* initValueVar = valueToken->variable();
+                    if (initValueVar && !isVariableWithoutSideEffects(*initValueVar))
+                    {
+                        return withoutSideEffects = false;
+                    }
+                    if ((valueToken->tokType() == Token::Type::eFunction) || 
+                        (valueToken->tokType() == Token::Type::eName) ||
+                        (valueToken->tokType() == Token::Type::eLambda) ||
+                        (valueToken->tokType() == Token::Type::eOther))
+                    {
+                        return withoutSideEffects = false;
+                    }
+                }
+            }
+        }
+
+        if (!emptyBody)
             return (withoutSideEffects = false);
     }
 
@@ -1502,17 +1539,10 @@ bool CheckUnusedVar::isRecordTypeWithoutSideEffects(const Type* type)
 
     // Is there a member variable with possible side effects
     for (const Variable& var : type->classScope->varlist) {
-        if (var.isPointer())
+        withoutSideEffects = isVariableWithoutSideEffects(var);
-            continue;
+        if (!withoutSideEffects)
-
+        {
-        const Type* variableType = var.type();
+            return withoutSideEffects;
-        if (variableType) {
-            if (!isRecordTypeWithoutSideEffects(variableType))
-                return (withoutSideEffects = false);
-        } else {
-            ValueType::Type valueType = var.valueType()->type;
-            if ((valueType == ValueType::Type::UNKNOWN_TYPE) || (valueType == ValueType::Type::NONSTD))
-                return (withoutSideEffects = false);
         }
     }
 
@@ -1520,6 +1550,24 @@ bool CheckUnusedVar::isRecordTypeWithoutSideEffects(const Type* type)
     return (withoutSideEffects = true);
 }
 
+bool CheckUnusedVar::isVariableWithoutSideEffects(const Variable& var)
+{
+    if (var.isPointer())
+        return true;
+
+    const Type* variableType = var.type();
+    if (variableType) {
+        if (!isRecordTypeWithoutSideEffects(variableType))
+            return false;
+    } else {
+        ValueType::Type valueType = var.valueType()->type;
+        if ((valueType == ValueType::Type::UNKNOWN_TYPE) || (valueType == ValueType::Type::NONSTD))
+            return false;
+    }
+
+    return true;
+}
+
 bool CheckUnusedVar::isEmptyType(const Type* type)
 {
     // a type that has no variables and no constructor

lib/checkunusedvar.h

@@ -34,6 +34,7 @@ class Token;
 class Tokenizer;
 class Type;
 class Variables;
+class Variable;
 
 /// @addtogroup Checks
 /// @{
@@ -70,6 +71,7 @@ public:
 
 private:
     bool isRecordTypeWithoutSideEffects(const Type* type);
+    bool isVariableWithoutSideEffects(const Variable& var);
     bool isEmptyType(const Type* type);
 
     // Error messages..

test/testunusedvar.cpp

@@ -286,12 +286,94 @@ private:
             "}");
         ASSERT_EQUALS("[test.cpp:6]: (style) Unused variable: e\n", errout.str());
 
+        functionVariableUsage(
+            "class F {\n"
+            "public:\n"
+            "   F() : x(0) {}\n"
+            "   int x;\n"
+            "};\n"
+            "void f() {\n"
+            "   F f;\n"
+            "}");
+        ASSERT_EQUALS("[test.cpp:7]: (style) Unused variable: f\n", errout.str());
+
+        functionVariableUsage(
+            "class F {\n"
+            "public:\n"
+            "   F() : x{0} {}\n"
+            "   int x;\n"
+            "};\n"
+            "void f() {\n"
+            "   F f;\n"
+            "}");
+        ASSERT_EQUALS("[test.cpp:7]: (style) Unused variable: f\n", errout.str());
+
+        functionVariableUsage(
+            "int y = 0;\n"
+            "class F {\n"
+            "public:\n"
+            "   F() : x(y) {}\n"
+            "   int x;\n"
+            "};\n"
+            "void f() {\n"
+            "   F f;\n"
+            "}");
+        ASSERT_EQUALS("[test.cpp:8]: (style) Unused variable: f\n", errout.str());
+
+        functionVariableUsage(
+            "int y = 0;"
+            "class F {\n"
+            "public:\n"
+            "   F() : x(++y) {}\n"
+            "   int x;\n"
+            "};\n"
+            "void f() {\n"
+            "   F f;\n"
+            "}");
+        ASSERT_EQUALS("[test.cpp:7]: (style) Unused variable: f\n", errout.str());
+
+        functionVariableUsage(
+            "int y = 0;"
+            "class F {\n"
+            "public:\n"
+            "   F() : x(--y) {}\n"
+            "   int x;\n"
+            "};\n"
+            "void f() {\n"
+            "   F f;\n"
+            "}");
+        ASSERT_EQUALS("[test.cpp:7]: (style) Unused variable: f\n", errout.str());
+
+        functionVariableUsage(
+            "int y = 0;"
+            "class F {\n"
+            "public:\n"
+            "   F() : x(y+=1) {}\n"
+            "   int x;\n"
+            "};\n"
+            "void f() {\n"
+            "   F f;\n"
+            "}");
+        ASSERT_EQUALS("[test.cpp:7]: (style) Unused variable: f\n", errout.str());
+
+        functionVariableUsage(
+            "int y = 0;"
+            "class F {\n"
+            "public:\n"
+            "   F() : x(y-=1) {}\n"
+            "   int x;\n"
+            "};\n"
+            "void f() {\n"
+            "   F f;\n"
+            "}");
+        ASSERT_EQUALS("[test.cpp:7]: (style) Unused variable: f\n", errout.str());
+
         // non-empty constructor
         functionVariableUsage(
             "class F {\n"
             "public:\n"
             "   F() {\n"
-            "       int i =0;\n"
+            "       int i = 0;\n"
             "       (void) i;"
             "   }\n"
             "};\n"
@@ -305,7 +387,7 @@ private:
             "class F {\n"
             "public:\n"
             "   F() {\n"
-            "       int i =0;\n"
+            "       int i = 0;\n"
             "       (void) i;"
             "   }\n"
             "};\n"
@@ -318,6 +400,25 @@ private:
             "}");
         ASSERT_EQUALS("", errout.str());
 
+        // side-effect variable in initialization list
+        functionVariableUsage(
+            "class F {\n"
+            "public:\n"
+            "   F() {\n"
+            "       int i = 0;\n"
+            "       (void) i;"
+            "   }\n"
+            "};\n"
+            "class G {\n"
+            "public:\n"
+            "   G() : f(F()) {}\n"
+            "   F f;"
+            "};\n"
+            "void f() {\n"
+            "   G g;\n"
+            "}");
+        ASSERT_EQUALS("", errout.str());
+
         // unknown variable type
         functionVariableUsage(
             "class H {\n"
@@ -329,7 +430,98 @@ private:
             "}");
         ASSERT_EQUALS("", errout.str());
 
+        // unknown variable type in initialization list
+        functionVariableUsage(
+            "class H {\n"
+            "public:\n"
+            "   H() : x{0}, u(1) {}\n"
+            "   int x;"
+            "   unknown_type u;\n"
+            "};\n"
+            "void f() {\n"
+            "   H h;\n"
+            "}");
+        ASSERT_EQUALS("", errout.str());
 
+        // unknown variable type used for initialization 
+        functionVariableUsage(
+            "unknown_type y = 0;\n"
+            "class F {\n"
+            "public:\n"
+            "   F() : x(y) {}\n"
+            "   int x;\n"
+            "};\n"
+            "void f() {\n"
+            "   F f;\n"
+            "}");
+        ASSERT_EQUALS("", errout.str());
+
+        functionVariableUsage(
+            "int sideEffectFunc();\n"
+            "class F {\n"
+            "public:\n"
+            "   F() : x(sideEffectFunc()) {}\n"
+            "   int x;\n"
+            "};\n"
+            "void f() {\n"
+            "   F f;\n"
+            "}");
+        ASSERT_EQUALS("", errout.str());
+
+        functionVariableUsage(
+            "class F {\n"
+            "public:\n"
+            "   F() : x(unknownFunc()) {}\n"
+            "   int x;\n"
+            "};\n"
+            "void f() {\n"
+            "   F f;\n"
+            "}");
+        ASSERT_EQUALS("", errout.str());
+
+        functionVariableUsage(
+            "class F {\n"
+            "public:\n"
+            "   F() : x(++unknownValue) {}\n"
+            "   int x;\n"
+            "};\n"
+            "void f() {\n"
+            "   F f;\n"
+            "}");
+        ASSERT_EQUALS("", errout.str());
+
+        functionVariableUsage(
+            "class F {\n"
+            "public:\n"
+            "   F() : x(--unknownValue) {}\n"
+            "   int x;\n"
+            "};\n"
+            "void f() {\n"
+            "   F f;\n"
+            "}");
+        ASSERT_EQUALS("", errout.str());
+
+        functionVariableUsage(
+            "class F {\n"
+            "public:\n"
+            "   F() : x(unknownValue+=1) {}\n"
+            "   int x;\n"
+            "};\n"
+            "void f() {\n"
+            "   F f;\n"
+            "}");
+        ASSERT_EQUALS("", errout.str());
+        
+        functionVariableUsage(
+            "class F {\n"
+            "public:\n"
+            "   F() : x(unknownValue-=1) {}\n"
+            "   int x;\n"
+            "};\n"
+            "void f() {\n"
+            "   F f;\n"
+            "}");
+        ASSERT_EQUALS("", errout.str());
     }
 
     // #5355 - False positive: Variable is not assigned a value.
@@ -4033,7 +4225,7 @@ private:
                               "    std::cout << \"test\" << std::endl;\n"
                               "    delete fred;\n"
                               "}");
-        ASSERT_EQUALS("", errout.str());
+        ASSERT_EQUALS("[test.cpp:4]: (style) Variable 'fred' is allocated memory that is never used.\n", errout.str());
 
         functionVariableUsage("void foo()\n"
                               "{\n"