unused variables: fixed false negatives with the help of the symbol database. ticket: #2317

lib/checkother.cpp

@@ -1641,10 +1641,31 @@ void CheckOther::functionVariableUsage()
                     else if (var && var->_type == Variables::pointer &&
                              Token::Match(start, "%var% = new|malloc|calloc|g_malloc|kmalloc|vmalloc"))
                     {
-                        if (start->strAt(2) == "new" && !start->tokAt(3)->isStandardType())
-                            variables.write(varid1);
-                        else
+                        bool allocate = true;
+
+                        if (start->strAt(2) == "new")
+                        {
+                            // is it a user defined type?
+                            if (!start->tokAt(3)->isStandardType())
+                            {
+                                // lookup the type
+                                const SymbolDatabase::SpaceInfo *type = symbolDatabase->findVarType(info, start->tokAt(3));
+
+                                // unknown type?
+                                if (!type)
+                                    allocate = false;
+
+                                // has default constructor or
+                                // has members with unknown type or default constructor
+                                else if (type->needInitialization == SymbolDatabase::SpaceInfo::False)
+                                    allocate = false;
+                            }
+                        }
+
+                        if (allocate)
                             variables.allocateMemory(varid1);
+                        else
+                            variables.write(varid1);
                     }
                     else
                     {

lib/symboldatabase.cpp

@@ -957,6 +957,23 @@ SymbolDatabase::SpaceInfo::SpaceInfo(SymbolDatabase *check_, const Token *classD
         nestedIn->nestedList.push_back(this);
 }
 
+bool
+SymbolDatabase::SpaceInfo::hasDefaultConstructor() const
+{
+    if (numConstructors)
+    {
+        std::list<Func>::const_iterator func;
+
+        for (func = functionList.begin(); func != functionList.end(); ++func)
+        {
+            if (func->type == Func::Constructor &&
+                func->argDef->link() == func->argDef->next())
+                return true;
+        }
+    }
+    return false;
+}
+
 // Get variable list..
 void SymbolDatabase::SpaceInfo::getVarList()
 {

lib/symboldatabase.h

@@ -232,6 +232,8 @@ public:
         unsigned int getNestedNonFunctions() const;
 
         bool isBaseClassFunc(const Token *tok);
+
+        bool hasDefaultConstructor() const;
     };
 
     bool isMemberVar(const SpaceInfo *info, const Token *tok);
@@ -246,6 +248,14 @@ public:
     /** @brief Information about all namespaces/classes/structrues */
     std::list<SpaceInfo *> spaceInfoList;
 
+    /**
+     * @brief find a variable type if it's a user defined type
+     * @param start scope to start looking in
+     * @param type token containing variable type
+     * @return pointer to type if found or NULL if not found
+     */
+    const SpaceInfo *findVarType(const SpaceInfo *start, const Token *type) const;
+
 private:
     void addFunction(SpaceInfo **info, const Token **tok, const Token *argStart);
     void addNewFunction(SpaceInfo **info, const Token **tok);
@@ -253,8 +263,6 @@ private:
     bool isFunction(const Token *tok, const Token **funcStart, const Token **argStart) const;
     bool argsMatch(const SpaceInfo *info, const Token *first, const Token *second, const std::string &path, unsigned int depth) const;
 
-    const SpaceInfo *findVarType(const SpaceInfo *start, const Token *type) const;
-
     const Tokenizer *_tokenizer;
     const Settings *_settings;
     ErrorLogger *_errorLogger;

test/testunusedvar.cpp

@@ -79,6 +79,7 @@ private:
         TEST_CASE(localvar29); // ticket #2206 (array initialization)
         TEST_CASE(localvar30);
         TEST_CASE(localvar31); // ticket #2286
+        TEST_CASE(localvar32); // ticket #2330
         TEST_CASE(localvaralias1);
         TEST_CASE(localvaralias2); // ticket #1637
         TEST_CASE(localvaralias3); // ticket #1639
@@ -1334,6 +1335,16 @@ private:
                               "}\n");
         ASSERT_EQUALS("", errout.str());
     }
+    
+    void localvar32() // ticket #2330
+    {
+        functionVariableUsage("void f() {\n"
+							  "    int x;\n"
+                              "    fstream &f = getfile();\n"
+                              "    f >> x;\n"
+                              "}\n");
+        ASSERT_EQUALS("", errout.str());
+    }
 
     void localvaralias1()
     {
@@ -2556,6 +2567,24 @@ private:
                               "}\n");
         ASSERT_EQUALS("", errout.str());
 
+        functionVariableUsage("struct Fred { int a; };\n"
+                              "void foo()\n"
+                              "{\n"
+                              "    Fred* fred = new Fred;\n"
+                              "    std::cout << \"test\" << std::endl;\n"
+                              "    delete fred;\n"
+                              "}\n");
+        ASSERT_EQUALS("[test.cpp:4]: (style) Variable 'fred' is allocated memory that is never used\n", errout.str());
+
+        functionVariableUsage("struct Fred { int a; Fred() : a(0) {} };\n"
+                              "void foo()\n"
+                              "{\n"
+                              "    Fred* fred = new Fred;\n"
+                              "    std::cout << \"test\" << std::endl;\n"
+                              "    delete fred;\n"
+                              "}\n");
+        ASSERT_EQUALS("", errout.str());
+
         functionVariableUsage("void foo()\n"
                               "{\n"
                               "    Fred* fred = malloc(sizeof(Fred));\n"