Fixed #162 (Initialisation of a variable by itself)

lib/checkother.cpp

@@ -349,6 +349,31 @@ void CheckOther::checkRedundantAssignmentInSwitch()
     }
 }
 
+
+//---------------------------------------------------------------------------
+//    int x = 1;
+//    x = x;            // <- redundant assignment to self
+//
+//    int y = y;        // <- redundant initialization to self
+//---------------------------------------------------------------------------
+void CheckOther::checkSelfAssignment()
+{
+    if (!_settings->_checkCodingStyle)
+        return;
+
+    const char selfAssignmentPattern[] = "%var% = %var% ;|=|)";
+    const Token *tok = Token::findmatch(_tokenizer->tokens(), selfAssignmentPattern);
+    while (tok)
+    {
+        if (tok->varId() && tok->varId() == tok->tokAt(2)->varId())
+        {
+            selfAssignmentError(tok, tok->str());
+        }
+
+        tok = Token::findmatch(tok->next(), selfAssignmentPattern);
+    }
+}
+
 //---------------------------------------------------------------------------
 // strtol(str, 0, radix)  <- radix must be 0 or 2-36
 //---------------------------------------------------------------------------
@@ -4236,3 +4261,9 @@ void CheckOther::redundantAssignmentInSwitchError(const Token *tok, const std::s
     reportError(tok, Severity::style,
                 "redundantAssignInSwitch", "Redundant assignment of \"" + varname + "\" in switch");
 }
+
+void CheckOther::selfAssignmentError(const Token *tok, const std::string &varname)
+{
+    reportError(tok, Severity::style,
+                "selfAssignment", "Redundant assignment of \"" + varname + "\" to itself");
+}

lib/checkother.h

@@ -85,6 +85,7 @@ public:
         checkOther.invalidScanf();
 
         checkOther.nullConstantDereference();
+        checkOther.checkSelfAssignment();
 
         // New type of check: Check execution paths
         checkOther.executionPaths();
@@ -192,6 +193,9 @@ public:
     /** @brief %Check for assigning to the same variable twice in a switch statement*/
     void checkRedundantAssignmentInSwitch();
 
+    /** @brief %Check for assigning a variable to itself*/
+    void checkSelfAssignment();
+
     // Error messages..
     void cstyleCastError(const Token *tok);
     void redundantIfDelete0Error(const Token *tok);
@@ -220,6 +224,7 @@ public:
     void fflushOnInputStreamError(const Token *tok, const std::string &varname);
     void emptyCatchBlockError(const Token *tok);
     void redundantAssignmentInSwitchError(const Token *tok, const std::string &varname);
+    void selfAssignmentError(const Token *tok, const std::string &varname);
 
     void getErrorMessages()
     {
@@ -251,6 +256,7 @@ public:
         sizeofCalculationError(0);
         emptyCatchBlockError(0);
         redundantAssignmentInSwitchError(0, "varname");
+        selfAssignmentError(0, "varname");
         invalidScanfError(0);
 
         // optimisations
@@ -291,6 +297,7 @@ public:
                "* redundant assignment in a switch statement\n"
                "* look for 'sizeof sizeof ..'\n"
                "* look for calculations inside sizeof()\n"
+               "* assignment of a variable to itself\n"
 
                // optimisations
                "* optimisation: detect post increment/decrement\n"

test/testother.cpp

@@ -104,6 +104,7 @@ private:
 
         TEST_CASE(switchRedundantAssignmentTest);
 
+        TEST_CASE(selfAssignment);
         TEST_CASE(testScanf1);
         TEST_CASE(testScanf2);
     }
@@ -136,6 +137,7 @@ private:
         checkOther.checkMathFunctions();
         checkOther.checkEmptyStringTest();
         checkOther.checkFflushOnInputStream();
+        checkOther.checkSelfAssignment();
         checkOther.invalidScanf();
     }
 
@@ -3012,6 +3014,39 @@ private:
         ASSERT_EQUALS("", errout.str());
     }
 
+    void selfAssignment()
+    {
+        check("void foo()\n"
+              "{\n"
+              "        int x = 1;\n"
+              "        x = x;\n"
+              "        return 0;\n"
+              "}\n");
+        ASSERT_EQUALS("[test.cpp:4]: (style) Redundant assignment of \"x\" to itself\n", errout.str());
+
+        check("void foo()\n"
+              "{\n"
+              "        int x = x;\n"
+              "        return 0;\n"
+              "}\n");
+        ASSERT_EQUALS("[test.cpp:3]: (style) Redundant assignment of \"x\" to itself\n", errout.str());
+
+        check("void foo()\n"
+              "{\n"
+              "        std::string var = var = \"test\";\n"
+              "        return 0;\n"
+              "}\n");
+        ASSERT_EQUALS("[test.cpp:3]: (style) Redundant assignment of \"var\" to itself\n", errout.str());
+
+        check("void foo()\n"
+              "{\n"
+              "        int x = 1;\n"
+              "        x = x + 1;\n"
+              "        return 0;\n"
+              "}\n");
+        ASSERT_EQUALS("", errout.str());
+    }
+
     void testScanf1()
     {
         check("#include <stdio.h>\n"