Fixed #1574 (chain assignments could be simplified)

http://sourceforge.net/apps/trac/cppcheck/ticket/1574

lib/tokenize.cpp

@@ -1400,6 +1400,8 @@ bool Tokenizer::tokenize(std::istream &code, const char FileName[], const std::s
     // Split up variable declarations.
     simplifyVarDecl();
 
+    simplifyVariableMultipleAssign();
+
     // Change initialisation of variable to assignment
     simplifyInitVar();
 
@@ -4645,6 +4647,43 @@ void Tokenizer::simplifyIfAssign()
 }
 
 
+void Tokenizer::simplifyVariableMultipleAssign()
+{
+    for (Token *tok = _tokens; tok; tok = tok->next())
+    {
+        if (Token::Match(tok, "%var% = %var% = %num% ;") ||
+            Token::Match(tok, "%var% = %var% = %var% ;"))
+        {
+
+            // skip intermediate assignments
+            Token *tok2 = tok->previous();
+            while (tok2 &&
+                   tok2->str() == "=" &&
+                   Token::Match(tok2->previous(), "%var%"))
+            {
+                tok2 = tok2->tokAt(-2);
+            }
+
+            if (tok2->str() != ";")
+            {
+                continue;
+            }
+
+            Token *stopAt = tok->tokAt(2);
+            const Token *valueTok = tok->tokAt(4);
+            const std::string value(valueTok->str());
+            tok2 = tok2->next();
+
+            while (tok2 != stopAt)
+            {
+                tok2->next()->insertToken(";");
+                tok2->next()->insertToken(value);
+                tok2 = tok2->tokAt(4);
+            }
+        }
+    }
+}
+
 
 void Tokenizer::simplifyIfNot()
 {

lib/tokenize.h

@@ -187,6 +187,12 @@ public:
      */
     void simplifyIfAssign();
 
+    /**
+     * Simplify multiple assignmetns.
+     * Example: "a = b = c = 0;" => "a = 0; b = 0; c = 0;"
+     */
+    void simplifyVariableMultipleAssign();
+
     /**
      * simplify if-not
      * Example: "if(0==x);" => "if(!x);"

test/testunusedvar.cpp

@@ -74,6 +74,7 @@ private:
         TEST_CASE(localvar9); // ticket #1605
         TEST_CASE(localvar10);
         TEST_CASE(localvar11);
+        TEST_CASE(localvar12);
         TEST_CASE(localvaralias1);
         TEST_CASE(localvaralias2); // ticket #1637
         TEST_CASE(localvarasm);
@@ -892,7 +893,11 @@ private:
                               "    int a, b, c;\n"
                               "    a = b = c = 0;\n"
                               "}\n");
-        ASSERT_EQUALS("[test.cpp:3]: (style) Variable 'a' is assigned a value that is never used\n", errout.str());
+        ASSERT_EQUALS(
+                "[test.cpp:3]: (style) Variable 'a' is assigned a value that is never used\n"
+                "[test.cpp:3]: (style) Variable 'b' is assigned a value that is never used\n"
+                "[test.cpp:3]: (style) Variable 'c' is assigned a value that is never used\n",
+                errout.str());
 
         functionVariableUsage("int * foo()\n"
                               "{\n"
@@ -998,6 +1003,42 @@ private:
         ASSERT_EQUALS("", errout.str());
     }
 
+    void localvar12()
+    {
+        // ticket #1574
+        functionVariableUsage("void foo()\n"
+                              "{\n"
+                              "    int a, b, c, d, e, f;\n"
+                              "    a = b = c = d = e = f = 0;\n"
+                              "\n"
+                              "}\n");
+        ASSERT_EQUALS(
+                "[test.cpp:3]: (style) Variable 'a' is assigned a value that is never used\n"
+                "[test.cpp:3]: (style) Variable 'b' is assigned a value that is never used\n"
+                "[test.cpp:3]: (style) Variable 'c' is assigned a value that is never used\n"
+                "[test.cpp:3]: (style) Variable 'd' is assigned a value that is never used\n"
+                "[test.cpp:3]: (style) Variable 'e' is assigned a value that is never used\n"
+                "[test.cpp:3]: (style) Variable 'f' is assigned a value that is never used\n",
+                errout.str());
+
+        functionVariableUsage("void foo()\n"
+                              "{\n"
+                              "    int a, b, c = 0;\n"
+                              "    a = b = c;\n"
+                              "\n"
+                              "}\n");
+        ASSERT_EQUALS(
+                "[test.cpp:3]: (style) Variable 'a' is assigned a value that is never used\n"
+                "[test.cpp:3]: (style) Variable 'b' is assigned a value that is never used\n",
+                errout.str());
+
+        TODO_ASSERT_EQUALS(
+                "[test.cpp:3]: (style) Variable 'a' is assigned a value that is never used\n"
+                "[test.cpp:3]: (style) Variable 'b' is assigned a value that is never used\n"
+                "[test.cpp:3]: (style) Variable 'c' is assigned a value that is never used\n",
+                errout.str());
+    }
+
     void localvaralias1()
     {
         functionVariableUsage("void foo()\n"