Tokenizer: simplify calculations with zero better

lib/tokenize.cpp

@@ -6270,6 +6270,29 @@ bool Tokenizer::simplifyCalculations()
 
         if (tok->isNumber())
         {
+            if (tok->str() == "0")
+            {
+                if (Token::Match(tok->previous(), "[+-] 0"))
+                {
+                    tok = tok->previous();
+                    tok->deleteThis();
+                    tok->deleteThis();
+                    ret = true;
+                }
+                else if (Token::Match(tok->previous(), "[=([,] 0 +"))
+                {
+                    tok->deleteThis();
+                    tok->deleteThis();
+                    ret = true;
+                }
+                else if (Token::Match(tok->previous(), "[=[(,] 0 * %any% [+-*/,]);]"))
+                {
+                    tok->deleteNext();
+                    tok->deleteNext();
+                    ret = true;
+                }
+            }
+
             if (Token::simpleMatch(tok->previous(), "* 1") || Token::simpleMatch(tok, "1 *"))
             {
                 if (Token::simpleMatch(tok->previous(), "*"))

test/testbufferoverrun.cpp

@@ -1193,8 +1193,7 @@ private:
               "        data[(i-0)/2] = 0;\n"
               "    }\n"
               "}\n");
-        ASSERT_EQUALS("", errout.str());
+        ASSERT_EQUALS("[test.cpp:5]: (error) Array 'data[8]' index 17 out of bounds\n", errout.str());
-        TODO_ASSERT_EQUALS("[test.cpp:5]: (error) Array index out of bounds\n", errout.str());
     }
 
     void array_index_negative()

test/testsimplifytokens.cpp

@@ -2507,6 +2507,9 @@ private:
         ASSERT_EQUALS("int a [ 4 ] ;", tok("int a[(10)-1-5];"));
         ASSERT_EQUALS("int a [ i - 9 ] ;", tok("int a[i - 10 + 1];"));
 
+        ASSERT_EQUALS("x = y ;", tok("x=0+y+0-0;"));
+        ASSERT_EQUALS("x = 0 ;", tok("x=0*y;"));
+
         ASSERT_EQUALS("x = 501 ;", tok("x = 1000 + 2 >> 1;"));
         ASSERT_EQUALS("x = 125 ;", tok("x = 1000 / 2 >> 2;"));