Array index out of bounds: prevent false positive when a dimension for an array is unknown

lib/checkbufferoverrun.cpp

@@ -1093,6 +1093,10 @@ void CheckBufferOverrun::checkScope(const Token *tok, const ArrayInfo &arrayInfo
                     totalElements *= arrayInfo.num(ri);
                 }
 
+                // totalElements == 0 => Unknown size
+                if (totalElements == 0)
+                    continue;
+
                 // just taking the address?
                 const bool addr(Token::Match(tok->previous(), "[.&]") ||
                                 Token::simpleMatch(tok->tokAt(-2), "& ("));

test/testbufferoverrun.cpp

@@ -1159,7 +1159,13 @@ private:
               "}\n");
         ASSERT_EQUALS("[test.cpp:6]: (error) Array 'a[6][6][6]' index a[6][6][2] out of bounds\n", errout.str());
 
-
+        // unknown dim..
+        check("void f()\n"
+              "{\n"
+              "  int a[2][countof(x)] = {{1,2},{3,4}};\n"
+              "  a[0][0] = 0;\n"
+              "}\n");
+        ASSERT_EQUALS("", errout.str());
     }
 
     void array_index_switch_in_for()