Pointers: 0 is a null pointer constant

According to MISRA C 2012 8.11 zero is a null pointer constant, and so
should not be flagged as non_compliant.

Author: lcartey

c/common/src/codingstandards/c/Pointers.qll

@@ -62,12 +62,7 @@ class ArrayPointerArithmeticExpr extends PointerArithmeticExpr, ArrayExpr {
 predicate isNullPointerConstant(Expr e) {
   e.findRootCause() instanceof NULLMacro
   or
-  exists(CStyleCast c |
-    not c.isImplicit() and
-    c.getExpr() = e and
-    e instanceof Zero and
-    c.getType() instanceof VoidPointerType
-  )
+  e instanceof Zero
   or
   isNullPointerConstant(e.(Conversion).getExpr())
 }

c/misra/test/rules/RULE-11-4/ConversionBetweenPointerToObjectAndIntegerType.expected

@@ -1,6 +1,3 @@
-| test.c:5:21:5:42 | (unsigned int)... | Cast performed between a pointer to object type and a pointer to an integer type. |
-| test.c:5:35:5:42 | (int *)... | Cast performed between a pointer to object type and a pointer to an integer type. |
 | test.c:6:21:6:37 | (unsigned int)... | Cast performed between a pointer to object type and a pointer to an integer type. |
 | test.c:8:8:8:24 | (unsigned int)... | Cast performed between a pointer to object type and a pointer to an integer type. |
-| test.c:10:22:10:22 | (unsigned int *)... | Cast performed between a pointer to object type and a pointer to an integer type. |
 | test.c:12:22:12:39 | (unsigned int *)... | Cast performed between a pointer to object type and a pointer to an integer type. |

c/misra/test/rules/RULE-11-4/test.c

@@ -2,12 +2,12 @@
 
 void f1(void) {
   unsigned int v1 = (unsigned int)(void *)0; // COMPLIANT
-  unsigned int v2 = (unsigned int)(int *)0;  // NON_COMPLIANT
+  unsigned int v2 = (unsigned int)(int *)0;  // COMPLIANT
   unsigned int v3 = (unsigned int)&v2;       // NON_COMPLIANT
   v3 = v2;                                   // COMPLIANT
   v3 = (unsigned int)&v2;                    // NON_COMPLIANT
   v3 = NULL;                                 // COMPLIANT
-  unsigned int *v4 = 0;                      // NON_COMPLIANT
+  unsigned int *v4 = 0;                      // COMPLIANT
   unsigned int *v5 = NULL;                   // COMPLIANT
   unsigned int *v6 = (unsigned int *)v2;     // NON_COMPLIANT
 }