c-typeck.c

gcc库的原代码,对编程有很大帮助.

		  if (comptypes (TREE_TYPE (memb), TREE_VALUE (p1)))
		    {
		      TREE_VALUE (n) = TREE_VALUE (p1);
		      if (pedantic)
			pedwarn ("function types not truly compatible in ANSI C");
		      goto parm_done;
		    }
	      }
	    TREE_VALUE (n) = common_type (TREE_VALUE (p1), TREE_VALUE (p2));
	  parm_done: ;
	  }

	t1 = build_function_type (valtype, newargs);
	/* ... falls through ... */
      }

    default:
      return build_type_attribute_variant (t1, attributes);
    }

}

/* Return 1 if TYPE1 and TYPE2 are compatible types for assignment
   or various other operations.  Return 2 if they are compatible
   but a warning may be needed if you use them together.  */

int
comptypes (type1, type2)
     tree type1, type2;
{
  register tree t1 = type1;
  register tree t2 = type2;
  int attrval, val;

  /* Suppress errors caused by previously reported errors.  */

  if (t1 == t2 || TREE_CODE (t1) == ERROR_MARK || TREE_CODE (t2) == ERROR_MARK)
    return 1;

  /* Treat an enum type as the integer type of the same width and 
     signedness.  */

  if (TREE_CODE (t1) == ENUMERAL_TYPE)
    t1 = type_for_size (TYPE_PRECISION (t1), TREE_UNSIGNED (t1));
  if (TREE_CODE (t2) == ENUMERAL_TYPE)
    t2 = type_for_size (TYPE_PRECISION (t2), TREE_UNSIGNED (t2));

  if (t1 == t2)
    return 1;

  /* Different classes of types can't be compatible.  */

  if (TREE_CODE (t1) != TREE_CODE (t2)) return 0;

  /* Qualifiers must match.  */

  if (TYPE_READONLY (t1) != TYPE_READONLY (t2))
    return 0;
  if (TYPE_VOLATILE (t1) != TYPE_VOLATILE (t2))
    return 0;

  /* Allow for two different type nodes which have essentially the same
     definition.  Note that we already checked for equality of the type
     type qualifiers (just above).  */

  if (TYPE_MAIN_VARIANT (t1) == TYPE_MAIN_VARIANT (t2))
    return 1;

#ifndef COMP_TYPE_ATTRIBUTES
#define COMP_TYPE_ATTRIBUTES(t1,t2)	1
#endif

  /* 1 if no need for warning yet, 2 if warning cause has been seen.  */
  if (! (attrval = COMP_TYPE_ATTRIBUTES (t1, t2)))
     return 0;

  /* 1 if no need for warning yet, 2 if warning cause has been seen.  */
  val = 0;

  switch (TREE_CODE (t1))
    {
    case POINTER_TYPE:
      val = (TREE_TYPE (t1) == TREE_TYPE (t2)
	      ? 1 : comptypes (TREE_TYPE (t1), TREE_TYPE (t2)));
      break;

    case FUNCTION_TYPE:
      val = function_types_compatible_p (t1, t2);
      break;

    case ARRAY_TYPE:
      {
	tree d1 = TYPE_DOMAIN (t1);
	tree d2 = TYPE_DOMAIN (t2);
	val = 1;

	/* Target types must match incl. qualifiers.  */
	if (TREE_TYPE (t1) != TREE_TYPE (t2)
	    && 0 == (val = comptypes (TREE_TYPE (t1), TREE_TYPE (t2))))
	  return 0;

	/* Sizes must match unless one is missing or variable.  */
	if (d1 == 0 || d2 == 0 || d1 == d2
	    || TREE_CODE (TYPE_MIN_VALUE (d1)) != INTEGER_CST
	    || TREE_CODE (TYPE_MIN_VALUE (d2)) != INTEGER_CST
	    || TREE_CODE (TYPE_MAX_VALUE (d1)) != INTEGER_CST
	    || TREE_CODE (TYPE_MAX_VALUE (d2)) != INTEGER_CST)
	  break;

	if (! ((TREE_INT_CST_LOW (TYPE_MIN_VALUE (d1))
		  == TREE_INT_CST_LOW (TYPE_MIN_VALUE (d2)))
		 && (TREE_INT_CST_HIGH (TYPE_MIN_VALUE (d1))
		     == TREE_INT_CST_HIGH (TYPE_MIN_VALUE (d2)))
		 && (TREE_INT_CST_LOW (TYPE_MAX_VALUE (d1))
		     == TREE_INT_CST_LOW (TYPE_MAX_VALUE (d2)))
		 && (TREE_INT_CST_HIGH (TYPE_MAX_VALUE (d1))
		     == TREE_INT_CST_HIGH (TYPE_MAX_VALUE (d2)))))
	   val = 0;
        break;
      }

    case RECORD_TYPE:
      if (maybe_objc_comptypes (t1, t2, 0) == 1)
	val = 1;
      break;
    }
  return attrval == 2 && val == 1 ? 2 : val;
}

/* Return 1 if TTL and TTR are pointers to types that are equivalent,
   ignoring their qualifiers.  */

static int
comp_target_types (ttl, ttr)
     tree ttl, ttr;
{
  int val;

  /* Give maybe_objc_comptypes a crack at letting these types through.  */
  if (val = maybe_objc_comptypes (ttl, ttr, 1) >= 0)
    return val;

  val = comptypes (TYPE_MAIN_VARIANT (TREE_TYPE (ttl)),
		   TYPE_MAIN_VARIANT (TREE_TYPE (ttr)));

  if (val == 2 && pedantic)
    pedwarn ("types are not quite compatible");
  return val;
}

/* Subroutines of `comptypes'.  */

/* Return 1 if two function types F1 and F2 are compatible.
   If either type specifies no argument types,
   the other must specify a fixed number of self-promoting arg types.
   Otherwise, if one type specifies only the number of arguments, 
   the other must specify that number of self-promoting arg types.
   Otherwise, the argument types must match.  */

static int
function_types_compatible_p (f1, f2)
     tree f1, f2;
{
  tree args1, args2;
  /* 1 if no need for warning yet, 2 if warning cause has been seen.  */
  int val = 1;
  int val1;

  if (!(TREE_TYPE (f1) == TREE_TYPE (f2)
	|| (val = comptypes (TREE_TYPE (f1), TREE_TYPE (f2)))))
    return 0;

  args1 = TYPE_ARG_TYPES (f1);
  args2 = TYPE_ARG_TYPES (f2);

  /* An unspecified parmlist matches any specified parmlist
     whose argument types don't need default promotions.  */

  if (args1 == 0)
    {
      if (!self_promoting_args_p (args2))
	return 0;
      /* If one of these types comes from a non-prototype fn definition,
	 compare that with the other type's arglist.
	 If they don't match, ask for a warning (but no error).  */
      if (TYPE_ACTUAL_ARG_TYPES (f1)
	  && 1 != type_lists_compatible_p (args2, TYPE_ACTUAL_ARG_TYPES (f1)))
	val = 2;
      return val;
    }
  if (args2 == 0)
    {
      if (!self_promoting_args_p (args1))
	return 0;
      if (TYPE_ACTUAL_ARG_TYPES (f2)
	  && 1 != type_lists_compatible_p (args1, TYPE_ACTUAL_ARG_TYPES (f2)))
	val = 2;
      return val;
    }

  /* Both types have argument lists: compare them and propagate results.  */
  val1 = type_lists_compatible_p (args1, args2);
  return val1 != 1 ? val1 : val;
}

/* Check two lists of types for compatibility,
   returning 0 for incompatible, 1 for compatible,
   or 2 for compatible with warning.  */

static int
type_lists_compatible_p (args1, args2)
     tree args1, args2;
{
  /* 1 if no need for warning yet, 2 if warning cause has been seen.  */
  int val = 1;
  int newval = 0;

  while (1)
    {
      if (args1 == 0 && args2 == 0)
	return val;
      /* If one list is shorter than the other,
	 they fail to match.  */
      if (args1 == 0 || args2 == 0)
	return 0;
      /* A null pointer instead of a type
	 means there is supposed to be an argument
	 but nothing is specified about what type it has.
	 So match anything that self-promotes.  */
      if (TREE_VALUE (args1) == 0)
	{
	  if (! self_promoting_type_p (TREE_VALUE (args2)))
	    return 0;
	}
      else if (TREE_VALUE (args2) == 0)
	{
	  if (! self_promoting_type_p (TREE_VALUE (args1)))
	    return 0;
	}
      else if (! (newval = comptypes (TREE_VALUE (args1), TREE_VALUE (args2))))
	{
	  /* Allow  wait (union {union wait *u; int *i} *)
	     and  wait (union wait *)  to be compatible.  */
	  if (TREE_CODE (TREE_VALUE (args1)) == UNION_TYPE
	      && (TYPE_NAME (TREE_VALUE (args1)) == 0
		  || TYPE_TRANSPARENT_UNION (TREE_VALUE (args1)))
	      && TREE_CODE (TYPE_SIZE (TREE_VALUE (args1))) == INTEGER_CST
	      && tree_int_cst_equal (TYPE_SIZE (TREE_VALUE (args1)),
				     TYPE_SIZE (TREE_VALUE (args2))))
	    {
	      tree memb;
	      for (memb = TYPE_FIELDS (TREE_VALUE (args1));
		   memb; memb = TREE_CHAIN (memb))
		if (comptypes (TREE_TYPE (memb), TREE_VALUE (args2)))
		  break;
	      if (memb == 0)
		return 0;
	    }
	  else if (TREE_CODE (TREE_VALUE (args2)) == UNION_TYPE
		   && (TYPE_NAME (TREE_VALUE (args2)) == 0
		       || TYPE_TRANSPARENT_UNION (TREE_VALUE (args2)))
		   && TREE_CODE (TYPE_SIZE (TREE_VALUE (args2))) == INTEGER_CST
		   && tree_int_cst_equal (TYPE_SIZE (TREE_VALUE (args2)),
					  TYPE_SIZE (TREE_VALUE (args1))))
	    {
	      tree memb;
	      for (memb = TYPE_FIELDS (TREE_VALUE (args2));
		   memb; memb = TREE_CHAIN (memb))
		if (comptypes (TREE_TYPE (memb), TREE_VALUE (args1)))
		  break;
	      if (memb == 0)
		return 0;
	    }
	  else
	    return 0;
	}

      /* comptypes said ok, but record if it said to warn.  */
      if (newval > val)
	val = newval;

      args1 = TREE_CHAIN (args1);
      args2 = TREE_CHAIN (args2);
    }
}

/* Return 1 if PARMS specifies a fixed number of parameters
   and none of their types is affected by default promotions.  */

int
self_promoting_args_p (parms)
     tree parms;
{
  register tree t;
  for (t = parms; t; t = TREE_CHAIN (t))
    {
      register tree type = TREE_VALUE (t);

      if (TREE_CHAIN (t) == 0 && type != void_type_node)
	return 0;

      if (type == 0)
	return 0;

      if (TYPE_MAIN_VARIANT (type) == float_type_node)
	return 0;

      if (C_PROMOTING_INTEGER_TYPE_P (type))
	return 0;
    }
  return 1;
}

/* Return 1 if TYPE is not affected by default promotions.  */

static int
self_promoting_type_p (type)
     tree type;
{
  if (TYPE_MAIN_VARIANT (type) == float_type_node)
    return 0;

  if (C_PROMOTING_INTEGER_TYPE_P (type))
    return 0;

  return 1;
}

/* Return an unsigned type the same as TYPE in other respects.  */

tree
unsigned_type (type)
     tree type;
{
  tree type1 = TYPE_MAIN_VARIANT (type);
  if (type1 == signed_char_type_node || type1 == char_type_node)
    return unsigned_char_type_node;
  if (type1 == integer_type_node)
    return unsigned_type_node;
  if (type1 == short_integer_type_node)
    return short_unsigned_type_node;
  if (type1 == long_integer_type_node)
    return long_unsigned_type_node;
  if (type1 == long_long_integer_type_node)
    return long_long_unsigned_type_node;
  if (type1 == intDI_type_node)
    return unsigned_intDI_type_node;
  if (type1 == intSI_type_node)
    return unsigned_intSI_type_node;
  if (type1 == intHI_type_node)
    return unsigned_intHI_type_node;
  if (type1 == intQI_type_node)
    return unsigned_intQI_type_node;
  return type;
}

/* Return a signed type the same as TYPE in other respects.  */

tree
signed_type (type)
     tree type;
{
  tree type1 = TYPE_MAIN_VARIANT (type);
  if (type1 == unsigned_char_type_node || type1 == char_type_node)
    return signed_char_type_node;
  if (type1 == unsigned_type_node)
    return integer_type_node;
  if (type1 == short_unsigned_type_node)
    return short_integer_type_node;
  if (type1 == long_unsigned_type_node)
    return long_integer_type_node;
  if (type1 == long_long_unsigned_type_node)
    return long_long_integer_type_node;
  if (type1 == unsigned_intDI_type_node)
    return intDI_type_node;
  if (type1 == unsigned_intSI_type_node)
    return intSI_type_node;
  if (type1 == unsigned_intHI_type_node)
    return intHI_type_node;
  if (type1 == unsigned_intQI_type_node)
    return intQI_type_node;
  return type;
}

/* Return a type the same as TYPE except unsigned or
   signed according to UNSIGNEDP.  */

tree
signed_or_unsigned_type (unsignedp, type)
     int unsignedp;
     tree type;
{
  if (! INTEGRAL_TYPE_P (type))
    return type;
  if (TYPE_PRECISION (type) == TYPE_PRECISION (signed_char_type_node))
    return unsignedp ? unsigned_char_type_node : signed_char_type_node;
  if (TYPE_PRECISION (type) == TYPE_PRECISION (integer_type_node)) 
    return unsignedp ? unsigned_type_node : integer_type_node;
  if (TYPE_PRECISION (type) == TYPE_PRECISION (short_integer_type_node)) 
    return unsignedp ? short_unsigned_type_node : short_integer_type_node;
  if (TYPE_PRECISION (type) == TYPE_PRECISION (long_integer_type_node)) 
    return unsignedp ? long_unsigned_type_node : long_integer_type_node;
  if (TYPE_PRECISION (type) == TYPE_PRECISION (long_long_integer_type_node)) 
    return (unsignedp ? long_long_unsigned_type_node
	    : long_long_integer_type_node);
  return type;
}

/* Compute the value of the `sizeof' operator.  */

tree
c_sizeof (type)
     tree type;
{
  enum tree_code code = TREE_CODE (type);
  tree t;