typeck.c

来自「GCC编译器源代码」· C语言 代码 · 共 2,225 行 · 第 1/5 页

	  else if (TREE_CODE (ttl) == POINTER_TYPE
		   || TREE_CODE (ttl) == ARRAY_TYPE)
	    {
	      if (comp_ptr_ttypes (ttl, ttr))
		return 1;
	      else if (comp_ptr_ttypes (ttr, ttl))
		return -1;
	      return 0;
	    }
	}

      /* Const and volatile mean something different for function types,
	 so the usual checks are not appropriate.  */
      if (TREE_CODE (ttl) == FUNCTION_TYPE || TREE_CODE (ttl) == METHOD_TYPE)
	return comp_target_types (ttl, ttr, nptrs - 1);

      /* Make sure that the cv-quals change only in the same direction as
	 the target type.  */
      {
	int t;
	int c = TYPE_READONLY (ttl) - TYPE_READONLY (ttr);
	int v = TYPE_VOLATILE (ttl) - TYPE_VOLATILE (ttr);

	if ((c > 0 && v < 0) || (c < 0 && v > 0))
	  return 0;

	if (TYPE_MAIN_VARIANT (ttl) == TYPE_MAIN_VARIANT (ttr))
	  return (c + v < 0) ? -1 : 1;

	t = comp_target_types (ttl, ttr, nptrs - 1);
	if ((t == 1 && c + v >= 0) || (t == -1 && c + v <= 0))
	  return t;

	return 0;
      }
    }

  if (TREE_CODE (ttr) == REFERENCE_TYPE)
    return comp_target_types (TREE_TYPE (ttl), TREE_TYPE (ttr), nptrs);
  if (TREE_CODE (ttr) == ARRAY_TYPE)
    return comp_array_types (comp_target_types, ttl, ttr, 0);
  else if (TREE_CODE (ttr) == FUNCTION_TYPE || TREE_CODE (ttr) == METHOD_TYPE)
    if (comp_target_types (TREE_TYPE (ttl), TREE_TYPE (ttr), nptrs))
      switch (comp_target_parms (TYPE_ARG_TYPES (ttl), TYPE_ARG_TYPES (ttr), 1))
	{
	case 0:
	  return 0;
	case 1:
	  return 1;
	case 2:
	  return -1;
	default:
	  my_friendly_abort (112);
	}
    else
      return 0;

  /* for C++ */
  else if (TREE_CODE (ttr) == OFFSET_TYPE)
    {
      /* Contravariance: we can assign a pointer to base member to a pointer
	 to derived member.  Note difference from simple pointer case, where
	 we can pass a pointer to derived to a pointer to base.  */
      if (comptypes (TYPE_OFFSET_BASETYPE (ttr), TYPE_OFFSET_BASETYPE (ttl), 0))
	return comp_target_types (TREE_TYPE (ttl), TREE_TYPE (ttr), nptrs);
      else if (comptypes (TYPE_OFFSET_BASETYPE (ttl), TYPE_OFFSET_BASETYPE (ttr), 0)
	       && comp_target_types (TREE_TYPE (ttl), TREE_TYPE (ttr), nptrs))
	return -1;
    }
  else if (IS_AGGR_TYPE (ttl))
    {
      if (nptrs < 0)
	return 0;
      if (comptypes (build_pointer_type (ttl), build_pointer_type (ttr), 0))
	return 1;
      if (comptypes (build_pointer_type (ttr), build_pointer_type (ttl), 0))
	return -1;
      return 0;
    }

  return 0;
}

/* If two types share a common base type, return that basetype.
   If there is not a unique most-derived base type, this function
   returns ERROR_MARK_NODE.  */

static tree
common_base_type (tt1, tt2)
     tree tt1, tt2;
{
  tree best = NULL_TREE;
  int i;

  /* If one is a baseclass of another, that's good enough.  */
  if (UNIQUELY_DERIVED_FROM_P (tt1, tt2))
    return tt1;
  if (UNIQUELY_DERIVED_FROM_P (tt2, tt1))
    return tt2;

  /* Otherwise, try to find a unique baseclass of TT1
     that is shared by TT2, and follow that down.  */
  for (i = CLASSTYPE_N_BASECLASSES (tt1)-1; i >= 0; i--)
    {
      tree basetype = TYPE_BINFO_BASETYPE (tt1, i);
      tree trial = common_base_type (basetype, tt2);
      if (trial)
	{
	  if (trial == error_mark_node)
	    return trial;
	  if (best == NULL_TREE)
	    best = trial;
	  else if (best != trial)
	    return error_mark_node;
	}
    }

  /* Same for TT2.  */
  for (i = CLASSTYPE_N_BASECLASSES (tt2)-1; i >= 0; i--)
    {
      tree basetype = TYPE_BINFO_BASETYPE (tt2, i);
      tree trial = common_base_type (tt1, basetype);
      if (trial)
	{
	  if (trial == error_mark_node)
	    return trial;
	  if (best == NULL_TREE)
	    best = trial;
	  else if (best != trial)
	    return error_mark_node;
	}
    }
  return best;
}

/* Subroutines of `comptypes'.  */

/* Return 1 if two parameter type lists PARMS1 and PARMS2
   are equivalent in the sense that functions with those parameter types
   can have equivalent types.
   If either list is empty, we win.
   Otherwise, the two lists must be equivalent, element by element.

   C++: See comment above about TYPE1, TYPE2, STRICT.
   If STRICT == 3, it means checking is strict, but do not compare
   default parameter values.  */

int
compparms (parms1, parms2, strict)
     tree parms1, parms2;
     int strict;
{
  register tree t1 = parms1, t2 = parms2;

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

  if (strict <= 0 && t1 == 0)
	return self_promoting_args_p (t2);
  if (strict < 0 && t2 == 0)
	return self_promoting_args_p (t1);

  while (1)
    {
      if (t1 == 0 && t2 == 0)
	return 1;
      /* If one parmlist is shorter than the other,
	 they fail to match, unless STRICT is <= 0.  */
      if (t1 == 0 || t2 == 0)
	{
	  if (strict > 0)
	    return 0;
	  if (strict < 0)
	    return 1;
	  if (strict == 0)
	    return t1 && TREE_PURPOSE (t1);
	}
      if (! comptypes (TREE_VALUE (t2), TREE_VALUE (t1), strict))
	{
	  if (strict > 0)
	    return 0;
	  if (strict == 0)
	    return t2 == void_list_node && TREE_PURPOSE (t1);
	  return TREE_PURPOSE (t1) || TREE_PURPOSE (t2);
	}

      t1 = TREE_CHAIN (t1);
      t2 = TREE_CHAIN (t2);
    }
}

/* This really wants return whether or not parameter type lists
   would make their owning functions assignment compatible or not.  */

static int
comp_target_parms (parms1, parms2, strict)
     tree parms1, parms2;
     int strict;
{
  register tree t1 = parms1, t2 = parms2;
  int warn_contravariance = 0;

  /* An unspecified parmlist matches any specified parmlist
     whose argument types don't need default promotions.
     @@@ see 13.3.3 for a counterexample...  */

  if (t1 == 0 && t2 != 0)
    {
      cp_pedwarn ("ANSI C++ prohibits conversion from `(%#T)' to `(...)'",
		  parms2);
      return self_promoting_args_p (t2);
    }
  if (t2 == 0)
    return self_promoting_args_p (t1);

  for (; t1 || t2; t1 = TREE_CHAIN (t1), t2 = TREE_CHAIN (t2))
    {
      tree p1, p2;

      /* If one parmlist is shorter than the other,
	 they fail to match, unless STRICT is <= 0.  */
      if (t1 == 0 || t2 == 0)
	{
	  if (strict > 0)
	    return 0;
	  if (strict < 0)
	    return 1 + warn_contravariance;
	  return ((t1 && TREE_PURPOSE (t1)) + warn_contravariance);
	}
      p1 = TREE_VALUE (t1);
      p2 = TREE_VALUE (t2);
      if (p1 == p2)
	continue;

      if ((TREE_CODE (p1) == POINTER_TYPE && TREE_CODE (p2) == POINTER_TYPE)
	  || (TREE_CODE (p1) == REFERENCE_TYPE && TREE_CODE (p2) == REFERENCE_TYPE))
	{
	  if (strict <= 0
	      && (TYPE_MAIN_VARIANT (TREE_TYPE (p1))
		  == TYPE_MAIN_VARIANT (TREE_TYPE (p2))))
	    continue;

	  /* The following is wrong for contravariance,
	     but many programs depend on it.  */
	  if (TREE_TYPE (p1) == void_type_node)
	    continue;
	  if (TREE_TYPE (p2) == void_type_node)
	    {
	      warn_contravariance = 1;
	      continue;
	    }
	  if (IS_AGGR_TYPE (TREE_TYPE (p1)))
	    {
	      if (comptypes (p2, p1, 0) == 0)
		{
		  if (comptypes (p1, p2, 0) != 0)
		    warn_contravariance = 1;
		  else
		    return 0;
		}
	      continue;
	    }
	}
      /* Note backwards order due to contravariance.  */
      if (comp_target_types (p2, p1, 1) == 0)
	{
	  if (comp_target_types (p1, p2, 1))
	    {
	      warn_contravariance = 1;
	      continue;
	    }
	  if (strict != 0)
	    return 0;
	}
      /* Target types are compatible--just make sure that if
	 we use parameter lists, that they are ok as well.  */
      if (TREE_CODE (p1) == FUNCTION_TYPE || TREE_CODE (p1) == METHOD_TYPE)
	switch (comp_target_parms (TYPE_ARG_TYPES (p1),
				   TYPE_ARG_TYPES (p2),
				   strict))
	  {
	  case 0:
	    return 0;
	  case 1:
	    break;
	  case 2:
	    warn_contravariance = 1;
	  }

      if (TREE_PURPOSE (t1) && TREE_PURPOSE (t2))
	{
	  int cmp = simple_cst_equal (TREE_PURPOSE (t1), TREE_PURPOSE (t2));
	  if (cmp < 0)
	    my_friendly_abort (114);
	  if (cmp == 0)
	    return 0;
	}
    }
  return 1 + warn_contravariance;
}

/* 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 an unsigned type the same as TYPE in other respects.

   C++: must make these work for type variants as well.  */

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 signed_or_unsigned_type (1, 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 signed_or_unsigned_type (0, 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)
      || TREE_UNSIGNED (type) == unsignedp)
    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;

  if (processing_template_decl)
    return build_min (SIZEOF_EXPR, sizetype, type);

  if (code == FUNCTION_TYPE)
    {
      if (pedantic || warn_pointer_arith)
	pedwarn ("ANSI C++ forbids taking the sizeof a function type");
      return size_int (1);
    }
  if (code == METHOD_TYPE)
    {
      if (pedantic || warn_pointer_arith)
	pedwarn ("ANSI C++ forbids taking the sizeof a method type");
      return size_int (1);
    }
  if (code == VOID_TYPE)
    {
      if (pedantic || warn_pointer_arith)
	pedwarn ("ANSI C++ forbids taking the sizeof a void type");
      return size_int (1);
    }
  if (code == ERROR_MARK)