decl2.c

gcc库的原代码,对编程有很大帮助.

   C++:

   If class A defines that certain functions in class B are friends, then
   the way I have set things up, it is B who is interested in permission
   granted by A.  However, it is in A's context that these declarations
   are parsed.  By returning a void_type_node, class A does not attempt
   to incorporate the declarations of the friends within its structure.

   DO NOT MAKE ANY CHANGES TO THIS CODE WITHOUT MAKING CORRESPONDING
   CHANGES TO CODE IN `start_method'.  */

tree
grokfield (declarator, declspecs, raises, init, asmspec_tree, attrlist)
     tree declarator, declspecs, raises, init, asmspec_tree, attrlist;
{
  register tree value;
  char *asmspec = 0;
  int flags = LOOKUP_ONLYCONVERTING;

  /* Convert () initializers to = initializers.  */
  if (init == NULL_TREE && declarator != NULL_TREE
      && TREE_CODE (declarator) == CALL_EXPR
      && TREE_OPERAND (declarator, 0)
      && (TREE_CODE (TREE_OPERAND (declarator, 0)) == IDENTIFIER_NODE
	  || TREE_CODE (TREE_OPERAND (declarator, 0)) == SCOPE_REF)
      && parmlist_is_exprlist (TREE_OPERAND (declarator, 1)))
    {
      init = TREE_OPERAND (declarator, 1);
      declarator = TREE_OPERAND (declarator, 0);
      flags = 0;
    }

  if (init
      && TREE_CODE (init) == TREE_LIST
      && TREE_VALUE (init) == error_mark_node
      && TREE_CHAIN (init) == NULL_TREE)
	init = NULL_TREE;

  value = grokdeclarator (declarator, declspecs, FIELD, init != 0,
			  raises, attrlist);
  if (! value)
    return value; /* friend or constructor went bad.  */

  /* Pass friendly classes back.  */
  if (TREE_CODE (value) == VOID_TYPE)
    return void_type_node;

  if (DECL_NAME (value) != NULL_TREE
      && IDENTIFIER_POINTER (DECL_NAME (value))[0] == '_'
      && ! strcmp (IDENTIFIER_POINTER (DECL_NAME (value)), "_vptr"))
    cp_error ("member `%D' conflicts with virtual function table field name", value);

  /* Stash away type declarations.  */
  if (TREE_CODE (value) == TYPE_DECL)
    {
      DECL_NONLOCAL (value) = 1;
      DECL_CONTEXT (value) = current_class_type;
      DECL_CLASS_CONTEXT (value) = current_class_type;
      CLASSTYPE_LOCAL_TYPEDECLS (current_class_type) = 1;

      /* If we declare a typedef name for something that has no name,
	 the typedef name is used for linkage.  See 7.1.3 p4 94/0158. */
      if (TYPE_NAME (TREE_TYPE (value))
	  && TREE_CODE (TYPE_NAME (TREE_TYPE (value))) == TYPE_DECL
	  && ANON_AGGRNAME_P (TYPE_IDENTIFIER (TREE_TYPE (value))))
	{
	  TYPE_NAME (TREE_TYPE (value)) = value;
	  TYPE_STUB_DECL (TREE_TYPE (value)) = value;
	}

      pushdecl_class_level (value);
      return value;
    }

  if (IS_SIGNATURE (current_class_type)
      && TREE_CODE (value) != FUNCTION_DECL)
    {
      error ("field declaration not allowed in signature");
      return void_type_node;
    }

  if (DECL_IN_AGGR_P (value))
    {
      cp_error ("`%D' is already defined in the class %T", value,
		  DECL_CONTEXT (value));
      return void_type_node;
    }

  if (flag_cadillac)
    cadillac_start_decl (value);

  if (asmspec_tree)
    asmspec = TREE_STRING_POINTER (asmspec_tree);

  if (init)
    {
      if (IS_SIGNATURE (current_class_type)
	  && TREE_CODE (value) == FUNCTION_DECL)
	{
	  error ("function declarations cannot have initializers in signature");
	  init = NULL_TREE;
	}
      else if (TREE_CODE (value) == FUNCTION_DECL)
	{
	  grok_function_init (value, init);
	  init = NULL_TREE;
	}
      else if (pedantic && TREE_CODE (value) != VAR_DECL)
	/* Already complained in grokdeclarator.  */
	init = NULL_TREE;
      else
	{
	  /* We allow initializers to become parameters to base
             initializers.  */
	  if (TREE_CODE (init) == TREE_LIST)
	    {
	      if (TREE_CHAIN (init) == NULL_TREE)
		init = TREE_VALUE (init);
	      else
		init = digest_init (TREE_TYPE (value), init, (tree *)0);
	    }
	  
	  if (TREE_CODE (init) == CONST_DECL)
	    init = DECL_INITIAL (init);
	  else if (TREE_READONLY_DECL_P (init))
	    init = decl_constant_value (init);
	  else if (TREE_CODE (init) == CONSTRUCTOR)
	    init = digest_init (TREE_TYPE (value), init, (tree *)0);
	  my_friendly_assert (TREE_PERMANENT (init), 192);
	  if (init == error_mark_node)
	    /* We must make this look different than `error_mark_node'
	       because `decl_const_value' would mis-interpret it
	       as only meaning that this VAR_DECL is defined.  */
	    init = build1 (NOP_EXPR, TREE_TYPE (value), init);
	  else if (! TREE_CONSTANT (init))
	    {
	      /* We can allow references to things that are effectively
		 static, since references are initialized with the address.  */
	      if (TREE_CODE (TREE_TYPE (value)) != REFERENCE_TYPE
		  || (TREE_STATIC (init) == 0
		      && (TREE_CODE_CLASS (TREE_CODE (init)) != 'd'
			  || DECL_EXTERNAL (init) == 0)))
		{
		  error ("field initializer is not constant");
		  init = error_mark_node;
		}
	    }
	}
    }

  /* The corresponding pop_obstacks is in cp_finish_decl.  */
  push_obstacks_nochange ();

  if (TREE_CODE (value) == VAR_DECL)
    {
      /* We cannot call pushdecl here, because that would
	 fill in the value of our TREE_CHAIN.  Instead, we
	 modify cp_finish_decl to do the right thing, namely, to
	 put this decl out straight away.  */
      if (TREE_PUBLIC (value))
	{
	  /* current_class_type can be NULL_TREE in case of error.  */
	  if (asmspec == 0 && current_class_type)
	    {
	      TREE_PUBLIC (value) = 1;
	      DECL_INITIAL (value) = error_mark_node;
	      DECL_ASSEMBLER_NAME (value)
		= build_static_name (current_class_type, DECL_NAME (value));
	    }
	  pending_statics = perm_tree_cons (NULL_TREE, value, pending_statics);

	  /* Static consts need not be initialized in the class definition.  */
	  if (init != NULL_TREE && TYPE_NEEDS_CONSTRUCTING (TREE_TYPE (value)))
	    {
	      static int explanation = 0;

	      error ("initializer invalid for static member with constructor");
	      if (explanation++ == 0)
		error ("(you really want to initialize it separately)");
	      init = 0;
	    }
	  /* Force the compiler to know when an uninitialized static
	     const member is being used.  */
	  if (TYPE_READONLY (value) && init == 0)
	    TREE_USED (value) = 1;
	}
      DECL_INITIAL (value) = init;
      DECL_IN_AGGR_P (value) = 1;

      cp_finish_decl (value, init, asmspec_tree, 1, flags);
      pushdecl_class_level (value);
      return value;
    }
  if (TREE_CODE (value) == FIELD_DECL)
    {
      if (asmspec)
	{
	  /* This must override the asm specifier which was placed
	     by grokclassfn.  Lay this out fresh.  */
	  DECL_RTL (value) = NULL_RTX;
	  DECL_ASSEMBLER_NAME (value) = get_identifier (asmspec);
	}
      if (DECL_INITIAL (value) == error_mark_node)
	init = error_mark_node;
      cp_finish_decl (value, init, asmspec_tree, 1, flags);
      DECL_INITIAL (value) = init;
      DECL_IN_AGGR_P (value) = 1;
      return value;
    }
  if (TREE_CODE (value) == FUNCTION_DECL)
    {
      check_default_args (value);
      if (DECL_CHAIN (value) != NULL_TREE)
	{
	  /* Need a fresh node here so that we don't get circularity
	     when we link these together.  */
	  value = copy_node (value);
	  /* When does this happen?  */
	  my_friendly_assert (init == NULL_TREE, 193);
	}
      if (asmspec)
	{
	  /* This must override the asm specifier which was placed
	     by grokclassfn.  Lay this out fresh.  */
	  DECL_RTL (value) = NULL_RTX;
	  DECL_ASSEMBLER_NAME (value) = get_identifier (asmspec);
	}
      cp_finish_decl (value, init, asmspec_tree, 1, flags);

      /* Pass friends back this way.  */
      if (DECL_FRIEND_P (value))
	return void_type_node;

#if 0 /* Just because a fn is declared doesn't mean we'll try to define it.  */
      if (current_function_decl && ! IS_SIGNATURE (current_class_type))
	cp_error ("method `%#D' of local class must be defined in class body",
		  value);
#endif

      DECL_IN_AGGR_P (value) = 1;
      return value;
    }
  my_friendly_abort (21);
  /* NOTREACHED */
  return NULL_TREE;
}

/* Like `grokfield', but for bitfields.
   WIDTH is non-NULL for bit fields only, and is an INTEGER_CST node.  */

tree
grokbitfield (declarator, declspecs, width)
     tree declarator, declspecs, width;
{
  register tree value = grokdeclarator (declarator, declspecs, BITFIELD,
					0, NULL_TREE, NULL_TREE);

  if (! value) return NULL_TREE; /* friends went bad.  */

  /* Pass friendly classes back.  */
  if (TREE_CODE (value) == VOID_TYPE)
    return void_type_node;

  if (TREE_CODE (value) == TYPE_DECL)
    {
      cp_error ("cannot declare `%D' to be a bitfield type", value);
      return NULL_TREE;
    }

  if (IS_SIGNATURE (current_class_type))
    {
      error ("field declaration not allowed in signature");
      return void_type_node;
    }

  if (DECL_IN_AGGR_P (value))
    {
      cp_error ("`%D' is already defined in the class %T", value,
		  DECL_CONTEXT (value));
      return void_type_node;
    }

  GNU_xref_member (current_class_name, value);

  if (TREE_STATIC (value))
    {
      cp_error ("static member `%D' cannot be a bitfield", value);
      return NULL_TREE;
    }
  cp_finish_decl (value, NULL_TREE, NULL_TREE, 0, 0);

  if (width != error_mark_node)
    {
      /* detect invalid field size.  */
      if (TREE_CODE (width) == CONST_DECL)
	width = DECL_INITIAL (width);
      else if (TREE_READONLY_DECL_P (width))
	width = decl_constant_value (width);
      if (TREE_CODE (width) != INTEGER_CST)
	{
	  cp_error ("structure field `%D' width not an integer constant",
		      value);
	  DECL_INITIAL (value) = NULL_TREE;
	}
      else
	{
	  constant_expression_warning (width);
	  DECL_INITIAL (value) = width;
	  DECL_BIT_FIELD (value) = 1;
	}
    }

  DECL_IN_AGGR_P (value) = 1;
  return value;
}

#if 0
/* Like GROKFIELD, except that the declarator has been
   buried in DECLSPECS.  Find the declarator, and
   return something that looks like it came from
   GROKFIELD.  */
tree
groktypefield (declspecs, parmlist)
     tree declspecs;
     tree parmlist;
{
  tree spec = declspecs;
  tree prev = NULL_TREE;

  tree type_id = NULL_TREE;
  tree quals = NULL_TREE;
  tree lengths = NULL_TREE;
  tree decl = NULL_TREE;

  while (spec)
    {
      register tree id = TREE_VALUE (spec);

      if (TREE_CODE (spec) != TREE_LIST)
	/* Certain parse errors slip through.  For example,
	   `int class ();' is not caught by the parser. Try
	   weakly to recover here.  */
	return NULL_TREE;

      if (TREE_CODE (id) == TYPE_DECL
	  || (TREE_CODE (id) == IDENTIFIER_NODE && TREE_TYPE (id)))
	{
	  /* We have a constructor/destructor or
	     conversion operator.  Use it.  */
	  if (prev)
	    TREE_CHAIN (prev) = TREE_CHAIN (spec);
	  else
	    declspecs = TREE_CHAIN (spec);

	  type_id = id;
	  goto found;
	}
      prev = spec;
      spec = TREE_CHAIN (spec);
    }

  /* Nope, we have a conversion operator to a scalar type or something
     else, that includes things like constructor declarations for
     templates.  */
  spec = declspecs;
  while (spec)
    {
      tree id = TREE_VALUE (spec);

      if (TREE_CODE (id) == IDENTIFIER_NODE)
	{
	  if (id == ridpointers[(int)RID_INT]
	      || id == ridpointers[(int)RID_DOUBLE]
	      || id == ridpointers[(int)RID_FLOAT]
	      || id == ridpointers[(int)RID_WCHAR])
	    {
	      if (type_id)
		error ("extra `%s' ignored",
		       IDENTIFIER_POINTER (id));
	      else
		type_id = id;
	    }
	  else if (id == ridpointers[(int)RID_LONG]
		   || id == ridpointers[(int)RID_SHORT]
		   || id == ridpointers[(int)RID_CHAR])
	    {
	      lengths = tree_cons (NULL_TREE, id, lengths);
	    }
	  else if (id == ridpointers[(int)RID_VOID])
	    {
	      if (type_id)
		error ("spurious `void' type ignored");
	      else
		error ("conversion to `void' type invalid");
	    }
	  else if (id == ridpointers[(int)RID_AUTO]
		   || id == ridpointers[(int)RID_REGISTER]
		   || id == ridpointers[(int)RID_TYPEDEF]
		   || id == ridpointers[(int)RID_CONST]
		   || id == ridpointers[(int)RID_VOLATILE])
	    {
	      error ("type specifier `%s' used invalidly",
		     IDENTIFIER_POINTER (id));
	    }
	  else if (id == ridpointers[(int)RID_FRIEND]
		   || id == ridpointers[(int)RID_VIRTUAL]
		   || id == ridpointers[(int)RID_INLINE]
		   || id == ridpointers[(int)RID_UNSIGNED]
		   || id == ridpointers[(int)RID_SIGNED]
		   || id == ridpointers[(int)RID_STATIC]
		   || id == ridpointers[(int)RID_EXTERN])
	    {
	      quals = tree_cons (NULL_TREE, id, quals);
	    }
	  else
	    {
	      /* Happens when we have a global typedef
		 and a class-local member function with
		 the same name.  */
	      type_id = id;
	      goto found;
	    }
	}
      else if (TREE_CODE (id) == RECORD_TYPE)
	{
	  type_id = TYPE_NAME (id);
	  if (TREE_CODE (type_id) == TYPE_DECL)
	    type_id = DECL_NAME (type_id);
	  if (type_id == NULL_TREE)
	    error ("identifier for aggregate type conversion omitted");
	}
      else if (TREE_CODE_CLASS (TREE_CODE (id)) == 't')
	error ("`operator' missing on conversion operator or tag missing from type");
      else
	my_friendly_abort (194);
      spec = TREE_CHAIN (spec);
    }

  if (type_id)
    declspecs = chainon (lengths, quals);
  else if (lengths)
    {