pt.c

gcc-2.95.3 Linux下最常用的C编译器

/* Handle parameterized types (templates) for GNU C++.
   Copyright (C) 1992, 93-97, 1998, 1999 Free Software Foundation, Inc.
   Written by Ken Raeburn ([e-mail]) while at Watchmaker Computing.
   Rewritten by Jason Merrill ([e-mail]).

This file is part of GNU CC.

GNU CC is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.

GNU CC is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with GNU CC; see the file COPYING.  If not, write to
the Free Software Foundation, 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA.  */

/* Known bugs or deficiencies include:

     all methods must be provided in header files; can't use a source
     file that contains only the method templates and "just win".  */

#include "config.h"
#include "system.h"
#include "obstack.h"

#include "tree.h"
#include "flags.h"
#include "cp-tree.h"
#include "decl.h"
#include "parse.h"
#include "lex.h"
#include "output.h"
#include "defaults.h"
#include "except.h"
#include "toplev.h"
#include "rtl.h"
#include "varray.h"

/* The type of functions taking a tree, and some additional data, and
   returning an int.  */
typedef int (*tree_fn_t) PROTO((tree, void*));

extern struct obstack permanent_obstack;

extern int lineno;
extern char *input_filename;

tree current_template_parms;
HOST_WIDE_INT processing_template_decl;

/* The PENDING_TEMPLATES is a TREE_LIST of templates whose
   instantiations have been deferred, either because their definitions
   were not yet available, or because we were putting off doing the
   work.  The TREE_PURPOSE of each entry is a SRCLOC indicating where
   the instantiate request occurred; the TREE_VALUE is a either a DECL
   (for a function or static data member), or a TYPE (for a class)
   indicating what we are hoping to instantiate.  */
static tree pending_templates;
static tree *template_tail = &pending_templates;

static tree maybe_templates;
static tree *maybe_template_tail = &maybe_templates;

int minimal_parse_mode;

int processing_specialization;
int processing_explicit_instantiation;
int processing_template_parmlist;
static int template_header_count;

static tree saved_trees;
static varray_type inline_parm_levels;
static size_t inline_parm_levels_used;

#define obstack_chunk_alloc xmalloc
#define obstack_chunk_free free

#define UNIFY_ALLOW_NONE 0
#define UNIFY_ALLOW_MORE_CV_QUAL 1
#define UNIFY_ALLOW_LESS_CV_QUAL 2
#define UNIFY_ALLOW_DERIVED 4
#define UNIFY_ALLOW_INTEGER 8

#define GTB_VIA_VIRTUAL 1 /* The base class we are examining is
			     virtual, or a base class of a virtual
			     base.  */
#define GTB_IGNORE_TYPE 2 /* We don't need to try to unify the current
			     type with the desired type.  */

static int resolve_overloaded_unification PROTO((tree, tree, tree, tree,
						 unification_kind_t, int));
static int try_one_overload PROTO((tree, tree, tree, tree, tree,
				   unification_kind_t, int));
static int unify PROTO((tree, tree, tree, tree, int));
static void add_pending_template PROTO((tree));
static int push_tinst_level PROTO((tree));
static tree classtype_mangled_name PROTO((tree));
static char *mangle_class_name_for_template PROTO((char *, tree, tree));
static tree tsubst_expr_values PROTO((tree, tree));
static int list_eq PROTO((tree, tree));
static tree get_class_bindings PROTO((tree, tree, tree));
static tree coerce_template_parms PROTO((tree, tree, tree, int, int));
static void tsubst_enum	PROTO((tree, tree, tree));
static tree add_to_template_args PROTO((tree, tree));
static tree add_outermost_template_args PROTO((tree, tree));
static void maybe_adjust_types_for_deduction PROTO((unification_kind_t, tree*,
						    tree*)); 
static int  type_unification_real PROTO((tree, tree, tree, tree,
					 int, unification_kind_t, int));
static void note_template_header PROTO((int));
static tree maybe_fold_nontype_arg PROTO((tree));
static tree convert_nontype_argument PROTO((tree, tree));
static tree convert_template_argument PROTO ((tree, tree, tree, int,
					      int , tree));
static tree get_bindings_overload PROTO((tree, tree, tree));
static int for_each_template_parm PROTO((tree, tree_fn_t, void*));
static tree build_template_parm_index PROTO((int, int, int, tree, tree));
static int inline_needs_template_parms PROTO((tree));
static void push_inline_template_parms_recursive PROTO((tree, int));
static tree retrieve_specialization PROTO((tree, tree));
static tree register_specialization PROTO((tree, tree, tree));
static int unregister_specialization PROTO((tree, tree));
static tree reduce_template_parm_level PROTO((tree, tree, int));
static tree build_template_decl PROTO((tree, tree));
static int mark_template_parm PROTO((tree, void *));
static tree tsubst_friend_function PROTO((tree, tree));
static tree tsubst_friend_class PROTO((tree, tree));
static tree get_bindings_real PROTO((tree, tree, tree, int));
static int template_decl_level PROTO((tree));
static tree maybe_get_template_decl_from_type_decl PROTO((tree));
static int check_cv_quals_for_unify PROTO((int, tree, tree));
static tree tsubst_template_arg_vector PROTO((tree, tree, int));
static tree tsubst_template_parms PROTO((tree, tree, int));
static void regenerate_decl_from_template PROTO((tree, tree));
static tree most_specialized PROTO((tree, tree, tree));
static tree most_specialized_class PROTO((tree, tree));
static tree most_general_template PROTO((tree));
static void set_mangled_name_for_template_decl PROTO((tree));
static int template_class_depth_real PROTO((tree, int));
static tree tsubst_aggr_type PROTO((tree, tree, int, tree, int));
static tree tsubst_decl PROTO((tree, tree, tree, tree));
static tree tsubst_arg_types PROTO((tree, tree, int, tree));
static tree tsubst_function_type PROTO((tree, tree, int, tree));
static void check_specialization_scope PROTO((void));
static tree process_partial_specialization PROTO((tree));
static void set_current_access_from_decl PROTO((tree));
static void check_default_tmpl_args PROTO((tree, tree, int, int));
static tree tsubst_call_declarator_parms PROTO((tree, tree, int, tree));
static tree get_template_base_recursive PROTO((tree, tree,
					       tree, tree, tree, int)); 
static tree get_template_base PROTO((tree, tree, tree, tree));
static tree try_class_unification PROTO((tree, tree, tree, tree));
static int coerce_template_template_parms PROTO((tree, tree, int,
						 tree, tree));
static tree determine_specialization PROTO((tree, tree, tree *, int));
static int template_args_equal PROTO((tree, tree));
static void print_template_context PROTO((int));
static int has_pvbases_p PROTO((tree, tree));

/* We use TREE_VECs to hold template arguments.  If there is only one
   level of template arguments, then the TREE_VEC contains the
   arguments directly.  If there is more than one level of template
   arguments, then each entry in the TREE_VEC is itself a TREE_VEC,
   containing the template arguments for a single level.  The first
   entry in the outer TREE_VEC is the outermost level of template
   parameters; the last is the innermost.  

   It is incorrect to ever form a template argument vector containing
   only one level of arguments, but which is a TREE_VEC containing as
   its only entry the TREE_VEC for that level.  */

/* Non-zero if the template arguments is actually a vector of vectors,
   rather than just a vector.  */
#define TMPL_ARGS_HAVE_MULTIPLE_LEVELS(NODE) \
  (NODE != NULL_TREE						\
   && TREE_CODE (NODE) == TREE_VEC				\
   && TREE_VEC_LENGTH (NODE) > 0				\
   && TREE_VEC_ELT (NODE, 0) != NULL_TREE			\
   && TREE_CODE (TREE_VEC_ELT (NODE, 0)) == TREE_VEC)

/* The depth of a template argument vector.  When called directly by
   the parser, we use a TREE_LIST rather than a TREE_VEC to represent
   template arguments.  In fact, we may even see NULL_TREE if there
   are no template arguments.  In both of those cases, there is only
   one level of template arguments.  */
#define TMPL_ARGS_DEPTH(NODE)					\
  (TMPL_ARGS_HAVE_MULTIPLE_LEVELS (NODE) ? TREE_VEC_LENGTH (NODE) : 1)

/* The LEVELth level of the template ARGS.  Note that template
   parameter levels are indexed from 1, not from 0.  */
#define TMPL_ARGS_LEVEL(ARGS, LEVEL)		\
  (TMPL_ARGS_HAVE_MULTIPLE_LEVELS (ARGS) 	\
   ? TREE_VEC_ELT ((ARGS), (LEVEL) - 1) : ARGS)

/* Set the LEVELth level of the template ARGS to VAL.  This macro does
   not work with single-level argument vectors.  */
#define SET_TMPL_ARGS_LEVEL(ARGS, LEVEL, VAL)	\
  (TREE_VEC_ELT ((ARGS), (LEVEL) - 1) = (VAL))

/* Accesses the IDXth parameter in the LEVELth level of the ARGS.  */
#define TMPL_ARG(ARGS, LEVEL, IDX)				\
  (TREE_VEC_ELT (TMPL_ARGS_LEVEL (ARGS, LEVEL), IDX))

/* Set the IDXth element in the LEVELth level of ARGS to VAL.  This
   macro does not work with single-level argument vectors.  */
#define SET_TMPL_ARG(ARGS, LEVEL, IDX, VAL)			\
  (TREE_VEC_ELT (TREE_VEC_ELT ((ARGS), (LEVEL) - 1), (IDX)) = (VAL))

/* Given a single level of template arguments in NODE, return the
   number of arguments.  */
#define NUM_TMPL_ARGS(NODE) 				\
  ((NODE) == NULL_TREE ? 0 				\
   : (TREE_CODE (NODE) == TREE_VEC 			\
      ? TREE_VEC_LENGTH (NODE) : list_length (NODE)))

/* The number of levels of template parameters given by NODE.  */
#define TMPL_PARMS_DEPTH(NODE) \
  (TREE_INT_CST_HIGH (TREE_PURPOSE (NODE)))

/* Do any processing required when DECL (a member template declaration
   using TEMPLATE_PARAMETERS as its innermost parameter list) is
   finished.  Returns the TEMPLATE_DECL corresponding to DECL, unless
   it is a specialization, in which case the DECL itself is returned.  */

tree
finish_member_template_decl (decl)
  tree decl;
{
  if (decl == NULL_TREE || decl == void_type_node)
    return NULL_TREE;
  else if (decl == error_mark_node)
    /* By returning NULL_TREE, the parser will just ignore this
       declaration.  We have already issued the error.  */
    return NULL_TREE;
  else if (TREE_CODE (decl) == TREE_LIST)
    {
      /* Assume that the class is the only declspec.  */
      decl = TREE_VALUE (decl);
      if (IS_AGGR_TYPE (decl) && CLASSTYPE_TEMPLATE_INFO (decl)
	  && ! CLASSTYPE_TEMPLATE_SPECIALIZATION (decl))
	{
	  tree tmpl = CLASSTYPE_TI_TEMPLATE (decl);
	  check_member_template (tmpl);
	  return tmpl;
	}
      return NULL_TREE;
    }
  else if (DECL_TEMPLATE_INFO (decl))
    {
      if (!DECL_TEMPLATE_SPECIALIZATION (decl))
	{
	  check_member_template (DECL_TI_TEMPLATE (decl));
	  return DECL_TI_TEMPLATE (decl);
	}
      else
	return decl;
    } 
  else
    cp_error ("invalid member template declaration `%D'", decl);

  return error_mark_node;
}

/* Returns the template nesting level of the indicated class TYPE.
   
   For example, in:
     template <class T>
     struct A
     {
       template <class U>
       struct B {};
     };

   A<T>::B<U> has depth two, while A<T> has depth one.  
   Both A<T>::B<int> and A<int>::B<U> have depth one, if
   COUNT_SPECIALIZATIONS is 0 or if they are instantiations, not
   specializations.  

   This function is guaranteed to return 0 if passed NULL_TREE so
   that, for example, `template_class_depth (current_class_type)' is
   always safe.  */

static int 
template_class_depth_real (type, count_specializations)
     tree type;
     int count_specializations;
{
  int depth;

  for (depth = 0; 
       type && TREE_CODE (type) != NAMESPACE_DECL;
       type = (TREE_CODE (type) == FUNCTION_DECL) 
	 ? DECL_REAL_CONTEXT (type) : TYPE_CONTEXT (type))
    {
      if (TREE_CODE (type) != FUNCTION_DECL)
	{
	  if (CLASSTYPE_TEMPLATE_INFO (type)
	      && PRIMARY_TEMPLATE_P (CLASSTYPE_TI_TEMPLATE (type))
	      && ((count_specializations
		   && CLASSTYPE_TEMPLATE_SPECIALIZATION (type))
		  || uses_template_parms (CLASSTYPE_TI_ARGS (type))))
	    ++depth;
	}
      else 
	{
	  if (DECL_TEMPLATE_INFO (type)
	      && PRIMARY_TEMPLATE_P (DECL_TI_TEMPLATE (type))
	      && ((count_specializations
		   && DECL_TEMPLATE_SPECIALIZATION (type))
		  || uses_template_parms (DECL_TI_ARGS (type))))
	    ++depth;
	}
    }

  return depth;
}

/* Returns the template nesting level of the indicated class TYPE.
   Like template_class_depth_real, but instantiations do not count in
   the depth.  */

int 
template_class_depth (type)
     tree type;
{
  return template_class_depth_real (type, /*count_specializations=*/0);
}

/* Returns 1 if processing DECL as part of do_pending_inlines
   needs us to push template parms.  */

static int
inline_needs_template_parms (decl)
     tree decl;
{
  if (! DECL_TEMPLATE_INFO (decl))
    return 0;

  return (TMPL_PARMS_DEPTH (DECL_TEMPLATE_PARMS (most_general_template (decl)))
	  > (processing_template_decl + DECL_TEMPLATE_SPECIALIZATION (decl)));
}

/* Subroutine of maybe_begin_member_template_processing.
   Push the template parms in PARMS, starting from LEVELS steps into the
   chain, and ending at the beginning, since template parms are listed
   innermost first.  */

static void
push_inline_template_parms_recursive (parmlist, levels)
     tree parmlist;
     int levels;
{
  tree parms = TREE_VALUE (parmlist);
  int i;

  if (levels > 1)
    push_inline_template_parms_recursive (TREE_CHAIN (parmlist), levels - 1);

  ++processing_template_decl;
  current_template_parms
    = tree_cons (build_int_2 (0, processing_template_decl),
		 parms, current_template_parms);
  TEMPLATE_PARMS_FOR_INLINE (current_template_parms) = 1;

  pushlevel (0);
  for (i = 0; i < TREE_VEC_LENGTH (parms); ++i) 
    {
      tree parm = TREE_VALUE (TREE_VEC_ELT (parms, i));
      my_friendly_assert (TREE_CODE_CLASS (TREE_CODE (parm)) == 'd', 0);

      switch (TREE_CODE (parm))
	{
	case TYPE_DECL:
	case TEMPLATE_DECL:
	  pushdecl (parm);
	  break;

	case PARM_DECL:
	  {
	    /* Make a CONST_DECL as is done in process_template_parm.
	       It is ugly that we recreate this here; the original
	       version built in process_template_parm is no longer
	       available.  */
	    tree decl = build_decl (CONST_DECL, DECL_NAME (parm),
				    TREE_TYPE (parm));
	    SET_DECL_ARTIFICIAL (decl);
	    DECL_INITIAL (decl) = DECL_INITIAL (parm);
	    DECL_TEMPLATE_PARM_P (decl) = 1;
	    pushdecl (decl);
	  }
	  break;

	default:
	  my_friendly_abort (0);
	}
    }
}

/* Restore the template parameter context for a member template or
   a friend template defined in a class definition.  */

void
maybe_begin_member_template_processing (decl)
     tree decl;
{
  tree parms;
  int levels = 0;

  if (inline_needs_template_parms (decl))
    {
      parms = DECL_TEMPLATE_PARMS (most_general_template (decl));
      levels = TMPL_PARMS_DEPTH (parms) - processing_template_decl;

      if (DECL_TEMPLATE_SPECIALIZATION (decl))
	{
	  --levels;
	  parms = TREE_CHAIN (parms);
	}

      push_inline_template_parms_recursive (parms, levels);
    }

  /* Remember how many levels of template parameters we pushed so that