pt.c

gcc-2.95.3 Linux下最常用的C编译器

	}
    }

  if (specialization || member_specialization)
    {
      tree t = TYPE_ARG_TYPES (TREE_TYPE (decl));
      for (; t; t = TREE_CHAIN (t))
	if (TREE_PURPOSE (t))
	  {
	    cp_pedwarn
	      ("default argument specified in explicit specialization");
	    break;
	  }
      if (current_lang_name == lang_name_c)
	cp_error ("template specialization with C linkage");
    }

  if (specialization || member_specialization || explicit_instantiation)
    {
      tree tmpl = NULL_TREE;
      tree targs = NULL_TREE;

      /* Make sure that the declarator is a TEMPLATE_ID_EXPR.  */
      if (TREE_CODE (declarator) != TEMPLATE_ID_EXPR)
	{
	  tree fns;

	  my_friendly_assert (TREE_CODE (declarator) == IDENTIFIER_NODE, 
			      0);
	  if (!ctype)
	    fns = IDENTIFIER_NAMESPACE_VALUE (dname);
	  else
	    fns = dname;

	  declarator = 
	    lookup_template_function (fns, NULL_TREE);
	}

      if (declarator == error_mark_node)
	return error_mark_node;

      if (ctype != NULL_TREE && TYPE_BEING_DEFINED (ctype))
	{
	  if (!explicit_instantiation)
	    /* A specialization in class scope.  This is illegal,
	       but the error will already have been flagged by
	       check_specialization_scope.  */
	    return error_mark_node;
	  else
	    {
	      /* It's not legal to write an explicit instantiation in
		 class scope, e.g.:

	           class C { template void f(); }

		   This case is caught by the parser.  However, on
		   something like:
	       
		   template class C { void f(); };

		   (which is illegal) we can get here.  The error will be
		   issued later.  */
	      ;
	    }

	  return decl;
	}
      else if (TREE_CODE (TREE_OPERAND (declarator, 0)) == LOOKUP_EXPR)
	{
	  /* A friend declaration.  We can't do much, because we don't
	   know what this resolves to, yet.  */
	  my_friendly_assert (is_friend != 0, 0);
	  my_friendly_assert (!explicit_instantiation, 0);
	  SET_DECL_IMPLICIT_INSTANTIATION (decl);
	  return decl;
	} 
      else if (ctype != NULL_TREE 
	       && (TREE_CODE (TREE_OPERAND (declarator, 0)) ==
		   IDENTIFIER_NODE))
	{
	  /* Find the list of functions in ctype that have the same
	     name as the declared function.  */
	  tree name = TREE_OPERAND (declarator, 0);
	  tree fns = NULL_TREE;
	  int idx;

	  if (name == constructor_name (ctype) 
	      || name == constructor_name_full (ctype))
	    {
	      int is_constructor = DECL_CONSTRUCTOR_P (decl);
	      
	      if (is_constructor ? !TYPE_HAS_CONSTRUCTOR (ctype)
		  : !TYPE_HAS_DESTRUCTOR (ctype))
		{
		  /* From [temp.expl.spec]:
		       
		     If such an explicit specialization for the member
		     of a class template names an implicitly-declared
		     special member function (clause _special_), the
		     program is ill-formed.  

		     Similar language is found in [temp.explicit].  */
		  cp_error ("specialization of implicitly-declared special member function");
		  return error_mark_node;
		}

	      name = is_constructor ? ctor_identifier : dtor_identifier;
	    }

	  if (!IDENTIFIER_TYPENAME_P (name))
	    {
	      idx = lookup_fnfields_1 (ctype, name);
	      if (idx >= 0)
		fns = TREE_VEC_ELT (CLASSTYPE_METHOD_VEC (ctype), idx);
	    }
	  else
	    {
	      tree methods;

	      /* For a type-conversion operator, we cannot do a
		 name-based lookup.  We might be looking for `operator
		 int' which will be a specialization of `operator T'.
		 So, we find *all* the conversion operators, and then
		 select from them.  */
	      fns = NULL_TREE;

	      methods = CLASSTYPE_METHOD_VEC (ctype);
	      if (methods)
		for (idx = 2; idx < TREE_VEC_LENGTH (methods); ++idx) 
		  {
		    tree ovl = TREE_VEC_ELT (methods, idx);

		    if (!ovl || !DECL_CONV_FN_P (OVL_CURRENT (ovl)))
		      /* There are no more conversion functions.  */
		      break;

		    /* Glue all these conversion functions together
		       with those we already have.  */
		    for (; ovl; ovl = OVL_NEXT (ovl))
		      fns = ovl_cons (OVL_CURRENT (ovl), fns);
		  }
	    }
	      
	  if (fns == NULL_TREE) 
	    {
	      cp_error ("no member function `%D' declared in `%T'",
			name, ctype);
	      return error_mark_node;
	    }
	  else
	    TREE_OPERAND (declarator, 0) = fns;
	}
      
      /* Figure out what exactly is being specialized at this point.
	 Note that for an explicit instantiation, even one for a
	 member function, we cannot tell apriori whether the
	 instantiation is for a member template, or just a member
	 function of a template class.  Even if a member template is
	 being instantiated, the member template arguments may be
	 elided if they can be deduced from the rest of the
	 declaration.  */
      tmpl = determine_specialization (declarator, decl,
				       &targs, 
				       member_specialization);
	    
      if (!tmpl || tmpl == error_mark_node)
	/* We couldn't figure out what this declaration was
	   specializing.  */
	return error_mark_node;
      else
	{
	  tree gen_tmpl = most_general_template (tmpl);

	  if (explicit_instantiation)
	    {
	      /* We don't set DECL_EXPLICIT_INSTANTIATION here; that
		 is done by do_decl_instantiation later.  */ 

	      int arg_depth = TMPL_ARGS_DEPTH (targs);
	      int parm_depth = TMPL_PARMS_DEPTH (DECL_TEMPLATE_PARMS (tmpl));

	      if (arg_depth > parm_depth)
		{
		  /* If TMPL is not the most general template (for
		     example, if TMPL is a friend template that is
		     injected into namespace scope), then there will
		     be too many levels fo TARGS.  Remove some of them
		     here.  */
		  int i;
		  tree new_targs;

		  new_targs = make_temp_vec (parm_depth);
		  for (i = arg_depth - parm_depth; i < arg_depth; ++i)
		    TREE_VEC_ELT (new_targs, i - (arg_depth - parm_depth))
		      = TREE_VEC_ELT (targs, i);
		  targs = new_targs;
		}
		  
	      decl = instantiate_template (tmpl, targs);
	      return decl;
	    }
	  
	  /* If we though that the DECL was a member function, but it
	     turns out to be specializing a static member function,
	     make DECL a static member function as well.  */
	  if (DECL_STATIC_FUNCTION_P (tmpl)
	      && DECL_NONSTATIC_MEMBER_FUNCTION_P (decl))
	    {
	      revert_static_member_fn (&decl, 0, 0);
	      last_function_parms = TREE_CHAIN (last_function_parms);
	    }

	  /* Set up the DECL_TEMPLATE_INFO for DECL.  */
	  DECL_TEMPLATE_INFO (decl) 
	    = perm_tree_cons (tmpl, targs, NULL_TREE);

	  /* Mangle the function name appropriately.  Note that we do
	     not mangle specializations of non-template member
	     functions of template classes, e.g. with

	       template <class T> struct S { void f(); }

	     and given the specialization 

	       template <> void S<int>::f() {}

	     we do not mangle S<int>::f() here.  That's because it's
	     just an ordinary member function and doesn't need special
	     treatment.  We do this here so that the ordinary,
	     non-template, name-mangling algorith will not be used
	     later.  */
	  if ((is_member_template (tmpl) || ctype == NULL_TREE)
	      && name_mangling_version >= 1)
	    set_mangled_name_for_template_decl (decl);

	  if (is_friend && !have_def)
	    /* This is not really a declaration of a specialization.
	       It's just the name of an instantiation.  But, it's not
	       a request for an instantiation, either.  */
	    SET_DECL_IMPLICIT_INSTANTIATION (decl);

	  /* Register this specialization so that we can find it
	     again.  */
	  decl = register_specialization (decl, gen_tmpl, targs);
	}
    }
  
  return decl;
}

/* TYPE is being declared.  Verify that the use of template headers
   and such is reasonable.  Issue error messages if not.  */

void
maybe_check_template_type (type)
     tree type;
{
  if (template_header_count)
    {
      /* We are in the scope of some `template <...>' header.  */

      int context_depth 
	= template_class_depth_real (TYPE_CONTEXT (type),
				     /*count_specializations=*/1);

      if (template_header_count <= context_depth)
	/* This is OK; the template headers are for the context.  We
	   are actually too lenient here; like
	   check_explicit_specialization we should consider the number
	   of template types included in the actual declaration.  For
	   example, 

	     template <class T> struct S {
	       template <class U> template <class V>
	       struct I {};
	     }; 

	   is illegal, but:

	     template <class T> struct S {
	       template <class U> struct I;
	     }; 

	     template <class T> template <class U.
	     struct S<T>::I {};

	   is not.  */
	; 
      else if (template_header_count > context_depth + 1)
	/* There are two many template parameter lists.  */
	cp_error ("too many template parameter lists in declaration of `%T'", type); 
    }
}

/* Returns 1 iff PARMS1 and PARMS2 are identical sets of template
   parameters.  These are represented in the same format used for
   DECL_TEMPLATE_PARMS.  */

int comp_template_parms (parms1, parms2)
     tree parms1;
     tree parms2;
{
  tree p1;
  tree p2;

  if (parms1 == parms2)
    return 1;

  for (p1 = parms1, p2 = parms2; 
       p1 != NULL_TREE && p2 != NULL_TREE;
       p1 = TREE_CHAIN (p1), p2 = TREE_CHAIN (p2))
    {
      tree t1 = TREE_VALUE (p1);
      tree t2 = TREE_VALUE (p2);
      int i;

      my_friendly_assert (TREE_CODE (t1) == TREE_VEC, 0);
      my_friendly_assert (TREE_CODE (t2) == TREE_VEC, 0);

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

      for (i = 0; i < TREE_VEC_LENGTH (t2); ++i) 
	{
	  tree parm1 = TREE_VALUE (TREE_VEC_ELT (t1, i));
	  tree parm2 = TREE_VALUE (TREE_VEC_ELT (t2, i));

	  if (TREE_CODE (parm1) != TREE_CODE (parm2))
	    return 0;

	  if (TREE_CODE (parm1) == TEMPLATE_TYPE_PARM)
	    continue;
	  else if (!same_type_p (TREE_TYPE (parm1), TREE_TYPE (parm2)))
	    return 0;
	}
    }

  if ((p1 != NULL_TREE) != (p2 != NULL_TREE))
    /* One set of parameters has more parameters lists than the
       other.  */
    return 0;

  return 1;
}

/* Complain if DECL shadows a template parameter.

   [temp.local]: A template-parameter shall not be redeclared within its
   scope (including nested scopes).  */

void
check_template_shadow (decl)
     tree decl;
{
  tree olddecl;

  /* If we're not in a template, we can't possibly shadow a template
     parameter.  */
  if (!current_template_parms)
    return;

  /* Figure out what we're shadowing.  */
  if (TREE_CODE (decl) == OVERLOAD)
    decl = OVL_CURRENT (decl);
  olddecl = IDENTIFIER_VALUE (DECL_NAME (decl));

  /* If there's no previous binding for this name, we're not shadowing
     anything, let alone a template parameter.  */
  if (!olddecl)
    return;

  /* If we're not shadowing a template parameter, we're done.  Note
     that OLDDECL might be an OVERLOAD (or perhaps even an
     ERROR_MARK), so we can't just blithely assume it to be a _DECL
     node.  */
  if (TREE_CODE_CLASS (TREE_CODE (olddecl)) != 'd'
      || !DECL_TEMPLATE_PARM_P (olddecl))
    return;

  /* We check for decl != olddecl to avoid bogus errors for using a
     name inside a class.  We check TPFI to avoid duplicate errors for
     inline member templates.  */
  if (decl == olddecl 
      || TEMPLATE_PARMS_FOR_INLINE (current_template_parms))
    return;

  cp_error_at ("declaration of `%#D'", decl);
  cp_error_at (" shadows template parm `%#D'", olddecl);
}

/* Return a new TEMPLATE_PARM_INDEX with the indicated INDEX, LEVEL,
   ORIG_LEVEL, DECL, and TYPE.  */

static tree
build_template_parm_index (index, level, orig_level, decl, type)
     int index;
     int level;
     int orig_level;
     tree decl;
     tree type;
{
  tree t = make_node (TEMPLATE_PARM_INDEX);
  TEMPLATE_PARM_IDX (t) = index;
  TEMPLATE_PARM_LEVEL (t) = level;
  TEMPLATE_PARM_ORIG_LEVEL (t) = orig_level;
  TEMPLATE_PARM_DECL (t) = decl;
  TREE_TYPE (t) = type;

  return t;
}

/* Return a TEMPLATE_PARM_INDEX, similar to INDEX, but whose
   TEMPLATE_PARM_LEVEL has been decreased by LEVELS.  If such a
   TEMPLATE_PARM_INDEX already exists, it is returned; otherwise, a
   new one is created.  */

static tree 
reduce_template_parm_level (index, type, levels)
     tree index;
     tree type;
     int levels;
{
  if (TEMPLATE_PARM_DESCENDANTS (index) == NULL_TREE
      || (TEMPLATE_PARM_LEVEL (TEMPLATE_PARM_DESCENDANTS (index))
	  != TEMPLATE_PARM_LEVEL (index) - levels))
    {
      tree decl 
	= build_decl (TREE_CODE (TEMPLATE_PARM_DECL (index)),
		      DECL_NAME (TEMPLATE_PARM_DECL (index)),