pt.c

gcc-2.95.3 Linux下最常用的C编译器

     we can pop them later.  */
  if (!inline_parm_levels)
    VARRAY_INT_INIT (inline_parm_levels, 4, "inline_parm_levels");
  if (inline_parm_levels_used == inline_parm_levels->num_elements)
    VARRAY_GROW (inline_parm_levels, 2 * inline_parm_levels_used);
  VARRAY_INT (inline_parm_levels, inline_parm_levels_used) = levels;
  ++inline_parm_levels_used;
}

/* Undo the effects of begin_member_template_processing. */

void 
maybe_end_member_template_processing ()
{
  int i;

  if (!inline_parm_levels_used)
    return;

  --inline_parm_levels_used;
  for (i = 0; 
       i < VARRAY_INT (inline_parm_levels, inline_parm_levels_used);
       ++i) 
    {
      --processing_template_decl;
      current_template_parms = TREE_CHAIN (current_template_parms);
      poplevel (0, 0, 0);
    }
}

/* Returns non-zero iff T is a member template function.  We must be
   careful as in

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

   Here, f is a template function, and a member, but not a member
   template.  This function does not concern itself with the origin of
   T, only its present state.  So if we have 

     template <class T> class C { template <class U> void f(U); }

   then neither C<int>::f<char> nor C<T>::f<double> is considered
   to be a member template.  But, `template <class U> void
   C<int>::f(U)' is considered a member template.  */

int
is_member_template (t)
     tree t;
{
  if (!DECL_FUNCTION_TEMPLATE_P (t))
    /* Anything that isn't a function or a template function is
       certainly not a member template.  */
    return 0;

  /* A local class can't have member templates.  */
  if (hack_decl_function_context (t))
    return 0;

  return (DECL_FUNCTION_MEMBER_P (DECL_TEMPLATE_RESULT (t))
	  /* If there are more levels of template parameters than
	     there are template classes surrounding the declaration,
	     then we have a member template.  */
	  && (TMPL_PARMS_DEPTH (DECL_TEMPLATE_PARMS (t)) > 
	      template_class_depth (DECL_CLASS_CONTEXT (t))));
}

#if 0 /* UNUSED */
/* Returns non-zero iff T is a member template class.  See
   is_member_template for a description of what precisely constitutes
   a member template.  */

int
is_member_template_class (t)
     tree t;
{
  if (!DECL_CLASS_TEMPLATE_P (t))
    /* Anything that isn't a class template, is certainly not a member
       template.  */
    return 0;

  if (!DECL_CLASS_SCOPE_P (t))
    /* Anything whose context isn't a class type is surely not a
       member template.  */
    return 0;

  /* If there are more levels of template parameters than there are
     template classes surrounding the declaration, then we have a
     member template.  */
  return  (TMPL_PARMS_DEPTH (DECL_TEMPLATE_PARMS (t)) > 
	   template_class_depth (DECL_CONTEXT (t)));
}
#endif

/* Return a new template argument vector which contains all of ARGS,
   but has as its innermost set of arguments the EXTRA_ARGS.  The
   resulting vector will be built on a temporary obstack, and so must
   be explicitly copied to the permanent obstack, if required.  */

static tree
add_to_template_args (args, extra_args)
     tree args;
     tree extra_args;
{
  tree new_args;
  int extra_depth;
  int i;
  int j;

  extra_depth = TMPL_ARGS_DEPTH (extra_args);
  new_args = make_temp_vec (TMPL_ARGS_DEPTH (args) + extra_depth);

  for (i = 1; i <= TMPL_ARGS_DEPTH (args); ++i)
    SET_TMPL_ARGS_LEVEL (new_args, i, TMPL_ARGS_LEVEL (args, i));

  for (j = 1; j <= extra_depth; ++j, ++i)
    SET_TMPL_ARGS_LEVEL (new_args, i, TMPL_ARGS_LEVEL (extra_args, j));
    
  return new_args;
}

/* Like add_to_template_args, but only the outermost ARGS are added to
   the EXTRA_ARGS.  In particular, all but TMPL_ARGS_DEPTH
   (EXTRA_ARGS) levels are added.  This function is used to combine
   the template arguments from a partial instantiation with the
   template arguments used to attain the full instantiation from the
   partial instantiation.  */

static tree
add_outermost_template_args (args, extra_args)
     tree args;
     tree extra_args;
{
  tree new_args;

  /* If there are more levels of EXTRA_ARGS than there are ARGS,
     something very fishy is going on.  */
  my_friendly_assert (TMPL_ARGS_DEPTH (args) >= TMPL_ARGS_DEPTH (extra_args),
		      0);

  /* If *all* the new arguments will be the EXTRA_ARGS, just return
     them.  */
  if (TMPL_ARGS_DEPTH (args) == TMPL_ARGS_DEPTH (extra_args))
    return extra_args;

  /* For the moment, we make ARGS look like it contains fewer levels.  */
  TREE_VEC_LENGTH (args) -= TMPL_ARGS_DEPTH (extra_args);
  
  new_args = add_to_template_args (args, extra_args);

  /* Now, we restore ARGS to its full dimensions.  */
  TREE_VEC_LENGTH (args) += TMPL_ARGS_DEPTH (extra_args);

  return new_args;
}

/* We've got a template header coming up; push to a new level for storing
   the parms.  */

void
begin_template_parm_list ()
{
  /* We use a non-tag-transparent scope here, which causes pushtag to
     put tags in this scope, rather than in the enclosing class or
     namespace scope.  This is the right thing, since we want
     TEMPLATE_DECLS, and not TYPE_DECLS for template classes.  For a
     global template class, push_template_decl handles putting the
     TEMPLATE_DECL into top-level scope.  For a nested template class,
     e.g.:

       template <class T> struct S1 {
         template <class T> struct S2 {}; 
       };

     pushtag contains special code to call pushdecl_with_scope on the
     TEMPLATE_DECL for S2.  */
  pushlevel (0);
  declare_pseudo_global_level ();
  ++processing_template_decl;
  ++processing_template_parmlist;
  note_template_header (0);
}

/* This routine is called when a specialization is declared.  If it is
   illegal to declare a specialization here, an error is reported.  */

static void
check_specialization_scope ()
{
  tree scope = current_scope ();

  /* [temp.expl.spec] 
     
     An explicit specialization shall be declared in the namespace of
     which the template is a member, or, for member templates, in the
     namespace of which the enclosing class or enclosing class
     template is a member.  An explicit specialization of a member
     function, member class or static data member of a class template
     shall be declared in the namespace of which the class template
     is a member.  */
  if (scope && TREE_CODE (scope) != NAMESPACE_DECL)
    cp_error ("explicit specialization in non-namespace scope `%D'",
	      scope);

  /* [temp.expl.spec] 

     In an explicit specialization declaration for a member of a class
     template or a member template that appears in namespace scope,
     the member template and some of its enclosing class templates may
     remain unspecialized, except that the declaration shall not
     explicitly specialize a class member template if its enclosing
     class templates are not explicitly specialized as well.  */
  if (current_template_parms) 
    cp_error ("enclosing class templates are not explicitly specialized");
}

/* We've just seen template <>. */

void
begin_specialization ()
{
  note_template_header (1);
  check_specialization_scope ();
}

/* Called at then end of processing a declaration preceeded by
   template<>.  */

void 
end_specialization ()
{
  reset_specialization ();
}

/* Any template <>'s that we have seen thus far are not referring to a
   function specialization. */

void
reset_specialization ()
{
  processing_specialization = 0;
  template_header_count = 0;
}

/* We've just seen a template header.  If SPECIALIZATION is non-zero,
   it was of the form template <>.  */

static void 
note_template_header (specialization)
     int specialization;
{
  processing_specialization = specialization;
  template_header_count++;
}

/* We're beginning an explicit instantiation.  */

void
begin_explicit_instantiation ()
{
  ++processing_explicit_instantiation;
}


void
end_explicit_instantiation ()
{
  my_friendly_assert(processing_explicit_instantiation > 0, 0);
  --processing_explicit_instantiation;
}

/* The TYPE is being declared.  If it is a template type, that means it
   is a partial specialization.  Do appropriate error-checking.  */

void 
maybe_process_partial_specialization (type)
     tree type;
{
  if (IS_AGGR_TYPE (type) && CLASSTYPE_USE_TEMPLATE (type))
    {
      if (CLASSTYPE_IMPLICIT_INSTANTIATION (type)
	  && TYPE_SIZE (type) == NULL_TREE)
	{
	  if (current_namespace
	      != decl_namespace_context (CLASSTYPE_TI_TEMPLATE (type)))
	    {
	      cp_pedwarn ("specializing `%#T' in different namespace", type);
	      cp_pedwarn_at ("  from definition of `%#D'",
			     CLASSTYPE_TI_TEMPLATE (type));
	    }
	  SET_CLASSTYPE_TEMPLATE_SPECIALIZATION (type);
	  if (processing_template_decl)
	    push_template_decl (TYPE_MAIN_DECL (type));
	}
      else if (CLASSTYPE_TEMPLATE_INSTANTIATION (type))
	cp_error ("specialization of `%T' after instantiation", type);
    }
  else if (processing_specialization)
    cp_error ("explicit specialization of non-template `%T'", type);
}

/* Retrieve the specialization (in the sense of [temp.spec] - a
   specialization is either an instantiation or an explicit
   specialization) of TMPL for the given template ARGS.  If there is
   no such specialization, return NULL_TREE.  The ARGS are a vector of
   arguments, or a vector of vectors of arguments, in the case of
   templates with more than one level of parameters.  */
   
static tree
retrieve_specialization (tmpl, args)
     tree tmpl;
     tree args;
{
  tree s;

  my_friendly_assert (TREE_CODE (tmpl) == TEMPLATE_DECL, 0);

  /* There should be as many levels of arguments as there are
     levels of parameters.  */
  my_friendly_assert (TMPL_ARGS_DEPTH (args) 
		      == TMPL_PARMS_DEPTH (DECL_TEMPLATE_PARMS (tmpl)),
		      0);
		      
  for (s = DECL_TEMPLATE_SPECIALIZATIONS (tmpl);
       s != NULL_TREE;
       s = TREE_CHAIN (s))
    if (comp_template_args (TREE_PURPOSE (s), args))
      return TREE_VALUE (s);

  return NULL_TREE;
}

/* Returns non-zero iff DECL is a specialization of TMPL.  */

int
is_specialization_of (decl, tmpl)
     tree decl;
     tree tmpl;
{
  tree t;

  if (TREE_CODE (decl) == FUNCTION_DECL)
    {
      for (t = decl; 
	   t != NULL_TREE;
	   t = DECL_TEMPLATE_INFO (t) ? DECL_TI_TEMPLATE (t) : NULL_TREE)
	if (t == tmpl)
	  return 1;
    }
  else 
    {
      my_friendly_assert (TREE_CODE (decl) == TYPE_DECL, 0);

      for (t = TREE_TYPE (decl);
	   t != NULL_TREE;
	   t = CLASSTYPE_USE_TEMPLATE (t)
	     ? TREE_TYPE (CLASSTYPE_TI_TEMPLATE (t)) : NULL_TREE)
	if (same_type_p (TYPE_MAIN_VARIANT (t), 
			 TYPE_MAIN_VARIANT (TREE_TYPE (tmpl))))
	  return 1;
    }  

  return 0;
}

/* Register the specialization SPEC as a specialization of TMPL with
   the indicated ARGS.  Returns SPEC, or an equivalent prior
   declaration, if available.  */

static tree
register_specialization (spec, tmpl, args)
     tree spec;
     tree tmpl;
     tree args;
{
  tree s;

  my_friendly_assert (TREE_CODE (tmpl) == TEMPLATE_DECL, 0);

  if (TREE_CODE (spec) == FUNCTION_DECL 
      && uses_template_parms (DECL_TI_ARGS (spec)))
    /* This is the FUNCTION_DECL for a partial instantiation.  Don't
       register it; we want the corresponding TEMPLATE_DECL instead.
       We use `uses_template_parms (DECL_TI_ARGS (spec))' rather than
       the more obvious `uses_template_parms (spec)' to avoid problems
       with default function arguments.  In particular, given
       something like this:

          template <class T> void f(T t1, T t = T())

       the default argument expression is not substituted for in an
       instantiation unless and until it is actually needed.  */
    return spec;
    
  /* There should be as many levels of arguments as there are
     levels of parameters.  */
  my_friendly_assert (TMPL_ARGS_DEPTH (args) 
		      == TMPL_PARMS_DEPTH (DECL_TEMPLATE_PARMS (tmpl)),
		      0);

  for (s = DECL_TEMPLATE_SPECIALIZATIONS (tmpl);
       s != NULL_TREE;
       s = TREE_CHAIN (s))
    if (comp_template_args (TREE_PURPOSE (s), args))
      {
	tree fn = TREE_VALUE (s);

	if (DECL_TEMPLATE_SPECIALIZATION (spec))
	  {
	    if (DECL_TEMPLATE_INSTANTIATION (fn))
	      {
		if (TREE_USED (fn) 
		    || DECL_EXPLICIT_INSTANTIATION (fn))
		  {
		    cp_error ("specialization of %D after instantiation",
			      fn);
		    return spec;
		  }
		else
		  {
		    /* This situation should occur only if the first
		       specialization is an implicit instantiation,
		       the second is an explicit specialization, and
		       the implicit instantiation has not yet been
		       used.  That situation can occur if we have
		       implicitly instantiated a member function and
		       then specialized it later.

		       We can also wind up here if a friend
		       declaration that looked like an instantiation