decl.c

gcc-2.95.3 Linux下最常用的C编译器

static tree
lookup_name_current_level (name)
     tree name;
{
  register tree t;

  if (current_binding_level == global_binding_level)
    return IDENTIFIER_GLOBAL_VALUE (name);

  if (IDENTIFIER_LOCAL_VALUE (name) == 0)
    return 0;

  for (t = current_binding_level->names; t; t = TREE_CHAIN (t))
    if (DECL_NAME (t) == name)
      break;

  return t;
}

/* Use a binding level to record a labeled block declaration */

void
push_labeled_block (lb)
    tree lb;
{
  register tree name = DECL_NAME (LABELED_BLOCK_LABEL (lb));
  register struct binding_level *b = current_binding_level;
  tree oldlocal = IDENTIFIER_LOCAL_VALUE (name);
  if (oldlocal != 0)
      b->shadowed = tree_cons (name, oldlocal, b->shadowed);
  TREE_CHAIN (lb) = b->names;
  b->names = lb;
  IDENTIFIER_LOCAL_VALUE (name) = lb;
}

/* Pop the current binding level, reinstalling values for the previous
   labeled block */

void
pop_labeled_block ()
{
  struct binding_level *b = current_binding_level;
  tree label =  b->names;
  IDENTIFIER_LOCAL_VALUE (DECL_NAME (LABELED_BLOCK_LABEL (label))) = 
    NULL_TREE;
  if (b->shadowed)
    IDENTIFIER_LOCAL_VALUE (TREE_PURPOSE (b->shadowed)) = 
      TREE_VALUE (b->shadowed);

  /* Pop the current level, and free the structure for reuse.  */
  current_binding_level = current_binding_level->level_chain;
  b->level_chain = free_binding_level;
  free_binding_level = b;
}

/* Record a decl-node X as belonging to the current lexical scope.
   Check for errors (such as an incompatible declaration for the same
   name already seen in the same scope).

   Returns either X or an old decl for the same name.
   If an old decl is returned, it may have been smashed
   to agree with what X says.  */

tree
pushdecl (x)
     tree x;
{
  register tree t;
  register tree name = DECL_NAME (x);
  register struct binding_level *b = current_binding_level;

  DECL_CONTEXT (x) = current_function_decl;
  if (name)
    {
      char *file;
      int line;

      t = lookup_name_current_level (name);
      if (t != 0 && t == error_mark_node)
	/* error_mark_node is 0 for a while during initialization!  */
	{
	  t = 0;
	  error_with_decl (x, "`%s' used prior to declaration");
	}

      if (t != 0)
	{
	  file = DECL_SOURCE_FILE (t);
	  line = DECL_SOURCE_LINE (t);
	}

      /* If we're naming a hitherto-unnamed type, set its TYPE_NAME
	 to point to the TYPE_DECL.
	 Since Java does not have typedefs, a type can only have
	 one (true) name, given by a class, interface, or builtin. */
      if (TREE_CODE (x) == TYPE_DECL
	  && TYPE_NAME (TREE_TYPE (x)) == 0
	  && TREE_TYPE (x) != error_mark_node)
	{
	  TYPE_NAME (TREE_TYPE (x)) = x;
	  TYPE_STUB_DECL (TREE_TYPE (x)) = x;
	}

      /* This name is new in its binding level.
	 Install the new declaration and return it.  */
      if (b == global_binding_level)
	{
	  /* Install a global value.  */
	  
	  IDENTIFIER_GLOBAL_VALUE (name) = x;
	}
      else
	{
	  /* Here to install a non-global value.  */
	  tree oldlocal = IDENTIFIER_LOCAL_VALUE (name);
	  IDENTIFIER_LOCAL_VALUE (name) = x;

#if 0
	  /* Warn if shadowing an argument at the top level of the body.  */
	  if (oldlocal != 0 && !DECL_EXTERNAL (x)
	      /* This warning doesn't apply to the parms of a nested fcn.  */
	      && ! current_binding_level->parm_flag
	      /* Check that this is one level down from the parms.  */
	      && current_binding_level->level_chain->parm_flag
	      /* Check that the decl being shadowed
		 comes from the parm level, one level up.  */
	      && chain_member (oldlocal, current_binding_level->level_chain->names))
	    {
	      if (TREE_CODE (oldlocal) == PARM_DECL)
		pedwarn ("declaration of `%s' shadows a parameter",
			 IDENTIFIER_POINTER (name));
	      else
		pedwarn ("declaration of `%s' shadows a symbol from the parameter list",
			 IDENTIFIER_POINTER (name));
	    }

	  /* Maybe warn if shadowing something else.  */
	  else if (warn_shadow && !DECL_EXTERNAL (x)
		   /* No shadow warnings for internally generated vars.  */
		   && DECL_SOURCE_LINE (x) != 0
		   /* No shadow warnings for vars made for inlining.  */
		   && ! DECL_FROM_INLINE (x))
	    {
	      char *warnstring = 0;

	      if (TREE_CODE (x) == PARM_DECL
		  && current_binding_level->level_chain->parm_flag)
		/* Don't warn about the parm names in function declarator
		   within a function declarator.
		   It would be nice to avoid warning in any function
		   declarator in a declaration, as opposed to a definition,
		   but there is no way to tell it's not a definition.  */
		;
	      else if (oldlocal != 0 && TREE_CODE (oldlocal) == PARM_DECL)
		warnstring = "declaration of `%s' shadows a parameter";
	      else if (oldlocal != 0)
		warnstring = "declaration of `%s' shadows previous local";
	      else if (IDENTIFIER_GLOBAL_VALUE (name) != 0
		       && IDENTIFIER_GLOBAL_VALUE (name) != error_mark_node)
		warnstring = "declaration of `%s' shadows global declaration";

	      if (warnstring)
		warning (warnstring, IDENTIFIER_POINTER (name));
	    }
#endif

	  /* If storing a local value, there may already be one (inherited).
	     If so, record it for restoration when this binding level ends.  */
	  if (oldlocal != 0)
	    b->shadowed = tree_cons (name, oldlocal, b->shadowed);
	}
    }

  /* Put decls on list in reverse order.
     We will reverse them later if necessary.  */
  TREE_CHAIN (x) = b->names;
  b->names = x;

  return x;
}
void
pushdecl_force_head (x)
     tree x;
{
  current_binding_level->names = x;
}

/* Like pushdecl, only it places X in GLOBAL_BINDING_LEVEL, if appropriate.  */

tree
pushdecl_top_level (x)
     tree x;
{
  register tree t;
  register struct binding_level *b = current_binding_level;

  current_binding_level = global_binding_level;
  t = pushdecl (x);
  current_binding_level = b;
  return t;
}

/* Nonzero if we are currently in the global binding level.  */

int
global_bindings_p ()
{
  return current_binding_level == global_binding_level;
}

/* Return the list of declarations of the current level.
   Note that this list is in reverse order unless/until
   you nreverse it; and when you do nreverse it, you must
   store the result back using `storedecls' or you will lose.  */

tree
getdecls ()
{
  return current_binding_level->names;
}

/* Create a new `struct binding_level'.  */

static
struct binding_level *
make_binding_level ()
{
  /* NOSTRICT */
  return (struct binding_level *) xmalloc (sizeof (struct binding_level));
}

void
pushlevel (unused)
  int unused ATTRIBUTE_UNUSED;
{
  register struct binding_level *newlevel = NULL_BINDING_LEVEL;

#if 0
  /* If this is the top level of a function,
     just make sure that NAMED_LABELS is 0.  */

  if (current_binding_level == global_binding_level)
    named_labels = 0;
#endif

  /* Reuse or create a struct for this binding level.  */

  if (free_binding_level)
    {
      newlevel = free_binding_level;
      free_binding_level = free_binding_level->level_chain;
    }
  else
    {
      newlevel = make_binding_level ();
    }

  /* Add this level to the front of the chain (stack) of levels that
     are active.  */

  *newlevel = clear_binding_level;
  newlevel->level_chain = current_binding_level;
  current_binding_level = newlevel;
  newlevel->keep = keep_next_level_flag;
  keep_next_level_flag = 0;
  newlevel->keep_if_subblocks = keep_next_if_subblocks;
  keep_next_if_subblocks = 0;
}

/* Exit a binding level.
   Pop the level off, and restore the state of the identifier-decl mappings
   that were in effect when this level was entered.

   If KEEP is nonzero, this level had explicit declarations, so
   and create a "block" (a BLOCK node) for the level
   to record its declarations and subblocks for symbol table output.

   If FUNCTIONBODY is nonzero, this level is the body of a function,
   so create a block as if KEEP were set and also clear out all
   label names.

   If REVERSE is nonzero, reverse the order of decls before putting
   them into the BLOCK.  */

tree
poplevel (keep, reverse, functionbody)
     int keep;
     int reverse;
     int functionbody;
{
  register tree link;
  /* The chain of decls was accumulated in reverse order.
     Put it into forward order, just for cleanliness.  */
  tree decls;
  tree subblocks = current_binding_level->blocks;
  tree block = 0;
  tree decl;
  int block_previously_created;

  keep |= current_binding_level->keep;

  /* Get the decls in the order they were written.
     Usually current_binding_level->names is in reverse order.
     But parameter decls were previously put in forward order.  */

  if (reverse)
    current_binding_level->names
      = decls = nreverse (current_binding_level->names);
  else
    decls = current_binding_level->names;

  /* Output any nested inline functions within this block
     if they weren't already output.  */

  for (decl = decls; decl; decl = TREE_CHAIN (decl))
    if (TREE_CODE (decl) == FUNCTION_DECL
	&& ! TREE_ASM_WRITTEN (decl)
	&& DECL_INITIAL (decl) != 0
	&& TREE_ADDRESSABLE (decl))
      {
	/* If this decl was copied from a file-scope decl
	   on account of a block-scope extern decl,
	   propagate TREE_ADDRESSABLE to the file-scope decl.

	   DECL_ABSTRACT_ORIGIN can be set to itself if warn_return_type is
	   true, since then the decl goes through save_for_inline_copying.  */
	if (DECL_ABSTRACT_ORIGIN (decl) != 0
	    && DECL_ABSTRACT_ORIGIN (decl) != decl)
	  TREE_ADDRESSABLE (DECL_ABSTRACT_ORIGIN (decl)) = 1;
	else
	  {
	    push_function_context ();
	    output_inline_function (decl);
	    pop_function_context ();
	  }
      }

  /* If there were any declarations in that level,
     or if this level is a function body,
     create a BLOCK to record them for the life of this function.  */

  block = 0;
  block_previously_created = (current_binding_level->this_block != 0);
  if (block_previously_created)
    block = current_binding_level->this_block;
  else if (keep || functionbody
	   || (current_binding_level->keep_if_subblocks && subblocks != 0))
    block = make_node (BLOCK);
  if (block != 0)
    {
      BLOCK_VARS (block) = decls;
      BLOCK_TYPE_TAGS (block) = NULL_TREE;
      BLOCK_SUBBLOCKS (block) = subblocks;
      remember_end_note (block);
    }

  /* In each subblock, record that this is its superior.  */

  for (link = subblocks; link; link = TREE_CHAIN (link))
    BLOCK_SUPERCONTEXT (link) = block;

  /* Clear out the meanings of the local variables of this level.  */

  for (link = decls; link; link = TREE_CHAIN (link))
    {
      tree name = DECL_NAME (link);
      if (name != 0 && IDENTIFIER_LOCAL_VALUE (name) == link)
	{
	  /* If the ident. was used or addressed via a local extern decl,
	     don't forget that fact.  */
	  if (DECL_EXTERNAL (link))
	    {
	      if (TREE_USED (link))
		TREE_USED (name) = 1;
	      if (TREE_ADDRESSABLE (link))
		TREE_ADDRESSABLE (DECL_ASSEMBLER_NAME (link)) = 1;
	    }
	  IDENTIFIER_LOCAL_VALUE (name) = 0;
	}
    }

  /* Restore all name-meanings of the outer levels
     that were shadowed by this level.  */

  for (link = current_binding_level->shadowed; link; link = TREE_CHAIN (link))
    IDENTIFIER_LOCAL_VALUE (TREE_PURPOSE (link)) = TREE_VALUE (link);

  /* If the level being exited is the top level of a function,
     check over all the labels, and clear out the current
     (function local) meanings of their names.  */

  if (functionbody)
    {
      /* If this is the top level block of a function,
	 the vars are the function's parameters.
	 Don't leave them in the BLOCK because they are
	 found in the FUNCTION_DECL instead.  */

      BLOCK_VARS (block) = 0;

      /* Clear out the definitions of all label names,
	 since their scopes end here,
	 and add them to BLOCK_VARS.  */

#if 0
      for (link = named_labels; link; link = TREE_CHAIN (link))
	{
	  register tree label = TREE_VALUE (link);

	  if (DECL_INITIAL (label) == 0)
	    {
	      error_with_decl (label, "label `%s' used but not defined");
	      /* Avoid crashing later.  */
	      define_label (input_filename, lineno,
			    DECL_NAME (label));
	    }
	  else if (warn_unused && !TREE_USED (label))
	    warning_with_decl (label, "label `%s' defined but not used");