Class-ify macro_buffer

This patch changes macro_buffer to be a bit more of a C++ class,
adding constructors, a destructor, and some members.  Then this is
used to remove various cleanups in macroexp.c.

2018-02-08  Tom Tromey  <tom@tromey.com>

	* macroexp.c (struct macro_buffer): Add initializers for some
	members.
	(init_buffer, init_shared_buffer, free_buffer)
	(free_buffer_return_text): Remove.
	(macro_buffer): New constructors.
	(~macro_buffer): New destructor.
	(macro_buffer::set_shared): New method.
	(macro_buffer::resize_buffer, macro_buffer::appendc)
	(macro_buffer::appendmem): Now methods, not free functions.
	(set_token, append_tokens_without_splicing, stringify)
	(macro_stringify): Update.
	(gather_arguments): Change return type.  Remove argc_p argument,
	add args_ptr argument.  Use std::vector.
	(substitute_args): Remove argc argument.  Accept std::vector.
	(expand): Update.  Use std::vector.
	(scan, macro_expand, macro_expand_next): Update.

2 files changed, 185 insertions, 240 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 49306ac..2a989cc 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,24 @@
 2018-02-08  Tom Tromey  <tom@tromey.com>
 
+	* macroexp.c (struct macro_buffer): Add initializers for some
+	members.
+	(init_buffer, init_shared_buffer, free_buffer)
+	(free_buffer_return_text): Remove.
+	(macro_buffer): New constructors.
+	(~macro_buffer): New destructor.
+	(macro_buffer::set_shared): New method.
+	(macro_buffer::resize_buffer, macro_buffer::appendc)
+	(macro_buffer::appendmem): Now methods, not free functions.
+	(set_token, append_tokens_without_splicing, stringify)
+	(macro_stringify): Update.
+	(gather_arguments): Change return type.  Remove argc_p argument,
+	add args_ptr argument.  Use std::vector.
+	(substitute_args): Remove argc argument.  Accept std::vector.
+	(expand): Update.  Use std::vector.
+	(scan, macro_expand, macro_expand_next): Update.
+
+2018-02-08  Tom Tromey  <tom@tromey.com>
+
 	* symtab.c (default_collect_symbol_completion_matches_break_on):
 	Use unique_xmalloc_ptr.
 	* macroscope.h: (sal_macro_scope, user_macro_scope)
diff --git a/gdb/macroexp.c b/gdb/macroexp.c
index aefb13a..02cf26f 100644
--- a/gdb/macroexp.c
+++ b/gdb/macroexp.c
@@ -65,121 +65,110 @@ struct macro_buffer
      no token abutting the end of TEXT (it's just whitespace), and
      again, we set this equal to LEN.  We set this to -1 if we don't
      know the nature of TEXT.  */
-  int last_token;
+  int last_token = -1;
 
   /* If this buffer is holding the result from get_token, then this 
      is non-zero if it is an identifier token, zero otherwise.  */
-  int is_identifier;
-};
-
-
-/* Set the macro buffer *B to the empty string, guessing that its
-   final contents will fit in N bytes.  (It'll get resized if it
-   doesn't, so the guess doesn't have to be right.)  Allocate the
-   initial storage with xmalloc.  */
-static void
-init_buffer (struct macro_buffer *b, int n)
-{
-  b->size = n;
-  if (n > 0)
-    b->text = (char *) xmalloc (n);
-  else
-    b->text = NULL;
-  b->len = 0;
-  b->shared = false;
-  b->last_token = -1;
-}
-
-
-/* Set the macro buffer *BUF to refer to the LEN bytes at ADDR, as a
-   shared substring.  */
-
-static void
-init_shared_buffer (struct macro_buffer *buf, const char *addr, int len)
-{
-  /* The function accept a "const char *" addr so that clients can
-     pass in string literals without casts.  */
-  buf->text = (char *) addr;
-  buf->len = len;
-  buf->shared = true;
-  buf->size = 0;
-  buf->last_token = -1;
-}
+  int is_identifier = 0;
 
 
-/* Free the text of the buffer B.  Raise an error if B is shared.  */
-static void
-free_buffer (struct macro_buffer *b)
-{
-  gdb_assert (! b->shared);
-  if (b->size)
-    xfree (b->text);
-}
+  macro_buffer ()
+    : text (NULL),
+      len (0),
+      size (0),
+      shared (false)
+  {
+  }
 
-/* Like free_buffer, but return the text as an xstrdup()d string.
-   This only exists to try to make the API relatively clean.  */
+  /* Set the macro buffer to the empty string, guessing that its
+     final contents will fit in N bytes.  (It'll get resized if it
+     doesn't, so the guess doesn't have to be right.)  Allocate the
+     initial storage with xmalloc.  */
+  explicit macro_buffer (int n)
+    : len (0),
+      size (n),
+      shared (false)
+  {
+    if (n > 0)
+      text = (char *) xmalloc (n);
+    else
+      text = NULL;
+  }
 
-static char *
-free_buffer_return_text (struct macro_buffer *b)
-{
-  gdb_assert (! b->shared);
-  gdb_assert (b->size);
-  /* Nothing to do.  */
-  return b->text;
-}
+  /* Set the macro buffer to refer to the LEN bytes at ADDR, as a
+     shared substring.  */
+  macro_buffer (const char *addr, int len)
+  {
+    set_shared (addr, len);
+  }
 
-/* A cleanup function for macro buffers.  */
-static void
-cleanup_macro_buffer (void *untyped_buf)
-{
-  free_buffer ((struct macro_buffer *) untyped_buf);
-}
+  /* Set the macro buffer to refer to the LEN bytes at ADDR, as a
+     shared substring.  */
+  void set_shared (const char *addr, int len_)
+  {
+    text = (char *) addr;
+    len = len_;
+    size = 0;
+    shared = true;
+  }
 
+  ~macro_buffer ()
+  {
+    if (! shared && size)
+      xfree (text);
+  }
 
-/* Resize the buffer B to be at least N bytes long.  Raise an error if
-   B shouldn't be resized.  */
-static void
-resize_buffer (struct macro_buffer *b, int n)
-{
-  /* We shouldn't be trying to resize shared strings.  */
-  gdb_assert (! b->shared);
-  
-  if (b->size == 0)
-    b->size = n;
-  else
-    while (b->size <= n)
-      b->size *= 2;
+  /* Release the text of the buffer to the caller, which is now
+     responsible for freeing it.  */
+  char *release ()
+  {
+    gdb_assert (! shared);
+    gdb_assert (size);
+    char *result = text;
+    text = NULL;
+    return result;
+  }
 
-  b->text = (char *) xrealloc (b->text, b->size);
-}
+  /* Resize the buffer to be at least N bytes long.  Raise an error if
+     the buffer shouldn't be resized.  */
+  void resize_buffer (int n)
+  {
+    /* We shouldn't be trying to resize shared strings.  */
+    gdb_assert (! shared);
 
+    if (size == 0)
+      size = n;
+    else
+      while (size <= n)
+	size *= 2;
 
-/* Append the character C to the buffer B.  */
-static void
-appendc (struct macro_buffer *b, int c)
-{
-  int new_len = b->len + 1;
+    text = (char *) xrealloc (text, size);
+  }
 
-  if (new_len > b->size)
-    resize_buffer (b, new_len);
+  /* Append the character C to the buffer.  */
+  void appendc (int c)
+  {
+    int new_len = len + 1;
 
-  b->text[b->len] = c;
-  b->len = new_len;
-}
+    if (new_len > size)
+      resize_buffer (new_len);
 
+    text[len] = c;
+    len = new_len;
+  }
 
-/* Append the LEN bytes at ADDR to the buffer B.  */
-static void
-appendmem (struct macro_buffer *b, const char *addr, int len)
-{
-  int new_len = b->len + len;
+  /* Append the COUNT bytes at ADDR to the buffer.  */
+  void appendmem (const char *addr, int count)
+  {
+    int new_len = len + count;
 
-  if (new_len > b->size)
-    resize_buffer (b, new_len);
+    if (new_len > size)
+      resize_buffer (new_len);
 
-  memcpy (b->text + b->len, addr, len);
-  b->len = new_len;
-}
+    memcpy (text + len, addr, count);
+    len = new_len;
+  }
+};
 
 
 
@@ -216,7 +205,7 @@ macro_is_identifier_nondigit (int c)
 static void
 set_token (struct macro_buffer *tok, char *start, char *end)
 {
-  init_shared_buffer (tok, start, end - start);
+  tok->set_shared (start, end - start);
   tok->last_token = 0;
 
   /* Presumed; get_identifier may overwrite this.  */
@@ -596,7 +585,7 @@ append_tokens_without_splicing (struct macro_buffer *dest,
   
   /* First, just try appending the two, and call get_token to see if
      we got a splice.  */
-  appendmem (dest, src->text, src->len);
+  dest->appendmem (src->text, src->len);
 
   /* If DEST originally had no token abutting its end, then we can't
      have spliced anything, so we're done.  */
@@ -608,9 +597,8 @@ append_tokens_without_splicing (struct macro_buffer *dest,
 
   /* Set DEST_TAIL to point to the last token in DEST, followed by
      all the stuff we just appended.  */
-  init_shared_buffer (&dest_tail,
-                      dest->text + dest->last_token,
-                      dest->len - dest->last_token);
+  dest_tail.set_shared (dest->text + dest->last_token,
+			dest->len - dest->last_token);
 
   /* Re-parse DEST's last token.  We know that DEST used to contain
      at least one token, so if it doesn't contain any after the
@@ -630,12 +618,11 @@ append_tokens_without_splicing (struct macro_buffer *dest,
      its original length and try again, but separate the texts with a
      space.  */
   dest->len = original_dest_len;
-  appendc (dest, ' ');
-  appendmem (dest, src->text, src->len);
+  dest->appendc (' ');
+  dest->appendmem (src->text, src->len);
 
-  init_shared_buffer (&dest_tail,
-                      dest->text + dest->last_token,
-                      dest->len - dest->last_token);
+  dest_tail.set_shared (dest->text + dest->last_token,
+			dest->len - dest->last_token);
 
   /* Try to re-parse DEST's last token, as above.  */
   if (get_token (&new_token, &dest_tail)
@@ -671,7 +658,7 @@ stringify (struct macro_buffer *dest, const char *arg, int len)
     --len;
 
   /* Insert the string.  */
-  appendc (dest, '"');
+  dest->appendc ('"');
   while (len > 0)
     {
       /* We could try to handle strange cases here, like control
@@ -679,7 +666,7 @@ stringify (struct macro_buffer *dest, const char *arg, int len)
       if (macro_is_whitespace (*arg))
 	{
 	  /* Replace a sequence of whitespace with a single space.  */
-	  appendc (dest, ' ');
+	  dest->appendc (' ');
 	  while (len > 1 && macro_is_whitespace (arg[1]))
 	    {
 	      ++arg;
@@ -688,15 +675,15 @@ stringify (struct macro_buffer *dest, const char *arg, int len)
 	}
       else if (*arg == '\\' || *arg == '"')
 	{
-	  appendc (dest, '\\');
-	  appendc (dest, *arg);
+	  dest->appendc ('\\');
+	  dest->appendc (*arg);
 	}
       else
-	appendc (dest, *arg);
+	dest->appendc (*arg);
       ++arg;
       --len;
     }
-  appendc (dest, '"');
+  dest->appendc ('"');
   dest->last_token = dest->len;
 }
 
@@ -705,14 +692,13 @@ stringify (struct macro_buffer *dest, const char *arg, int len)
 char *
 macro_stringify (const char *str)
 {
-  struct macro_buffer buffer;
   int len = strlen (str);
+  struct macro_buffer buffer (len);
 
-  init_buffer (&buffer, len);
   stringify (&buffer, str, len);
-  appendc (&buffer, '\0');
+  buffer.appendc ('\0');
 
-  return free_buffer_return_text (&buffer);
+  return buffer.release ();
 }
 
 
@@ -759,22 +745,19 @@ currently_rescanning (struct macro_name_list *list, const char *name)
    baz).
 
    If SRC doesn't start with an open paren ( token at all, return
-   zero, leave SRC unchanged, and don't set *ARGC_P to anything.
+   false, leave SRC unchanged, and don't set *ARGS_PTR to anything.
 
    If SRC doesn't contain a properly terminated argument list, then
    raise an error.
-   
+
    For a variadic macro, NARGS holds the number of formal arguments to
    the macro.  For a GNU-style variadic macro, this should be the
    number of named arguments.  For a non-variadic macro, NARGS should
    be -1.
 
-   Otherwise, return a pointer to the first element of an array of
-   macro buffers referring to the argument texts, and set *ARGC_P to
-   the number of arguments we found --- the number of elements in the
-   array.  The macro buffers share their text with SRC, and their
-   last_token fields are initialized.  The array is allocated with
-   xmalloc, and the caller is responsible for freeing it.
+   Otherwise, return true and set *ARGS_PTR to a vector of macro
+   buffers referring to the argument texts.  The macro buffers share
+   their text with SRC, and their last_token fields are initialized.
 
    NOTE WELL: if SRC starts with a open paren ( token followed
    immediately by a close paren ) token (e.g., the invocation looks
@@ -787,53 +770,36 @@ currently_rescanning (struct macro_name_list *list, const char *name)
    Consume the tokens from SRC; after this call, SRC contains the text
    following the invocation.  */
 
-static struct macro_buffer *
-gather_arguments (const char *name, struct macro_buffer *src,
-		  int nargs, int *argc_p)
+static bool
+gather_arguments (const char *name, struct macro_buffer *src, int nargs,
+		  std::vector<struct macro_buffer> *args_ptr)
 {
   struct macro_buffer tok;
-  int args_len, args_size;
-  struct macro_buffer *args = NULL;
-  struct cleanup *back_to = make_cleanup (free_current_contents, &args);
+  std::vector<struct macro_buffer> args;
 
   /* Does SRC start with an opening paren token?  Read from a copy of
      SRC, so SRC itself is unaffected if we don't find an opening
      paren.  */
   {
-    struct macro_buffer temp;
-
-    init_shared_buffer (&temp, src->text, src->len);
+    struct macro_buffer temp (src->text, src->len);
 
     if (! get_token (&tok, &temp)
         || tok.len != 1
         || tok.text[0] != '(')
-      {
-        discard_cleanups (back_to);
-        return 0;
-      }
+      return false;
   }
 
   /* Consume SRC's opening paren.  */
   get_token (&tok, src);
 
-  args_len = 0;
-  args_size = 6;
-  args = XNEWVEC (struct macro_buffer, args_size);
-
   for (;;)
     {
       struct macro_buffer *arg;
       int depth;
 
-      /* Make sure we have room for the next argument.  */
-      if (args_len >= args_size)
-        {
-          args_size *= 2;
-          args = XRESIZEVEC (struct macro_buffer, args, args_size);
-        }
-
       /* Initialize the next argument.  */
-      arg = &args[args_len++];
+      args.emplace_back ();
+      arg = &args.back ();
       set_token (arg, src->text, src->text);
 
       /* Gather the argument's tokens.  */
@@ -842,7 +808,7 @@ gather_arguments (const char *name, struct macro_buffer *src,
         {
           if (! get_token (&tok, src))
             error (_("Malformed argument list for macro `%s'."), name);
-      
+
           /* Is tok an opening paren?  */
           if (tok.len == 1 && tok.text[0] == '(')
             depth++;
@@ -856,22 +822,15 @@ gather_arguments (const char *name, struct macro_buffer *src,
                 {
 		  /* In the varargs case, the last argument may be
 		     missing.  Add an empty argument in this case.  */
-		  if (nargs != -1 && args_len == nargs - 1)
+		  if (nargs != -1 && args.size () == nargs - 1)
 		    {
-		      /* Make sure we have room for the argument.  */
-		      if (args_len >= args_size)
-			{
-			  args_size++;
-			  args = XRESIZEVEC (struct macro_buffer, args,
-					     args_size);
-			}
-		      arg = &args[args_len++];
+		      args.emplace_back ();
+		      arg = &args.back ();
 		      set_token (arg, src->text, src->text);
 		    }
 
-                  discard_cleanups (back_to);
-                  *argc_p = args_len;
-                  return args;
+		  *args_ptr = std::move (args);
+		  return true;
                 }
 
               depth--;
@@ -882,7 +841,7 @@ gather_arguments (const char *name, struct macro_buffer *src,
              variadic macro and we are computing the last argument, we
              want to include the comma and remaining tokens.  */
           else if (tok.len == 1 && tok.text[0] == ',' && depth == 0
-		   && (nargs == -1 || args_len < nargs))
+		   && (nargs == -1 || args.size () < nargs))
             break;
 
           /* Extend the current argument to enclose this token.  If
@@ -971,7 +930,7 @@ get_next_token_for_substitution (struct macro_buffer *replacement_list,
 }
 
 /* Given the macro definition DEF, being invoked with the actual
-   arguments given by ARGC and ARGV, substitute the arguments into the
+   arguments given by ARGV, substitute the arguments into the
    replacement list, and store the result in DEST.
 
    IS_VARARGS should be true if DEF is a varargs macro.  In this case,
@@ -986,16 +945,14 @@ get_next_token_for_substitution (struct macro_buffer *replacement_list,
    NO_LOOP.  */
 
 static void
-substitute_args (struct macro_buffer *dest, 
+substitute_args (struct macro_buffer *dest,
                  struct macro_definition *def,
 		 int is_varargs, const struct macro_buffer *va_arg_name,
-                 int argc, struct macro_buffer *argv,
+		 const std::vector<struct macro_buffer> &argv,
                  struct macro_name_list *no_loop,
                  macro_lookup_ftype *lookup_func,
                  void *lookup_baton)
 {
-  /* A macro buffer for the macro's replacement list.  */
-  struct macro_buffer replacement_list;
   /* The token we are currently considering.  */
   struct macro_buffer tok;
   /* The replacement list's pointer from just before TOK was lexed.  */
@@ -1008,8 +965,9 @@ substitute_args (struct macro_buffer *dest,
      lexed.  */
   char *lookahead_rl_start;
 
-  init_shared_buffer (&replacement_list, def->replacement,
-                      strlen (def->replacement));
+  /* A macro buffer for the macro's replacement list.  */
+  struct macro_buffer replacement_list (def->replacement,
+					strlen (def->replacement));
 
   gdb_assert (dest->len == 0);
   dest->last_token = 0;
@@ -1066,7 +1024,7 @@ substitute_args (struct macro_buffer *dest,
 
 	  /* If __VA_ARGS__ is empty, then drop the contents of
 	     __VA_OPT__.  */
-	  if (argv[argc - 1].len == 0)
+	  if (argv.back ().len == 0)
 	    continue;
 	}
       else if (token_is_vaopt)
@@ -1082,7 +1040,7 @@ substitute_args (struct macro_buffer *dest,
          that to DEST.  */
       if (tok.text > original_rl_start)
         {
-          appendmem (dest, original_rl_start, tok.text - original_rl_start);
+          dest->appendmem (original_rl_start, tok.text - original_rl_start);
           dest->last_token = dest->len;
         }
 
@@ -1135,9 +1093,9 @@ substitute_args (struct macro_buffer *dest,
 					def->argc, def->argv);
 
 	      if (arg != -1)
-		appendmem (dest, argv[arg].text, argv[arg].len);
+		dest->appendmem (argv[arg].text, argv[arg].len);
 	      else
-		appendmem (dest, tok.text, tok.len);
+		dest->appendmem (tok.text, tok.len);
 	    }
 
 	  /* Apply a possible sequence of ## operators.  */
@@ -1160,8 +1118,8 @@ substitute_args (struct macro_buffer *dest,
 		  if (! (is_varargs
 			 && tok.len == va_arg_name->len
 			 && !memcmp (tok.text, va_arg_name->text, tok.len)
-			 && argv[argc - 1].len == 0))
-		    appendmem (dest, ",", 1);
+			 && argv.back ().len == 0))
+		    dest->appendmem (",", 1);
 		  prev_was_comma = 0;
 		}
 
@@ -1175,9 +1133,9 @@ substitute_args (struct macro_buffer *dest,
 					    def->argc, def->argv);
 
 		  if (arg != -1)
-		    appendmem (dest, argv[arg].text, argv[arg].len);
+		    dest->appendmem (argv[arg].text, argv[arg].len);
 		  else
-		    appendmem (dest, tok.text, tok.len);
+		    dest->appendmem (tok.text, tok.len);
 		}
 
 	      /* Now read another token.  If it is another splice, we
@@ -1198,7 +1156,7 @@ substitute_args (struct macro_buffer *dest,
 	  if (prev_was_comma)
 	    {
 	      /* We saw a comma.  Insert it now.  */
-	      appendmem (dest, ",", 1);
+	      dest->appendmem (",", 1);
 	    }
 
           dest->last_token = dest->len;
@@ -1221,14 +1179,12 @@ substitute_args (struct macro_buffer *dest,
 
 	  if (arg != -1)
 	    {
-	      struct macro_buffer arg_src;
-
 	      /* Expand any macro invocations in the argument text,
 		 and append the result to dest.  Remember that scan
 		 mutates its source, so we need to scan a new buffer
 		 referring to the argument's text, not the argument
 		 itself.  */
-	      init_shared_buffer (&arg_src, argv[arg].text, argv[arg].len);
+	      struct macro_buffer arg_src (argv[arg].text, argv[arg].len);
 	      scan (dest, &arg_src, no_loop, lookup_func, lookup_baton);
 	      substituted = 1;
 	    }
@@ -1275,22 +1231,15 @@ expand (const char *id,
   /* What kind of macro are we expanding?  */
   if (def->kind == macro_object_like)
     {
-      struct macro_buffer replacement_list;
-
-      init_shared_buffer (&replacement_list, def->replacement,
-                          strlen (def->replacement));
+      struct macro_buffer replacement_list (def->replacement,
+					    strlen (def->replacement));
 
       scan (dest, &replacement_list, &new_no_loop, lookup_func, lookup_baton);
       return 1;
     }
   else if (def->kind == macro_function_like)
     {
-      struct cleanup *back_to = make_cleanup (null_cleanup, 0);
-      int argc = 0;
-      struct macro_buffer *argv = NULL;
-      struct macro_buffer substituted;
-      struct macro_buffer substituted_src;
-      struct macro_buffer va_arg_name = {0};
+      struct macro_buffer va_arg_name;
       int is_varargs = 0;
 
       if (def->argc >= 1)
@@ -1299,8 +1248,7 @@ expand (const char *id,
 	    {
 	      /* In C99-style varargs, substitution is done using
 		 __VA_ARGS__.  */
-	      init_shared_buffer (&va_arg_name, "__VA_ARGS__",
-				  strlen ("__VA_ARGS__"));
+	      va_arg_name.set_shared ("__VA_ARGS__", strlen ("__VA_ARGS__"));
 	      is_varargs = 1;
 	    }
 	  else
@@ -1313,43 +1261,36 @@ expand (const char *id,
 		  /* In GNU-style varargs, the name of the
 		     substitution parameter is the name of the formal
 		     argument without the "...".  */
-		  init_shared_buffer (&va_arg_name,
-				      def->argv[def->argc - 1],
-				      len - 3);
+		  va_arg_name.set_shared (def->argv[def->argc - 1], len - 3);
 		  is_varargs = 1;
 		}
 	    }
 	}
 
-      make_cleanup (free_current_contents, &argv);
-      argv = gather_arguments (id, src, is_varargs ? def->argc : -1,
-			       &argc);
-
+      std::vector<struct macro_buffer> argv;
       /* If we couldn't find any argument list, then we don't expand
          this macro.  */
-      if (! argv)
-        {
-          do_cleanups (back_to);
-          return 0;
-        }
+      if (!gather_arguments (id, src, is_varargs ? def->argc : -1,
+			     &argv))
+	return 0;
 
       /* Check that we're passing an acceptable number of arguments for
          this macro.  */
-      if (argc != def->argc)
+      if (argv.size () != def->argc)
         {
-	  if (is_varargs && argc >= def->argc - 1)
+	  if (is_varargs && argv.size () >= def->argc - 1)
 	    {
 	      /* Ok.  */
 	    }
           /* Remember that a sequence of tokens like "foo()" is a
              valid invocation of a macro expecting either zero or one
              arguments.  */
-          else if (! (argc == 1
+          else if (! (argv.size () == 1
 		      && argv[0].len == 0
 		      && def->argc == 0))
             error (_("Wrong number of arguments to macro `%s' "
                    "(expected %d, got %d)."),
-                   id, def->argc, argc);
+                   id, def->argc, int (argv.size ()));
         }
 
       /* Note that we don't expand macro invocations in the arguments
@@ -1358,10 +1299,9 @@ expand (const char *id,
          splicing operator "##" don't get macro references expanded,
          so we can't really tell whether it's appropriate to macro-
          expand an argument until we see how it's being used.  */
-      init_buffer (&substituted, 0);
-      make_cleanup (cleanup_macro_buffer, &substituted);
+      struct macro_buffer substituted (0);
       substitute_args (&substituted, def, is_varargs, &va_arg_name,
-		       argc, argv, no_loop, lookup_func, lookup_baton);
+		       argv, no_loop, lookup_func, lookup_baton);
 
       /* Now `substituted' is the macro's replacement list, with all
          argument values substituted into it properly.  Re-scan it for
@@ -1373,11 +1313,9 @@ expand (const char *id,
          text pointer around, and we still need to be able to find
          `substituted's original text buffer after scanning it so we
          can free it.  */
-      init_shared_buffer (&substituted_src, substituted.text, substituted.len);
+      struct macro_buffer substituted_src (substituted.text, substituted.len);
       scan (dest, &substituted_src, &new_no_loop, lookup_func, lookup_baton);
 
-      do_cleanups (back_to);
-
       return 1;
     }
   else
@@ -1465,7 +1403,7 @@ scan (struct macro_buffer *dest,
          that to DEST.  */
       if (tok.text > original_src_start)
         {
-          appendmem (dest, original_src_start, tok.text - original_src_start);
+          dest->appendmem (original_src_start, tok.text - original_src_start);
           dest->last_token = dest->len;
         }
 
@@ -1479,7 +1417,7 @@ scan (struct macro_buffer *dest,
      src, copy it to dest.  */
   if (src->len)
     {
-      appendmem (dest, src->text, src->len);
+      dest->appendmem (src->text, src->len);
       dest->last_token = dest->len;
     }
 }
@@ -1490,21 +1428,16 @@ macro_expand (const char *source,
               macro_lookup_ftype *lookup_func,
               void *lookup_func_baton)
 {
-  struct macro_buffer src, dest;
-  struct cleanup *back_to;
-
-  init_shared_buffer (&src, source, strlen (source));
+  struct macro_buffer src (source, strlen (source));
 
-  init_buffer (&dest, 0);
+  struct macro_buffer dest (0);
   dest.last_token = 0;
-  back_to = make_cleanup (cleanup_macro_buffer, &dest);
 
   scan (&dest, &src, 0, lookup_func, lookup_func_baton);
 
-  appendc (&dest, '\0');
+  dest.appendc ('\0');
 
-  discard_cleanups (back_to);
-  return gdb::unique_xmalloc_ptr<char> (dest.text);
+  return gdb::unique_xmalloc_ptr<char> (dest.release ());
 }
 
 
@@ -1522,23 +1455,18 @@ macro_expand_next (const char **lexptr,
                    macro_lookup_ftype *lookup_func,
                    void *lookup_baton)
 {
-  struct macro_buffer src, dest, tok;
-  struct cleanup *back_to;
+  struct macro_buffer tok;
 
   /* Set up SRC to refer to the input text, pointed to by *lexptr.  */
-  init_shared_buffer (&src, *lexptr, strlen (*lexptr));
+  struct macro_buffer src (*lexptr, strlen (*lexptr));
 
   /* Set up DEST to receive the expansion, if there is one.  */
-  init_buffer (&dest, 0);
+  struct macro_buffer dest (0);
   dest.last_token = 0;
-  back_to = make_cleanup (cleanup_macro_buffer, &dest);
 
   /* Get the text's first preprocessing token.  */
   if (! get_token (&tok, &src))
-    {
-      do_cleanups (back_to);
-      return 0;
-    }
+    return 0;
 
   /* If it's a macro invocation, expand it.  */
   if (maybe_expand (&dest, &tok, &src, 0, lookup_func, lookup_baton))
@@ -1546,15 +1474,13 @@ macro_expand_next (const char **lexptr,
       /* It was a macro invocation!  Package up the expansion as a
          null-terminated string and return it.  Set *lexptr to the
          start of the next token in the input.  */
-      appendc (&dest, '\0');
-      discard_cleanups (back_to);
+      dest.appendc ('\0');
       *lexptr = src.text;
-      return dest.text;
+      return dest.release ();
     }
   else
     {
       /* It wasn't a macro invocation.  */
-      do_cleanups (back_to);
       return 0;
     }
 }