Introduce class completion_tracker & rewrite completion<->readline interaction

This patch reworks the whole completion machinery, and prepares it
for later enhancements.

Adds a new "completion_tracker" class that is meant to hold everything
about the state of the current completion operation.

This class now has the responsibility of tracking the list of
completion matches, and checking whether the max completions limit has
been reached.  You can look at this as this patch starting out by
C++fying the existing "completion_tracker" in symtab.c (it's just an
htab_t typedef currently), moving it to completer.h/c, and then making
it a class/generalizing/enhancing it.

Unlike with the current tracking, completion_tracker now checks
whether the limit has been reached on each completion match list
insertion.  This both simplifies the max-completions handling code
(maybe_add_completion_enum is gone, for example), and is a
prerequisite for follow up patches.

The current completion_tracker is only used for symbol completions,
and the symbol code gets at the current instance via globals.  This
patch cleans that up by adding a completion_tracker reference to the
signature of the completion functions, and passing the tracker around
everywhere necessary.

Then, the patch changes how the completion match list is handed over
to readline.  Currently, we're using the rl_completion_entry_function
readline entry point, and the patch switches to
rl_attempted_completion_function.  A following patch will want to let
GDB itself decide the common completion prefix between all matches
(what readline calls the "lowest common denominator"), instead of
having readline compute it, and that's not possible with the
rl_completion_entry_function entry point.  Also,
rl_attempted_completion_function lets GDB hand over the match list to
readline as an array in one go instead of passing down matches one by
one, so from that angle it's a nicer entry point anyway.

Lastly, the patch catches exceptions around the readline entry points,
because we can't let C++ exceptions cross readline.  We handle that in
the readline input entry point, but the completion entry point isn't
guarded, so GDB can abort if completion throws.  E.g., in current
master:

 (gdb) b -function "fun<tab>
 terminate called after throwing an instance of 'gdb_exception_RETURN_MASK_ERROR'
 Aborted (core dumped)

This patch fixes that.  This will be exercised in the new tests added
later on in the series.

gdb/ChangeLog:
2017-07-17  Pedro Alves  <palves@redhat.com>

	* ada-lang.c (symbol_completion_match): Adjust comments.
	(symbol_completion_add): Replace vector parameter with
	completion_tracker parameter.  Use it.
	(ada_make_symbol_completion_list): Rename to...
	(ada_collect_symbol_completion_matches): ... this.  Add
	completion_tracker parameter and use it.
	(ada_language_defn): Adjust.
	* break-catch-syscall.c (catch_syscall_completer): Adjust
	prototype and work with completion_tracker instead of VEC.
	* breakpoint.c (condition_completer): Adjust prototype and work
	with completion_tracker instead of VEC.
	* c-lang.c (c_language_defn, cplus_language_defn)
	(asm_language_defn, minimal_language_defn): Adjust to renames.
	* cli/cli-cmds.c (complete_command): Rework using
	completion_tracker.  Catch exceptions when completing.
	* cli/cli-decode.c (integer_unlimited_completer)
	(complete_on_cmdlist, complete_on_enum): Adjust prototype and work
	with completion_tracker instead of VEC.
	* command.h (struct completion_tracker): Forward declare.
	(completer_ftype, completer_handle_brkchars_ftype): Change
	types.
	(complete_on_cmdlist, complete_on_enum): Adjust.
	* completer.c: Include <algorithm>.
	(struct gdb_completer_state): New.
	(current_completion): New global.
	(readline_line_completion_function): Delete.
	(noop_completer, filename_completer)
	(filename_completer_handle_brkchars, complete_files_symbols)
	(linespec_location_completer): Adjust to work with a
	completion_tracker instead of a VEC.
	(string_or_empty): New.
	(collect_explicit_location_matches): Adjust to work with a
	completion_tracker instead of a VEC.
	(explicit_location_completer): Rename to ...
	(complete_explicit_location): ... this and adjust to work with a
	completion_tracker instead of a VEC.
	(location_completer): Adjust to work with a completion_tracker
	instead of a VEC.
	(add_struct_fields): Adjust to work with a completion_list instead
	of VEC.
	(expression_completer): Rename to ...
	(complete_expression): ... this and adjust to work with a
	completion_tracker instead of a VEC.  Use complete_files_symbols.
	(expression_completer): Reimplement on top of complete_expression.
	(symbol_completer): Adjust to work with a completion_tracker
	instead of a VEC.
	(enum complete_line_internal_reason): Add describing comments.
	(complete_line_internal_normal_command): Adjust to work with a
	completion_tracker instead of a VEC.
	(complete_line_internal): Rename to ...
	(complete_line_internal_1): ... this and adjust to work with a
	completion_tracker instead of a VEC.  Assert TEXT is NULL in the
	handle_brkchars phase.
	(new_completion_tracker): Delete.
	(complete_line_internal): Reimplement as TRY/CATCH wrapper around
	complete_line_internal_1.
	(free_completion_tracker): Delete.
	(INITIAL_COMPLETION_HTAB_SIZE): New.
	(completion_tracker::completion_tracker)
	(completion_tracker::~completion_tracker): New.
	(maybe_add_completion): Delete.
	(completion_tracker::maybe_add_completion)
	(completion_tracker::add_completion)
	(completion_tracker::add_completions): New.
	(throw_max_completions_reached_error): Delete.
	(complete_line): Adjust to work with a completion_tracker instead
	of a VEC.  Don't create a completion_tracker_t or check for max
	completions here.
	(command_completer, command_completer_handle_brkchars)
	(signal_completer, reg_or_group_completer_1)
	(reg_or_group_completer, default_completer_handle_brkchars):
	Adjust to work with a completion_tracker.
	(gdb_completion_word_break_characters_throw): New.
	(gdb_completion_word_break_characters): Reimplement.
	(line_completion_function): Delete.
	(completion_tracker::recompute_lowest_common_denominator)
	(expand_preserving_ws)
	(completion_tracker::build_completion_result)
	(completion_result::completion_result)
	(completion_result::completion_result)
	(completion_result::~completion_result)
	(completion_result::completion_result)
	(completion_result::release_match_list, compare_cstrings)
	(completion_result::sort_match_list)
	(completion_result::reset_match_list)
	(gdb_rl_attempted_completion_function_throw)
	(gdb_rl_attempted_completion_function): New.
	* completer.h (completion_list, struct completion_result)
	(class completion_tracker): New.
	(complete_line): Add completion_tracker parameter.
	(readline_line_completion_function): Delete.
	(gdb_rl_attempted_completion_function): New.
	(noop_completer, filename_completer, expression_completer)
	(location_completer, symbol_completer, command_completer)
	(signal_completer, reg_or_group_completer): Update prototypes.
	(completion_tracker_t, new_completion_tracker)
	(make_cleanup_free_completion_tracker): Delete.
	(enum maybe_add_completion_enum): Delete.
	(maybe_add_completion): Delete.
	(throw_max_completions_reached_error): Delete.
	* corefile.c (complete_set_gnutarget): Adjust to work with a
	completion_tracker instead of a VEC.
	* cp-abi.c (cp_abi_completer): Adjust to work with a
	completion_tracker instead of a VEC.
	* d-lang.c (d_language_defn): Adjust.
	* disasm.c (disassembler_options_completer): Adjust to work with a
	completion_tracker instead of a VEC.
	* f-lang.c (f_make_symbol_completion_list): Rename to ...
	(f_collect_symbol_completion_matches): ... this.  Adjust to work
	with a completion_tracker instead of a VEC.
	(f_language_defn): Adjust.
	* go-lang.c (go_language_defn): Adjust.
	* guile/scm-cmd.c (cmdscm_add_completion, cmdscm_completer):
	Adjust to work with a completion_tracker instead of a VEC.
	* infrun.c (handle_completer): Likewise.
	* interps.c (interpreter_completer): Likewise.
	* interps.h (interpreter_completer): Likewise.
	* language.c (unknown_language_defn, auto_language_defn)
	(local_language_defn): Adjust.
	* language.h (language_defn::la_make_symbol_completion_list):
	Rename to ...
	(language_defn::la_collect_symbol_completion_matches): ... this
	and adjust to work with a completion_tracker instead of a VEC.
	* m2-lang.c (m2_language_defn): Adjust.
	* objc-lang.c (objc_language_defn): Adjust.
	* opencl-lang.c (opencl_language_defn): Adjust.
	* p-lang.c (pascal_language_defn): Adjust.
	* python/py-cmd.c (cmdpy_completer_helper): Handle NULL word.
	(cmdpy_completer_handle_brkchars, cmdpy_completer): Adjust to work
	with a completion_tracker.
	* rust-lang.c (rust_language_defn): Adjust.
	* symtab.c (free_completion_list, do_free_completion_list)
	(return_val, completion_tracker): Delete.
	(completion_list_add_name, completion_list_add_symbol)
	(completion_list_add_msymbol, completion_list_objc_symbol)
	(completion_list_add_fields, add_symtab_completions): Add
	completion_tracker parameter and use it.
	(default_make_symbol_completion_list_break_on_1): Rename to...
	(default_collect_symbol_completion_matches_break_on): ... this.
	Add completion_tracker parameter and use it instead of allocating
	a completion tracker here.
	(default_make_symbol_completion_list_break_on): Delete old
	implementation.
	(default_make_symbol_completion_list): Delete.
	(default_collect_symbol_completion_matches): New.
	(make_symbol_completion_list): Delete.
	(collect_symbol_completion_matches): New.
	(make_symbol_completion_type): Rename to ...
	(collect_symbol_completion_matches_type): ... this.  Add
	completion_tracker parameter and use it instead of VEC.
	(make_file_symbol_completion_list_1): Rename to...
	(collect_file_symbol_completion_matches): ... this.  Add
	completion_tracker parameter and use it instead of VEC.
	(make_file_symbol_completion_list): Delete.
	(add_filename_to_list): Use completion_list instead of a VEC.
	(add_partial_filename_data::list): Now a completion_list.
	(make_source_files_completion_list): Work with a completion_list
	instead of a VEC.
	* symtab.h: Include "completer.h".
	(default_make_symbol_completion_list_break_on)
	(default_make_symbol_completion_list, make_symbol_completion_list)
	(make_symbol_completion_type, make_file_symbol_completion_list)
	(make_source_files_completion_list): Delete.
	(default_collect_symbol_completion_matches_break_on)
	(default_collect_symbol_completion_matches)
	(collect_symbol_completion_matches)
	(collect_symbol_completion_matches_type)
	(collect_file_symbol_completion_matches)
	(make_source_files_completion_list): New.
	* top.c (init_main): Don't install a rl_completion_entry_function
	hook.  Install a rl_attempted_completion_function hook instead.
	* tui/tui-layout.c (layout_completer): Adjust to work with a
	completion_tracker.
	* tui/tui-regs.c (tui_reggroup_completer):
	* tui/tui-win.c (window_name_completer, focus_completer)
	(winheight_completer): Adjust to work with a completion_tracker.
	* value.c: Include "completer.h".
	(complete_internalvar): Adjust to work with a completion_tracker.
	* value.h (complete_internalvar): Likewise.

1 files changed, 91 insertions, 181 deletions

diff --git a/gdb/symtab.c b/gdb/symtab.c
index e5cd397..57fb355 100644
--- a/gdb/symtab.c
+++ b/gdb/symtab.c
@@ -4747,44 +4747,13 @@ compare_symbol_name (const char *name, const char *sym_text, int sym_text_len)
   return 1;
 }
 
-/* Free any memory associated with a completion list.  */
-
-static void
-free_completion_list (VEC (char_ptr) **list_ptr)
-{
-  int i;
-  char *p;
-
-  for (i = 0; VEC_iterate (char_ptr, *list_ptr, i, p); ++i)
-    xfree (p);
-  VEC_free (char_ptr, *list_ptr);
-}
-
-/* Callback for make_cleanup.  */
-
-static void
-do_free_completion_list (void *list)
-{
-  free_completion_list ((VEC (char_ptr) **) list);
-}
-
-static VEC (char_ptr) *return_val;
-
-/* Tracker for how many unique completions have been generated.  Used
-   to terminate completion list generation early if the list has grown
-   to a size so large as to be useless.  This helps avoid GDB seeming
-   to lock up in the event the user requests to complete on something
-   vague that necessitates the time consuming expansion of many symbol
-   tables.  */
-
-static completion_tracker_t completion_tracker;
-
 /*  Test to see if the symbol specified by SYMNAME (which is already
    demangled for C++ symbols) matches SYM_TEXT in the first SYM_TEXT_LEN
    characters.  If so, add it to the current completion list.  */
 
 static void
-completion_list_add_name (const char *symname,
+completion_list_add_name (completion_tracker &tracker,
+			  const char *symname,
 			  const char *sym_text, int sym_text_len,
 			  const char *text, const char *word)
 {
@@ -4797,7 +4766,6 @@ completion_list_add_name (const char *symname,
 
   {
     char *newobj;
-    enum maybe_add_completion_enum add_status;
 
     if (word == sym_text)
       {
@@ -4819,45 +4787,33 @@ completion_list_add_name (const char *symname,
 	strcat (newobj, symname);
       }
 
-    add_status = maybe_add_completion (completion_tracker, newobj);
+    gdb::unique_xmalloc_ptr<char> completion (newobj);
 
-    switch (add_status)
-      {
-      case MAYBE_ADD_COMPLETION_OK:
-	VEC_safe_push (char_ptr, return_val, newobj);
-	break;
-      case MAYBE_ADD_COMPLETION_OK_MAX_REACHED:
-	VEC_safe_push (char_ptr, return_val, newobj);
-	throw_max_completions_reached_error ();
-      case MAYBE_ADD_COMPLETION_MAX_REACHED:
-	xfree (newobj);
-	throw_max_completions_reached_error ();
-      case MAYBE_ADD_COMPLETION_DUPLICATE:
-	xfree (newobj);
-	break;
-      }
+    tracker.add_completion (std::move (completion));
   }
 }
 
 /* completion_list_add_name wrapper for struct symbol.  */
 
 static void
-completion_list_add_symbol (symbol *sym,
+completion_list_add_symbol (completion_tracker &tracker,
+			    symbol *sym,
 			    const char *sym_text, int sym_text_len,
 			    const char *text, const char *word)
 {
-  completion_list_add_name (SYMBOL_NATURAL_NAME (sym),
+  completion_list_add_name (tracker, SYMBOL_NATURAL_NAME (sym),
 			    sym_text, sym_text_len, text, word);
 }
 
 /* completion_list_add_name wrapper for struct minimal_symbol.  */
 
 static void
-completion_list_add_msymbol (minimal_symbol *sym,
+completion_list_add_msymbol (completion_tracker &tracker,
+			     minimal_symbol *sym,
 			     const char *sym_text, int sym_text_len,
 			     const char *text, const char *word)
 {
-  completion_list_add_name (MSYMBOL_NATURAL_NAME (sym),
+  completion_list_add_name (tracker, MSYMBOL_NATURAL_NAME (sym),
 			    sym_text, sym_text_len, text, word);
 }
 
@@ -4865,7 +4821,8 @@ completion_list_add_msymbol (minimal_symbol *sym,
    again and feed all the selectors into the mill.  */
 
 static void
-completion_list_objc_symbol (struct minimal_symbol *msymbol,
+completion_list_objc_symbol (completion_tracker &tracker,
+			     struct minimal_symbol *msymbol,
 			     const char *sym_text, int sym_text_len,
 			     const char *text, const char *word)
 {
@@ -4883,7 +4840,8 @@ completion_list_objc_symbol (struct minimal_symbol *msymbol,
 
   if (sym_text[0] == '[')
     /* Complete on shortened method method.  */
-    completion_list_add_name (method + 1, sym_text, sym_text_len, text, word);
+    completion_list_add_name (tracker, method + 1,
+			      sym_text, sym_text_len, text, word);
 
   while ((strlen (method) + 1) >= tmplen)
     {
@@ -4904,9 +4862,11 @@ completion_list_objc_symbol (struct minimal_symbol *msymbol,
       memcpy (tmp, method, (category - method));
       tmp[category - method] = ' ';
       memcpy (tmp + (category - method) + 1, selector, strlen (selector) + 1);
-      completion_list_add_name (tmp, sym_text, sym_text_len, text, word);
+      completion_list_add_name (tracker, tmp,
+				sym_text, sym_text_len, text, word);
       if (sym_text[0] == '[')
-	completion_list_add_name (tmp + 1, sym_text, sym_text_len, text, word);
+	completion_list_add_name (tracker, tmp + 1,
+				  sym_text, sym_text_len, text, word);
     }
 
   if (selector != NULL)
@@ -4917,7 +4877,8 @@ completion_list_objc_symbol (struct minimal_symbol *msymbol,
       if (tmp2 != NULL)
 	*tmp2 = '\0';
 
-      completion_list_add_name (tmp, sym_text, sym_text_len, text, word);
+      completion_list_add_name (tracker, tmp,
+				sym_text, sym_text_len, text, word);
     }
 }
 
@@ -4968,9 +4929,10 @@ language_search_unquoted_string (const char *text, const char *p)
 }
 
 static void
-completion_list_add_fields (struct symbol *sym, const char *sym_text,
-			    int sym_text_len, const char *text,
-			    const char *word)
+completion_list_add_fields (completion_tracker &tracker,
+			    struct symbol *sym,
+			    const char *sym_text, int sym_text_len,
+			    const char *text, const char *word)
 {
   if (SYMBOL_CLASS (sym) == LOC_TYPEDEF)
     {
@@ -4981,7 +4943,7 @@ completion_list_add_fields (struct symbol *sym, const char *sym_text,
       if (c == TYPE_CODE_UNION || c == TYPE_CODE_STRUCT)
 	for (j = TYPE_N_BASECLASSES (t); j < TYPE_NFIELDS (t); j++)
 	  if (TYPE_FIELD_NAME (t, j))
-	    completion_list_add_name (TYPE_FIELD_NAME (t, j),
+	    completion_list_add_name (tracker, TYPE_FIELD_NAME (t, j),
 				      sym_text, sym_text_len, text, word);
     }
 }
@@ -4990,6 +4952,7 @@ completion_list_add_fields (struct symbol *sym, const char *sym_text,
 
 static void
 add_symtab_completions (struct compunit_symtab *cust,
+			completion_tracker &tracker,
 			const char *sym_text, int sym_text_len,
 			const char *text, const char *word,
 			enum type_code code)
@@ -5011,18 +4974,18 @@ add_symtab_completions (struct compunit_symtab *cust,
 	  if (code == TYPE_CODE_UNDEF
 	      || (SYMBOL_DOMAIN (sym) == STRUCT_DOMAIN
 		  && TYPE_CODE (SYMBOL_TYPE (sym)) == code))
-	    completion_list_add_symbol (sym,
+	    completion_list_add_symbol (tracker, sym,
 					sym_text, sym_text_len,
 					text, word);
 	}
     }
 }
 
-static void
-default_make_symbol_completion_list_break_on_1 (const char *text,
-						const char *word,
-						const char *break_on,
-						enum type_code code)
+void
+default_collect_symbol_completion_matches_break_on
+  (completion_tracker &tracker,
+   const char *text, const char *word,
+   const char *break_on, enum type_code code)
 {
   /* Problem: All of the symbols have to be copied because readline
      frees them.  I'm not going to worry about this; hopefully there
@@ -5039,7 +5002,6 @@ default_make_symbol_completion_list_break_on_1 (const char *text,
   const char *sym_text;
   /* Length of sym_text.  */
   int sym_text_len;
-  struct cleanup *cleanups;
 
   /* Now look for the symbol we are supposed to complete on.  */
   {
@@ -5109,9 +5071,6 @@ default_make_symbol_completion_list_break_on_1 (const char *text,
     }
   gdb_assert (sym_text[sym_text_len] == '\0' || sym_text[sym_text_len] == '(');
 
-  completion_tracker = new_completion_tracker ();
-  cleanups = make_cleanup_free_completion_tracker (&completion_tracker);
-
   /* At this point scan through the misc symbol vectors and add each
      symbol you find to the list.  Eventually we want to ignore
      anything that isn't a text symbol (everything else will be
@@ -5122,18 +5081,21 @@ default_make_symbol_completion_list_break_on_1 (const char *text,
       ALL_MSYMBOLS (objfile, msymbol)
 	{
 	  QUIT;
-	  completion_list_add_msymbol (msymbol, sym_text, sym_text_len, text,
-				       word);
 
-	  completion_list_objc_symbol (msymbol, sym_text, sym_text_len, text,
-				       word);
+	  completion_list_add_msymbol (tracker,
+				       msymbol, sym_text, sym_text_len,
+				       text, word);
+
+	  completion_list_objc_symbol (tracker,
+				       msymbol, sym_text, sym_text_len,
+				       text, word);
 	}
     }
 
   /* Add completions for all currently loaded symbol tables.  */
   ALL_COMPUNITS (objfile, cust)
-    add_symtab_completions (cust, sym_text, sym_text_len, text, word,
-			    code);
+    add_symtab_completions (cust, tracker,
+			    sym_text, sym_text_len, text, word, code);
 
   /* Look through the partial symtabs for all symbols which begin by
      matching SYM_TEXT.  Expand all CUs that you find to the list.  */
@@ -5147,6 +5109,7 @@ default_make_symbol_completion_list_break_on_1 (const char *text,
 			   [&] (compunit_symtab *symtab) /* expansion notify */
 			     {
 			       add_symtab_completions (symtab,
+						       tracker,
 						       sym_text, sym_text_len,
 						       text, word, code);
 			     },
@@ -5169,14 +5132,17 @@ default_make_symbol_completion_list_break_on_1 (const char *text,
 	  {
 	    if (code == TYPE_CODE_UNDEF)
 	      {
-		completion_list_add_symbol (sym, sym_text, sym_text_len, text,
+		completion_list_add_symbol (tracker, sym,
+					    sym_text, sym_text_len, text,
 					    word);
-		completion_list_add_fields (sym, sym_text, sym_text_len, text,
+		completion_list_add_fields (tracker, sym,
+					    sym_text, sym_text_len, text,
 					    word);
 	      }
 	    else if (SYMBOL_DOMAIN (sym) == STRUCT_DOMAIN
 		     && TYPE_CODE (SYMBOL_TYPE (sym)) == code)
-	      completion_list_add_symbol (sym, sym_text, sym_text_len, text,
+	      completion_list_add_symbol (tracker, sym,
+					  sym_text, sym_text_len, text,
 					  word);
 	  }
 
@@ -5194,11 +5160,13 @@ default_make_symbol_completion_list_break_on_1 (const char *text,
     {
       if (surrounding_static_block != NULL)
 	ALL_BLOCK_SYMBOLS (surrounding_static_block, iter, sym)
-	  completion_list_add_fields (sym, sym_text, sym_text_len, text, word);
+	  completion_list_add_fields (tracker, sym,
+				      sym_text, sym_text_len, text, word);
 
       if (surrounding_global_block != NULL)
 	ALL_BLOCK_SYMBOLS (surrounding_global_block, iter, sym)
-	  completion_list_add_fields (sym, sym_text, sym_text_len, text, word);
+	  completion_list_add_fields (tracker, sym,
+				      sym_text, sym_text_len, text, word);
     }
 
   /* Skip macros if we are completing a struct tag -- arguable but
@@ -5214,7 +5182,7 @@ default_make_symbol_completion_list_break_on_1 (const char *text,
 				 macro_source_file *,
 				 int)
 	{
-	  completion_list_add_name (macro_name,
+	  completion_list_add_name (tracker, macro_name,
 				    sym_text, sym_text_len,
 				    text, word);
 	};
@@ -5237,74 +5205,52 @@ default_make_symbol_completion_list_break_on_1 (const char *text,
       /* User-defined macros are always visible.  */
       macro_for_each (macro_user_macros, add_macro_name);
     }
-
-  do_cleanups (cleanups);
 }
 
-VEC (char_ptr) *
-default_make_symbol_completion_list_break_on (const char *text,
-					      const char *word,
-					      const char *break_on,
-					      enum type_code code)
-{
-  struct cleanup *back_to;
-
-  return_val = NULL;
-  back_to = make_cleanup (do_free_completion_list, &return_val);
-
-  TRY
-    {
-      default_make_symbol_completion_list_break_on_1 (text, word,
-						      break_on, code);
-    }
-  CATCH (except, RETURN_MASK_ERROR)
-    {
-      if (except.error != MAX_COMPLETIONS_REACHED_ERROR)
-	throw_exception (except);
-    }
-  END_CATCH
-
-  discard_cleanups (back_to);
-  return return_val;
-}
-
-VEC (char_ptr) *
-default_make_symbol_completion_list (const char *text, const char *word,
-				     enum type_code code)
+void
+default_collect_symbol_completion_matches (completion_tracker &tracker,
+					   const char *text, const char *word,
+					   enum type_code code)
 {
-  return default_make_symbol_completion_list_break_on (text, word, "", code);
+  return default_collect_symbol_completion_matches_break_on (tracker,
+							     text, word, "",
+							     code);
 }
 
-/* Return a vector of all symbols (regardless of class) which begin by
-   matching TEXT.  If the answer is no symbols, then the return value
-   is NULL.  */
+/* Collect all symbols (regardless of class) which begin by matching
+   TEXT.  */
 
-VEC (char_ptr) *
-make_symbol_completion_list (const char *text, const char *word)
+void
+collect_symbol_completion_matches (completion_tracker &tracker,
+				   const char *text, const char *word)
 {
-  return current_language->la_make_symbol_completion_list (text, word,
-							   TYPE_CODE_UNDEF);
+  current_language->la_collect_symbol_completion_matches (tracker,
+							  text, word,
+							  TYPE_CODE_UNDEF);
 }
 
-/* Like make_symbol_completion_list, but only return STRUCT_DOMAIN
-   symbols whose type code is CODE.  */
+/* Like collect_symbol_completion_matches, but only collect
+   STRUCT_DOMAIN symbols whose type code is CODE.  */
 
-VEC (char_ptr) *
-make_symbol_completion_type (const char *text, const char *word,
-			     enum type_code code)
+void
+collect_symbol_completion_matches_type (completion_tracker &tracker,
+					const char *text, const char *word,
+					enum type_code code)
 {
   gdb_assert (code == TYPE_CODE_UNION
 	      || code == TYPE_CODE_STRUCT
 	      || code == TYPE_CODE_ENUM);
-  return current_language->la_make_symbol_completion_list (text, word, code);
+  current_language->la_collect_symbol_completion_matches (tracker,
+							  text, word, code);
 }
 
-/* Like make_symbol_completion_list, but returns a list of symbols
-   defined in all source files name SRCFILE.  */
+/* Like collect_symbol_completion_matches, but collects a list of
+   symbols defined in all source files named SRCFILE.  */
 
-static VEC (char_ptr) *
-make_file_symbol_completion_list_1 (const char *text, const char *word,
-				    const char *srcfile)
+void
+collect_file_symbol_completion_matches (completion_tracker &tracker,
+					const char *text, const char *word,
+					const char *srcfile)
 {
   /* The symbol we are completing on.  Points in same buffer as text.  */
   const char *sym_text;
@@ -5345,7 +5291,7 @@ make_file_symbol_completion_list_1 (const char *text, const char *word,
       /* A double-quoted string is never a symbol, nor does it make sense
          to complete it any other way.  */
       {
-	return NULL;
+	return;
       }
     else
       {
@@ -5361,42 +5307,11 @@ make_file_symbol_completion_list_1 (const char *text, const char *word,
   iterate_over_symtabs (srcfile, [&] (symtab *s)
     {
       add_symtab_completions (SYMTAB_COMPUNIT (s),
+			      tracker,
 			      sym_text, sym_text_len,
 			      text, word, TYPE_CODE_UNDEF);
       return false;
     });
-
-  return (return_val);
-}
-
-/* Wrapper around make_file_symbol_completion_list_1
-   to handle MAX_COMPLETIONS_REACHED_ERROR.  */
-
-VEC (char_ptr) *
-make_file_symbol_completion_list (const char *text, const char *word,
-				  const char *srcfile)
-{
-  struct cleanup *back_to, *cleanups;
-
-  completion_tracker = new_completion_tracker ();
-  cleanups = make_cleanup_free_completion_tracker (&completion_tracker);
-  return_val = NULL;
-  back_to = make_cleanup (do_free_completion_list, &return_val);
-
-  TRY
-    {
-      make_file_symbol_completion_list_1 (text, word, srcfile);
-    }
-  CATCH (except, RETURN_MASK_ERROR)
-    {
-      if (except.error != MAX_COMPLETIONS_REACHED_ERROR)
-	throw_exception (except);
-    }
-  END_CATCH
-
-  discard_cleanups (back_to);
-  do_cleanups (cleanups);
-  return return_val;
 }
 
 /* A helper function for make_source_files_completion_list.  It adds
@@ -5405,7 +5320,7 @@ make_file_symbol_completion_list (const char *text, const char *word,
 
 static void
 add_filename_to_list (const char *fname, const char *text, const char *word,
-		      VEC (char_ptr) **list)
+		      completion_list *list)
 {
   char *newobj;
   size_t fnlen = strlen (fname);
@@ -5430,7 +5345,7 @@ add_filename_to_list (const char *fname, const char *text, const char *word,
       newobj[text - word] = '\0';
       strcat (newobj, fname);
     }
-  VEC_safe_push (char_ptr, *list, newobj);
+  list->emplace_back (newobj);
 }
 
 static int
@@ -5458,7 +5373,7 @@ struct add_partial_filename_data
   const char *text;
   const char *word;
   int text_len;
-  VEC (char_ptr) **list;
+  completion_list *list;
 };
 
 /* A callback for map_partial_symbol_filenames.  */
@@ -5490,19 +5405,18 @@ maybe_add_partial_symtab_filename (const char *filename, const char *fullname,
     }
 }
 
-/* Return a vector of all source files whose names begin with matching
+/* Return a list of all source files whose names begin with matching
    TEXT.  The file names are looked up in the symbol tables of this
-   program.  If the answer is no matchess, then the return value is
-   NULL.  */
+   program.  */
 
-VEC (char_ptr) *
+completion_list
 make_source_files_completion_list (const char *text, const char *word)
 {
   struct compunit_symtab *cu;
   struct symtab *s;
   struct objfile *objfile;
   size_t text_len = strlen (text);
-  VEC (char_ptr) *list = NULL;
+  completion_list list;
   const char *base_name;
   struct add_partial_filename_data datum;
   struct cleanup *back_to;
@@ -5510,8 +5424,6 @@ make_source_files_completion_list (const char *text, const char *word)
   if (!have_full_symbols () && !have_partial_symbols ())
     return list;
 
-  back_to = make_cleanup (do_free_completion_list, &list);
-
   filename_seen_cache filenames_seen;
 
   ALL_FILETABS (objfile, cu, s)
@@ -5547,8 +5459,6 @@ make_source_files_completion_list (const char *text, const char *word)
   map_symbol_filenames (maybe_add_partial_symtab_filename, &datum,
 			0 /*need_fullname*/);
 
-  discard_cleanups (back_to);
-
   return list;
 }