[RFA 10/23] Remove make_cleanup_restore_current_language

[Tom Tromey <tom@tromey.com>]

This patch replaces make_cleanup_restore_current_language with an RAII
class that saves the current language, and restores it when the object
is destroyed.

2017-05-02  Tom Tromey  <tom@tromey.com>

	* utils.h (make_cleanup_restore_current_language): Remove.
	* utils.c (do_restore_current_language)
	(make_cleanup_restore_current_language): Remove.
	* parse.c (parse_exp_in_context_1)
	(parse_expression_with_language): Use save_language.
	* mi/mi-main.c (mi_cmd_execute): Use save_language.
	* language.h (save_language): New class.
---
 gdb/ChangeLog    | 10 ++++++++++
 gdb/language.h   | 25 +++++++++++++++++++++++++
 gdb/mi/mi-main.c |  6 ++----
 gdb/parse.c      | 22 +++++++---------------
 gdb/utils.c      | 22 ----------------------
 gdb/utils.h      |  2 --
 6 files changed, 44 insertions(+), 43 deletions(-)

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 50d8794..1c3b738 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,15 @@
 2017-05-02  Tom Tromey  <tom@tromey.com>
 
+	* utils.h (make_cleanup_restore_current_language): Remove.
+	* utils.c (do_restore_current_language)
+	(make_cleanup_restore_current_language): Remove.
+	* parse.c (parse_exp_in_context_1)
+	(parse_expression_with_language): Use save_language.
+	* mi/mi-main.c (mi_cmd_execute): Use save_language.
+	* language.h (save_language): New class.
+
+2017-05-02  Tom Tromey  <tom@tromey.com>
+
 	* source.c (get_filename_and_charpos, forward_search_command)
 	(reverse_search_command): Use fd_closer.
 	* procfs.c (load_syscalls, proc_get_LDT_entry)
diff --git a/gdb/language.h b/gdb/language.h
index 58bcbe8..f543da5 100644
--- a/gdb/language.h
+++ b/gdb/language.h
@@ -609,4 +609,29 @@ void default_get_string (struct value *value, gdb_byte **buffer, int *length,
 void c_get_string (struct value *value, gdb_byte **buffer, int *length,
 		   struct type **char_type, const char **charset);
 
+/* Save the current language and restore it upon destruction.  */
+
+class save_language
+{
+public:
+
+  explicit save_language (enum language new_lang)
+    : m_lang (current_language->la_language)
+  {
+    set_language (new_lang);
+  }
+
+  ~save_language ()
+  {
+    set_language (m_lang);
+  }
+
+  save_language (const save_language &) = delete;
+  save_language &operator= (const save_language &) = delete;
+
+private:
+
+  enum language m_lang;
+};
+
 #endif /* defined (LANGUAGE_H) */
diff --git a/gdb/mi/mi-main.c b/gdb/mi/mi-main.c
index cb68fd6..aa44876 100644
--- a/gdb/mi/mi-main.c
+++ b/gdb/mi/mi-main.c
@@ -2242,11 +2242,9 @@ mi_cmd_execute (struct mi_parse *parse)
 	error (_("Invalid frame id: %d"), frame);
     }
 
+  gdb::optional<save_language> lang_saver;
   if (parse->language != language_unknown)
-    {
-      make_cleanup_restore_current_language ();
-      set_language (parse->language);
-    }
+    lang_saver.emplace (parse->language);
 
   current_context = parse;
 
diff --git a/gdb/parse.c b/gdb/parse.c
index 3dd7075..84fce19 100644
--- a/gdb/parse.c
+++ b/gdb/parse.c
@@ -50,6 +50,7 @@
 #include "objfiles.h"
 #include "user-regs.h"
 #include <algorithm>
+#include "common/gdb_optional.h"
 
 /* Standard set of definitions for printing, dumping, prefixifying,
  * and evaluating expressions.  */
@@ -1136,7 +1137,7 @@ parse_exp_in_context_1 (const char **stringptr, CORE_ADDR pc,
 			const struct block *block,
 			int comma, int void_context_p, int *out_subexp)
 {
-  struct cleanup *old_chain, *inner_chain;
+  struct cleanup *old_chain;
   const struct language_defn *lang = NULL;
   struct parser_state ps;
   int subexp;
@@ -1214,8 +1215,8 @@ parse_exp_in_context_1 (const char **stringptr, CORE_ADDR pc,
      to the value matching SELECTED_FRAME as set by get_current_arch.  */
 
   initialize_expout (&ps, 10, lang, get_current_arch ());
-  inner_chain = make_cleanup_restore_current_language ();
-  set_language (lang->la_language);
+
+  save_language lang_saver (lang->la_language);
 
   TRY
     {
@@ -1250,7 +1251,6 @@ parse_exp_in_context_1 (const char **stringptr, CORE_ADDR pc,
   if (expressiondebug)
     dump_prefix_expression (ps.expout, gdb_stdlog);
 
-  do_cleanups (inner_chain);
   discard_cleanups (old_chain);
 
   *stringptr = lexptr;
@@ -1275,19 +1275,11 @@ parse_expression (const char *string)
 expression_up
 parse_expression_with_language (const char *string, enum language lang)
 {
-  struct cleanup *old_chain = NULL;
-
+  gdb::optional<save_language> lang_saver;
   if (current_language->la_language != lang)
-    {
-      old_chain = make_cleanup_restore_current_language ();
-      set_language (lang);
-    }
-
-  expression_up expr = parse_expression (string);
+    lang_saver.emplace (lang);
 
-  if (old_chain != NULL)
-    do_cleanups (old_chain);
-  return expr;
+  return parse_expression (string);
 }
 
 /* Parse STRING as an expression.  If parsing ends in the middle of a
diff --git a/gdb/utils.c b/gdb/utils.c
index bffce78..1a66896 100644
--- a/gdb/utils.c
+++ b/gdb/utils.c
@@ -307,28 +307,6 @@ make_cleanup_free_so (struct so_list *so)
   return make_cleanup (do_free_so, so);
 }
 
-/* Helper for make_cleanup_restore_current_language.  */
-
-static void
-do_restore_current_language (void *p)
-{
-  enum language saved_lang = (enum language) (uintptr_t) p;
-
-  set_language (saved_lang);
-}
-
-/* Remember the current value of CURRENT_LANGUAGE and make it restored when
-   the cleanup is run.  */
-
-struct cleanup *
-make_cleanup_restore_current_language (void)
-{
-  enum language saved_lang = current_language->la_language;
-
-  return make_cleanup (do_restore_current_language,
-		       (void *) (uintptr_t) saved_lang);
-}
-
 /* Helper function for make_cleanup_clear_parser_state.  */
 
 static void
diff --git a/gdb/utils.h b/gdb/utils.h
index 7afb3c5..1f01bdd 100644
--- a/gdb/utils.h
+++ b/gdb/utils.h
@@ -91,8 +91,6 @@ extern struct cleanup *make_cleanup_value_free (struct value *);
 struct so_list;
 extern struct cleanup *make_cleanup_free_so (struct so_list *so);
 
-extern struct cleanup *make_cleanup_restore_current_language (void);
-
 /* A deleter for a hash table.  */
 struct htab_deleter
 {
-- 
2.9.3