Remove make_cleanup_restore_current_language

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.

ChangeLog
2017-08-03  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
	scoped_restore_current_language.
	* mi/mi-main.c (mi_cmd_execute): Use
	scoped_restore_current_language.
	* language.h (scoped_restore_current_language): New class.

gdb/ChangeLog

@@ -1,3 +1,15 @@
+2017-08-03  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
+	scoped_restore_current_language.
+	* mi/mi-main.c (mi_cmd_execute): Use
+	scoped_restore_current_language.
+	* language.h (scoped_restore_current_language): New class.
+
 2017-08-03  Tom Tromey  <tom@tromey.com>
 
 	* compile/compile.c (cleanup_unlink_file): Remove.

gdb/language.h

@@ -633,4 +633,30 @@ extern const struct language_defn opencl_language_defn;
 extern const struct language_defn pascal_language_defn;
 extern const struct language_defn rust_language_defn;
 
+/* Save the current language and restore it upon destruction.  */
+
+class scoped_restore_current_language
+{
+public:
+
+  explicit scoped_restore_current_language ()
+    : m_lang (current_language->la_language)
+  {
+  }
+
+  ~scoped_restore_current_language ()
+  {
+    set_language (m_lang);
+  }
+
+  scoped_restore_current_language (const scoped_restore_current_language &)
+      = delete;
+  scoped_restore_current_language &operator=
+      (const scoped_restore_current_language &) = delete;
+
+private:
+
+  enum language m_lang;
+};
+
 #endif /* defined (LANGUAGE_H) */

gdb/mi/mi-main.c

@@ -2243,9 +2243,10 @@ mi_cmd_execute (struct mi_parse *parse)
 	error (_("Invalid frame id: %d"), frame);
     }
 
+  gdb::optional<scoped_restore_current_language> lang_saver;
   if (parse->language != language_unknown)
     {
-      make_cleanup_restore_current_language ();
+      lang_saver.emplace ();
       set_language (parse->language);
     }
 

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;
@@ -1214,7 +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 ();
+
+  scoped_restore_current_language lang_saver;
   set_language (lang->la_language);
 
   TRY
@@ -1250,7 +1252,6 @@ 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 +1276,14 @@ parse_expression (const char *string)
 expression_up
 parse_expression_with_language (const char *string, enum language lang)
 {
-  struct cleanup *old_chain = NULL;
-
+  gdb::optional<scoped_restore_current_language> lang_saver;
   if (current_language->la_language != lang)
     {
-      old_chain = make_cleanup_restore_current_language ();
+      lang_saver.emplace ();
       set_language (lang);
     }
 
-  expression_up expr = parse_expression (string);
-
-  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

gdb/utils.c

@@ -286,28 +286,6 @@ 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

gdb/utils.h

@@ -113,8 +113,6 @@ 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
 {