Add setting to control frame language mismatch warning

A customer noted that there is no way to prevent the "current language
does not match this frame" warning.  This patch adds a new setting to
allow this warning to be suppressed.

Reviewed-By: Eli Zaretskii <eliz@gnu.org>
Approved-By: Andrew Burgess <aburgess@redhat.com>

gdb/NEWS

@@ -85,6 +85,11 @@ set style line-number background COLOR
 set style line-number intensity VALUE
   Control the styling of line numbers printed by GDB.
 
+set warn-language-frame-mismatch [on|off]
+show warn-language-frame-mismatch
+  Control the warning that is emitted when specifying a language that
+  does not match the current frame's language.
+
 maintenance info inline-frames [ADDRESS]
   New command which displays GDB's inline-frame information for the
   current address, or for ADDRESS if specified.  The output identifies

gdb/doc/gdb.texinfo

@@ -16795,6 +16795,19 @@ written in one source language can be used by a main program written in
 a different source language.  Using @samp{set language auto} in this
 case frees you from having to set the working language manually.
 
+The warning is enabled by default, but it can be controlled via a
+setting:
+
+@table @code
+@item set warn-language-frame-mismatch [on|off]
+@kindex warn-language-frame-mismatch
+Enable or disable the warning that is issued when the current language
+is set to a value that does not match the current frame.
+
+@item show warn-language-frame-mismatch
+Show whether the frame-mismatch warning will be issued.
+@end table
+
 @node Show
 @section Displaying the Language
 

gdb/language.c

@@ -82,6 +82,9 @@ static const struct language_defn *global_current_language;
 static lazily_set_language_ftype *lazy_language_setter;
 enum language_mode language_mode = language_mode_auto;
 
+/* Whether to warn on language changes.  */
+bool warn_frame_lang_mismatch = true;
+
 /* See language.h.  */
 
 const struct language_defn *
@@ -168,7 +171,7 @@ show_language_command (struct ui_file *file, int from_tty,
 		_("The current source language is \"%s\".\n"),
 		current_language->name ());
 
-  if (has_stack_frames ())
+  if (warn_frame_lang_mismatch && has_stack_frames ())
     {
       frame_info_ptr frame;
 
@@ -1144,5 +1147,15 @@ For Fortran the default is off; for other languages the default is on."),
 			show_case_command,
 			&setlist, &showlist);
 
+  add_setshow_boolean_cmd ("warn-language-frame-mismatch", class_obscure,
+			   &warn_frame_lang_mismatch, _("\
+Enable or disable the frame language-mismatch warning."),
+			   _("\
+Show the current setting of the frame language-mismatch warning."),
+			   _("\
+The frame-language-mismatch warning is issued when the current language\n\
+does not match the selected frame's language."), nullptr, nullptr,
+			   &setlist, &showlist);
+
   add_set_language_command ();
 }

gdb/language.h

@@ -731,6 +731,10 @@ extern const struct language_defn *expected_language;
 
 extern const char lang_frame_mismatch_warn[];
 
+/* Controls whether to warn on a frame language mismatch.  */
+
+extern bool warn_frame_lang_mismatch;
+
 /* language_mode == 
    language_mode_auto:   current_language automatically set upon selection
    of scope (e.g. stack frame)

gdb/testsuite/gdb.base/langs.exp

@@ -98,9 +98,9 @@ clean_restart $binfile
 # Try exercising the "minimal" language a bit...
 
 if {[runto csub]} {
-    gdb_test "set lang minimal" \
-             "Warning: the current language does not match this frame." \
-             "set lang to minimal"
+    # Also test warn-language-frame-mismatch.
+    gdb_test_no_output "set warn-language-frame-mismatch off"
+    gdb_test_no_output "set lang minimal" "set lang to minimal"
     
     gdb_test "print x" " = 5000" "print parameter value"
 

gdb/testsuite/gdb.base/with.exp

@@ -238,7 +238,7 @@ with_test_prefix "errors" {
 
     # Try ambiguous settings.
     gdb_test "with w" \
-	"Ambiguous set command \"w\": watchdog, width, write\\."
+	"Ambiguous set command \"w\": warn-language-frame-mismatch, watchdog, width, write\\."
     gdb_test "with print m" \
 	"Ambiguous set print command \"m\": max-depth, max-symbolic-offset, memory-tag-violations\\."
 

gdb/top.c

@@ -388,7 +388,7 @@ check_frame_language_change (void)
   /* FIXME: This should be cacheing the frame and only running when
      the frame changes.  */
 
-  if (has_stack_frames ())
+  if (warn_frame_lang_mismatch && has_stack_frames ())
     {
       enum language flang;