Ensure class_alias is only used for user-defined aliases.

This commit finally does the (small) change that started this patch
series.

It ensures that the class_alias is only used for user-defined aliases.
So, the few GDB pre-defined aliases that were using the 'class_alias'
class are now using a real help class, typically the class of
the aliased command.

gdb/ChangeLog

2020-05-15  Philippe Waroquiers  <philippe.waroquiers@skynet.be>

	* command.h (enum command_class): Improve comments, document
	that class_alias is for user-defined aliases, give the class
	name for each class, remove unused class_xdb.
	* cli/cli-decode.c (add_com_alias): Document THECLASS intended usage.
	* breakpoint.c (_initialize_breakpoint): Replace class_alias
	by a precise class.
	* infcmd.c (_initialize_infcmd): Likewise.
	* reverse.c (_initialize_reverse): Likewise.
	* stack.c (_initialize_stack): Likewise.
	* symfile.c (_initialize_symfile): Likewise.
	* tracepoint.c (_initialize_tracepoint): Likewise.

gdb/testsuite/ChangeLog

2020-05-15  Philippe Waroquiers  <philippe.waroquiers@skynet.be>

	* gdb.base/alias.exp: Verify 'help aliases' shows user defined aliases.

1 files changed, 5 insertions, 5 deletions

diff --git a/gdb/reverse.c b/gdb/reverse.c
index 1ccb9d2..583e0d0 100644
--- a/gdb/reverse.c
+++ b/gdb/reverse.c
@@ -330,7 +330,7 @@ _initialize_reverse ()
 Step program backward until it reaches the beginning of another source line.\n\
 Argument N means do this N times (or till program stops for another reason).")
 	   );
-  add_com_alias ("rs", "reverse-step", class_alias, 1);
+  add_com_alias ("rs", "reverse-step", class_run, 1);
 
   add_com ("reverse-next", class_run, reverse_next, _("\
 Step program backward, proceeding through subroutine calls.\n\
@@ -338,26 +338,26 @@ Like the \"reverse-step\" command as long as subroutine calls do not happen;\n\
 when they do, the call is treated as one instruction.\n\
 Argument N means do this N times (or till program stops for another reason).")
 	   );
-  add_com_alias ("rn", "reverse-next", class_alias, 1);
+  add_com_alias ("rn", "reverse-next", class_run, 1);
 
   add_com ("reverse-stepi", class_run, reverse_stepi, _("\
 Step backward exactly one instruction.\n\
 Argument N means do this N times (or till program stops for another reason).")
 	   );
-  add_com_alias ("rsi", "reverse-stepi", class_alias, 0);
+  add_com_alias ("rsi", "reverse-stepi", class_run, 0);
 
   add_com ("reverse-nexti", class_run, reverse_nexti, _("\
 Step backward one instruction, but proceed through called subroutines.\n\
 Argument N means do this N times (or till program stops for another reason).")
 	   );
-  add_com_alias ("rni", "reverse-nexti", class_alias, 0);
+  add_com_alias ("rni", "reverse-nexti", class_run, 0);
 
   add_com ("reverse-continue", class_run, reverse_continue, _("\
 Continue program being debugged but run it in reverse.\n\
 If proceeding from breakpoint, a number N may be used as an argument,\n\
 which means to set the ignore count of that breakpoint to N - 1 (so that\n\
 the breakpoint won't break until the Nth time it is reached)."));
-  add_com_alias ("rc", "reverse-continue", class_alias, 0);
+  add_com_alias ("rc", "reverse-continue", class_run, 0);
 
   add_com ("reverse-finish", class_run, reverse_finish, _("\
 Execute backward until just before selected stack frame is called."));