gdb: introduce "set index-cache enabled", deprecate "set index-cache on/off"

The "set index-cache" command is used at the same time as a prefix
command (prefix for "set index-cache directory", for example), and a
boolean setting for turning the index-cache on and off.  Even though I
did introduce that, I now don't think it's a good idea to do something
non-standard like this.

First, there's no dedicated CLI command to show whether the index-cache
is enabled, so it has to be custom output in the "show index-cache
handler".  Also, it means there's no good way a MI frontend can find out
if the index-cache is enabled.  "-gdb-show index-cache" doesn't show it
in the MI output record:

    (gdb) interpreter-exec mi "-gdb-show index-cache"
    ~"\n"
    ~"The index cache is currently disabled.\n"
    ^done,showlist={option={name="directory",value="/home/simark/.cache/gdb"}}

Fix this by introducing "set/show index-cache enabled on/off", regular
boolean setting commands.  Keep commands "set index-cache on" and "set
index-cache off" as deprecated aliases of "set index-cache enabled",
with respectively the default arguments "on" and "off".

Update tests using "set index-cache on/off" to use the new command.
Update the regexps in gdb.base/maint.exp to figure out whether the
index-cache is enabled or not.  Update the doc to mention the new
commands.

Change-Id: I7d5aaaf7fd22bf47bd03e0023ef4fbb4023b37b3

1 files changed, 4 insertions, 4 deletions

diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index 308a97a..fc8e5bd 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -21795,14 +21795,14 @@ Indices only work when using DWARF debugging information, not stabs.
 @cindex automatic symbol index cache
 It is possible for @value{GDBN} to automatically save a copy of this index in a
 cache on disk and retrieve it from there when loading the same binary in the
-future.  This feature can be turned on with @kbd{set index-cache on}.  The
-following commands can be used to tweak the behavior of the index cache.
+future.  This feature can be turned on with @kbd{set index-cache enabled on}.
+The following commands can be used to tweak the behavior of the index cache.
 
 @table @code
 
 @kindex set index-cache
-@item set index-cache on
-@itemx set index-cache off
+@item set index-cache enabled on
+@itemx set index-cache enabled off
 Enable or disable the use of the symbol index cache.
 
 @item set index-cache directory @var{directory}