MI: Add new command -complete

There is a CLI command 'complete' intended to use with emacs. Such a command
would also be useful for MI frontends, when separate CLI and MI channels cannot
be used. For example, on Windows (because of lack of PTYs) or when GDB is used
through SSH session.

This commit adds a new '-complete' MI command.

gdb/Changelog:
2019-01-28  Jan Vrany  <jan.vrany@fit.cvut.cz>

	* mi/mi-cmds.h (mi_cmd_complete): New function.
	* mi/mi-main.c (mi_cmd_complete): Likewise.
	* mi/mi-cmds.c: Define new MI command -complete.
	* NEWS: Mention new -complete command.

gdb/doc/ChangeLog:
2019-01-28  Jan Vrany  <jan.vrany@fit.cvut.cz>

	* gdb.texinfo (Miscellaneous GDB/MI Commands): Document new
	MI command -complete.

gdb/testsuite/ChangeLog:
2019-01-28  Jan Vrany  <jan.vrany@fit.cvut.cz>

	* gdb.mi/mi-complete.exp: New file.
	* gdb.mi/mi-complete.cc: Likewise.

2 files changed, 70 insertions, 0 deletions

diff --git a/gdb/doc/ChangeLog b/gdb/doc/ChangeLog
index 4ea3250..55dab15 100644
--- a/gdb/doc/ChangeLog
+++ b/gdb/doc/ChangeLog
@@ -1,3 +1,8 @@
+2019-01-28  Jan Vrany  <jan.vrany@fit.cvut.cz>
+
+	* gdb.texinfo (Miscellaneous GDB/MI Commands): Document new
+	MI command -complete.
+
 2019-05-14  Tom de Vries  <tdevries@suse.de>
 
 	* gdb.texinfo (Automatic symbol index cache): Add concept and command
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index 328d510..37e2f14 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -34538,6 +34538,71 @@ fullname="/home/nickrob/myprog.c",line="73",arch="i386:x86_64"@}
 (gdb)
 @end smallexample
 
+@subheading The @code{-complete} Command
+@findex -complete
+
+@subheading Synopsis
+
+@smallexample
+-complete @var{command}
+@end smallexample
+
+Show a list of completions for partially typed CLI @var{command}.
+
+This command is intended for @sc{gdb/mi} frontends that cannot use two separate
+CLI and MI channels - for example: because of lack of PTYs like on Windows or
+because @value{GDBN} is used remotely via a SSH connection.
+
+@subheading Result
+
+The result consists of two or three fields:
+
+@table @samp
+@item completion
+This field contains the completed @var{command}.  If @var{command}
+has no known completions, this field is omitted.
+
+@item matches
+This field contains a (possibly empty) array of matches.  It is always present.
+
+@item max_completions_reached
+This field contains @code{1} if number of known completions is above
+@code{max-completions} limit (see @ref{Completion}), otherwise it contains
+@code{0}.  It is always present.
+
+@end table
+
+@subheading @value{GDBN} Command
+
+The corresponding @value{GDBN} command is @samp{complete}.
+
+@subheading Example
+
+@smallexample
+(gdb)
+-complete br
+^done,completion="break",
+      matches=["break","break-range"],
+      max_completions_reached="0"
+(gdb)
+-complete "b ma"
+^done,completion="b ma",
+      matches=["b madvise","b main"],max_completions_reached="0"
+(gdb)
+-complete "b push_b"
+^done,completion="b push_back(",
+      matches=[
+       "b A::push_back(void*)",
+       "b std::string::push_back(char)",
+       "b std::vector<int, std::allocator<int> >::push_back(int&&)"],
+      max_completions_reached="0"
+(gdb)
+-complete "nonexist"
+^done,matches=[],max_completions_reached="0"
+(gdb)
+
+@end smallexample
+
 @node Annotations
 @chapter @value{GDBN} Annotations