[Bug cli/20819] New: Binding Control-j in inputrc breaks "layout asm"

[wchargin at gmail dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=20819

Bug ID: 20819
Summary: Binding Control-j in inputrc breaks "layout asm"
Product: gdb
Version: 7.7
Status: UNCONFIRMED
Severity: normal
Priority: P2
Component: cli
Assignee: unassigned at sourceware dot org
Reporter: wchargin at gmail dot com
Target Milestone: ---

Steps to reproduce:
1. Replace contents of ~/.inputrc with the single line "Control-j:
menu-complete".
2. Open gdb.
3. Enter "layout asm" and press Enter.
4. Type "help" and press Enter.

Expected behavior: the help menu should appear.

Actual behavior: the prompt begins menu-completing through "help <",
"help >", "help -", "help !", "help +", "help actions", "help
add-auto-load-safe-path", etc.

Hypothesis: because J is ASCII 0x4a, Ctrl-J is 0x4a & ~(0x40), and so a
newline character 0x0a is incorrectly triggering menu-complete.

Note that this behavior does not impact other programs that use
readline, like bash(1) and python(1).

This is GNU gdb (Ubuntu 7.7.1-0ubuntu5~14.04.2) 7.7.1.

[tromey at sourceware dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=20819

Tom Tromey <tromey at sourceware dot org> changed:

What |Removed |Added
----------------------------------------------------------------------------
Component|cli |tui

[tromey at sourceware dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=20819

Tom Tromey <tromey at sourceware dot org> changed:

What |Removed |Added
----------------------------------------------------------------------------
CC| |tromey at sourceware dot org

--- Comment #1 from Tom Tromey <tromey at sourceware dot org> ---
I am not sure I understand this bug.

It seems to me that C-j is enter. So, if you rebind it to menu-complete,
that is what you should expect to get. Maybe the weird part is that
"layout asm" works?

[wchargin at gmail dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=20819

--- Comment #2 from William Chargin <wchargin at gmail dot com> ---
Yes, the ASCII for C-j is the same as the ASCII for Enter. But in other
TUI applications, C-j can be bound separately.

That is, other applications that use readline and .inputrc do not suffer
from this problem. With "Control-j: menu-complete", pressing C-j in a
Python REPL performs menu completion, while pressing Enter executes the
current statement. In a Bash shell, pressing C-j performs menu
completion, while pressing Enter executes the current command line.

(The same is true for applications like Vim: you can "inoremap <C-j>"
without affecting the behavior of Enter. But Vim operates in raw mode
and does not use readline, so the comparison is less apt.)

It seems that GDB is the odd one out here, no?

[tromey at sourceware dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=20819

--- Comment #3 from Tom Tromey <tromey at sourceware dot org> ---
Thanks for the explanation.

I played with a simple readline application and .inputrc.
For me, the enter key is bound to C-m, not C-j, which explains
what you are seeing in those other applications.

[tromey at sourceware dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=20819

Tom Tromey <tromey at sourceware dot org> changed:

What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Last reconfirmed| |2018-09-03
Ever confirmed|0 |1

--- Comment #4 from Tom Tromey <tromey at sourceware dot org> ---
Confirmed.

[wchargin at gmail dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=20819

--- Comment #5 from William Chargin <wchargin at gmail dot com> ---
Confirmed; good catch.

It seems that in GDB's default layout Enter is bound to C-m, whereas in
layout asm it is bound to C-j (and not also C-m). It would be nice to
make these consistent so that users can bind one or the other that works
in all cases, preferably fixing layout asm to be consistent with other
readline applications.

[tromey at sourceware dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=20819

--- Comment #6 from Tom Tromey <tromey at sourceware dot org> ---
This line in tui-io.c:

ch = wgetch (w);

... return 10 when I press enter and when I press C-j.
This happens because tui_enable calls "nl()".
"nonl()" (love those curses API names) is needed to differentiate
these -- but it also affects output.

Wrapping the wgetch call with this seems to help.

[tromey at sourceware dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=20819

--- Comment #7 from Tom Tromey <tromey at sourceware dot org> ---
I sent a patch to gdb-patches.

[tromey at sourceware dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=20819

Tom Tromey <tromey at sourceware dot org> changed:

What |Removed |Added
----------------------------------------------------------------------------
Assignee|unassigned at sourceware dot org |tromey at sourceware dot org

[tromey at sourceware dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=20819

Tom Tromey <tromey at sourceware dot org> changed:

What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |RESOLVED
Resolution|--- |FIXED
Target Milestone|--- |8.3

--- Comment #8 from Tom Tromey <tromey at sourceware dot org> ---
Fixed by commit 7a9569281a63e472750e3b7b481e2cdf5c931ed8,
but I typod the bug # and so it didn't show up here.