When you run lldb without colors (`-X`), the status line looks weird
because it doesn't have a background. You end up with what appears to be
floating text at the bottom of your terminal.
This patch changes the statusline to use the reverse video effect, even
when colors are off. The effect doesn't introduce any new colors and
just inverts the foreground and background color.
I considered an alternative approach which changes the behavior of the
`-X` option, so that turning off colors doesn't prevent emitting
non-color related control characters such as bold, underline, and
reverse video. I decided to go with this more targeted fix as (1) nobody
is asking for this more general change and (2) it introduces significant
complexity to plumb this through using a setting and driver flag so that
it can be disabled when running the tests.
Fixes#134112.
Simplify and fix the logic to clear the old statusline when the terminal
window dimensions have changed. I accidentally broke the terminal
resizing behavior when addressing code review feedback.
I'd really like to figure out a way to test this. PExpect isn't a good
fit for this, because I really need to check the result, rather than the
control characters, as the latter doesn't tell me whether any part of
the old statusline is still visible.
When redrawing the statusline, the current implementation would clear
the current line before drawing the new content. Since we always
overwrite the whole statusline from beginning to end, there's no need to
clear it and we can avoid the potential for flickering.
Add a statusline to command-line LLDB to display information about the
current state of the debugger. The statusline is a dedicated area
displayed at the bottom of the screen. The information displayed is
configurable through a setting consisting of LLDB’s format strings.
Enablement
----------
The statusline is enabled by default, but can be disabled with the
following setting:
```
(lldb) settings set show-statusline false
```
Configuration
-------------
The statusline is configurable through the `statusline-format` setting.
The default configuration shows the target name, the current file, the
stop reason and any ongoing progress events.
```
(lldb) settings show statusline-format
statusline-format (format-string) = "${ansi.bg.blue}${ansi.fg.black}{${target.file.basename}}{ | ${line.file.basename}:${line.number}:${line.column}}{ | ${thread.stop-reason}}{ | {${progress.count} }${progress.message}}"
```
The statusline supersedes the current progress reporting implementation.
Consequently, the following settings no longer have any effect (but
continue to exist to not break anyone's `.lldbinit`):
```
show-progress -- Whether to show progress or not if the debugger's output is an interactive color-enabled terminal.
show-progress-ansi-prefix -- When displaying progress in a color-enabled terminal, use the ANSI terminal code specified in this format immediately before the progress message.
show-progress-ansi-suffix -- When displaying progress in a color-enabled terminal, use the ANSI terminal code specified in this format immediately after the progress message.
```
Format Strings
--------------
LLDB's format strings are documented in the LLDB documentation and on
the website: https://lldb.llvm.org/use/formatting.html#format-strings.
The current implementation is relatively limited but various
improvements have been discussed in the RFC.
One such improvement is being to display a string when a format string
is empty. Right now, when launching LLDB without a target, the
statusline will be empty, which is expected, but looks rather odd.
RFC
---
The full RFC can be found on Discourse:
https://discourse.llvm.org/t/rfc-lldb-statusline/83948
