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
