winbar disappears when changing the buffer in a window

[puremourning]

Problem

When setting a window-local winbar, this option is lost when changing the currently displayed buffer.

Steps to reproduce

• nvim -Nu NONE
• :e a
• :setlocal winbar=foo
• :e b

---

Then

• :bu a

Expected behavior

Winbar foo is displayed in the window when both a and b buffers are displayed.

Actual behaviour:

winbaar is removed when switching to b
winbaar is returned when switching back to a

I.e. the option seems to be buffer-local not window-local, or setlocal is setting it in the buffer not the window.

From the help:

'winbar' 'wbr'          string (default empty)
                        global or local to window global-local

Neovim version (nvim -v)

NVIM v0.10.0-dev-111+g9e5f9c25d

Vim (not Nvim) behaves the same?

Vim behaves as expected when using nnoremenu WinBar.foo

Operating system/version

macOS

Terminal name/version

iTerm2

$TERM environment variable

xterm-256color

Installation

build from source, brew

[rewhile]

I wonder if this is related to #11525

Anyhow, this patch seems to work for me:

diff --git a/src/nvim/buffer_defs.h b/src/nvim/buffer_defs.h
index c80890994..5c9116172 100644
--- a/src/nvim/buffer_defs.h
+++ b/src/nvim/buffer_defs.h
@@ -209,7 +209,7 @@ typedef struct {
   char *wo_stl;
 #define w_p_stl w_onebuf_opt.wo_stl     // 'statusline'
   char *wo_wbr;
-#define w_p_wbr w_onebuf_opt.wo_wbr   // 'winbar'
+#define w_p_wbr w_allbuf_opt.wo_wbr   // 'winbar'
   int wo_scb;
 #define w_p_scb w_onebuf_opt.wo_scb    // 'scrollbind'
   int wo_diff_saved;           // options were saved for starting diff mode

Screencast.from.2023-04-18.02-15-15.webm

[puremourning]

wonder if this is related to #11525

Could be. Certainly my eyebrows raised when I read the linked discussion. TIL and all that.

Either way, I think this issue illustrates that using a buffer option for WinBar is unfortunate, requiring a bunch of additional hoop jumping and likely a source of confusing bugs for future me.

[puremourning]

@nullchilly I tried your patch and confirm that it behaves more like I would expect.

The comment here would tend to agree:

// Options local to a window.
// They are local because they influence the layout of the window or
// depend on the window layout.
// There are two values: w_onebuf_opt is local to the buffer currently in
// this window, w_allbuf_opt is for all buffers in this window.

LGTM!

[zeertzjq]

Duplicate of #11525

[puremourning]

The problem here is this choice (to use an option) makes WinBar unusable, fiddly and likely to be buggy. As mentioned a trivial change essentially fixes that, but now it's bundled with a 4 year old issue that will never be resolved. Fine, i guess.

[zeertzjq]

As mentioned a trivial change essentially fixes that

This change is unwanted.

[puremourning]

Would you mind elaborating?

[zeertzjq]

Because this should be solved by adding a general way to change the w_allbuf_opt of a global-local window option instead. Note that it is also not exactly the same #11525.