BufWinEnter not called for floating window buffer

[stevearc]

Problem

When opening a floating window with nvim_open_win and enter = false, the BufWinEnter autocmd is not called for the buffer.

Steps to reproduce

Here is a minimal repro

local bufnr = vim.api.nvim_create_buf(false, true)
vim.api.nvim_buf_set_lines(bufnr, 0, 1, false, { "Waiting..." })

vim.api.nvim_create_autocmd("BufWinEnter", {
	desc = "Aerial render symbols after buffer loads in window",
	buffer = bufnr,
	once = true,
	callback = function(params)
		vim.api.nvim_buf_set_lines(params.buf, 0, 1, false, { "BufWinEnter called" })
	end,
})

vim.api.nvim_open_win(bufnr, false, {
	relative = "editor",
	row = 2,
	col = 2,
	width = 40,
	height = 20,
	style = "minimal",
})

Sourcing this file on nightly produces a floating window that says "Waiting...". Sourcing it in 0.9.x produces a floating window that says "BufWinEnter called". BufWinEnter is called if we pass enter = true in nvim_open_win. This also does not appear to occur with splits.

Expected behavior

BufWinEnter should be called when the buffer is first displayed in the floating window

Neovim version (nvim -v)

v0.10.0-dev-2143+g3f188bc53

Vim (not Nvim) behaves the same?

N/A

Operating system/version

Ubuntu 22.04

Terminal name/version

kitty 0.31.0

$TERM environment variable

tmux-256color

Installation

build from source

[zeertzjq]

Related #15300

[zeertzjq]

Hmm, the current behavior is inconsistent with nvim_win_set_buf

[stevearc]

If enter = false why would you expect BufWinEnter to fire?

I would expect BufEnter to not fire, since we're not entering the buffer, but from :help BufWinEnter:

BufWinEnter			After a buffer is displayed in a window.  This
				may be when the buffer is loaded (after
				processing modelines) or when a hidden buffer
				is displayed (and is no longer hidden).

That to me sounds like it should fire even if the window doesn't have focus. Another way to put it: I would expect there to be an invariant that if a buffer is displayed in a window, BufWinEnter has been dispatched.

[glepnir]

there use enter as condition so when it's false . BufWinEnter not fired in win_set_buf, maybe can trigger it under win_set_buf

neovim/src/nvim/api/win_config.c

Lines 202 to 203 in 1233ac4

	Boolean noautocmd = !enter || fconfig.noautocmd;
	win_set_buf(wp, buf, noautocmd, err);

[asmodeus812]

@justinmk Not sure if related, but on the contrary, if we create the hover window, and set focused = false, vim.fn.win_gettype() still returns "popup", if we call it right after the hover is opened. even though the focus stays on the main window, and does not enter the hover (this happens with pretty much all popup windows)