sessionoptions: allow exclude nofile buffers from save

[przepompownia]

Actual behaviour

Currently (neovim-0.5.0+ubuntu1+git202005022020-d13c164-00e710e) mksession does not allow exclude nofile buffers (NERDTree windows for example) using sessionoptions.

Expected behaviour

Nothing more than the title says.

[justinmk]

I suppose there is a vim patch for this? That would be worth mentioning. PR welcome https://github.com/neovim/neovim/wiki/Merging-patches-from-upstream-Vim

[przepompownia]

I did not see any equivalent in Vim (8.2.0510-1). I am not familiar with C and so unable to make any reasonable patch.

[justinmk]

is this feature in Vim or not?

[przepompownia]

Not.

[Zeioth]

At least change it to bug so people know it needs to be fixed; This issue is preventing any Neovim session with a nofile buftype from saving correctly.

[sarmong]

blank option is apparently already checking for nofile buffers. Is there a need for another option?

neovim/src/nvim/ex_session.c

Lines 197 to 201 in 0792cf7

	if (wp->w_buffer->b_fname == NULL
	// When 'buftype' is "nofile" can't restore the window contents.
	|| (!wp->w_buffer->terminal && bt_nofilename(wp->w_buffer))) {
	return ssop_flags & SSOP_BLANK;
	}

[przepompownia]

After executing

local bufname = 'nofileBuffer'
local buf = vim.fn.bufadd(bufname)
vim.bo[buf].buflisted = true
vim.cmd([[set sessionoptions-=blank]])
vim.cmd.mksession({bang = true})

Session.vim contains

badd +0 nofileBuffer

blank seems to affect only windows.

Four years after this issue was created I use a custom command that cleans environment before mksession. It seems that we need something more flexible than adding the next parameter for such particular case. From the perspective of my needs this issue can be closed.

[sarmong]

Apparently, it also checks for buflisted. With your code above, if you set buflisted to false, the buffer is not saved to session file.