Segfault with "nvim -u NONE --headless --embed -es"

[blueyed]

(gdb) bt
#0  0x000055ad021a832a in linecopy (grid=0x55ad02447320 <default_grid>, to=21, from=from@entry=22, col=0, width=width@entry=80) at ../src/nvim/screen.c:6209
#1  0x000055ad021aa0a0 in grid_del_lines (grid=<optimized out>, row=21, line_count=1, end=24, col=<optimized out>, width=80) at ../src/nvim/screen.c:6353
#2  0x000055ad02224064 in msg_scroll_up () at ../src/nvim/message.c:2075
#3  0x000055ad02224263 in msg_puts_display (str=0x7ffe12247a00 "\n", maxlen=-1, attr=0, recurse=0) at ../src/nvim/message.c:1915
#4  0x000055ad02228cca in msg_puts_attr_len (str=str@entry=0x7ffe12247a00 "\n", len=len@entry=-1, attr=attr@entry=0) at ../src/nvim/message.c:1818
#5  0x000055ad02228dbd in msg_puts_attr (s=s@entry=0x7ffe12247a00 "\n", attr=attr@entry=0) at ../src/nvim/message.c:1764
#6  0x000055ad02228f72 in msg_putchar_attr (c=c@entry=10, attr=attr@entry=0) at ../src/nvim/message.c:1259
#7  0x000055ad02228fb2 in msg_putchar (c=c@entry=10) at ../src/nvim/message.c:1244
#8  0x000055ad0222959a in msg_start () at ../src/nvim/message.c:1208
#9  0x000055ad02277e1c in gotocmdline (clr=clr@entry=1) at ../src/nvim/ex_getln.c:3535
#10 0x000055ad0227c2a3 in command_line_enter (firstc=firstc@entry=58, count=count@entry=1, indent=indent@entry=0) at ../src/nvim/ex_getln.c:315
#11 0x000055ad0227c735 in getcmdline (firstc=firstc@entry=58, count=count@entry=1, indent=indent@entry=0) at ../src/nvim/ex_getln.c:2021
#12 0x000055ad0227c78a in getexline (c=58, cookie=<optimized out>, indent=0) at ../src/nvim/ex_getln.c:2205
#13 0x000055ad0228ef87 in do_cmdline (cmdline=<optimized out>, cmdline@entry=0x0, fgetline=0x55ad0227c766 <getexline>, cookie=cookie@entry=0x0, flags=flags@entry=0)
    at ../src/nvim/ex_docmd.c:512
#14 0x000055ad02293113 in do_exmode (improved=<optimized out>) at ../src/nvim/ex_docmd.c:229
#15 0x000055ad02214732 in normal_check (state=0x7ffe122483c0) at ../src/nvim/normal.c:1349
#16 0x000055ad021796e4 in state_enter (s=0x7ffe122483c0) at ../src/nvim/state.c:28
#17 0x000055ad022156d1 in normal_enter (cmdwin=<optimized out>, noexmode=<optimized out>) at ../src/nvim/normal.c:462
#18 0x000055ad0224153d in main (argc=<optimized out>, argv=<optimized out>) at ../src/nvim/main.c:597

Just noticed this when adding -es to a test in Neomake where I am using an embedded Neovim, which apparently hangs due to waiting for hit-Enter (from :echom I've added for debugging).
The test is at https://github.com/neomake/neomake/blob/6e5ff157a678812454d8bf465b630875f9a8c476/tests/compat.vader#L80-L86 - would be interested in how to ignore hit-enter there in general.

NVIM v0.4.0-744-ga541c681f

[justinmk]

For your use-case don't use --embed unless you actually want to connect a UI. --embed causes msg_use_printf() to return false, that's why msg_puts_attr_len calls msg_puts_display.

Meanwhile, there does seem to be a bug here.

[blueyed]

@justinmk
Thanks, it seemed like --embed would be a shortcut, but neomake/neomake#2368 appears to work better in this case.

[glacambre]

As far as I know there's no way to use stdin as both an msgpack-rpc channel and a regular "textual channel", right? So would fixing this issue be as simple as making neovim print an error message and quit when both --embed and -es are present?

[justinmk]

making neovim print an error message and quit when both --embed and -es are present?

That makes sense to me. 👍