Syntax highlighting needs to be turned on manually for certain languages

[vmchale]

Problem

Syntax highlighting isn't there when I open a file on the command-line. I have to pull it up by :syntax enable; after that it works.

Steps to reproduce

The syntax highlighting plugin in question is here: https://github.com/vmchale/jacinda-vim

As an example, open a *.jac file, e.g.: https://github.com/vmchale/jacinda/blob/main/examples/nmCtx.jac

Running nvim nmCtx.jac opens the file but with no syntax highlighting until :syntax enable. Curiously, running nvim following by :edit nmCtx.jac works.

Many other languages do work, e.g. Haskell syntax highlighting, Rust syntax highlighting, but occasionally others fail.

Expected behavior

I would expect syntax highlighting to be on when opening a file from the command-line.

Neovim version (nvim -v)

0.10.0

Vim (not Nvim) behaves the same?

Vim 9.0.639 works correctly, syntax is turned on in my .vimrc

Operating system/version

MacOS 14.5

Terminal name/version

Iterm2

$TERM environment variable

xterm-256color

Installation

Github tarball

[clason]

You need to provide a reproducible config with nvim --clean -u test.lua. (And just to save some time, you cannot lazy-load filetype plugins.)

[vmchale]

The problem happens even with vim-plug

Seems to have been around at least a year: https://www.reddit.com/r/neovim/comments/11banfa/cant_get_syntax_highlighting_to_work_correctly/ja0ptzq/

[clason]

That doesn't absolve you from the need to provide a minimal reproducible config here. Reddit posts are virtually useless as actionable bug reports.

[justinmk]

Vim 9.0.639 works correctly, syntax is turned on in my .vimrc

Depends on when your config calls :syntax enable.

A workaround might be to put your syntax file in after/syntax/ instead of syntax/. Example: https://github.com/justinmk/vim-syntax-extra/tree/master/after/syntax

[icholy]

@vmchale I cannot reproduce issue on 0.10.0 or master. https://github.com/icholy/nvim-bug-28793