Auto-indent after carriage return after line containing open curly brace

Question

I recently upgraded my Cygwin from a 2015 installation (5 years ago) to the current "2020" version. Gvim now automatically indents by shiftwidth columns when I press return after a curly brace { on a line by itself. From an initial web search, I think this might be related to the cindent option, so I issued the command set nocindent. The behaviour still persists. Can someone suggest what help page to look at next?

Background: I've been using autoindent for years, but that only matches the indentation of a new line to the indentation of the preceding line, which is what I want. What I'm trying to disable is indentation that is shiftwidth more than in the preceding line. I am using the same vimrc file as before the 2020 upgrade of Cygwin.

Here are some key options in my vim session:

indentexpr=GetTeXIndent()
tabstop=3
shiftwidth=3
nocindent
nosmartindent
filetype=tex

Here is a minimum working example (MWE) file test.tex that exhibits my problem:

% test.tex
%---------
%        1         2
%234567890123456789012345   <-- Physical character column number
      navigation and direct manipulation of the data.\footnote
      {%

I position my cursor on the { in column 7 and, in normal mode, press S or C to enter insert mode (and overwrite the text). I then enter {%<CR>, which creates a new line and positions the insertion point on column 10.

Even as I was typing the preceding paragraph and this paragraph, whenever I press <CR> to start a new line following a line containing the { character, the insertion point gets indented to column 4 instead of being positioned on column 1. (Yes, all of this text was composed in the file test.tex). The :map command shows that the key { is not mapped to anything.

For those who have tried the MWE, even if you don't know the answer, it would be helpful in identifying the cause of the problem to know whether you get the same behaviour.

New info

The unwanted extra indentation only afflicts a text file if the file name extension is *.tex, not if it is *.txt. It seems that I need to delve into how syntax-dependent behaviour controlled by the file type. I peeked into /usr/share/vim/vim81/syntax/tex.vim, but I think that deciphering it will be a long-term endeavour.

Answer 1

This behavior is being enabled by the custom indentation function for the tex filetype.

You can configure the behavior of that function, by setting some variables in your vimrc.

For your specific case, to disable indentation after braces, you can use:

let g:tex_indent_brace = 0

The tex indentation also indents \item elements in a special way, which you can disable with:

let g:tex_indent_items = 0

---

If you want to completely block Vim indentation for filetype tex, one good way to do it is to create an indent/tex.vim file that supercedes the one you want to block.

You can create a file ~/.vim/indent/tex.vim, which comes earlier than the one in Vim runtimes in the search path, and add the following contents to it:

let b:did_indent = 1

This way, when the one you want to block gets to run, it will see that indentation is already configured and so it will skip it.

(That's better than messing with permissions or removing the indent/tex.vim in runtimes, since an operating system update will probably revert those changes.)

---

Note that you can't really avoid the indentation function by unsetting indentexpr from your vimrc. The indentation plugin will always load when the filetype is determined, which happens much later than your vimrc.

Disabling indentation plugins altogether from your vimrc will work, so filetype plugin off works as long as nothing else is re-enabling it later on. (Check with a plain :filetype, which will tell you which items are enabled.)

It's unclear why you started getting these starting with an upgrade, since that code in indent/tex.vim seems to be around for quite a long time... Perhaps you didn't have the Vim runtime files installed and now you do?

Another possibility is that, starting with Vim 8, if you don't have a vimrc file, a default one will be loaded, which will most likely enable all filetype support and have these plug-ins start to load when previously they wouldn't. See :help defaults.vim for details on that. In any case, the solution for that one is simple, just create a vimrc file, even if it's an empty one, that will prevent you from getting the settings from the defaults file.

Answer 2

Based on this page, I found that :set indentexpr= removed tex file-dependent extraneous indentation. I intend to put it in my vimrc file.

Just a cautionary note: As filbranden said, this solution might not be persistent. If you are able to get any of his solutions working, it will less of a hack than :set indentexpr=. If for some reason you are running into problems, however, and don't have the time to troubleshoot and experiment, then :set indentexpr= might get you going for the immediate present.

To possibly save others time, based on this page, I also tried the following without success:

filetype indent off
filetype indent plugin off