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With ignorecase set, I am able to jump to a tag Foo by typing :ltag foo. However, doing so causes the message

Using tag with different case!

to appear at the bottom of the screen, along with a ~0.5s delay during which vim does not update. The same message and delay appear when jumping to another tag (which does not match in case) with :tnext or :tprevious. This occurs even with tagcase set to ignore.

How can I prevent this from occurring? I can do so by preceding the command with silent, but this also suppresses the "tag x of y" message, which I want to keep.

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2 Answers 2

Reset to default
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According to my reading of the code you've found the only way to avoid that stuff: use of silent.

This appends the warning...nothing can prevent it except for disabling ignorecase et al...

if (ic)
    STRCAT(IObuff, _("  Using tag with different case!"));

Then a bit later the warning is printed and a nice one second freeze is initiated...

if (ic && !msg_scrolled && msg_silent == 0)
{
    out_flush();
    ui_delay(1000L, TRUE);
}

As you can see, the only (partial cuz you lose the rest of the message) recourse is silent.

Why so strict? I'm guessing but it may be because doing case-insensitive matching "disables binary searching" of tags and apparently relies then on a secondary, slower search method. That's according to help: scroll down about 30 lines below :h tag-priority to see what I'm talking about.

Oh yeah, I should mention the location of the above code in case someone's interested. It's in tag.c, function do_tag()...which rings in at an eye popping nearly 1000 lines...imagine a function/method of that length in, say, Python or Java. ;) Anyways, just search for the warning in that file ("Using tag with different case!").

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1

Well, it turns out there's at least one way to avoid the message:

:ltag /\cfoo

will match a tag called Foo without producing error output. (Somehow :ltag /foo with ignorecase set, which should theoretically behave the same way, still produces the warning and delay on a tag Foo.)

To make this more convenient to type, I've added the mapping

nnoremap <Leader>t :ltag /\c

to my .vimrc. The one disadvantage here is that if you want to match a tag name exactly (say you also have a tag barfoobaz, which you don't want to match), you have to either type out ^foo$ or delete the /\c and type Foo (with correct capitalization, to avoid the delay).

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  • There may be a subtle difference. If your tag files are "case-fold sorted" then matches can be found with the binary type of search when using ignorecase and a simple search term. If you use a regex, though, Vim will do a linear search. (Per help, binary search is "a LOT faster"....presumably O(log n) vs O(n) or something like that)
    – B Layer
    Jul 31, 2020 at 23:00
  • Side note: some regexes, theoretically, should not prevent a binary search. For example, one that just uses ^ (start of line anchor). Whether Vim optimizes out such things I've not checked.
    – B Layer
    Jul 31, 2020 at 23:17

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