Rietveld seems to have a limit of 255 characters;
-------------------------
Upload server: https://codereview.chromium.org (change with -s/--server)
Issue created. URL: https://codereview.chromium.org/1991643002 (patchset: 1)
  --> ERROR: Upload content errors:
{'filename': [u'Ensure this value has at most 255 characters (it has 412).']}
-------------------------

Example CL https://codereview.chromium.org/1990763002 which has a very long file name (which if submitted would break windows bots and other Windows users) but that there doesn't seem to be anything stopping me from submitting?

See also  bug 609871  and bug 611437 - as the latter case shows, we also need to watch out for generated files.

CL which passed CQ and failed on waterfall later: https://codereview.chromium.org/1949503002.

Well, this seems like a perfect case for PRESUBMIT check to be added to root PRESUBMIT.py of chromium/src.

FTR, Gerrit codereview won't have this limit for CLs.

This issue has been Available for over a year. If it's no longer important or seems unlikely to be fixed, please consider closing it out. If it is important, please re-triage the issue.

Sorry for the inconvenience if the bug really should have been left as Available. If you change it back, also remove the "Hotlist-Recharge-Cold" label.

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Since we have moved to Gerrit now, does this mean we can close this?

No, the underlying problem on Windows is still there.

I haven't looked into this and this is under CCI so marking untriaged for someone else to have a look.

-> martiniss, since he's been dealing with this recently.

There is also EncFS with a 142 char filename limit.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/97a39414a80f02e03837fa60e603466958708b44

commit 97a39414a80f02e03837fa60e603466958708b44
Author: Stephen Martinis <martiniss@chromium.org>
Date: Thu Jun 07 23:06:05 2018

Add presubmit check for long paths

Bug:  612667 
Change-Id: I6bd52794bf6122813770338a93509d295bf4a7cb
Reviewed-on: https://chromium-review.googlesource.com/1060458
Reviewed-by: Dirk Pranke <dpranke@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Commit-Queue: Stephen Martinis <martiniss@chromium.org>
Cr-Commit-Position: refs/heads/master@{#565452}
[modify] https://crrev.com/97a39414a80f02e03837fa60e603466958708b44/PRESUBMIT.py