git/t/t6134-pathspec-in-submodule.sh
Stefan Beller 2d81c48fa7 pathspec: give better message for submodule related pathspec error
Every once in a while someone complains to the mailing list to have
run into this weird assertion[1]. The usual response from the mailing
list is link to old discussions[2], and acknowledging the problem
stating it is known.

This patch accomplishes two things:

  1. Switch assert() to die("BUG") to give a more readable message.

  2. Take one of the cases where we hit a BUG and turn it into a normal
     "there was something wrong with the input" message.

     This assertion triggered for cases where there wasn't a programming
     bug, but just bogus input. In particular, if the user asks for a
     pathspec that is inside a submodule, we shouldn't assert() or
     die("BUG"); we should tell the user their request is bogus.

     The only reason we did not check for it, is the expensive nature
     of such a check, so callers avoid setting the flag
     PATHSPEC_STRIP_SUBMODULE_SLASH_EXPENSIVE. However when we die due
     to bogus input, the expense of CPU cycles spent outweighs the user
     wondering what went wrong, so run that check unconditionally before
     dying with a more generic error message.

Note: There is a case (e.g. "git -C submodule add .") in which we call
strip_submodule_slash_expensive, as git-add requests it via the flag
PATHSPEC_STRIP_SUBMODULE_SLASH_EXPENSIVE, but the assert used to
trigger nevertheless, because the flag PATHSPEC_LITERAL was not set,
such that we executed

	if (item->nowildcard_len < prefixlen)
		item->nowildcard_len = prefixlen;

and prefixlen was not adapted (e.g. it was computed from "submodule/")
So in the die_inside_submodule_path function we also need handle paths,
that were stripped before, i.e. are the exact submodule path. This
is why the conditions in die_inside_submodule_path are slightly
different than in strip_submodule_slash_expensive.

[1] https://www.google.com/search?q=item-%3Enowildcard_len
[2] http://git.661346.n2.nabble.com/assert-failed-in-submodule-edge-case-td7628687.html
    https://www.spinics.net/lists/git/msg249473.html

Helped-by: Jeff King <peff@peff.net>
Helped-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-01-09 15:19:22 -08:00

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#!/bin/sh
test_description='test case exclude pathspec'
. ./test-lib.sh
test_expect_success 'setup a submodule' '
test_create_repo pretzel &&
: >pretzel/a &&
git -C pretzel add a &&
git -C pretzel commit -m "add a file" -- a &&
git submodule add ./pretzel sub &&
git commit -a -m "add submodule" &&
git submodule deinit --all
'
cat <<EOF >expect
fatal: Pathspec 'sub/a' is in submodule 'sub'
EOF
test_expect_success 'error message for path inside submodule' '
echo a >sub/a &&
test_must_fail git add sub/a 2>actual &&
test_cmp expect actual
'
cat <<EOF >expect
fatal: Pathspec '.' is in submodule 'sub'
EOF
test_expect_success 'error message for path inside submodule from within submodule' '
test_must_fail git -C sub add . 2>actual &&
test_cmp expect actual
'
test_done