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The "check-chainlint" target runs automatically when running tests and
performs self-checks to verify that the chainlinter itself produces the
expected output. Originally, the chainlinter was implemented via sed,
but the infrastructure has been rewritten in fb41727b7e (t: retire
unused chainlint.sed, 2022-09-01) to use a Perl script instead.
The rewrite caused some slight whitespace changes in the output that are
ultimately not of much importance. In order to be able to assert that
the actual chainlinter errors match our expectations we thus have to
ignore whitespace characters when diffing them. As the `-w` flag is not
in POSIX we try to use `git diff -w --no-index` before we fall back to
`diff -w -u`.
To accomodate for cases where the host system has no Git installation we
use the locally-compiled version of Git. This can result in problems
though when the Git project's repository is using extensions that the
locally-compiled version of Git doesn't understand. It will refuse to
run and thus cause the checks to fail.
Instead of improving the detection logic, fix our ".expect" files so
that we do not need any post-processing at all anymore. This allows us
to drop the `-w` flag when diffing so that we can always use diff(1)
now.
Note that we keep some of the post-processing of `chainlint.pl` output
intact to strip leading line numbers generated by the script. Having
these would cause a rippling effect whenever we add a new test that
sorts into the middle of existing tests and would require us to
renumerate all subsequent lines, which seems rather pointless.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Reviewed-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Now that chainlint.pl is functional, take advantage of the existing
chainlint self-tests to validate its operation. (While at it, stop
validating chainlint.sed against the self-tests since it will soon be
retired.)
Due to chainlint.sed implementation limitations leaking into the
self-test "expect" files, a few of them require minor adjustment to make
them compatible with chainlint.pl which does not share those
limitations.
First, because `sed` does not provide any sort of real recursion,
chainlint.sed only emulates recursion into subshells, and each level of
recursion leads to a multiplicative increase in complexity of the `sed`
rules. To avoid substantial complexity, chainlint.sed, therefore, only
emulates subshell recursion one level deep. Any subshell deeper than
that is passed through as-is, which means that &&-chains are not checked
in deeper subshells. chainlint.pl, on the other hand, employs a proper
recursive descent parser, thus checks subshells to any depth and
correctly flags broken &&-chains in deep subshells.
Second, due to sed's line-oriented nature, chainlint.sed, by necessity,
folds multi-line quoted strings into a single line. chainlint.pl, on the
other hand, employs a proper lexical analyzer which preserves quoted
strings as-is, including embedded newlines.
Furthermore, the output of chainlint.sed and chainlint.pl do not match
precisely in terms of whitespace. However, since the purpose of the
self-checks is to verify that the ?!AMP?! annotations are being
correctly added, minor whitespace differences are immaterial. For this
reason, rather than adjusting whitespace in all existing self-test
"expect" files to match the new linter's output, the `check-chainlint`
target ignores whitespace differences. Since `diff -w` is not POSIX,
`check-chainlint` attempts to employ `git diff -w`, and only falls back
to non-POSIX `diff -w` (and `-u`) if `git diff` is not available.
Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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The --chain-lint option uses heuristics and knowledge of shell syntax to
detect broken &&-chains in subshells by pure textual inspection. The
heuristics handle a range of stylistic variations in existing tests
(evolved over the years), however, they are still best-guesses. As such,
it is possible for future changes to accidentally break assumptions upon
which the heuristics are based. Protect against this possibility by
adding tests which check the linter itself for correctness.
In addition to protecting against regressions, these tests help document
(for humans) expected behavior, which is important since the linter's
implementation language ('sed') does not necessarily lend itself to easy
comprehension.
Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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