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Because `sed` is line-oriented, for ease of implementation, when
chainlint.sed encounters an opening subshell in which the first command
is cuddled with the "(", it splits the line into two lines: one
containing only "(", and the other containing whatever follows "(".
This allows chainlint.sed to get by with a single set of regular
expressions for matching shell statements rather than having to
duplicate each expression (one set for matching non-cuddled statements,
and one set for matching cuddled statements).
However, although syntactically and semantically immaterial, this
transformation has no value to test authors and might even confuse them
into thinking that the linter is misbehaving by inserting (whitespace)
line-noise into the shell code it is validating. Moreover, it also
allows an implementation detail of chainlint.sed to seep into the
chainlint self-test "expect" files, which potentially makes it difficult
to reuse the self-tests should a more capable chainlint ever be
developed.
To address these concerns, stop splitting cuddled "(..." into two lines.
Note that, as an implementation artifact, due to sed's line-oriented
nature, this change inserts a blank line at output time just before the
"(..." line is emitted. It would be possible to suppress this blank line
but doing so would add a fair bit of complexity to chainlint.sed.
Therefore, rather than suppressing the extra blank line, the Makefile's
`check-chainlint` target which runs the chainlint self-tests is instead
modified to ignore blank lines when comparing chainlint output against
the self-test "expect" output. This is a reasonable compromise for two
reasons. First, the purpose of the chainlint self-tests is to verify
that the ?!AMP?! annotations are being correctly added; precise
whitespace is immaterial. Second, by necessity, chainlint.sed itself
already throws away all blank lines within subshells since, when
checking for a broken &&-chain, it needs to check the final _statement_
in a subshell, not the final _line_ (which might be blank), thus it has
never made any attempt to precisely reproduce blank lines in its output.
Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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chainlint.sed inserts a ">" annotation at the beginning of a line to
signal that its heuristics have identified an end-of-subshell. This was
useful as a debugging aid during development of the script, but it has
no value to test writers and might even confuse them into thinking that
the linter is misbehaving by inserting line-noise into the shell code it
is validating. Moreover, its presence also potentially makes it
difficult to reuse the chainlint self-test "expect" output should a more
capable linter ever be developed. Therefore, drop the ">" annotation.
Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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>From inception, when chainlint.sed encountered a line using semicolon to
separate commands rather than `&&`, it would insert a ?!SEMI?!
annotation at the beginning of the line rather ?!AMP?! even though the
&&-chain is also broken by the semicolon. Given a line such as:
?!SEMI?! cmd1; cmd2 &&
the ?!SEMI?! annotation makes it easier to see what the problem is than
if the output had been:
?!AMP?! cmd1; cmd2 &&
which might confuse the test author into thinking that the linter is
broken (since the line clearly ends with `&&`).
However, now that the ?!AMP?! an ?!SEMI?! annotations are inserted at
the point of breakage rather than at the beginning of the line, and
taking into account that both represent a broken &&-chain, there is
little reason to distinguish between the two. Using ?!AMP?! alone is
sufficient to point the test author at the problem. For instance, in:
cmd1; ?!AMP?! cmd2 &&
cmd3
it is clear that the &&-chain is broken between `cmd1` and `cmd2`.
Likewise, in:
cmd1 && cmd2 ?!AMP?!
cmd3
it is clear that the &&-chain is broken between `cmd2` and `cmd3`.
Finally, in:
cmd1; ?!AMP?! cmd2 ?!AMP?!
cmd3
it is clear that the &&-chain is broken between each command.
Hence, there is no longer a good reason to make a distinction between a
broken &&-chain due to a semicolon and a broken chain due to a missing
`&&` at end-of-line. Therefore, drop the ?!SEMI?! annotation and use
?!AMP?! exclusively.
Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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chainlint.sed flags ";" when used as a command terminator since it
breaks the &&-chain, thus can allow failures to go undetected. However,
when a command terminated by ";" is the last command in the body of a
compound statement, such as `command-2` in:
if test $# -gt 1
then
command-1 &&
command-2;
fi
then the ";" is harmless and the exit code from `command-2` is passed
through untouched and becomes the exit code of the compound statement,
as if the ";" was not present. Therefore, tolerate a trailing ";" in
this position rather than complaining about broken &&-chain.
Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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When chainlint.sed detects commands separated by a semicolon rather than
by `&&`, it places a ?!SEMI?! annotation at the beginning of the line.
However, this is an unusual location for programmers accustomed to error
messages (from compilers, for instance) indicating the exact point of
the problem. Therefore, relocate the ?!SEMI?! annotation to the location
of the semicolon in order to better direct the programmer's attention to
the source of the problem.
Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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When chainlint.sed detects a broken &&-chain, it places an ?!AMP?!
annotation at the beginning of the line. However, this is an unusual
location for programmers accustomed to error messages (from compilers,
for instance) indicating the exact point of the problem. Therefore,
relocate the ?!AMP?! annotation to the end of the line in order to
better direct the programmer's attention to the source of the problem.
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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Eric Sunshine