[libvirt] [PATCH] build: exclude more files from all the syntax checks

Eric Blake eblake at redhat.com
Fri Oct 6 17:57:38 UTC 2017

On 10/06/2017 12:07 PM, Jim Meyering wrote:
> On Fri, Oct 6, 2017 at 7:47 AM, Eric Blake <eblake at redhat.com> wrote:
>> On 10/05/2017 06:07 AM, Pino Toscano wrote:
>>> The majority of the syntax check is taylored for C sources, so some of
>>> the checks already cause false positives for non-C sources (and thus
>>> there are exclusion regexps in place).
>>> Instead, just exclude more non-C files from all the checks:

>> Maybe it's worth teaching upstream gnulib syntax-check to make it easier
>> to auto-exclude non-C files from checks that ARE specific to the C
>> language, without weakening the global checks that are good on all
>> files.  Maybe even something as simple as adding some sort of language=
>> tag to feed to $(_sc_search_regexp (if not specified, run on all files,
>> but if specified as C, the syntax-check is specific to C-like files, so
>> it limits to .h, .c. .y).
>> I'm adding the gnulib list to get feedback on the idea; maybe Jim
>> Meyering has an opinion as one of the original syntax-check authors.
> Hi Eric,
> Is there some reason not to use a directive like this in a rule
> applying exclusively to version-controlled C-like files?
>   in_vc_files='\.[chly]$$'

So we already have the mechanism - we just have to use it in the right
places ;)

Some of the existing maint.mk rules don't use it (for a quick example,
sc_cast_of_x_alloc_return_value, sc_cast_of_alloca_return_value) - but
it may also be a question of how often these rules are firing on non-C
files to let us know that we even have false positives.

> I looked at libvirt's cfg.mk, and if you add that line to the
> sc_prohibit_sprintf rule, you can then remove the lines that exempt
> files with unrelated suffixes from that rule:

Indeed, that's probably the best fix for libvirt: for any rule in cfg.mk
that we want to run only on C files, use in_vc_files= to make it obvious.

> exclude_file_name_regexp--sc_prohibit_sprintf = \
>   ^(cfg\.mk|docs/hacking\.html\.in|.*\.stp|.*\.pl)$$
> Another rule that can catch things in any non-binary file is
> sc_prohibit_undesirable_word_seq, even if it's only for pet peeves
> like detecting "can not".

And sc_space_tab is globally useful, etc.

> ...
>>>  # Files that should never cause syntax check failures.
>>> -  (^(docs/(news(-[0-9]*)?\.html\.in|.*\.patch))|\.(po|fig|gif|ico|png))$$
>>> +  \.(po|fig|gif|ico|png|pot|pl|spec|spec\.in|js|woff|diff|patch|html\.in|stp|syms|conf|data|cpuinfo)$$

There ARE some files that are always worth excluding: the list of
graphic binary files (such as .png) makes obvious sense.  But it's a
high bar to globally exclude a file from all syntax checks, especially
when it's relatively easy to write specific checks to be language specific.

Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org

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