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    SubjectRe: [PATCH 1/1] checkpatch.pl: thou shalt not use () or (...) in function declarations
    On 22/03/12 17:22 +0100, ext Jiri Slaby wrote:
    > On 03/22/2012 04:27 PM, Phil Carmody wrote:
    > > After HPA's wonderful lkml post, referenced, it seems worth trying to
    > > detect this robomatically.
    > >
    > > Signed-off-by: Phil Carmody <ext-phil.2.carmody@nokia.com>
    > > ---
    > > scripts/checkpatch.pl | 4 ++++
    > > 1 files changed, 4 insertions(+), 0 deletions(-)
    > >
    > > diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
    > > index a3b9782..3993011 100755
    > > --- a/scripts/checkpatch.pl
    > > +++ b/scripts/checkpatch.pl
    > > @@ -1881,6 +1881,10 @@ sub process {
    > > substr($ctx, 0, $name_len + 1, '');
    > > $ctx =~ s/\)[^\)]*$//;
    > >
    > > + if ($ctx =~ /^\s*(?:\.\.\.)?\s*$/) {
    > > + # HPA explains why: http://lwn.net/Articles/487493/
    > > + ERROR("(...) and () are not sufficiently informative function declarations\n$hereline");
    > > + }
    >
    > That explanation is not fully correct. C99 explicitly says (6.7.5.3.14):
    > An identifier list declares only the identifiers of the parameters of
    > the function. An empty list in a function declarator that is part of a
    > definition of that function specifies that the function has no
    > parameters. The empty list in a function declarator that is not part of
    > a definition of that function specifies that no information about the
    > number or types of the parameters is supplied.
    >
    > So what you are trying to force here holds only for (forward)
    > declarations. Not for functions with definitions (bodies). Is checkpatch
    > capable to differ between those?

    I know I've already agreed to the above, as it makes perfect sense, but
    I've just come across this, and it appears we're both wrong.

    http://www.open-std.org/jtc1/sc22/wg14/www/docs/dr_317.htm
    """"
    ...
    void f(){}
    ...
    Question 1: Does such a function definition give the function a type including a prototype for the rest of the translation unit?
    ...
    Committee Response
    The grammar states that an empty parens stands for an empty identifier list not an empty parameter-type-list.
    The answer to question #1 is NO
    """

    So it appears () is never sufficiently informative.
    Phil
    --
    Phil Carmody


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