[debbugs-tracker] bug#19634: closed (counting MANY function args more reliably)

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Your message dated Sun, 25 Jan 2015 09:15:58 -0800
with message-id <address@hidden>
and subject line Re: bug#19634: counting MANY function args more reliably
has caused the debbugs.gnu.org bug report #19634,
regarding counting MANY function args more reliably
to be marked as done.

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19634: http://debbugs.gnu.org/cgi/bugreport.cgi?bug=19634
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--- Begin Message --- Subject: counting MANY function args more reliably Date: Tue, 20 Jan 2015 01:26:25 -0800 User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.3.0 Commit ef5a526f1b51b76b0f753e0936c80743a7f4463d fixed a bug in Emacs where the C code passed 10 arguments to a function using the MANY calling convention, but the caller mistakenly passed 8 as the argument count, and this mistakenly discarded the last two arguments; see <http://bugs.gnu.org/3228#63>.

To help prevent this sort of mistake in the future, I would like to install something like the attached patch, which uses a new C macro CALLN to count these arguments automatically. The key lines in the patch are the following additions to lisp.h:

#define CALLMANY(f, array) (f) (ARRAYELTS (array), array)

#define CALLN(f, ...) CALLMANY (f, ((Lisp_Object []) {__VA_ARGS__}))

This lets code use 'return CALLN (foo, a, b, c, d);' instead of the current error-prone usages which are like '{ Lisp_Object args[4]; args[0] = a; args[1] = b; args[2] = c; args[3] = d; return foo (3, args); }'. (Oops, that last '3' should have been a '4'....)

This patch still needs a ChangeLog entry and some more testing on my part, but I thought I'd get it out for review now.

calln.diff
Description: Text Data

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> Subject: 
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> Re: bug#19634: counting MANY function args more reliably
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> Date: 
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> Sun, 25 Jan 2015 09:15:58 -0800
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> Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.4.0
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> Stefan Monnier wrote:
> > I like that,
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> Thanks, I tested the patch on a few more platforms, rebased it to the current 
> master, added some commentary in response to the remarks in this bug report, and 
> installed the patch into the master as commit 
> a3689d3c661fe36df971c875760f8d500b5ae994.
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