From: Stephen Berman <stephen.berman@gmx.net>
To: 14565@debbugs.gnu.org
Subject: bug#14565: 24.3.50; Error with byte-compiled function using backward-char
Date: Thu, 06 Jun 2013 20:30:41 +0200 [thread overview]
Message-ID: <87ppvzytv2.fsf@rosalinde.fritz.box> (raw)
In-Reply-To: <87txlbz59q.fsf@rosalinde.fritz.box> (Stephen Berman's message of "Thu, 06 Jun 2013 16:24:17 +0200")
On Thu, 06 Jun 2013 16:24:17 +0200 Stephen Berman <stephen.berman@gmx.net> wrote:
> When I evaluate and invoke each of the following functions, they both
> work as expected:
>
> (defun my-test-1 () (forward-char nil))
>
> (defun my-test-2 () (backward-char nil))
>
> But if I byte-compile them, only my-test-1 works; my-test-2 raises a
> Lisp error: (wrong-type-argument number-or-marker-p nil)
>
> Here are the byte codes:
>
> (byte-code "\300\301\302\"\207" [defalias my-test-1 #[nil "\300u\207" [nil] 1]] 3)
>
> (byte-code "\300\301\302\"\207" [defalias my-test-2 #[nil "\300[u\207" [nil] 1]] 3)
>
> and here is the disassembled code:
>
> byte code for my-test-1:
> args: nil
> 0 constant nil
> 1 forward-char
> 2 return
>
> byte code for my-test-2:
> args: nil
> 0 constant nil
> 1 negate
> 2 forward-char
> 3 return
If `negate' in the byte code corresponds to the case Bnegate in
exec_byte_code, then IIUC nil fails the test for INTEGERP so is passed
to Fminus, and from there to arith_driver, where it fails
CHECK_NUMBER_OR_FLOAT_COERCE_MARKER, which via CHECK_TYPE signals the
wrong-type-argument error. If this is what happens, then the byte code
of backward-char is at odds with its definition via move_point in
cmds.c, which explicitly checks whether the argument is nil, and if so
sets it to 1, which for Fbackward_char is then negated. Or have I
completely misunderstood and if so, what is the error due to?
Steve Berman
next prev parent reply other threads:[~2013-06-06 18:30 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-06-06 14:24 bug#14565: 24.3.50; Error with byte-compiled function using backward-char Stephen Berman
2013-06-06 18:30 ` Stephen Berman [this message]
2013-06-06 21:05 ` Glenn Morris
2013-06-07 2:28 ` Glenn Morris
2013-06-07 9:40 ` Stephen Berman
2013-06-08 13:20 ` Stephen Berman
2013-06-08 13:46 ` Stephen Berman
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