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sub prototypes not tracking refalias \&foo = \&bar #16987
Description
Migrated from rt.perl.org#134072 (status was 'pending release')
Searchable as RT134072$
Migrated from rt.perl.org#134072 (status was 'pending release')
Searchable as RT134072$
Activity
p5pRT commentedon Apr 30, 2019
From @jimav
Created by @jimav
This is a bug report for perl from jim.avera@gmail.com,
generated with the help of perlbug 1.40 running under perl 5.26.2.
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Not sure whether this is intended behavior, but just in case it's not...
The refalias
\&foo = \&bar
is documented as "foo() now means bar()", but it doesn't entirely:
In subsequently-compiled code, the compiler still wants calls
to foo() to match the old foo's prototype, not the prototype of bar.
#!/usr/bin/perl
use strict; use warnings; use v5.22.0;
use feature 'refaliasing';
no warnings 'experimental::refaliasing';
sub foo($$$$) { }
sub bar($) { }
BEGIN{ \&foo = \&bar; }
foo(1); # Gets "Not enough arguments for main::foo"
Perl Info
p5pRT commentedon May 1, 2019
From @tonycoz
On Tue, 30 Apr 2019 16:50:20 -0700, jim.avera@gmail.com wrote:
It's worse than that:
./perl -Ilib -Mfeature=refaliasing -e 'sub foo { print "foo\n" } sub bar { print "bar\n" } \&foo = \&bar; $n = "foo"; &$n'
Aliasing via reference is experimental at -e line 1.
foo
It seems to be caused by the optimization of storing coderefs as GVs - pp_refassign is expecting a GV on the left for your sample code, but gets the CVref instead and so nothing happens:
switch (left ? SvTYPE(left) : 0) {
case 0:
{
SV * const old = PAD_SV(ARGTARG);
PAD_SETSV(ARGTARG, SvREFCNT_inc_NN(SvRV(sv)));
SvREFCNT_dec(old);
if ((PL_op->op_private & (OPpLVAL_INTRO|OPpPAD_STATE))
== OPpLVAL_INTRO)
SAVECLEARSV(PAD_SVl(ARGTARG));
break;
}
case SVt_PVGV:
if (PL_op->op_private & OPpLVAL_INTRO) {
S_localise_gv_slot(aTHX_ (GV *)left, type);
}
gv_setref(left, sv);
SvSETMAGIC(left);
break;
case SVt_PVAV:
assert(key);
if (UNLIKELY(PL_op->op_private & OPpLVAL_INTRO)) {
S_localise_aelem_lval(aTHX_ (AV *)left, key,
SvCANEXISTDELETE(left));
}
av_store((AV *)left, SvIV(key), SvREFCNT_inc_simple_NN(SvRV(sv)));
break;
case SVt_PVHV:
if (UNLIKELY(PL_op->op_private & OPpLVAL_INTRO)) {
assert(key);
S_localise_helem_lval(aTHX_ (HV *)left, key,
SvCANEXISTDELETE(left));
}
(void)hv_store_ent((HV *)left, key, SvREFCNT_inc_simple_NN(SvRV(sv)), 0);
}
Tony
p5pRT commentedon May 1, 2019
The RT System itself - Status changed from 'new' to 'open'
p5pRT commentedon May 15, 2019
From @tonycoz
On Tue, 30 Apr 2019 16:50:20 -0700, jim.avera@gmail.com wrote:
Fix attached.
With the fix your code produces:
$ ./perl -Ilib ../134072.pl
Subroutine main::foo redefined at ../134072.pl line 11.
Prototype mismatch: sub main::foo ($$$$) vs ($) at ../134072.pl line 11.
bar
Tony
Tony
p5pRT commentedon May 15, 2019
From @tonycoz
0001-perl-134072-allow-foo-bar-to-work-in-main.patch
p5pRT commentedon Jun 12, 2019
From @tonycoz
On Tue, 14 May 2019 23:09:38 -0700, tonyc wrote:
Applied as 40258da.
Tony
p5pRT commentedon Jun 12, 2019
@tonycoz - Status changed from 'open' to 'pending release'