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Non-finite repeat count warning isn't emitted consistently #15929

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p5pRT opened this issue Mar 23, 2017 · 4 comments
Open

Non-finite repeat count warning isn't emitted consistently #15929

p5pRT opened this issue Mar 23, 2017 · 4 comments
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distro-Linux type-core

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@p5pRT
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p5pRT commented Mar 23, 2017

Migrated from rt.perl.org#131050 (status was 'open')

Searchable as RT131050$
@p5pRT
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p5pRT commented Mar 23, 2017

From @mauke

Created by @mauke

$ perl -wE '$_ = 2 x ("inf" + 0); say "[$_]"'
Non-finite repeat count does nothing at -e line 1.
[]

Good.

$ perl -wE '$_ = 2 x "inf"; say "[$_]"'
[]

No warning here. I think this is a bug because the right operand of x should be
in numeric context anyway.

Perl Info 

Flags:
    category=core
    severity=low

Site configuration information for perl 5.24.1:

Configured by mauke at Sun Feb 19 23:06:44 CET 2017.

Summary of my perl5 (revision 5 version 24 subversion 1) configuration:
   
  Platform:
    osname=linux, osvers=4.9.6-1-arch, archname=i686-linux
    uname='linux simplicio 4.9.6-1-arch #1 smp preempt thu jan 26 09:41:20 cet 2017 i686 gnulinux '
    config_args=''
    hint=recommended, useposix=true, d_sigaction=define
    useithreads=undef, usemultiplicity=undef
    use64bitint=undef, use64bitall=undef, uselongdouble=undef
    usemymalloc=n, bincompat5005=undef
  Compiler:
    cc='cc', ccflags ='-fwrapv -fno-strict-aliasing -pipe -fstack-protector-strong -I/usr/local/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64',
    optimize='-O2 -flto',
    cppflags='-fwrapv -fno-strict-aliasing -pipe -fstack-protector-strong -I/usr/local/include'
    ccversion='', gccversion='6.3.1 20170109', gccosandvers=''
    intsize=4, longsize=4, ptrsize=4, doublesize=8, byteorder=1234, doublekind=3
    d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=12, longdblkind=3
    ivtype='long', ivsize=4, nvtype='double', nvsize=8, Off_t='off_t', lseeksize=8
    alignbytes=4, prototype=define
  Linker and Libraries:
    ld='cc', ldflags ='-fstack-protector-strong -L/usr/local/lib'
    libpth=/usr/local/lib /usr/lib/gcc/i686-pc-linux-gnu/6.3.1/include-fixed /usr/lib /lib
    libs=-lpthread -lnsl -lgdbm -ldb -ldl -lm -lcrypt -lutil -lc -lgdbm_compat
    perllibs=-lpthread -lnsl -ldl -lm -lcrypt -lutil -lc
    libc=libc-2.24.so, so=so, useshrplib=false, libperl=libperl.a
    gnulibc_version='2.24'
  Dynamic Linking:
    dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-Wl,-E'
    cccdlflags='-fPIC', lddlflags='-shared -O2 -flto -L/usr/local/lib -fstack-protector-strong'



@INC for perl 5.24.1:
    /home/mauke/usr/lib/perl5/site_perl/5.24.1/i686-linux
    /home/mauke/usr/lib/perl5/site_perl/5.24.1
    /home/mauke/usr/lib/perl5/5.24.1/i686-linux
    /home/mauke/usr/lib/perl5/5.24.1


Environment for perl 5.24.1:
    HOME=/home/mauke
    LANG=en_US.UTF-8
    LANGUAGE=en_US
    LC_COLLATE=C
    LC_MONETARY=de_DE.UTF-8
    LC_TIME=de_DE.UTF-8
    LD_LIBRARY_PATH (unset)
    LOGDIR (unset)
    PATH=/home/mauke/perl5/perlbrew/bin:/home/mauke/bin:/usr/local/sbin:/usr/local/bin:/usr/bin:/usr/bin/site_perl:/usr/bin/vendor_perl:/usr/bin/core_perl
    PERLBREW_BASHRC_VERSION=0.73
    PERLBREW_HOME=/home/mauke/.perlbrew
    PERLBREW_ROOT=/home/mauke/perl5/perlbrew
    PERL_BADLANG (unset)
    PERL_UNICODE=SAL
    SHELL=/bin/bash

@p5pRT
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p5pRT commented Jun 5, 2017

From @tonycoz

$ perl -wE '$_ = 2 x ("inf" + 0); say "[$_]"'
Non-finite repeat count does nothing at -e line 1.
[]

Good.

$ perl -wE '$_ = 2 x "inf"; say "[$_]"'
[]

No warning here. I think this is a bug because the right operand of x
should be
in numeric context anyway.

Something like​:

Inline Patch 
diff --git a/pp.c b/pp.c
index 6df2101..2ad4021 100644
--- a/pp.c
+++ b/pp.c
@@ -1804,8 +1804,11 @@ PP(pp_repeat)
                 count = (IV)nv;
         }
     }
-    else
+    else {
        count = SvIV_nomg(sv);
+        if (SvNOKp(sv) && Perl_isinfnan(SvNVX(sv)))
+            infnan = TRUE;
+    }
 
     if (infnan) {
         Perl_ck_warner(aTHX_ packWARN(WARN_NUMERIC),
(it might better to just:   if \(SvNOKp\(sv\)\) goto the\_nokp\_case; \)

fixes your case, but doesn't help if the count is overloaded​:

  $ ./perl -Ilib -wE '$x = bless {}, "Foo"; say "[", "x" x $x, "]"; package Foo; use overload "0+" => sub { "Inf" };'
  []

which I don't see a fix for without making a smarter SvIV() interface.

Tony

@p5pRT
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p5pRT commented Jun 5, 2017

The RT System itself - Status changed from 'new' to 'open'

@p5pRT
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p5pRT commented Nov 2, 2017

From zefram@fysh.org

Similar inconsistent behaviour​:

$ perl -lwe '@​a=qw(aa bb cc); print $a["inf"]; print $a["inf" + 0]'
aa
cc

Seems that bare "inf" is zeroish in an integer context, while an "inf"
that has been numericised is detectably non-integer.

-zefram

@xenu xenu removed the affects-5.24 label Nov 19, 2021
@xenu xenu removed the Severity Low label Dec 29, 2021
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