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[perl #133339] 'Exiting eval via next' when explicit label given

From:
" Ed Avis "
Date:
July 6, 2018 16:57
Subject:
[perl #133339] 'Exiting eval via next' when explicit label given
Message ID:
rt-4.0.24-15137-1530896220-234.133339-75-0@perl.org
# New Ticket Created by  "Ed Avis" 
# Please include the string:  [perl #133339]
# in the subject line of all future correspondence about this issue. 
# <URL: https://rt.perl.org/Ticket/Display.html?id=133339 >



This is a bug report for perl from eda@waniasset.com,
generated with the help of perlbug 1.40 running under perl 5.22.2.


-----------------------------------------------------------------
[Please describe your issue here]

I think I understand the rationale for this warning:

% perl -wE 'foreach (1) { eval { next } }'
Exiting eval via next at -e line 1.

However, when the loop label is explicitly given, I don't believe it should warn

% perl -wE 'LOOP: foreach (1) { eval { next LOOP } }'
Exiting eval via next at -e line 1.

The programmer has specified exactly which control flow structure the
next (or break or redo) should affect, so there is no need for a
warning about possible confusion with whether or not the 'eval' block
counts as a control flow structure.

In my opinion the whole warning about 'Exiting eval via next' is a
little dubious, but the scope of this bug report is only in the
specific case when a loop label is provided.  It should be turned off
in that case.  Changing it in general would be a different bug.

I guess though it could still warn when the labelled block *is* an eval!

% perl -wE 'FOO: eval { redo FOO }'

[Please do not change anything below this line]
-----------------------------------------------------------------
---
Flags:
    category=core
    severity=low
---
Site configuration information for perl 5.22.2:

Configured by Red Hat, Inc. at Fri Nov  4 14:35:02 UTC 2016.

Summary of my perl5 (revision 5 version 22 subversion 2) configuration:
   
  Platform:
    osname=linux, osvers=4.7.9-200.fc24.x86_64, archname=x86_64-linux-thread-multi
    uname='linux buildvm-12.phx2.fedoraproject.org 4.7.9-200.fc24.x86_64 #1 smp thu oct 20 14:26:16 utc 2016 x86_64 x86_64 x86_64 gnulinux '
    config_args='-des -Doptimize=none -Dccflags=-O2 -g -pipe -Wall -Werror=format-security -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong --param=ssp-buffer-size=4 -grecord-gcc-switches  -m64 -mtune=generic -Dldflags=-Wl,-z,relro  -Dccdlflags=-Wl,--enable-new-dtags -Wl,-z,relro  -Dlddlflags=-shared -Wl,-z,relro  -Dshrpdir=/usr/lib64 -DDEBUGGING=-g -Dversion=5.22.2 -Dmyhostname=localhost -Dperladmin=root@localhost -Dcc=gcc -Dcf_by=Red Hat, Inc. -Dprefix=/usr -Dvendorprefix=/usr -Dsiteprefix=/usr/local -Dsitelib=/usr/local/share/perl5 -Dsitearch=/usr/local/lib64/perl5 -Dprivlib=/usr/share/perl5 -Dvendorlib=/usr/share/perl5/vendor_perl -Darchlib=/usr/lib64/perl5 -Dvendorarch=/usr/lib64/perl5/vendor_perl -Darchname=x86_64-linux-thread-multi -Dlibpth=/usr/local/lib64 /lib64 /usr/lib64 -Duseshrplib -Dusethreads -Duseithreads -Dusedtrace=/usr/bin/dtrace -Duselargefiles -Dd_semctl_semun -Di_db -Ui_ndbm -Di_gdbm -Di_shadow -Di_syslog -Dman3ext=3pm -Duseperlio -Dinstallu
 srbinperl=n -Ubincompat5005 -Uversiononly -Dpager=/usr/bin/less -isr -Dd_gethostent_r_proto -Ud_endhostent_r_proto -Ud_sethostent_r_proto -Ud_endprotoent_r_proto -Ud_setprotoent_r_proto -Ud_endservent_r_proto -Ud_setservent_r_proto -Dscriptdir=/usr/bin -Dusesitecustomize'
    hint=recommended, useposix=true, d_sigaction=define
    useithreads=define, usemultiplicity=define
    use64bitint=define, use64bitall=define, uselongdouble=undef
    usemymalloc=n, bincompat5005=undef
  Compiler:
    cc='gcc', ccflags ='-D_REENTRANT -D_GNU_SOURCE -O2 -g -pipe -Wall -Werror=format-security -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong --param=ssp-buffer-size=4 -grecord-gcc-switches -m64 -mtune=generic -fwrapv -fno-strict-aliasing -I/usr/local/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64',
    optimize='  -g',
    cppflags='-D_REENTRANT -D_GNU_SOURCE -O2 -g -pipe -Wall -Werror=format-security -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong --param=ssp-buffer-size=4 -grecord-gcc-switches -m64 -mtune=generic -fwrapv -fno-strict-aliasing -I/usr/local/include'
    ccversion='', gccversion='5.3.1 20160406 (Red Hat 5.3.1-6)', gccosandvers=''
    intsize=4, longsize=8, ptrsize=8, doublesize=8, byteorder=12345678, doublekind=3
    d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=16, longdblkind=3
    ivtype='long', ivsize=8, nvtype='double', nvsize=8, Off_t='off_t', lseeksize=8
    alignbytes=8, prototype=define
  Linker and Libraries:
    ld='gcc', ldflags ='-Wl,-z,relro  -fstack-protector-strong -L/usr/local/lib'
    libpth=/usr/local/lib64 /lib64 /usr/lib64 /usr/local/lib /usr/lib /lib/../lib64 /usr/lib/../lib64 /lib
    libs=-lpthread -lresolv -lnsl -lgdbm -ldb -ldl -lm -lcrypt -lutil -lc -lgdbm_compat
    perllibs=-lpthread -lresolv -lnsl -ldl -lm -lcrypt -lutil -lc
    libc=libc-2.22.so, so=so, useshrplib=true, libperl=libperl.so
    gnulibc_version='2.22'
  Dynamic Linking:
    dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-Wl,--enable-new-dtags -Wl,-z,relro '
    cccdlflags='-fPIC', lddlflags='-shared -Wl,-z,relro  -L/usr/local/lib -fstack-protector-strong'

Locally applied patches:
    Fedora Patch1: Removes date check, Fedora/RHEL specific
    Fedora Patch3: support for libdir64
    Fedora Patch4: use libresolv instead of libbind
    Fedora Patch5: USE_MM_LD_RUN_PATH
    Fedora Patch6: Skip hostname tests, due to builders not being network capable
    Fedora Patch7: Dont run one io test due to random builder failures
    Fedora Patch15: Define SONAME for libperl.so
    Fedora Patch16: Install libperl.so to -Dshrpdir value
    Fedora Patch22: Document Math::BigInt::CalcEmu requires Math::BigInt (CPAN RT#85015)
    Fedora Patch26: Make *DBM_File desctructors thread-safe (RT#61912)
    Fedora Patch27: Make PadlistNAMES() lvalue again (CPAN RT#101063)
    Fedora Patch28: Make magic vtable writable as a work-around for Coro (CPAN RT#101063)
    Fedora Patch29: Fix duplicating PerlIO::encoding when spawning threads (RT#31923)
    Fedora Patch30: Do not let XSLoader load relative paths (CVE-2016-6185)
    Fedora Patch31: Avoid loading optional modules from default . (CVE-2016-1238)
    Fedora Patch32: Fix a crash in lexical scope warnings (RT#128597)
    Fedora Patch33: Do not mangle errno from failed socket calls (RT#128316)
    Fedora Patch34: Fix crash in "evalbytes S" (RT#129196)
    Fedora Patch35: Fix crash in "evalbytes S" (RT#129196)
    Fedora Patch36: Fix crash in "evalbytes S" (RT#129196)
    Fedora Patch37: Fix crash in splice (RT#129164, RT#129166, RT#129167)
    Fedora Patch38: Fix string overrun in Perl_gv_fetchmethod_pvn_flags (RT#129267)
    Fedora Patch39: Fix string overrun in Perl_gv_fetchmethod_pvn_flags (RT#129267)
    Fedora Patch40: Fix string overrun in Perl_gv_fetchmethod_pvn_flags (RT#129267)
    Fedora Patch41: Fix string overrun in Perl_gv_fetchmethod_pvn_flags (RT#129267)
    Fedora Patch42: Fix string overrun in Perl_gv_fetchmethod_pvn_flags (RT#129267)
    Fedora Patch43: Fix crash when matching UTF-8 string with non-UTF-8 substrings (RT#129350)
    Fedora Patch44: Fix parsing perl options in shell bang line (RT#129336)
    Fedora Patch45: Fix firstchar bitmap under UTF-8 with prefix optimization (RT#129950)
    Fedora Patch46: Avoid infinite loop in h2xs tool if enum and type have the same name (RT130001)
    Fedora Patch47: Fix stack handling when calling chdir without an argument (RT#129130)
    Fedora Patch200: Link XS modules to libperl.so with EU::CBuilder on Linux
    Fedora Patch201: Link XS modules to libperl.so with EU::MM on Linux

---
@INC for perl 5.22.2:
    /home/eda/lib64/perl5/
    /usr/local/lib64/perl5
    /usr/local/share/perl5
    /usr/lib64/perl5/vendor_perl
    /usr/share/perl5/vendor_perl
    /usr/lib64/perl5
    /usr/share/perl5

---
Environment for perl 5.22.2:
    HOME=/home/eda
    LANG=en_GB.UTF-8
    LANGUAGE (unset)
    LC_COLLATE=C
    LC_CTYPE=en_GB.UTF-8
    LC_MESSAGES=en_GB.UTF-8
    LC_MONETARY=en_GB.UTF-8
    LC_NUMERIC=en_GB.UTF-8
    LC_TIME=en_GB.UTF-8
    LD_LIBRARY_PATH (unset)
    LOGDIR (unset)
    PATH=/home/eda/bin:/home/eda/bin:/usr/local/bin:/usr/bin:/sbin:/usr/sbin:/sbin:/usr/sbin
    PERL5LIB=/home/eda/lib64/perl5/
    PERL_BADLANG (unset)
    SHELL=/bin/bash




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