Bug#931418: perl: no errors with strict subs and bareword following a minus operator

[Vincent Lefevre]

Package: perl
Version: 5.28.1-6
Severity: normal

The following does no yield any error:

  perl -e 'use strict; my $x = - Inf;'

This does not seem to be intended.

The strict(3perl) man page says:

    "strict subs"
      This disables the poetry optimization, generating a compile-time
      error if you try to use a bareword identifier that's not a
      subroutine, unless it is a simple identifier (no colons) and that
      it appears in curly braces or on the left hand side of the "=>"
      symbol.

          use strict 'subs';
          $SIG{PIPE} = Plumber;   # blows up
          $SIG{PIPE} = "Plumber"; # fine: quoted string is always ok
          $SIG{PIPE} = \&Plumber; # preferred form

and the perldata(1) man page says:

    Some people may wish to outlaw barewords entirely.  If you say

        use strict 'subs';

    then any bareword that would NOT be interpreted as a subroutine call
    produces a compile-time error instead.  [...]

There does not seem to be an exception after a minus operator.

-- System Information:
Debian Release: 10.0
  APT prefers unstable-debug
  APT policy: (500, 'unstable-debug'), (500, 'stable-updates'), (500, 'unstable'), (500, 'testing'), (500, 'stable'), (1, 'experimental')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 4.19.0-5-amd64 (SMP w/12 CPU cores)
Kernel taint flags: TAINT_PROPRIETARY_MODULE, TAINT_OOT_MODULE, TAINT_UNSIGNED_MODULE
Locale: LANG=POSIX, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8), LANGUAGE=POSIX (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled

Versions of packages perl depends on:
ii  dpkg               1.19.7
ii  libperl5.28        5.28.1-6
ii  perl-base          5.28.1-6
ii  perl-modules-5.28  5.28.1-6

Versions of packages perl recommends:
ii  netbase  5.6

Versions of packages perl suggests:
pn  libb-debug-perl                                         <none>
pn  liblocale-codes-perl                                    <none>
pn  libterm-readline-gnu-perl | libterm-readline-perl-perl  <none>
ii  make                                                    4.2.1-1.2
ii  perl-doc                                                5.28.1-6

-- no debconf information