How to determine if 'strict' is enabled

[kcott]

Background

I'm doing some testing of Perl::Dist::APPerl on various platforms. I have a test script which currently checks that 'use v5.36;' enables the warnings pragma and features are enabled or disabled as appropriate.

Question

I'm looking for a platform-independent way to determine if the strict pragma is in effect without forcing an abort.

If strict is specifically used, it can be determined from %INC:

ken@titan ~/tmp
$ perl -e 'use strict; print "$_\n" for keys %INC;'
strict.pm

ken@titan ~/tmp
$ perl -e 'use strict; my $x = xyz;'
Bareword "xyz" not allowed while "strict subs" in use at -e line 1.
Execution of -e aborted due to compilation errors.

However, if strict is enabled automatically via use VERSION (where VERSION >= 5.12), this method doesn't work:

ken@titan ~/tmp
$ perl -e 'use 5.012; print "$_\n" for keys %INC;'

ken@titan ~/tmp
$ perl -e 'use 5.012; my $x = xyz;'
Bareword "xyz" not allowed while "strict subs" in use at -e line 1.
Execution of -e aborted due to compilation errors.

Any help with this would be appreciated. Thankyou.

[ikegami]

You can't use %INC.

$ perl -le'no strict;      print $INC{ "strict.pm" } ?1:0'
1   # False positive

$ perl -le'{ use strict; } print $INC{ "strict.pm" } ?1:0'
1   # False positive

$ perl -le'use JSON;       print $INC{ "strict.pm" } ?1:0'
1   # False positive

$ perl -le'use v5.20;      print $INC{ "strict.pm" } ?1:0'
0   # False negative

You can use ( caller(0) )[8] in a sub.

$ perl -le'
   sub f { ( ( caller(0) )[8] & 0x602 ) == 0x602 }
   print f ?1:0;
'
0

$ perl -le'
   sub f { ( ( caller(0) )[8] & 0x602 ) == 0x602 }
   use strict;
   print f ?1:0;
'
1

$ perl -le'
   sub f { ( ( caller(0) )[8] & 0x602 ) == 0x602 }
   use v5.20;
   print f ?1:0;
'
1

0x2 is strict refs, 0x200 is strict subs, and 0x400 is strict vars.

[stevieb]

This enlightened me.

Is this documented anywhere ikegami? If so, it's something I've completely overlooked, glossed over or for some reason over the years completely ignored.

[kcott]

G'day stevieb,

"Is this documented anywhere ikegami?"

I looked this up after ++ikegami's response. See caller for element-8, $hints, and subsequent discussion. See "strict's source code" for the numbers (0x2, 0x200, and 0x400).

[kcott]

G'day ikegami,

++ Thanks. That's just the sort of thing I was looking for.

[tobyink]

my $strict_enabled = do {
  my $code = sprintf( '$____DUMMY____%d = 1', 1_000_000 + int( rand 8_
+999_888 ) );
  not eval( $code );
};

if ( $strict_enabled ) {
  print "strict vars\n";
}
else {
  print "no strict vars\n";
}