And I'm talking about compile time:

Pragmas like use feature have the same import-timing like modules and all subs are declared at compile time.

Ah, you were talking about patching feature.pm. Yes, that (or something like that) would work. That's in line with what I said about it not being Try::Tiny's issue to resolve. Also, having feature.pm (or perlcritic) handle it would help with all non-builtin implementations of try (not just Try::Tiny's).

As I already said, both need to be patched. I don't see a way how use feature could warn about a later use Try::Tiny (... well except of a general solution°)

And I prefer to see the warning at the line where the use appears, not the one with conflicting 'try {}'.

In general any module exporting subs that conflict with potential built-ins should check at import time.

The needed code to check the hint-hash should be refactored from feature.pm into a separate module.

footnote

°) In theory one could write an INC-hook which wraps around each use and require and checks the namespaces and hint-hashes for conflicts.

Like this no modules need to be patched.

Not sure if this is not an overkill tho.

Cheers Rolf
_{(addicted to the Perl Programming Language :)
see Wikisyntax for the Monastery}

DEMO:

use strict;
use warnings;

# selfcontained simulation of feature pragma
  package my_feature;
  use Carp;
  sub import {
    my $pkg = (caller)[0];
    if ( grep {$_ eq "try"} @_ ) {
      for my $func (qw/try catch finally/) {
        carp "Warning: ${pkg}::$func() will be shadowed by feature 'tr
+y'"
          if exists &{"${pkg}::$func"};
      }
    }
  }
  1;

  BEGIN {  $INC{"my_feature.pm"} = "DEMO from " . __FILE__ }
# end simulation

package Foo;
use Try::Tiny;
use my_feature "try";
[download]

-->

perl /home/lanx/perl/pm/check_stash_sub.pl
Warning: Foo::try() will be shadowed by feature 'try' at /home/lanx/pe
+rl/pm/check_stash_sub.pl line 23.
Warning: Foo::catch() will be shadowed by feature 'try' at /home/lanx/
+perl/pm/check_stash_sub.pl line 23.
Warning: Foo::finally() will be shadowed by feature 'try' at /home/lan
+x/perl/pm/check_stash_sub.pl line 23.
[download]

NB: The warnings are emitted before any code following the use feature is compiled.

Cheers Rolf
_{(addicted to the Perl Programming Language :)
see Wikisyntax for the Monastery}