syntax error - perl-5.8 only

syphilis has asked for the wisdom of the Perl Monks concerning the following question:

Hi,
I'm trying to build Gtk2-1.22 on Win32 with perl-5.8.0.
It builds ok, but nearly all of the tests fail because of a syntax error in TestHelper.pm, which is one of the files that ship with the Gtk2 source. Surprisingly, (to me at least), identical syntax is considered fine in both perl-5.10.0 and perl-5.12.0.
The actual error is:

C:\build\Gtk2-1.222>perl -Mblib -c blib\lib/Gtk2/TestHelper.pm
syntax error at blib\lib/Gtk2/TestHelper.pm line 98, near "ok "
syntax error at blib\lib/Gtk2/TestHelper.pm line 100, near "}"
blib\lib/Gtk2/TestHelper.pm had compilation errors.
[download]

And here's the relevant section of the TestHelper.pm:

sub ok_idle ($;$) {
88:    my ($testsub, $test_name) = @_;
89:    run_main {
90:    # 0 Test::More::ok
91:    # 1 this block's ok() call
92:    # 2 idle callback in run_main
93:    # 3 Gtk2::main call in run_main
94:     # 4 Gtk2::main call in run_main (again)
95:     # 5 ok_idle
96:     # 6 the caller we want to print
97:     local $Test::Builder::Level = 6;
98:     ok ($testsub->(), $test_name);
99:     }
100: }
[download]

Does anyone know why perl-5.8 sees that as syntactically erroneous ? ... and what do do about it ?

I wondered if it might be something to do with the antiquated version of Test::Simple/Test::Builder I was running, so I updated to 0.96, and updated ExtUtils::MakeMaker to 6.57. Both of those modules passed all tests while building, but the syntax error persists.

Cheers,
Rob

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Re: syntax error - perl-5.8 only by DrHyde (Prior) on Oct 18, 2010 at 09:58 UTC
I've seen some weird syntax error-ish bugs around subs that are prototyped to take a sub-ref as an argument, which in recent perls lets you supply what looks like a block as their argument, just like your run_main presumably is. I thought that that was fixed in 5.8.*, but maybe it was still present in some early 5.8 releases. The fix in my case was to make the code block an explicit sub-ref, thus ... `run_main sub { ... };`	[reply] [d/l]
Re^2: syntax error - perl-5.8 only by syphilis (Archbishop) on Oct 20, 2010 at 06:12 UTC
I've seen some weird syntax error-ish bugs around subs that are prototyped to take a sub-ref as an argument Yes, that seems to be the trouble here. The problem is with the run_main prototype of `(;&)` If I change that to simply `(&)` all seems well on 5.8, except that run_main then needs to be called with at least one argument. That is, with a prototype specification of `(;&)` we can simply do `run_main;` on perl-5.10 and 5.12, but with a prototype specification of `(&)` on my perl-5.8.0, we're not allowed to do simply `run_main`. Instead we have to do `run_main sub {}` which looks very much like what you were suggesting. But that only works on my perl-5.8.0 if I also change the prototype from `(;&)` to `(&)` That's the best I've yet been able to come up with. This may well have been fixed in later versions of perl-5.8. I haven't checked. Sorry it took so long to reply - I was unable to access perlmonks last night (though access to every other site was fine). Cheers, Rob	[reply] [d/l] [select]
Re: syntax error - perl-5.8 only by Anonymous Monk on Oct 19, 2010 at 16:48 UTC
It's not something stupid to do with the space after "ok" is it? I'm asking because the first error says `near "ok_"` which looks a little odd.	[reply] [d/l]