ignore cygwin files that cannot be stat()ed in t/op/stat.t

This is a fix for github cygwin vm smoke runs, specifically the issue in:
https://github.com/Perl/perl5/issues/18193

The original cause of the issue was an update github did to their windows
vm image with version 20200920.1, wherein the status of a console being
attached is now unclear.

This has affected other projects as well
(example: https://github.com/actions/virtual-environments/issues/1679 )
and, relevant for us, shows itself as /dev/con(in|out|sole) not being
stat()able under cygwin.

As such, the fix for the test is to, under cygwin, identify such files,
and remove them from the dataset altogether before checking stat operations
on them.

(As a small freebie, this also dumps diagnostics of the check on failure.)

diff --git a/t/op/stat.t b/t/op/stat.t
index 5ad119c..4fe90ad 100644 (file)
--- a/t/op/stat.t
+++ b/t/op/stat.t
@@ -299,6 +299,11 @@ SKIP: {
     $DEV =~ s{^.+?\s\..+?$}{}m;
     @DEV =  grep { ! m{^\..+$} } @DEV;
 
+    # sometimes files cannot be stat'd on cygwin, making inspecting pointless
+    # remove them from both @DEV and $DEV
+    @DEV = grep $DEV =~ s/^.\?{9}.*\s$_(?: -> .*)?$//m ? () : $_, @DEV
+      if $Is_Cygwin;
+
     # Irix ls -l marks sockets with 'S' while 's' is a 'XENIX semaphore'.
     if ($^O eq 'irix') {
         $DEV =~ s{^S(.+?)}{s$1}mg;
@@ -309,7 +314,8 @@ SKIP: {
        my @c2 = eval qq[grep { $_[1] "/dev/\$_" } \@DEV];
        my $c1 = scalar @c1;
        my $c2 = scalar @c2;
-       is($c1, $c2, "ls and $_[1] agreeing on /dev ($c1 $c2)");
+       diag "= before", $DEV, "-", @DEV, "= after", @c1, "-", @c2, "="
+         unless is($c1, $c2, "ls and $_[1] agreeing on /dev ($c1 $c2)");
     };
 
 {