(?-xism:^foo\.c$)
That is a perfectly valid regexp. The (?- allows one to specifiy regexp option inside the regexp pattern itself.

In addition to build your alternation there is no need to extract the original regexp, since you can quite safely interpolate Regexp objects into patterns: 

my (@a) = (qr/^foo\.c$/,
           qr/^bar\.c$/,
          );
/$a[0]|$a[1]/;
#or
my $re = join("|", @a);
/$re/;

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--
integral, resident of freenode's #perl

In reply to Re: Getting regexp from Regexp references by integral
in thread Getting regexp from Regexp references by steves

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