Add the CAVEATS section for the call_sv() failures

diff --git a/caveats/RT69939.t b/caveats/RT69939.t
new file mode 100644 (file)
index 0000000..d6bb172
--- /dev/null
+++ b/caveats/RT69939.t
@@ -0,0 +1,31 @@
+#!perl -w
+# See the CAVEATS section in Mouse.pm
+use strict;
+use Test::More;
+
+{
+    package Class;
+    use Mouse;
+
+    has foo => (
+        is  => 'rw',
+
+        default => sub{
+            # Those eval()s which try to load missing modules in
+            # compile-time triggers a Perl bug (Ticket #69939).
+            # This is related not only to Mouse, but also to tie-modules.
+
+            #eval 'use MayNotBeInstalled';              # NG
+            #eval 'BEGIN{ require MayNotBeInstalled }'; # NG
+            eval{ eval 'use MayNotBeInstalled' };       # OK
+            ::pass 'in a default callback';
+        },
+    );
+}
+
+pass "class definition has been done";
+
+isa_ok(Class->new, 'Class');
+
+done_testing;
+

diff --git a/lib/Mouse.pm b/lib/Mouse.pm
index 41f6b0c..279d58c 100644 (file)
--- a/lib/Mouse.pm
+++ b/lib/Mouse.pm
@@ -402,6 +402,21 @@ You may use L</extends> to replace the superclass list.
 Please unimport Mouse (C<no Mouse>) so that if someone calls one of the
 keywords (such as L</extends>) it will break loudly instead breaking subtly.
 
+=head1 CAVEATS
+
+If you use Mouse::XS you might see a silent fatal error when you use
+callbacks which include C<eval 'use MayNotBeInstalled'>. This is not
+a bug in Mouse. In fact, it is a bug in Perl (RT #69939).
+
+To work around this problem, surround C<eval STRING> with C<eval BLOCK>:
+
+    sub callback {
+        # eval 'use MayNotBeInstalled';       # NG
+        eval{ eval 'use MayNotBeInstalled' }; # OK
+    }
+
+It seems ridiculous, but it works as you expected.
+
 =head1 SOURCE CODE ACCESS
 
 We have a public git repository: