fix detecting GD in BEGIN, with tests

[p5sagit/Devel-GlobalDestruction.git] / lib / Devel / GlobalDestruction.pm

diff --git a/lib/Devel/GlobalDestruction.pm b/lib/Devel/GlobalDestruction.pm
index e54d757..949d1d4 100644 (file)
--- a/lib/Devel/GlobalDestruction.pm
+++ b/lib/Devel/GlobalDestruction.pm
@@ -26,8 +26,16 @@ elsif (eval {
   # the eval already installed everything, nothing to do
 }
 else {
+  # internally, PL_main_start is nulled immediately before entering global destruction
+  # and we can use B to detect that.  It will also be null before the main runloop starts,
+  # so we check install a CHECK if needed to detect that.
   require B;
-  eval 'sub in_global_destruction () { B::main_start()->isa(q[B::NULL]) }; 1'
+  my $started = !B::main_start()->isa(q[B::NULL]);
+  unless ($started) {
+    eval 'CHECK { $started = 1 }; 1'
+      or die $@;
+  }
+  eval 'sub in_global_destruction () { $started && B::main_start()->isa(q[B::NULL]) }; 1'
     or die $@;
 }