Revert "Use $^S instead of caller in splain"

This reverts commit 019070c31184a4deb57cb85f7e597a789c6c5b54.

I misunderstood $^S, and thought I could simplify the code.  Contrary
to what perlvar says, $^S is undefined not only during compilation of
an eval or module, but also during compilation of the main program.

1 files changed, 8 insertions, 1 deletions

diff --git a/lib/diagnostics.pm b/lib/diagnostics.pm
index c734c852be..82fa700008 100644
--- a/lib/diagnostics.pm
+++ b/lib/diagnostics.pm
@@ -546,7 +546,14 @@ sub death_trap {
 
     # See if we are coming from anywhere within an eval. If so we don't
     # want to explain the exception because it's going to get caught.
-    my $in_eval = $^S || !defined $^S;
+    my $in_eval = 0;
+    my $i = 0;
+    while (my $caller = (caller($i++))[3]) {
+      if ($caller eq '(eval)') {
+	$in_eval = 1;
+	last;
+      }
+    }
 
     splainthis($exception) unless $in_eval;
     if (caller eq $WHOAMI) { print STDERR "INTERNAL EXCEPTION: $exception"; }