The meaning of $^S seems to have changed from perl 5.6.0 to perl 5.8.0.
There is mention in the Changes files of it being broken prior to perl
5.8.0, but if so, I no longer understand how it is supposed to work.
Take this module:

-----------
package T;

print '$^S is ', defined $^S ? "defined: '$^S'\n" : "not defined\n";

1;
-----------

With perl 560 I get these (sensible to me) results:

$ perl560 T.pm
$^S is defined: '0'

$ perl560 -MT -e 1
$^S is not defined

But with perl 588, I get this:

$ perl588 T.pm
$^S is defined: '0'

$ perl588 -MT -e 1
$^S is defined: '1'

The man page for $^S says this:

"$^S
$EXCEPTIONS_BEING_CAUGHT

Current state of the interpreter.

$^S State
--------- -------------------
undef Parsing module/eval
true (1) Executing an eval
false (0) Otherwise

The first state may happen in $SIG{__DIE__} and $SIG{__WARN__}
handlers."

It would seem to me that in the -MT case, the module is in fact being
"parsed", which would mean that $^S should be undef. For $^S to be 1,
it should be "executing an eval", which I don't believe -MT is doing.
In other words, the 560 behavior looks more correct to me than the 588
behavior. What am I missing here?

John.