Implement 'use MONKEY_TYPING'; augment and supersede are now forbidde…

…n without it. Infinitesimally small chance of entire works of Shakespeare being written as a side effect.

src/Perl6/Actions.pm

@@ -394,6 +394,9 @@ method statement_control:sym<use>($/) {
                 ),
             );
         }
+        elsif ~$<module_name> eq 'MONKEY_TYPING' {
+            $*MONKEY_TYPING := 1;
+        }
         else {
             need($<module_name>);
             import($/);

src/Perl6/Grammar.pm

@@ -85,7 +85,10 @@ method add_our_name($name) {
 method add_name($name) {
     if $*SCOPE eq 'augment' || $*SCOPE eq 'supersede' {
         unless self.is_name($name) {
-            pir::die("Can't $*SCOPE something that doesn't exist");
+            pir::die("Can't $*SCOPE $*PKGDECL that doesn't exist");
+        }
+        unless $*MONKEY_TYPING {
+            pir::die("Can't $*SCOPE $*PKGDECL $name without 'use MONKEY_TYPING'");
         }
     }
     else {
@@ -239,6 +242,7 @@ token comp_unit {
     :my %*METAOPGEN;                           # hash of generated metaops
     :my $*IN_DECL;                             # what declaration we're in
     :my $*IMPLICIT;                            # whether we allow an implicit param
+    :my $*MONKEY_TYPING := 0;                  # whether augment/supersede are allowed
     <.newpad>
     <.outerlex>
     <.finishpad>

src/core/traits.pm

@@ -1,3 +1,7 @@
+# Need to be able to augment in the setting, and this is the first file, so we
+# put this here.
+use MONKEY_TYPING;
+
 # XXX Signature is wrong really - will fix once we can parse other things.
 our multi trait_mod:<is>(Mu $child, Mu $parent) {
     $child.^add_parent($parent);