Fix Mu ~~ $smartmatch

perf/perf.TODO

@@ -15,3 +15,8 @@ Reduce redundant Cursor creation for, e.g., { say 2 }
 Reduce ContextHelper use in ws, or make it faster.
 
 81537 Mu.new attr: 14093 RxOp.zyg,
+
+Junctions: $x == any($y,$z) could be optimized to a == that knows it
+is dealing with a junction.  Once we have staticer types and can say
+that $x ~~ Any, then the == knows it has *exactly one* junction and
+can statically unroll the correct loop for epic win.

src/Op.pm6

@@ -38,7 +38,7 @@ method code_labelled($body, $label) { self.code($body) } #OK not used
 # binds.  Further, we don't need to generate the bvalues explicitly, since
 # we know they'll just be bound.
 method code_bvalue($body, $ro, $rhscg) { #OK not used
-    die "Illegal use of $.typename in bvalue context"; # XXX niecza
+    die "Illegal use of {self.WHAT.perl} in bvalue context";
 }
 
 method statement_level() { self }
@@ -633,7 +633,6 @@ class Attribute is Op {
     has $.accessor; # Bool
     has $.initializer; # Body, is rw
     has $.typeconstraint; # Array of Str
-    has $.sigil;
     has $.rw;
 
     method code($) { CgOp.corelex('Nil') }
@@ -702,7 +701,8 @@ class Lexical is Op {
 
     method code_bvalue($ , $ro, $rhscg) {
         CgOp.prog(
-            CgOp.scopedlex($.name, CgOp.newboundvar(+?$ro, +(?($.list || $.hash)), $rhscg)),
+            CgOp.scopedlex($.name, defined($ro) ?? CgOp.newboundvar(+?$ro,
+                +(?($.list || $.hash)), $rhscg) !! $rhscg),
             CgOp.scopedlex($.name));
     }
 }
@@ -740,7 +740,8 @@ class PackageVar is Op {
     method code_bvalue($ , $ro, $rhscg) {
         CgOp.prog(
             CgOp.scopedlex($.slot,
-                CgOp.newboundvar(+?$ro, +(?($.list || $.hash)), $rhscg)),
+                defined($ro) ?? CgOp.newboundvar(+?$ro,
+                    +(?($.list || $.hash)), $rhscg) !! $rhscg),
             CgOp.scopedlex($.slot));
     }
 }

src/OpHelpers.pm6

@@ -20,12 +20,10 @@ sub mkbool($i) is export { ::Op::Lexical.new(name => $i ?? 'True' !! 'False') }
 sub mktemptopic($/, $item, $expr) is export {
     mklet(mklex($/, '$_'), -> $old_ {
         ::Op::StatementList.new(|node($/), children => [
-            # XXX should be a raw bind
-            ::Op::Bind.new(:!readonly, lhs => mklex($/, '$_'), rhs => $item),
+            ::Op::Bind.new(:readonly(Bool), lhs=>mklex($/,'$_'), rhs => $item),
             mklet($expr, -> $result {
                 ::Op::StatementList.new(children => [
-                    # XXX should be a raw bind
-                    ::Op::Bind.new(:!readonly, lhs => mklex($/, '$_'),
+                    ::Op::Bind.new(:readonly(Bool), lhs => mklex($/, '$_'),
                         rhs => $old_),
                     $result]) }) ]) });
 }