Add dummy "is rw" trait for Routines. Doesn't do anything yet, but

allows us to properly future-proof code by adding "is rw" where it
will ultimately be needed.   Also mark many of the existing core
routines that are known to be "is rw".

src/core/Any-list.pm

@@ -56,7 +56,7 @@ augment class Any {
         fail('No values matched');
     }
 
-    our multi method grep(Mu $test) {
+    our multi method grep(Mu $test) is rw {
         gather {
             for @.list {
                 take $_ if $_ ~~ $test;
@@ -285,25 +285,25 @@ augment class Any {
         }
     }
 
-    multi method values() {
+    multi method values() is rw {
         gather for $.list -> $value {
             take $value;
         }
     }
 
-    multi method pairs() {
+    multi method pairs() is rw {
         self.kv.map(-> $key, $value { $key => $value; });
     }
 
-    our multi method postcircumfix:<[ ]>() { self.list }
+    our multi method postcircumfix:<[ ]>() is rw { self.list }
 
-    our multi method postcircumfix:<[ ]>(Whatever $w) { 
+    our multi method postcircumfix:<[ ]>(Whatever $w) is rw { 
         self[0..(self.elems-1)]
     }
 
-    our multi method postcircumfix:<[ ]>(&block) { self[&block(|(self.elems xx &block.count))]; }
+    our multi method postcircumfix:<[ ]>(&block) is rw { self[&block(|(self.elems xx &block.count))]; }
 
-    our multi method postcircumfix:<[ ]>(@pos) {
+    our multi method postcircumfix:<[ ]>(@pos) is rw {
         my $result = pir::new__ps('ResizablePMCArray');
         for @pos {
             pir::push($result, self[$_])
@@ -314,12 +314,12 @@ augment class Any {
         }
     }
 
-    our multi method postcircumfix:<[ ]>($pos) {
+    our multi method postcircumfix:<[ ]>($pos) is rw {
         fail "Cannot use negative index $pos on {self.WHO}" if $pos < 0;
         self.at_pos($pos)
     }
 
-    method at_pos($pos) {
+    method at_pos($pos) is rw {
         if self.defined {
             fail ".[$pos] out of range for type {self.WHAT}" if $pos != 0;
             return self;
@@ -331,15 +331,15 @@ augment class Any {
                 );
     }
 
-    our multi method postcircumfix:<{ }>() {
+    our multi method postcircumfix:<{ }>() is rw {
         self.values()
     }
 
-    our multi method postcircumfix:<{ }>(Whatever $w) {
+    our multi method postcircumfix:<{ }>(Whatever $w) is rw {
         self.{self.keys}
     }
 
-    our multi method postcircumfix:<{ }>(@keys) {
+    our multi method postcircumfix:<{ }>(@keys) is rw {
         my $result = pir::new__ps('ResizablePMCArray');
         for @keys {
             pir::push($result, self{$_})
@@ -350,9 +350,9 @@ augment class Any {
         }
     }
 
-    our multi method postcircumfix:<{ }>($key) { self.at_key($key) }
+    our multi method postcircumfix:<{ }>($key) is rw { self.at_key($key) }
 
-    method at_key($key) {
+    method at_key($key) is rw {
         fail "postcircumfix:<\{ \}> not defined for type {self.WHAT}"
             if self.defined;
         my $z = Any!butWHENCE(
@@ -365,8 +365,8 @@ augment class Any {
     # XXX Workarounds for Match objects which also ~~ Positional
     # (http://irclog.perlgeek.de/perl6/2010-09-07#i_2795277)
     # and RT #75868
-    our multi method postcircumfix:<[ ]>(Match $m) { self.[+$m] }
-    our multi method postcircumfix:<{ }>(Match $m) { self.{~$m} }
+    our multi method postcircumfix:<[ ]>(Match $m) is rw { self.[+$m] }
+    our multi method postcircumfix:<{ }>(Match $m) is rw { self.{~$m} }
 
     method !butWHENCE(&by) {
         pir::setprop__0PsP(pir::clone__PP(pir::descalarref__PP(self)), 'WHENCE', &by);

src/core/Array.pm

@@ -1,5 +1,5 @@
 augment class Array {
-    method at_pos($pos) {
+    method at_pos($pos) is rw {
         my $z = Any!butWHENCE(
                     { pir::set__vQiP(self!fill($pos+1), $pos, $z) }
                 );

src/core/Buf.pm

@@ -114,7 +114,7 @@ role Buf[::T = Int] does Stringy does Positional {
         @.contents.elems;
     }
 
-    multi method postcircumfix:<[ ]>($index) {
+    multi method postcircumfix:<[ ]>($index) is rw {
         @.contents[$index];
     }
 }

src/core/Hash.pm

@@ -1,5 +1,5 @@
 role Hash is EnumMap {
-    method at_key($key) {
+    method at_key($key) is rw {
         my $z = Any!butWHENCE(
                     { pir::set__vQsP($!storage, $key, $z); }
                 );

src/core/List.pm

@@ -26,7 +26,7 @@ augment class List does Positional {
         self.map({ .fmt($format) }).join($separator);
     }
 
-    multi method map(&block) {
+    multi method map(&block) is rw {
         Q:PIR {
             .local pmc self, mapiter, block
             mapiter = new ['MapIter']
@@ -44,7 +44,7 @@ augment class List does Positional {
         '(' ~ self.map({ $^a.perl }).join(', ') ~ ')';
     }
 
-    method reverse() {
+    method reverse() is rw {
         if self.elems ~~ Inf {
             fail "Cannot reverse an infinite list"
         }
@@ -144,7 +144,7 @@ augment class List does Positional {
         !$tseq;
     }
 
-    method at_pos($pos) {
+    method at_pos($pos) is rw {
         Q:PIR {
             .local pmc self, pos, items
             self = find_lex 'self'

src/core/traits.pm

@@ -24,6 +24,10 @@ our multi trait_mod:<is>(Routine $r, :$default!) {
     $r does role { method default { True } }
 }
 
+our multi trait_mod:<is>(Routine $r, :$rw!) {
+    $r does role { method rw { True } }
+}
+
 our multi trait_mod:<hides>(Mu $child, Mu $parent) {
     trait_mod:<is>($child, $parent);
     $child.^hides.push($parent);