Support where-free subsets

These are essentially like type aliases. This patch unlocks the forms: - subset MyInt of Int - my Int subset MyInt
rakudo · Feb 12, 2023 · d3d839c · d3d839c
1 parent 7b4e982
commit d3d839c
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Showing 2 changed files with 12 additions and 10 deletions.
diff --git a/src/Raku/Actions.nqp b/src/Raku/Actions.nqp
@@ -1711,7 +1711,7 @@ class Raku::Actions is HLL::Actions does Raku::CommonActions {
     method type_declarator:sym<subset>($/) {
         my $decl := self.r('Type', 'Subset').new(
             :name($<longname>.ast),
-            :where($<EXPR>.ast),
+            :where($<EXPR> ?? $<EXPR>.ast !! Mu),
             :traits($<trait>),
             :scope($*SCOPE)
         );

diff --git a/src/Raku/ast/type.rakumod b/src/Raku/ast/type.rakumod
@@ -350,7 +350,7 @@ class RakuAST::Type::Subset
 
     method visit-children(Code $visitor) {
         $visitor($!name);
-        $visitor($!where);
+        $visitor($!where) if $!where;
         # External constants break if visited with missing IMPL-QAST-DECL. Adding a sensible IMPL-QAST-DECL
         # results in lexical declarations for things like Int, which will break if added more than once.
         $visitor($!of) if $!of && !nqp::istype($!of, RakuAST::Declaration::External::Constant);
@@ -394,7 +394,7 @@ class RakuAST::Type::Subset
         }
 
         my $block;
-        if !$!where.IMPL-CURRIED && (!nqp::istype($!where, RakuAST::Code) || nqp::istype($!where, RakuAST::RegexThunk)) {
+        if $!where && !$!where.IMPL-CURRIED && (!nqp::istype($!where, RakuAST::Code) || nqp::istype($!where, RakuAST::RegexThunk)) {
             $block := RakuAST::Block.new(
                 body => RakuAST::Blockoid.new(
                     RakuAST::StatementList.new(
@@ -447,12 +447,14 @@ class RakuAST::Type::Subset
         if $!of {
             $type.HOW.set_of($type, $!of.compile-time-value);
         }
-        $type.HOW.set_where(
-            $type,
-            $!where.IMPL-CURRIED
-                ?? $!where.IMPL-CURRIED.meta-object
-                !! $!where.compile-time-value
-        );
+        if $!where {
+            $type.HOW.set_where(
+                $type,
+                $!where.IMPL-CURRIED
+                    ?? $!where.IMPL-CURRIED.meta-object
+                    !! $!where.compile-time-value
+            );
+        }
         $type
     }
-}
+}