Add support for Ruby 3.1's anonymous block forwarding.

Author: nirvdrum

CHANGELOG.md

@@ -5,6 +5,7 @@ New features:
 * Foreign strings now have all methods of Ruby `String`. They are treated as `#frozen?` UTF-8 Ruby Strings.
 * Add `Java.add_to_classpath` method to add jar paths at runtime (#2693, @bjfish).
 * Add support for Ruby 3.1's Hash shorthand/punning syntax (@nirvdrum).
+* Add support for Ruby 3.1's anonymous block forwarding syntax (@nirvdrum).
 
 Bug fixes:
 

src/main/java/org/truffleruby/parser/parser/ParserSupport.java

@@ -158,6 +158,8 @@ public class ParserSupport {
             .usAsciiString(FORWARD_ARGS_KWREST_VAR);
     /** The local variable to store the block from ... in */
     public static final String FORWARD_ARGS_BLOCK_VAR = Layouts.TEMP_PREFIX + "forward_block";
+    public static final TruffleString FORWARD_ARGS_BLOCK_VAR_TSTRING = TStringUtils
+            .usAsciiString(FORWARD_ARGS_BLOCK_VAR);
 
     // Parser states:
     protected StaticScope currentScope;
@@ -1536,6 +1538,11 @@ public void warning(SourceIndexLength position, String message) {
         warnings.warning(file, position.toSourceSection(lexer.getSource()).getStartLine(), message);
     }
 
+    public boolean local_id(String value) {
+        // FIXME: local_id_ref is more complicated and we just blanket look for a scope var of the same name.
+        return currentScope.isDefined(value) >= 0;
+    }
+
     // ENEBO: Totally weird naming (in MRI is not allocated and is a local var name) [1.9]
     public boolean is_local_id(TruffleString name) {
         return lexer.isIdentifierChar(name.readByteUncached(0, lexer.tencoding));