[GR-19220] Anonymous block forwarding (#2698)

PullRequest: truffleruby/3450

Author: bjfish

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:
 

spec/ruby/language/block_spec.rb

@@ -983,3 +983,77 @@ def a; 1; end
     end
   end
 end
+
+describe "Anonymous block forwarding" do
+  ruby_version_is "3.1" do
+    it "forwards blocks to other functions that formally declare anonymous blocks" do
+      eval <<-EOF
+          def b(&); c(&) end
+          def c(&); yield :non_null end
+      EOF
+
+      b { |c| c }.should == :non_null
+    end
+
+    it "requires the anonymous block parameter to be declared if directly passing a block" do
+      -> { eval "def a; b(&); end; def b; end" }.should raise_error(SyntaxError)
+    end
+
+    it "works when it's the only declared parameter" do
+      eval <<-EOF
+          def inner; yield end
+          def block_only(&); inner(&) end
+      EOF
+
+      block_only { 1 }.should == 1
+    end
+
+    it "works alongside positional parameters" do
+      eval <<-EOF
+          def inner; yield end
+          def pos(arg1, &); inner(&) end
+      EOF
+
+      pos(:a) { 1 }.should == 1
+    end
+
+    it "works alongside positional arguments and splatted keyword arguments" do
+      eval <<-EOF
+          def inner; yield end
+          def pos_kwrest(arg1, **kw, &); inner(&) end
+      EOF
+
+      pos_kwrest(:a, arg: 3) { 1 }.should == 1
+    end
+
+    it "works alongside positional arguments and disallowed keyword arguments" do
+      eval <<-EOF
+          def inner; yield end
+          def no_kw(arg1, **nil, &); inner(&) end
+      EOF
+
+      no_kw(:a) { 1 }.should == 1
+    end
+  end
+
+  ruby_version_is "3.2" do
+    it "works alongside explicit keyword arguments" do
+      eval <<-EOF
+          def inner; yield end
+          def rest_kw(*a, kwarg: 1, &); inner(&) end
+          def kw(kwarg: 1, &); inner(&) end
+          def pos_kw_kwrest(arg1, kwarg: 1, **kw, &); inner(&) end
+          def pos_rkw(arg1, kwarg1:, &); inner(&) end
+          def all(arg1, arg2, *rest, post1, post2, kw1: 1, kw2: 2, okw1:, okw2:, &); inner(&) end
+          def all_kwrest(arg1, arg2, *rest, post1, post2, kw1: 1, kw2: 2, okw1:, okw2:, **kw, &); inner(&) end
+      EOF
+
+      rest_kw { 1 }.should == 1
+      kw { 1 }.should == 1
+      pos_kw_kwrest(:a) { 1 }.should == 1
+      pos_rkw(:a, kwarg1: 3) { 1 }.should == 1
+      all(:a, :b, :c, :d, :e, okw1: 'x', okw2: 'y') { 1 }.should == 1
+      all_kwrest(:a, :b, :c, :d, :e, okw1: 'x', okw2: 'y') { 1 }.should == 1
+    end
+  end
+end

spec/truffleruby.mspec

@@ -103,6 +103,7 @@ class MSpecScript
 
   # Use spec/ruby/core/nil/nil_spec.rb as a dummy file to avoid being empty
   set :next, %w[
+    spec/ruby/language/block_spec.rb
     spec/ruby/language/hash_spec.rb
     spec/ruby/core/nil/nil_spec.rb
     spec/ruby/core/gc/measure_total_time_spec.rb

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));