Optimise AST to destructure block's single array argument for required keyword argument

Author: andrykonchin

spec/truffle/parsing/fixtures/block/destructuring_array_argument/when_keyword_arguments_present_and_should_destructure.yaml

@@ -4,8 +4,10 @@ notes: >
   It handles keyword arguments as usually.
   A simplified AST for array argument destructuring:
   
-    (WriteLocalVariableNode frameSlot = 3
-      (ReadKeywordArgumentNodeGen name = :c))
+    (ReadKeywordArgumentNodeGen name = :c)
+yarp_specific: true # there is optimization in destructuring a single array argument
+                    # to return ReadKeywordArgumentNodeGen for required keyword parameter
+                    # instead of (WriteLocalVariableNode (ReadKeywordArgumentNodeGen))
 focused_on_node: "org.truffleruby.language.methods.BlockDefinitionNode"
 ruby: |
   proc do |a, b, c:|
@@ -223,19 +225,13 @@ ast: |
                                                                                           flags = 0
                                                                                           frameSlot = 4 # %destructure_1
                                                                                           type = FRAME_LOCAL
-                                                          WriteLocalVariableNode
+                                                          ReadKeywordArgumentNodeGen
                                                               attributes:
                                                                   flags = 0
-                                                                  frameSlot = 3 # c
+                                                                  name = :c
                                                               children:
-                                                                  valueNode =
-                                                                      ReadKeywordArgumentNodeGen
-                                                                          attributes:
-                                                                              flags = 0
-                                                                              name = :c
-                                                                          children:
-                                                                              readUserKeywordsHashNode =
-                                                                                  ReadUserKeywordsHashNode
+                                                                  readUserKeywordsHashNode =
+                                                                      ReadUserKeywordsHashNode
                                                       ]
                                   NilLiteralNode
                                       attributes:

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

@@ -133,13 +133,11 @@ public RubyNode visitMultiTargetNode(Nodes.MultiTargetNode node) {
 
     @Override
     public RubyNode visitRequiredKeywordParameterNode(Nodes.RequiredKeywordParameterNode node) {
-        final int slot = environment.declareVar(node.name);
+        // Passing single array argument to a block with required keyword arguments should lead
+        // to ArgumentError 'missing keyword' in runtime.
+        // So use ReadKeywordArgumentNode to raise this exception.
         final var name = language.getSymbol(node.name);
-        final RubyNode readNode = ReadKeywordArgumentNode.create(name, null);
-
-        // actually if there is required keyword argument then ArgumentError 'missing keyword'
-        // should be raised in runtime before executing this node
-        return new WriteLocalVariableNode(slot, readNode);
+        return ReadKeywordArgumentNode.create(name, null);
     }
 
     @Override