From 046a96525b8e3d64cf1a4ac4a0c0c20fed1025d8 Mon Sep 17 00:00:00 2001
From: Flavio Soibelmann Glock <fglock@gmail.com>
Date: Mon, 23 Feb 2026 13:51:15 +0100
Subject: [PATCH] Fix interpreter shift/pop with default @_/@ARGV argument

The parser injects the default array (e.g. @main::ARGV at top level,
@_ inside a sub) directly as OperatorNode("@", IdentifierNode) on the
shift/pop node's operand. The bytecode compiler handlers were expecting
the operand to always be a ListNode wrapper, causing:

  shift requires array argument at -e line 2, near "say shift"

Fix: accept operand as either:
  - OperatorNode("@", ...) directly  (default @_/@ARGV case)
  - ListNode containing OperatorNode("@", ...)  (explicit array case)

Verified:
  ./jperl --interpreter -E 'say shift' 123        => 123
  ./jperl --interpreter -E 'say pop' 123          => 123
  sub foo { say shift } foo("hello")              => hello
  my @a=(1,2,3); say shift @a; say pop @a         => 1 / 3
---
 .../backend/bytecode/CompileOperator.java     | 46 +++++++++++--------
 1 file changed, 28 insertions(+), 18 deletions(-)

diff --git a/src/main/java/org/perlonjava/backend/bytecode/CompileOperator.java b/src/main/java/org/perlonjava/backend/bytecode/CompileOperator.java
index 4f2a84a88..29cf81ebc 100644
--- a/src/main/java/org/perlonjava/backend/bytecode/CompileOperator.java
+++ b/src/main/java/org/perlonjava/backend/bytecode/CompileOperator.java
@@ -894,19 +894,24 @@ public static void visitOperator(BytecodeCompiler bytecodeCompiler, OperatorNode
             bytecodeCompiler.lastResultReg = rd;
         } else if (op.equals("pop")) {
             // Array pop: $x = pop @array or $x = pop @$ref
-            // operand: ListNode containing OperatorNode("@", IdentifierNode or OperatorNode)
-            if (node.operand == null || !(node.operand instanceof ListNode)) {
+            // operand: OperatorNode("@", ...) directly (default @_/@ARGV injected by parser)
+            //       or ListNode containing OperatorNode("@", IdentifierNode or OperatorNode)
+            if (node.operand == null) {
                 bytecodeCompiler.throwCompilerException("pop requires array argument");
             }
 
-            ListNode list = (ListNode) node.operand;
-            if (list.elements.isEmpty() || !(list.elements.get(0) instanceof OperatorNode)) {
-                bytecodeCompiler.throwCompilerException("pop requires array variable");
-            }
-
-            OperatorNode arrayOp = (OperatorNode) list.elements.get(0);
-            if (!arrayOp.operator.equals("@")) {
+            OperatorNode arrayOp;
+            if (node.operand instanceof OperatorNode directOp && directOp.operator.equals("@")) {
+                // Direct OperatorNode("@", ...) - default array case
+                arrayOp = directOp;
+            } else if (node.operand instanceof ListNode list && !list.elements.isEmpty()
+                    && list.elements.get(0) instanceof OperatorNode listOp
+                    && listOp.operator.equals("@")) {
+                // ListNode-wrapped OperatorNode("@", ...) - explicit array case
+                arrayOp = listOp;
+            } else {
                 bytecodeCompiler.throwCompilerException("pop requires array variable: pop @array");
+                return;
             }
 
             int arrayReg = -1;  // Will be assigned in if/else blocks
@@ -953,19 +958,24 @@ public static void visitOperator(BytecodeCompiler bytecodeCompiler, OperatorNode
             bytecodeCompiler.lastResultReg = rd;
         } else if (op.equals("shift")) {
             // Array shift: $x = shift @array or $x = shift @$ref
-            // operand: ListNode containing OperatorNode("@", IdentifierNode or OperatorNode)
-            if (node.operand == null || !(node.operand instanceof ListNode)) {
+            // operand: OperatorNode("@", ...) directly (default @_/@ARGV injected by parser)
+            //       or ListNode containing OperatorNode("@", IdentifierNode or OperatorNode)
+            if (node.operand == null) {
                 bytecodeCompiler.throwCompilerException("shift requires array argument");
             }
 
-            ListNode list = (ListNode) node.operand;
-            if (list.elements.isEmpty() || !(list.elements.get(0) instanceof OperatorNode)) {
-                bytecodeCompiler.throwCompilerException("shift requires array variable");
-            }
-
-            OperatorNode arrayOp = (OperatorNode) list.elements.get(0);
-            if (!arrayOp.operator.equals("@")) {
+            OperatorNode arrayOp;
+            if (node.operand instanceof OperatorNode directOp && directOp.operator.equals("@")) {
+                // Direct OperatorNode("@", ...) - default array case
+                arrayOp = directOp;
+            } else if (node.operand instanceof ListNode list && !list.elements.isEmpty()
+                    && list.elements.get(0) instanceof OperatorNode listOp
+                    && listOp.operator.equals("@")) {
+                // ListNode-wrapped OperatorNode("@", ...) - explicit array case
+                arrayOp = listOp;
+            } else {
                 bytecodeCompiler.throwCompilerException("shift requires array variable: shift @array");
+                return;
             }
 
             int arrayReg = -1;  // Will be assigned in if/else blocks