fix ARGV default in shift

Author: fglock

src/main/java/org/perlonjava/parser/OperatorParser.java

@@ -18,8 +18,7 @@
 
 import static org.perlonjava.lexer.LexerTokenType.*;
 import static org.perlonjava.parser.NumberParser.parseNumber;
-import static org.perlonjava.parser.ParserNodeUtils.atUnderscore;
-import static org.perlonjava.parser.ParserNodeUtils.scalarUnderscore;
+import static org.perlonjava.parser.ParserNodeUtils.*;
 import static org.perlonjava.parser.SubroutineParser.consumeAttributes;
 import static org.perlonjava.parser.TokenUtils.consume;
 import static org.perlonjava.parser.TokenUtils.peek;
@@ -417,8 +416,9 @@ static OperatorNode parseOperatorWithOneOptionalArgument(Parser parser, LexerTok
                 case "pop":
                 case "shift":
                     // create `@_` variable
-                    // XXX in main program, use `@ARGV`
-                    operand = atUnderscore(parser);
+                    // in main program, use `@ARGV`
+                    boolean isSub = parser.ctx.symbolTable.getCurrentSubroutine() != null;
+                    operand = parser.isTopLevelScript && !isSub ? atArgv(parser) : atUnderscore(parser);
                     break;
                 case "localtime":
                 case "gmtime":

src/main/java/org/perlonjava/parser/ParserNodeUtils.java

@@ -108,6 +108,11 @@ static OperatorNode atUnderscore(Parser parser) {
                 new IdentifierNode("_", parser.tokenIndex), parser.tokenIndex);
     }
 
+    static OperatorNode atArgv(Parser parser) {
+        return new OperatorNode("@",
+                new IdentifierNode("main::ARGV", parser.tokenIndex), parser.tokenIndex);
+    }
+
     /**
      * Creates a ListNode containing @_ for passing as arguments to subroutine calls.
      * <p>