fix(parser): numeric filehandle diamond \<N\> (Acme::Buffy, open 0)

src/main/java/org/perlonjava/frontend/parser/FileHandle.java

@@ -271,7 +271,8 @@ public static Node parseBarewordHandle(Parser parser, String name) {
 
         // Check if this is a known file handle in the global I/O table
         // This helps distinguish between file handles and other barewords
-        if (GlobalVariable.existsGlobalIO(name) || isStandardFilehandle(name)) {
+        if (GlobalVariable.existsGlobalIO(name) || isStandardFilehandle(name)
+                || isAllDigitGlobName(name)) {
             // Create a GLOB reference for the file handle, like `\*FH`
             return new OperatorNode("\\",
                     new OperatorNode("*",
@@ -280,6 +281,24 @@ public static Node parseBarewordHandle(Parser parser, String name) {
         return null;
     }
 
+    /**
+     * Perl allows numeric typeglob names such as {@code open 0; print <0>}, where filehandle
+     * {@code 0} shares the {@code *0} stash entry with {@code $0} (program name).
+     */
+    private static boolean isAllDigitGlobName(String normalizedName) {
+        int idx = normalizedName.lastIndexOf("::");
+        String base = idx >= 0 ? normalizedName.substring(idx + 2) : normalizedName;
+        if (base.isEmpty()) {
+            return false;
+        }
+        for (int i = 0; i < base.length(); i++) {
+            if (!Character.isDigit(base.charAt(i))) {
+                return false;
+            }
+        }
+        return true;
+    }
+
     /**
      * Checks if a normalized name represents a standard filehandle.
      *

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

@@ -139,6 +139,24 @@ static Node parseDiamondOperator(Parser parser, LexerToken token) {
                 return diamond;
             }
 
+            // <0>, <1>, … — numeric filehandles (e.g. Acme::Buffy "open 0" reads $0)
+            if (operand.type == NUMBER && tokenText.matches("[0-9]+")
+                    && parser.tokens.get(parser.tokenIndex + 1).text.equals(">")) {
+                parser.tokenIndex++; // consume NUMBER
+                TokenUtils.consume(parser); // consume '>'
+                String digitName = operand.text;
+                GlobalVariable.getGlobalIO(FileHandle.normalizeBarewordHandle(parser, digitName));
+                Node globRef = FileHandle.parseBarewordHandle(parser, digitName);
+                if (globRef != null) {
+                    BinaryOperatorNode readlineNode = new BinaryOperatorNode("readline",
+                            globRef,
+                            new ListNode(parser.tokenIndex), currentTokenIndex);
+                    readlineNode.setAnnotation("handleName", digitName);
+                    return readlineNode;
+                }
+                parser.tokenIndex = currentTokenIndex;
+            }
+
             // Check if the token looks like a Bareword file handle
             if (operand.type == IDENTIFIER) {
                 Node fileHandle = FileHandle.parseFileHandle(parser);