From a3f62d3e009cd9a0c0f116db93078b32e79bd4d4 Mon Sep 17 00:00:00 2001
From: Steven Levithan <steves_list@hotmail.com>
Date: Thu, 19 Dec 2024 08:26:38 +0100
Subject: [PATCH] Don't add flag y if allowUnhandledGAnchors and has alts with
 and without leading \G

---
 src/transform.js | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/src/transform.js b/src/transform.js
index 31ee3a0..9ee151d 100644
--- a/src/transform.js
+++ b/src/transform.js
@@ -323,11 +323,14 @@ const FirstPassVisitor = {
         hasAltWithoutLeadG = true;
       }
     }
-    if (hasAltWithLeadG && hasAltWithoutLeadG && !allowUnhandledGAnchors) {
-      throw new Error(r`Uses "\G" in a way that's unsupported`);
+    if (hasAltWithLeadG) {
+      if (!hasAltWithoutLeadG) {
+        // Supported `\G` nodes will be removed (and add flag y) when traversed; others will error
+        leadingGs.forEach(g => supportedGNodes.add(g));
+      } else if (!allowUnhandledGAnchors) {
+        throw new Error(r`Uses "\G" in a way that's unsupported`);
+      }
     }
-    // Supported `\G` nodes will be removed when traversed; others will error
-    leadingGs.forEach(g => supportedGNodes.add(g))
   },
 
   Quantifier({node}) {