From 3ee05b2e0f6b61ce72acb435375aa8e75eb2f0f8 Mon Sep 17 00:00:00 2001
From: Steven Levithan <steves_list@hotmail.com>
Date: Thu, 19 Dec 2024 07:58:58 +0100
Subject: [PATCH] Don't add flag y for unsupported \G when using
 allowUnhandledGAnchors

---
 README.md                       | 4 ++--
 demo/index.html                 | 2 +-
 spec/match-search-start.spec.js | 2 +-
 src/options.js                  | 2 +-
 src/transform.js                | 5 +++--
 5 files changed, 8 insertions(+), 7 deletions(-)

diff --git a/README.md b/README.md
index 3f6eb5c..d7c5f32 100644
--- a/README.md
+++ b/README.md
@@ -212,8 +212,8 @@ Using a high limit has a small impact on performance. Generally, this is only a
 Advanced pattern options that override standard error checking and flags when enabled.
 
 - `allowOrphanBackrefs`: Useful with TextMate grammars that merge backreferences across patterns.
-- `allowUnhandledGAnchors`: Applies flag `y` for unsupported uses of `\G`, rather than erroring.
-  - Oniguruma-To-ES uses a variety of strategies to accurately emulate many common uses of `\G`. When using this option, if a `\G` is found that doesn't have a known emulation strategy, the `\G` is simply removed and JavaScript's `y` (`sticky`) flag is added. This might lead to some false positives and negatives, but is useful for non-critical matching (like syntax highlighting) when having some mismatches is better than not working.
+- `allowUnhandledGAnchors`: Removes unsupported uses of `\G`, rather than erroring.
+  - Oniguruma-To-ES uses a variety of strategies to accurately emulate many common uses of `\G`. When using this option, if a `\G` is found that doesn't have a known emulation strategy, the `\G` is simply removed. This might lead to some false positive matches, but is useful for non-critical matching (like syntax highlighting) when having some mismatches is better than not working.
 - `asciiWordBoundaries`: Use ASCII-based `\b` and `\B`, which increases search performance of generated regexes.
 - `captureGroup`: Oniguruma option `ONIG_OPTION_CAPTURE_GROUP`. Unnamed captures and numbered calls allowed when using named capture.
 
diff --git a/demo/index.html b/demo/index.html
index 48f19e2..6db978f 100644
--- a/demo/index.html
+++ b/demo/index.html
@@ -120,7 +120,7 @@ <h2>Try it</h2>
               <label>
                 <input type="checkbox" id="option-allowUnhandledGAnchors" onchange="setRule('allowUnhandledGAnchors', this.checked)">
                 <code>allowUnhandledGAnchors</code>
-                <span class="tip tip-xl">Applies flag <code>y</code> for unsupported uses of <code>\G</code>, rather than erroring</span>
+                <span class="tip tip-lg">Removes unsupported uses of <code>\G</code>, rather than erroring</span>
               </label>
             </p>
           </div>
diff --git a/spec/match-search-start.spec.js b/spec/match-search-start.spec.js
index a11a646..bbc99b0 100644
--- a/spec/match-search-start.spec.js
+++ b/spec/match-search-start.spec.js
@@ -135,7 +135,7 @@ describe('Assertion: Search start', () => {
       ];
       patterns.forEach(pattern => {
         expect(() => toDetails(pattern)).toThrow();
-        expect(toRegExp(pattern, {rules: {allowUnhandledGAnchors: true}}).sticky).toBe(true);
+        expect(() => toDetails(pattern, {rules: {allowUnhandledGAnchors: true}})).not.toThrow();
       });
     });
   });
diff --git a/src/options.js b/src/options.js
index 429d739..b866de0 100644
--- a/src/options.js
+++ b/src/options.js
@@ -55,7 +55,7 @@ function getOptions(options) {
     rules: {
       // Useful with TextMate grammars that merge backreferences across patterns.
       allowOrphanBackrefs: false,
-      // Applies flag `y` for unsupported uses of `\G`, rather than erroring.
+      // Removes unsupported uses of `\G`, rather than erroring.
       allowUnhandledGAnchors: false,
       // Use ASCII-based `\b` and `\B`, which increases search performance of generated regexes.
       asciiWordBoundaries: false,
diff --git a/src/transform.js b/src/transform.js
index e248520..31ee3a0 100644
--- a/src/transform.js
+++ b/src/transform.js
@@ -140,10 +140,11 @@ const FirstPassVisitor = {
       // string-terminating line feed
       replaceWith(parseFragment(r`(?<=\A|\n(?!\z))`));
     } else if (kind === AstAssertionKinds.search_start) {
-      if (!supportedGNodes.has(node) && !allowUnhandledGAnchors) {
+      if (supportedGNodes.has(node)) {
+        ast.flags.sticky = true;
+      } else if (!allowUnhandledGAnchors) {
         throw new Error(r`Uses "\G" in a way that's unsupported`);
       }
-      ast.flags.sticky = true;
       remove();
     } else if (kind === AstAssertionKinds.string_end_newline) {
       replaceWith(parseFragment(r`(?=\n?\z)`));