From 092cf0b3cafed3df12d8773c63f84720102f3e1d Mon Sep 17 00:00:00 2001
From: Pratik Karki <pratik@prertik.com>
Date: Thu, 19 Mar 2026 00:23:20 +0545
Subject: [PATCH] Bump fancy-regex to v0.17.0 (#51549)

This fixes "Error compiling regex: Look-behind assertion without
constant size" when using variable-length lookbehinds in search, such as
`(?<=^(?:\s{4})*)\s{4}`.

fancy-regex 0.17.0 adds support for variable-length lookbehinds using
regex-automata's DFA reverse search commit:
https://github.com/fancy-regex/fancy-regex/commit/b58fb31

Closes #50219

Before you mark this PR as ready for review, make sure that you have:
- [x] Added a solid test coverage and/or screenshots from doing manual
testing
- [x] Done a self-review taking into account security and performance
aspects
- [x] Aligned any UI changes with the [UI
checklist](https://github.com/zed-industries/zed/blob/main/CONTRIBUTING.md#uiux-checklist)

Release Notes:

- Fixed the error message on compilation of regular expressions
containing variable length lookbehind assertions

Previously:
<img width="1582" height="1377" alt="image"
src="https://github.com/user-attachments/assets/3e275891-aef5-482e-87f0-c47b9eac3c2a"
/>


Now:
<img width="1323" height="1015" alt="image"
src="https://github.com/user-attachments/assets/8638cd08-fcd0-40f9-8749-32e6352e89b7"
/>


Thanks to @vorahardik7 for helping out with a test example and
@AmaanBilwar for suggesting a fix!

Signed-off-by: Pratik Karki <pratik@prertik.com>
---
 Cargo.lock | 17 ++++++++++++++---
 Cargo.toml |  2 +-
 2 files changed, 15 insertions(+), 4 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index fc7acbbb8fdb870b951b61090b7238d453b03e12..ed17474f832d77f4fa5dd3471ecf1b5b098d4c77 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -6184,6 +6184,17 @@ dependencies = [
  "regex-syntax",
 ]
 
+[[package]]
+name = "fancy-regex"
+version = "0.17.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "72cf461f865c862bb7dc573f643dd6a2b6842f7c30b07882b56bd148cc2761b8"
+dependencies = [
+ "bit-set",
+ "regex-automata",
+ "regex-syntax",
+]
+
 [[package]]
 name = "fast-srgb8"
 version = "1.0.0"
@@ -9154,7 +9165,7 @@ dependencies = [
  "bytecount",
  "data-encoding",
  "email_address",
- "fancy-regex",
+ "fancy-regex 0.16.2",
  "fraction",
  "getrandom 0.3.4",
  "idna",
@@ -13144,7 +13155,7 @@ dependencies = [
  "dap",
  "encoding_rs",
  "extension",
- "fancy-regex",
+ "fancy-regex 0.17.0",
  "fs",
  "futures 0.3.31",
  "fuzzy",
@@ -17608,7 +17619,7 @@ dependencies = [
  "anyhow",
  "base64 0.22.1",
  "bstr",
- "fancy-regex",
+ "fancy-regex 0.16.2",
  "lazy_static",
  "regex",
  "rustc-hash 1.1.0",
diff --git a/Cargo.toml b/Cargo.toml
index 699c795710f327ce76e7c3203dcb978508c5b830..3b8ddd6404bcfd115e5ead25601e944197053bd6 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -556,7 +556,7 @@ emojis = "0.6.1"
 env_logger = "0.11"
 encoding_rs = "0.8"
 exec = "0.3.1"
-fancy-regex = "0.16.0"
+fancy-regex = "0.17.0"
 fork = "0.4.0"
 futures = "0.3"
 futures-concurrency = "7.7.1"