From 6782b9daa35e500f160523460573d2c130b94da5 Mon Sep 17 00:00:00 2001
From: Rebecca Turner <rbt@sent.as>
Date: Thu, 30 Nov 2023 10:15:18 -0800
Subject: [PATCH] lib.escapeRegex: fix with `boost::regex` implementation
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https://github.com/NixOS/nix/pull/7762 switched `nix` to use the
`boost::regex` implementation, which expects that all literal braces are
escaped. That is, the regex `\{crate}` no longer parses. We modify
`lib.escapeRegex` to accommodate this change. Fortunately, the old regex
implementation doesn't mind if closing braces are escaped as well, so
this is backwards compatible and we don't need to worry about
version-gating it.

Without this patch:

Old regex implementation:

    $ nix repl nixpkgs
    Welcome to Nix 2.18.1. Type :? for help.

    Loading installable 'flake:nixpkgs#'...
    Added 5 variables.
    nix-repl> builtins.match (lib.escapeRegex "{}") "{}"
    [ ]

    $ ~/nix/result/bin/nix repl nixpkgs
    Welcome to Nix 2.20.0pre20231130_dirty. Type :? for help.

`boost::regex` implementation:

    $ ~/nix/result/bin/nix repl nixpkgs
    Welcome to Nix 2.20.0pre20231130_dirty. Type :? for help.

    Loading installable 'flake:nixpkgs#'...
    Added 5 variables.
    nix-repl> builtins.match (lib.escapeRegex "{}") "{}"
    error:
           … while calling the 'match' builtin

             at «string»:1:1:

                1| builtins.match (lib.escapeRegex "{}") "{}"
                 | ^

           error: invalid regular expression '\{}'
---
 lib/strings.nix | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/strings.nix b/lib/strings.nix
index 695aaaacd3488..a3a1321aec346 100644
--- a/lib/strings.nix
+++ b/lib/strings.nix
@@ -530,7 +530,7 @@ rec {
        escapeRegex "[^a-z]*"
        => "\\[\\^a-z]\\*"
   */
-  escapeRegex = escape (stringToCharacters "\\[{()^$?*+|.");
+  escapeRegex = escape (stringToCharacters "\\[{}()^$?*+|.");
 
   /* Quotes a string if it can't be used as an identifier directly.