nixUnstable: patch boehmgc (nix#4944)

As has been done in https://github.com/NixOS/nix/pull/4944

This introduces the boehmgc_nix and boehmgc_nixUnstable attributes
which are useful for external packages that link with Nix and its
boehmgc.

pkgs/tools/package-management/nix/default.nix

@@ -2,7 +2,8 @@
 , storeDir ? "/nix/store"
 , stateDir ? "/nix/var"
 , confDir ? "/etc"
-, boehmgc
+, boehmgc_nix
+, boehmgc_nixUnstable
 , Security
 }:
 
@@ -209,7 +210,9 @@ in rec {
       sha256 = "sha256-ITp9ScRhB5syNh5NAI0kjX9o400syTR/Oo/5Ap+a+10=";
     };
 
-    inherit storeDir stateDir confDir boehmgc;
+    boehmgc = boehmgc_nix;
+
+    inherit storeDir stateDir confDir;
   });
 
   nixUnstable = lib.lowPrio (callPackage common rec {
@@ -224,7 +227,9 @@ in rec {
       sha256 = "sha256-ARRiLrDOK+JQtvVXsYegspENYimQzilvdTfO7eiBuaA=";
     };
 
-    inherit storeDir stateDir confDir boehmgc;
+    boehmgc = boehmgc_nixUnstable;
+
+    inherit storeDir stateDir confDir;
 
   });
 

pkgs/top-level/all-packages.nix

@@ -14669,6 +14669,18 @@ in
 
   boehmgc = callPackage ../development/libraries/boehm-gc { };
   boehmgc_766 = callPackage ../development/libraries/boehm-gc/7.6.6.nix { };
+  boehmgc_nix = pkgs.boehmgc.override {
+    enableLargeConfig = true;
+  };
+  boehmgc_nixUnstable = pkgs.boehmgc_nix.overrideAttrs (drv: {
+    patches = (drv.patches or []) ++ [
+      # Part of the GC solution in https://github.com/NixOS/nix/pull/4944
+      (pkgs.fetchpatch {
+        url = https://github.com/hercules-ci/nix/raw/5c58d84a76d96f269e3ff1e72c9c9ba5f68576af/boehmgc-coroutine-sp-fallback.diff;
+        sha256 = "sha256-JvnWVTlkltmQUs/0qApv/LPZ690UX1/2hEP+LYRwKbI=";
+      })
+    ];
+  });
 
   boolstuff = callPackage ../development/libraries/boolstuff { };
 
@@ -31157,7 +31169,6 @@ in
   inherit (callPackage ../tools/package-management/nix {
       storeDir = config.nix.storeDir or "/nix/store";
       stateDir = config.nix.stateDir or "/nix/var";
-      boehmgc = boehmgc.override { enableLargeConfig = true; };
       inherit (darwin.apple_sdk.frameworks) Security;
       })
     nix