Fix up dylibs on macOS

Author: Tom McLaughlin

assets/README.md

@@ -0,0 +1,2 @@
+
+The libffi.a in this folder was compiled from Nixpkgs master on 12/6/2024 on a x86_64-darwin machine. It's include to support cross-compiling to that target on an aarch64-darwin.

assets/libffi.a

@@ -1,6 +1,6 @@
 {
   inputs.flake-utils.url = "github:numtide/flake-utils";
-  inputs.haskellNix.url = "github:input-output-hk/haskell.nix";
+  inputs.haskellNix.url = "github:input-output-hk/haskell.nix/angerman/fix-install_name_tool";
   inputs.gitignore = {
     url = "github:hercules-ci/gitignore.nix";
     inputs.nixpkgs.follows = "nixpkgs";
@@ -40,7 +40,9 @@
 
                 modules = [{
                   packages.rust-notebook-language-server.components.exes.rust-notebook-language-server.dontStrip = false;
-                }];
+                } (
+                  pkgs.lib.optionalAttrs pkgs.stdenv.isDarwin (import ./nix/macos-modules.nix { inherit pkgs; })
+                )];
               };
           })
         ];

flake.lock

@@ -0,0 +1,32 @@
+
+# Example usage:
+# fix_dylib "./myapp" "libffi.8.dylib" "libffi.dylib"
+fix_dylib() {
+   local executable="$1"
+   local dylib_name="$2"
+   local target_name="$3"
+
+   if otool -L "$executable" | grep -q "/nix/store/.*/$dylib_name"; then
+       echo "Fixing $dylib_name reference in $executable"
+       local old_path=$(otool -L "$executable" | grep "/nix/store/.*/$dylib_name" | awk '{print $1}')
+       install_name_tool -change "$old_path" "/usr/lib/$target_name" "$executable"
+       if otool -L "$executable" | grep -q "/usr/lib/$target_name"; then
+           echo "Successfully fixed $dylib_name in $executable (now points to $target_name)"
+       else
+           echo "Failed to fix $dylib_name in $executable (attempted to point to $target_name)"
+           return 1
+       fi
+   fi
+}
+
+# Example usage:
+# check_no_nix_refs "./myapp"
+check_no_nix_refs() {
+   local executable="$1"
+
+   if otool -L "$executable" | tail -n +2 | grep -q "/nix/store/"; then
+       echo "ERROR: $executable still contains Nix store references:"
+       otool -L "$executable" | tail -n +2 | grep "/nix/store/"
+       return 1
+   fi
+}

flake.nix

@@ -0,0 +1,29 @@
+{ pkgs }:
+
+{
+  packages.rust-notebook-language-server.components.exes.rust-notebook-language-server.postInstall = ''
+    ${builtins.readFile ./fix-dylib.sh}
+
+    fix_dylib "$out/bin/rust-notebook-language-server" libiconv.2.dylib libiconv.dylib
+    fix_dylib "$out/bin/rust-notebook-language-server" libffi.8.dylib libffi.dylib
+    fix_dylib "$out/bin/rust-notebook-language-server" libpcre.1.dylib libpcre.dylib
+    fix_dylib "$out/bin/rust-notebook-language-server" libc++.1.0.dylib libc++.dylib
+    fix_dylib "$out/bin/rust-notebook-language-server" libc++abi.1.0.dylib libc++abi.dylib
+    check_no_nix_refs "$out/bin/rust-notebook-language-server"
+
+    strip "$out/bin/rust-notebook-language-server"
+  '';
+
+  packages.rust-notebook-language-server.components.exes.rust-notebook-language-server.configureFlags = let
+    # Nixpkgs can't currently give us a cross-compiled x86_64-darwin libffi.a when we're building on aarch64-darwin.
+    # So, we bundle one in the repo.
+    # Tried to also detect if we're on aarch64-darwin, so it can work normally if the build machine is x86_64-darwin,
+    # but that is deliberately difficult here (builtins.currentSystem is considered an "impure builtin".)
+    libffi = if pkgs.stdenv.targetPlatform.system == "x86_64-darwin"
+             then "${../assets/libffi.a}"
+             else "${pkgs.pkgsStatic.libffi}/lib/libffi.a";
+  in
+    [
+      ''--ghc-options="-optl-Wl,-dead_strip -optl-Wl,-dead_strip_dylibs -optl-Wl,-force_load,${libffi}"''
+    ];
+}

nix/fix-dylib.sh

@@ -1,7 +1,7 @@
 {-# LANGUAGE ConstraintKinds #-}
-{-# LANGUAGE PolyKinds #-}
-{-# LANGUAGE GADTs #-}
 {-# LANGUAGE DataKinds #-}
+{-# LANGUAGE GADTs #-}
+{-# LANGUAGE PolyKinds #-}
 {-# LANGUAGE RankNTypes #-}
 
 module Transform.Util where