ruby-modules: improve cross-compilation support

pkgs/development/ruby-modules/bundled-common/default.nix

@@ -1,4 +1,8 @@
-{ stdenv, runCommand, ruby, lib, rsync
+{ stdenv
+, lib
+, buildPackages
+, runCommand
+, ruby
 , defaultGemConfig, buildRubyGem, buildEnv
 , makeBinaryWrapper
 , bundler
@@ -190,7 +194,7 @@ let
       runCommand name' basicEnvArgs ''
         mkdir -p $out
         for i in $paths; do
-          ${rsync}/bin/rsync -a $i/lib $out/
+          ${buildPackages.rsync}/bin/rsync -a $i/lib $out/
         done
         eval "$postBuild"
       ''

pkgs/development/ruby-modules/bundled-common/functions.nix

@@ -59,8 +59,21 @@ in rec {
     then attrs // gemConfig.${attrs.gemName} attrs
     else attrs);
 
-  genStubsScript = { lib, ruby, confFiles, bundler, groups, binPaths, ... }: ''
-      ${ruby}/bin/ruby ${./gen-bin-stubs.rb} \
+  genStubsScript = { lib, runCommand, ruby, confFiles, bundler, groups, binPaths, ... }:
+    let
+      genStubsScript = runCommand "gen-bin-stubs"
+        {
+          strictDeps = true;
+          nativeBuildInputs = [ ruby ];
+        }
+        ''
+          cp ${./gen-bin-stubs.rb} $out
+          chmod +x $out
+          patchShebangs --build $out
+        '';
+    in
+    ''
+      ${genStubsScript} \
         "${ruby}/bin/ruby" \
         "${confFiles}/Gemfile" \
         "$out/${ruby.gemPath}" \

pkgs/development/ruby-modules/bundled-common/gen-bin-stubs.rb

@@ -1,3 +1,4 @@
+#!/usr/bin/env ruby
 require 'rbconfig'
 require 'rubygems'
 require 'rubygems/specification'

pkgs/development/ruby-modules/bundler-env/default.nix

@@ -1,5 +1,6 @@
 { ruby, lib, callPackage, defaultGemConfig, buildEnv, runCommand
-, bundler, rsync
+, buildPackages
+, bundler
 }@defs:
 
 { name ? null
@@ -21,7 +22,7 @@
 }@args:
 
 let
-  inherit (import ../bundled-common/functions.nix {inherit lib ruby gemConfig groups; }) genStubsScript;
+  inherit (import ../bundled-common/functions.nix { inherit lib ruby gemConfig groups; }) genStubsScript;
 
   basicEnv = (callPackage ../bundled-common { inherit bundler; }) (args // { inherit pname name; mainGemName = pname; });
 
@@ -51,7 +52,7 @@ in
         pathsToLink = [ "/lib" ];
 
         postBuild = genStubsScript {
-          inherit lib ruby bundler groups;
+          inherit lib runCommand ruby bundler groups;
           confFiles = basicEnv.confFiles;
           binPaths = [ basicEnv.gems.${pname} ];
         } + lib.optionalString (postBuild != null) postBuild;
@@ -67,7 +68,7 @@ in
         runCommand basicEnv.name bundlerEnvArgs ''
           mkdir -p $out
           for i in $paths; do
-            ${rsync}/bin/rsync -a $i/lib $out/
+            ${buildPackages.rsync}/bin/rsync -a $i/lib $out/
           done
           eval "$postBuild"
         ''

pkgs/development/ruby-modules/gem/default.nix

@@ -252,6 +252,18 @@ stdenv.mkDerivation ((builtins.removeAttrs attrs ["source"]) // {
     runHook postInstall
   '';
 
+  # For Ruby-generated binstubs, shebang paths are already in Nix store but for
+  # ruby used to build the package. Update them to match the host system. Note
+  # that patchShebangsAuto ignores scripts where shebang line is already in Nix
+  # store.
+  fixupPhase = attrs.fixupPhase or ''
+    runHook preFixup
+    if [[ -d $out/${ruby.gemPath}/bin ]]; then
+      patchShebangs --update --host $out/${ruby.gemPath}/bin
+    fi
+    runHook postFixup
+  '';
+
   propagatedBuildInputs = gemPath ++ propagatedBuildInputs;
   propagatedUserEnvPkgs = gemPath ++ propagatedUserEnvPkgs;