gforth: fix cross-compilation (#104778)

pkgs/by-name/gf/gforth/package.nix

@@ -2,7 +2,7 @@
   lib,
   stdenv,
   fetchFromGitHub,
-  callPackage,
+  buildPackages,
   autoreconfHook,
   gitUpdater,
   texinfo,
@@ -11,8 +11,8 @@
 }:
 
 let
-  swig = callPackage ./swig.nix { };
-  bootForth = callPackage ./boot-forth.nix { };
+  swig = buildPackages.callPackage ./swig.nix { };
+  bootForth = buildPackages.callPackage ./boot-forth.nix { };
   lispDir = "${placeholder "out"}/share/emacs/site-lisp";
 in
 stdenv.mkDerivation (finalAttrs: {
@@ -32,9 +32,14 @@ stdenv.mkDerivation (finalAttrs: {
     writableTmpDirAsHomeHook
     autoreconfHook
     texinfo
-    bootForth
     swig
-  ];
+  ]
+  ++ (
+    if (!stdenv.buildPlatform.canExecute stdenv.hostPlatform) then
+      [ buildPackages.gforth ]
+    else
+      [ bootForth ]
+  );
 
   buildInputs = [
     libffi
@@ -47,12 +52,41 @@ stdenv.mkDerivation (finalAttrs: {
   ]
   ++ lib.optionals (stdenv.hostPlatform.isDarwin && stdenv.hostPlatform.isx86_64) [
     "--build=x86_64-apple-darwin"
+  ]
+  ++ lib.optionals (!stdenv.buildPlatform.canExecute stdenv.hostPlatform) [
+    # Tries to run ./engine/gforth-ll
+    "--without-check"
+    # Use build-platform CC for helper programs that must run during build
+    "HOSTCC=${buildPackages.stdenv.cc}/bin/cc"
+    # Tell gforth's libcc where to find the cross compiler
+    "CROSS_PREFIX=${stdenv.hostPlatform.config}-"
+  ];
+
+  env = lib.optionalAttrs (!stdenv.buildPlatform.canExecute stdenv.hostPlatform) {
+    # Tell gforth's libcc to prefix compiler commands with the cross-compilation target
+    CROSS_PREFIX = "${stdenv.hostPlatform.config}-";
+  };
+
+  makeFlags = lib.optionals (stdenv.buildPlatform != stdenv.hostPlatform) [
+    "DITCENGINE=${buildPackages.gforth}/bin/gforth-ditc"
+    "GFORTH=${buildPackages.gforth}/bin/gforth"
+    "ENGINE=${buildPackages.gforth}/bin/gforth" # for ./preforth
   ];
 
   preConfigure = ''
     mkdir -p ${lispDir}
   '';
 
+  postConfigure = lib.optionalString (!stdenv.buildPlatform.canExecute stdenv.hostPlatform) ''
+    # Put the project-local (cross-aware) libtool first in PATH
+    mkdir -p .cross-bin
+    ln -sf "$PWD/libtool" .cross-bin/libtool
+    ln -sf "$PWD/libtool" ".cross-bin/${stdenv.hostPlatform.config}-libtool"
+    export PATH="$PWD/.cross-bin:$PATH"
+    # Remove 'check' from the default 'all' target (can't run cross binaries)
+    sed -i 's/^\(all:.*\) check/\1/' Makefile
+  '';
+
   passthru.updateScript = gitUpdater { };
 
   meta = {