hare: refactor cross-compilation tests

Now it does test for cross-compilation.

pkgs/by-name/ha/hare/cross-compilation-tests.nix

@@ -1,31 +1,40 @@
-{ lib
-, buildPackages
-, hare
-, runCommandNoCC
-, stdenv
-, writeText
+{
+  lib,
+  file,
+  hare,
+  runCommandNoCC,
+  writeText,
 }:
 let
-  inherit (stdenv.hostPlatform.uname) processor;
-  inherit (stdenv.hostPlatform) emulator;
+  archs = lib.concatStringsSep " " (
+    builtins.map (lib.removeSuffix "-linux") (
+      builtins.filter (lib.hasSuffix "-linux") hare.meta.platforms
+    )
+  );
   mainDotHare = writeText "main.ha" ''
-    use fmt;
-    use os;
-    export fn main() void = {
-        const machine = os::machine();
-        if (machine == "${processor}") {
-            fmt::println("os::machine() matches ${processor}")!;
-        } else {
-            fmt::fatalf("os::machine() does not match ${processor}: {}", machine);
-        };
-    };
+    export fn main() void = void;
   '';
 in
-runCommandNoCC "${hare.pname}-cross-compilation-test" { meta.timeout = 60; } ''
-  HARECACHE="$(mktemp -d --tmpdir harecache.XXXXXXXX)"
-  export HARECACHE
-  outbin="test-${processor}"
-  ${lib.getExe hare} build -q -a "${processor}" -o "$outbin" ${mainDotHare}
-  ${emulator buildPackages} "./$outbin"
-  : 1>$out
-''
+runCommandNoCC "${hare.pname}-cross-compilation-test"
+  {
+    nativeBuildInputs = [
+      hare
+      file
+    ];
+  }
+  ''
+    HARECACHE="$(mktemp -d)"
+    export HARECACHE
+    readonly binprefix="bin"
+    for a in ${archs}; do
+      outbin="$binprefix-$a"
+      set -x
+      hare build -o "$outbin" -q -R -a "$a" ${mainDotHare}
+      set +x
+      printf -- 'Built "%s" target\n' "$a"
+    done
+
+    file -- "$binprefix-"*
+
+    : 1>$out
+  ''

pkgs/by-name/ha/hare/package.nix

@@ -161,7 +161,12 @@ stdenv.mkDerivation (finalAttrs: {
       }
       // lib.optionalAttrs (stdenv.buildPlatform.canExecute stdenv.hostPlatform) {
         mimeModule = callPackage ./mime-module-test.nix { hare = finalAttrs.finalPackage; };
-      };
+      }
+      //
+        lib.optionalAttrs (enableCrossCompilation && stdenv.buildPlatform.canExecute stdenv.hostPlatform)
+          {
+            crossCompilation = callPackage ./cross-compilation-tests.nix { hare = finalAttrs.finalPackage; };
+          };
     # To be propagated by `hareHook`.
     inherit harec qbe;
   };