newsflash: fix cross compilation

overlays/cross.nix

@@ -863,6 +863,96 @@ in with final; {
   # );
   # 2023/07/31: upstreaming is blocked on vpnc cross compilation
   # networkmanager-vpnc = mvToNativeInputs [ glib ] prev.networkmanager-vpnc;
+
+  newsflash = prev.newsflash.overrideAttrs (upstream: {
+    nativeBuildInputs = (lib.filter (p: !lib.elem (p.pname or p.name) [ "gdk-pixbuf" "blueprint-compiler" ]) upstream.nativeBuildInputs) ++ [
+      buildPackages.git
+      (buildPackages.writeShellScriptBin "blueprint-compiler" ''
+        export GI_TYPELIB_PATH=${typelibPath [
+          buildPackages.clapper
+          buildPackages.glib
+          buildPackages.gtk4
+          buildPackages.gst_all_1.gstreamer
+          # some of these below are probably *not* needed
+          buildPackages.gst_all_1.gst-plugins-base
+          buildPackages.gst_all_1.gst-plugins-good
+          buildPackages.gst_all_1.gst-plugins-bad
+          buildPackages.gdk-pixbuf
+          buildPackages.graphene
+          buildPackages.harfbuzz
+          buildPackages.libadwaita
+          buildPackages.pango
+        ]}
+        exec ${lib.getExe buildPackages.blueprint-compiler} "$@"
+      '')
+    ];
+
+    # strictDeps = false;
+
+    postPatch = (upstream.postPatch or "") + ''
+      substituteInPlace src/meson.build --replace-fail \
+        "'src' / rust_target" \
+        "'src' / '${rust.toRustTarget stdenv.hostPlatform}' / rust_target"
+
+      rm build.rs
+
+      export OUT_DIR=$(pwd)
+
+      # from build.rs:
+      glib-compile-resources --sourcedir=data/resources --target=icons.gresource data/resources/icons.gresource.xml
+      glib-compile-resources --sourcedir=data/resources --target=styles.gresource data/resources/styles.gresource.xml
+      substitute data/io.gitlab.news_flash.NewsFlash.appdata.xml.in.in \
+        data/resources/io.gitlab.news_flash.NewsFlash.appdata.xml \
+        --replace-fail '@appid@' 'io.gitlab.news_flash.NewsFlash'
+      glib-compile-resources --sourcedir=data/resources --target=appdata.gresource data/resources/appdata.gresource.xml
+    '';
+
+    # nixpkgs sets CARGO_BUILD_TARGET to the build platform target, so correct that.
+    # fixes openssl not being able to find its library
+    buildPhase = ''
+      runHook preBuild
+
+      ${rust.envVars.setEnv} "CARGO_BUILD_TARGET=${rust.toRustTarget stdenv.hostPlatform}" ninja -j$NIX_BUILD_CORES
+
+      runHook postBuild
+    '';
+
+     env = let
+       inherit buildPackages stdenv rust;
+       ccForBuild = "${buildPackages.stdenv.cc}/bin/${buildPackages.stdenv.cc.targetPrefix}cc";
+       cxxForBuild = "${buildPackages.stdenv.cc}/bin/${buildPackages.stdenv.cc.targetPrefix}c++";
+       ccForHost = "${stdenv.cc}/bin/${stdenv.cc.targetPrefix}cc";
+       cxxForHost = "${stdenv.cc}/bin/${stdenv.cc.targetPrefix}c++";
+       rustBuildPlatform = rust.toRustTarget stdenv.buildPlatform;
+       rustTargetPlatform = rust.toRustTarget stdenv.hostPlatform;
+       rustTargetPlatformSpec = rust.toRustTargetSpec stdenv.hostPlatform;
+     in (upstream.env or {}) // {
+       # taken from <pkgs/build-support/rust/hooks/default.nix>
+       # fixes "cargo:warning=aarch64-unknown-linux-gnu-gcc: error: unrecognized command-line option ‘-m64’"
+       # XXX: these aren't necessarily valid environment variables: the referenced nix file is more clever to get them to work.
+       "CC_${rustBuildPlatform}" = "${ccForBuild}";
+       "CXX_${rustBuildPlatform}" = "${cxxForBuild}";
+       "CC_${rustTargetPlatform}" = "${ccForHost}";
+       "CXX_${rustTargetPlatform}" = "${cxxForHost}";
+        # fails to fix "Failed to find OpenSSL development headers."
+        # OPENSSL_NO_VENDOR = 1;
+        # OPENSSL_LIB_DIR = "${lib.getLib openssl}/lib";
+        # OPENSSL_DIR = "${lib.getDev openssl}";
+     };
+
+    # mesonFlags = let
+    #   crossFile = writeText "cross-file.conf" ''
+    #     [binaries]
+    #     rust = [ 'rustc', '--target', '${rust.toRustTargetSpec stdenv.hostPlatform}' ]
+    #   '';
+    # in
+    #   (upstream.mesonFlags or []) ++ [
+    #     "-Dprofile=development"
+    #   ] ++ lib.optionals (stdenv.hostPlatform != stdenv.buildPlatform) [
+    #     "--cross-file=${crossFile}"
+    #   ];
+  });
+
   # fixes "properties/gresource.xml: Permission denied"
   #   - by providing glib-compile-resources
   # 2024/05/31: upstreaming is blocked on qtsvg, qtimageformats, qtx11extras