build(client/electron): build Windows with MinGW (#1952)

Makefile

@@ -12,18 +12,17 @@ IMPORT_PATH=$(IMPORT_HOST)/Jigsaw-Code/outline-apps
 all: android apple linux windows
 
 ROOT_PKG=client/src/tun2socks
-# Don't strip Android debug symbols so we can upload them to crash reporting tools.
-ANDROID_BUILD_CMD=$(GOBIND) -a -ldflags '-w' -target=android -androidapi 19 -tags android -work
 
 android: $(BUILDDIR)/android/tun2socks.aar
 
 $(BUILDDIR)/android/tun2socks.aar: $(GOMOBILE)
 	mkdir -p "$(BUILDDIR)/android"
-	$(ANDROID_BUILD_CMD) -o "$@" $(IMPORT_PATH)/$(ROOT_PKG)/outline/tun2socks $(IMPORT_PATH)/$(ROOT_PKG)/outline/shadowsocks
+  # Don't strip Android debug symbols so we can upload them to crash reporting tools.
+	$(GOBIND) -target=android -androidapi 19 -tags android -work -a -ldflags '-w' -o "$@" $(IMPORT_PATH)/$(ROOT_PKG)/outline/tun2socks $(IMPORT_PATH)/$(ROOT_PKG)/outline/shadowsocks
 
 $(BUILDDIR)/ios/Tun2socks.xcframework: $(GOMOBILE)
   # -iosversion should match what outline-client supports.
-	$(GOBIND) -iosversion=12.0 -target=ios,iossimulator -o $@ -ldflags '-w' -bundleid org.outline.tun2socks $(IMPORT_PATH)/$(ROOT_PKG)/outline/tun2socks $(IMPORT_PATH)/$(ROOT_PKG)/outline/shadowsocks
+	$(GOBIND) -target=ios,iossimulator -iosversion=12.0 -bundleid org.outline.tun2socks -ldflags '-w' -o "$@" $(IMPORT_PATH)/$(ROOT_PKG)/outline/tun2socks $(IMPORT_PATH)/$(ROOT_PKG)/outline/shadowsocks
 
 $(BUILDDIR)/macos/Tun2socks.xcframework: $(GOMOBILE)
   # MACOSX_DEPLOYMENT_TARGET and -iosversion should match what outline-client supports.
@@ -38,7 +37,7 @@ $(BUILDDIR)/apple/Tun2socks.xcframework: $(BUILDDIR)/ios/Tun2socks.xcframework $
 XGO=$(GOBIN)/xgo
 TUN2SOCKS_VERSION=v1.16.11
 XGO_LDFLAGS='-w -X main.version=$(TUN2SOCKS_VERSION)'
-ELECTRON_PKG=$(ROOT_PKG)/outline/electron
+ELECTRON_PKG="./client/src/tun2socks/outline/electron"
 
 # TODO: build directly when on linux
 LINUX_BUILDDIR=$(BUILDDIR)/linux
@@ -56,16 +55,13 @@ WINDOWS_BUILDDIR=$(BUILDDIR)/windows
 
 windows: $(WINDOWS_BUILDDIR)/tun2socks.exe
 
-$(WINDOWS_BUILDDIR)/tun2socks.exe: $(XGO)
-	mkdir -p "$(WINDOWS_BUILDDIR)/$(IMPORT_PATH)"
-	$(XGO) -ldflags $(XGO_LDFLAGS) --targets=windows/386 -dest "$(WINDOWS_BUILDDIR)" -pkg $(ELECTRON_PKG) .
-	mv "$(WINDOWS_BUILDDIR)/$(IMPORT_PATH)-windows-386.exe" "$@"
-	rm -r "$(WINDOWS_BUILDDIR)/$(IMPORT_HOST)"
-
+$(WINDOWS_BUILDDIR)/tun2socks.exe:
+	mkdir -p "$(@D)"
+	GOOS=windows GOARCH=amd64 CGO_ENABLED=1 CC="x86_64-w64-mingw32-gcc" go build --ldflags=--extldflags=$(XGO_LDFLAGS) -o "$@" $(ELECTRON_PKG)
 
 $(GOMOBILE): go.mod
-	env GOBIN="$(GOBIN)" go install golang.org/x/mobile/cmd/gomobile
-	env GOBIN="$(GOBIN)" $(GOMOBILE) init
+	mkdir -p "$(@D)"
+	go build -o "$(@D)" golang.org/x/mobile/cmd/gomobile golang.org/x/mobile/cmd/gobind
 
 $(XGO): go.mod
 	env GOBIN="$(GOBIN)" go install github.com/crazy-max/xgo

src/electron/README.md

@@ -1,4 +1,4 @@
-## Electron Development Instructions
+# Electron Development Instructions
 
 Unlike the Android and Apple clients, the Windows and Linux clients use the Electron framework, rather than Cordova.
 
@@ -7,7 +7,6 @@ You will need [Docker](https://www.docker.com/) installed to build the Electron
 > If you can't use Docker, you can use [podman](https://podman.io) as substitute by running the following (for macOS):
 
 ```sh
-brew install podman
 podman machine init
 sudo ln -s $(which podman) /usr/local/bin/docker
 sudo /opt/homebrew/Cellar/podman/<podman version>/bin/podman-mac-helper install
@@ -28,7 +27,27 @@ To run the Electron clients, run:
 npm run action electron/start [windows|linux]
 ```
 
-### Windows
+## Windows
+
+To build for Windows on a macOS, you need to first install [MinGW-w64](https://www.mingw-w64.org/) v11.0.1+.
+
+With [MacPorts](https://www.mingw-w64.org/downloads/#macports) (official channel):
+
+```sh
+sudo port install x86_64-w64-mingw32-gcc @11.0.1
+```
+
+With Homebrew (unofficial, how to ensure consistent version?):
+
+```sh
+brew install mingw-w64
+```
+
+You can also build it on Ubuntu. To install MinGW-w64:
+
+```sh
+apt update && apt install -y gcc-mingw-w64-x86-64
+```
 
 To build the _release_ version of Windows installer, you'll also need: