add cross-compile flag to build command

cmd/project.go

@@ -158,6 +158,7 @@ type ProjectOptions struct {
 	selectedTemplate       *TemplateDetails
 	WailsVersion           string
 	typescriptDefsFilename string
+	Platform               string
 }
 
 // Defaults sets the default project template

cmd/wails/4_build.go

@@ -14,6 +14,7 @@ func init() {
 	var forceRebuild = false
 	var debugMode = false
 	var typescriptFilename = ""
+	var platform = ""
 
 	buildSpinner := spinner.NewSpinner()
 	buildSpinner.SetSpinSpeed(50)
@@ -24,7 +25,8 @@ func init() {
 		BoolFlag("p", "Package application on successful build", &packageApp).
 		BoolFlag("f", "Force rebuild of application components", &forceRebuild).
 		BoolFlag("d", "Build in Debug mode", &debugMode).
-		StringFlag("t", "Generate Typescript definitions to given file (at runtime)", &typescriptFilename)
+		StringFlag("t", "Generate Typescript definitions to given file (at runtime)", &typescriptFilename).
+		StringFlag("x", "Cross-compile application to specified platform via xgo", &platform)
 
 	initCmd.Action(func() error {
 
@@ -127,6 +129,9 @@ func init() {
 			buildSpinner.Success()
 		}
 
+		// Set cross-compile
+		projectOptions.Platform = platform
+
 		err = cmd.BuildApplication(projectOptions.BinaryName, forceRebuild, buildMode, packageApp, projectOptions)
 		if err != nil {
 			return err