internal/rosa: IR-curable source override

This creates a tarball in-memory for overriding hakurei-source.

Signed-off-by: Ophestra <cat@gensokyo.uk>

cmd/mbf/main.go

@@ -64,11 +64,12 @@ func main() {
 			return
 		}
 
-		e, ok := r.(rosa.LoadError)
-		if !ok {
+		switch r.(type) {
+		case rosa.LoadError, pkg.IRStringError:
+			log.Fatal(r)
+		default:
 			panic(r)
 		}
-		log.Fatal(e)
 	}()
 
 	ctx, stop := signal.NotifyContext(context.Background(),
@@ -86,6 +87,7 @@ func main() {
 		flagLTO   bool
 		flagPT    bool
 
+		flagSourcePath    string
 		flagCrossOverride int
 
 		addr net.UnixAddr
@@ -136,6 +138,12 @@ func main() {
 			}
 		}
 
+		if flagSourcePath != "" {
+			if err := rosa.Native().SetSource(os.DirFS(flagSourcePath)); err != nil {
+				return err
+			}
+		}
+
 		return nil
 	}).Flag(
 		&flagQuiet,
@@ -196,6 +204,10 @@ func main() {
 		&flagPT,
 		"parse-time", command.BoolFlag(false),
 		"Print duration of the initial azalea parse",
+	).Flag(
+		&flagSourcePath,
+		"source", command.StringFlag(""),
+		"Override hakurei source tree",
 	)
 
 	c.NewCommand(