internal/rosa: read-only access to built-ins

This removes potential footguns caused by mutable builtins without requiring unnecessary clones.

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

internal/rosa/rosa.go

@@ -624,33 +624,25 @@ func (attr *GenericHelper) script(t Toolchain, _ string) string {
 	return script
 }
 
-// native contains natively-implemented and built-in azalea-based [Artifact].
-// It is generally recommended to clone this instance for custom [Artifact]
-// registrations.
-var native S
-
-// Native returns the global [S].
-func Native() *S { return &native }
-
 // parseTime is the duration of early parsing of built-in azalea expressions.
 var parseTime time.Duration
 
 // ParseTime returns the time taken by early parsing of built-in azalea expressions.
 func ParseTime() time.Duration { return parseTime }
 
-// nativeB is the backing directory of built-in azalea-based [Artifact]
+// builtinAzalea is the backing directory of built-in azalea-based [Artifact]
 // implementations.
 //
 //go:embed package
-var nativeB embed.FS
+var builtinAzalea embed.FS
 
 func init() {
-	sub, err := fs.Sub(nativeB, "package")
+	sub, err := fs.Sub(builtinAzalea, "package")
 	if err != nil {
 		panic(err)
 	}
 	t := time.Now()
-	if err = native.RegisterFS(sub); err != nil {
+	if err = builtin.RegisterFS(sub); err != nil {
 		println(err.Error())
 		os.Exit(1)
 	}