Use the subrepo's FS for reading config and globbing

src/core/package.go

@@ -67,15 +67,7 @@
 	return t
 }
 
-// SourceRoot returns the root directory of source files for this package.
-// This is equivalent to .Name for in-repo packages but differs for those in subrepos.
-func (pkg *Package) SourceRoot() string {
-	if pkg.Subrepo != nil {
-		return pkg.Subrepo.Dir(pkg.Name)
-	}
-	return pkg.Name
-}
 
 // AddTarget adds a new target to this package with the given name.
 // It doesn't check for duplicates.
 func (pkg *Package) AddTarget(target *BuildTarget) {

src/core/state.go

@@ -255,7 +255,7 @@ func (state *BuildState) Initialise(subrepo *Subrepo) (err error) {
 		// handled for us already in plz.go
 		if state.CurrentSubrepo != "" {
 			state.RepoConfig = &Configuration{}
-			err = readConfigFilesInto(state.RepoConfig, append(subrepo.AdditionalConfigFiles, filepath.Join(subrepo.Root, ".plzconfig")))
+			err = readSubrepoConfig(state.RepoConfig, subrepo)
 			if err != nil {
 				return
 			}

src/core/subrepo.go

@@ -81,14 +81,14 @@ func (s *Subrepo) Dir(dir string) string {
 	return filepath.Join(s.Root, dir)
 }
 
-func readConfigFilesInto(repoConfig *Configuration, files []string) error {
-	for _, file := range files {
+func readSubrepoConfig(repoConfig *Configuration, subrepo *Subrepo) error {
+	for _, file := range subrepo.AdditionalConfigFiles {
 		err := readConfigFile(fs.HostFS, repoConfig, file, true)
 		if err != nil {
 			return err
 		}
 	}
-	return nil
+	return readConfigFile(subrepo.FS, repoConfig, ".plzconfig", true)
 }
 
 func validateSubrepoNameAndPluginConfig(config, repoConfig *Configuration, subrepo *Subrepo) error {

src/parse/asp/builtins.go

@@ -607,10 +607,14 @@ func glob(s *scope, args []pyObject) pyObject {
 	allowEmpty := args[4].IsTruthy()
 	exclude = append(exclude, s.state.Config.Parse.BuildFileName...)
 	if s.globber == nil {
-		s.globber = fs.NewGlobber(fs.HostFS, s.state.Config.Parse.BuildFileName)
+		if s.pkg.Subrepo != nil {
+			s.globber = fs.NewGlobber(s.pkg.Subrepo.FS, s.state.Config.Parse.BuildFileName)
+		} else {
+			s.globber = fs.NewGlobber(fs.HostFS, s.state.Config.Parse.BuildFileName)
+		}
 	}
 
-	glob := s.globber.Glob(s.pkg.SourceRoot(), include, exclude, hidden, includeSymlinks)
+	glob := s.globber.Glob(s.pkg.Name, include, exclude, hidden, includeSymlinks)
 	if !allowEmpty && len(glob) == 0 {
 		// Strip build file name from exclude list for error message
 		exclude = exclude[:len(exclude)-len(s.state.Config.Parse.BuildFileName)]