internal/mod/modregistry: add Module.Version method

This makes the API slightly more ergonomic, avoiding
the need for callers to pass the `*Module` around with
its corresponding version.

Signed-off-by: Roger Peppe <[email protected]>
Change-Id: I40496445fc75cbb18096b31eb703a94570b2ddbd
Reviewed-on: https://review.gerrithub.io/c/cue-lang/cue/+/1173787
TryBot-Result: CUEcueckoo <[email protected]>
Unity-Result: CUE porcuepine <[email protected]>
Reviewed-by: Daniel Martí <[email protected]>

internal/mod/modregistry/client.go

@@ -102,6 +102,7 @@ func (c *Client) GetModuleWithManifest(ctx context.Context, m module.Version, co
 	// TODO check that the other blobs are of the expected type (application/zip).
 	return &Module{
 		client:         c,
+		version:        m,
 		repo:           repoName,
 		manifest:       *manifest,
 		manifestDigest: digest.FromBytes(contents),
@@ -313,10 +314,15 @@ func checkModFile(m module.Version, f *zip.File) ([]byte, *modfile.File, error)
 type Module struct {
 	client         *Client
 	repo           string
+	version        module.Version
 	manifest       ocispec.Manifest
 	manifestDigest ociregistry.Digest
 }
 
+func (m *Module) Version() module.Version {
+	return m.version
+}
+
 // ModuleFile returns the contents of the cue.mod/module.cue file.
 func (m *Module) ModuleFile(ctx context.Context) ([]byte, error) {
 	r, err := m.client.registry.GetBlob(ctx, m.repo, m.manifest.Layers[1].Digest)