Expose proto generated sources via OutputGroup (#1827)

* Expose go_proto_library generated sources via "go_generated_srcs" OutputGroup.
* Rename cgo target to avoid invalid characters.

go/private/rules/cgo.bzl

@@ -514,7 +514,7 @@ def setup_cgo_library(name, srcs, cdeps, copts, cxxopts, cppopts, clinkopts, obj
         cgo_mode_info[cgo_info_name] = _encode_cgo_mode(goos, goarch, race = False, msan = True)
 
     # Collect everything in a single embedable, aspect-friendly library.
-    cgo_embed_name = name + "%cgo_embed"
+    cgo_embed_name = name + "__cgo_embed"
     _cgo_select_embed(
         name = cgo_embed_name,
         info = cgo_mode_info,

proto/def.bzl

@@ -99,21 +99,21 @@ def _go_proto_library_impl(ctx):
         srcs = go_srcs,
     )
     source = go.library_to_source(go, ctx.attr, library, False)
-    if not valid_archive:
-        return [library, source]
-    archive = go.archive(go, source)
-    return [
-        library,
-        source,
-        archive,
-        DefaultInfo(
-            files = depset([archive.data.file]),
-            runfiles = archive.runfiles,
-        ),
-        OutputGroupInfo(
-            compilation_outputs = [archive.data.file],
-        ),
-    ]
+    providers = [library, source]
+    output_groups = {
+        "go_generated_srcs": go_srcs,
+    }
+    if valid_archive:
+        archive = go.archive(go, source)
+        output_groups["compilation_outputs"] = [archive.data.file]
+        providers.extend([
+            archive,
+            DefaultInfo(
+                files = depset([archive.data.file]),
+                runfiles = archive.runfiles,
+            ),
+        ])
+    return providers + [OutputGroupInfo(**output_groups)]
 
 go_proto_library = go_rule(
     _go_proto_library_impl,