From ce13837558c13105d6b832795d27f0e672a22d9e Mon Sep 17 00:00:00 2001
From: Derek Cormier <derek@aspect.dev>
Date: Wed, 22 Feb 2023 12:50:33 -0800
Subject: [PATCH] fix: allow root repositories to override node toolchain
 version under bzlmod

---
 nodejs/extensions.bzl   | 15 +++++++++++++--
 nodejs/repositories.bzl |  4 ++++
 2 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/nodejs/extensions.bzl b/nodejs/extensions.bzl
index c1ed0befc0..3d2fc8b657 100644
--- a/nodejs/extensions.bzl
+++ b/nodejs/extensions.bzl
@@ -1,12 +1,19 @@
 "extensions for bzlmod"
 
-load(":repositories.bzl", "DEFAULT_NODE_VERSION", "nodejs_register_toolchains")
+load(":repositories.bzl", "DEFAULT_NODE_REPOSITORY", "DEFAULT_NODE_VERSION", "nodejs_register_toolchains")
 
 def _toolchain_extension(module_ctx):
     registrations = {}
     for mod in module_ctx.modules:
         for toolchain in mod.tags.toolchain:
+            if toolchain.name != DEFAULT_NODE_REPOSITORY and not mod.is_root:
+                fail("Only the root module may provide a name for the node toolchain.")
+
             if toolchain.name in registrations.keys():
+                if toolchain.name == DEFAULT_NODE_REPOSITORY:
+                    # Prioritize the root-most registration of the default node toolchain version and
+                    # ignore any further registrations (modules are processed breadth-first)
+                    continue
                 if toolchain.node_version == registrations[toolchain.name]:
                     # No problem to register a matching toolchain twice
                     continue
@@ -17,6 +24,7 @@ def _toolchain_extension(module_ctx):
                 ))
             else:
                 registrations[toolchain.name] = toolchain.node_version
+
     for name, node_version in registrations.items():
         nodejs_register_toolchains(
             name = name,
@@ -28,7 +36,10 @@ node = module_extension(
     implementation = _toolchain_extension,
     tag_classes = {
         "toolchain": tag_class(attrs = {
-            "name": attr.string(doc = "Base name for generated repositories"),
+            "name": attr.string(
+                doc = "Base name for generated repositories",
+                default = DEFAULT_NODE_REPOSITORY,
+            ),
             "node_version": attr.string(
                 doc = "Version of the Node.js interpreter",
                 default = DEFAULT_NODE_VERSION,
diff --git a/nodejs/repositories.bzl b/nodejs/repositories.bzl
index 39a3edf0ae..d00c2948f3 100644
--- a/nodejs/repositories.bzl
+++ b/nodejs/repositories.bzl
@@ -8,6 +8,10 @@ load("@bazel_skylib//lib:paths.bzl", "paths")
 load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
 load("@bazel_tools//tools/build_defs/repo:utils.bzl", "maybe")
 
+# Default base name for node toolchain repositories
+# created by the module extension
+DEFAULT_NODE_REPOSITORY = "nodejs"
+
 # Currently v16 is the default.
 # We can only change that in a major release of rules_nodejs,
 # as it's a semver-breaking change for our users who rely on it.