From 1f62032ab2f4be41ac5f006ce12590469f9144fc Mon Sep 17 00:00:00 2001
From: psalaberria002 <psalaberria002@gmail.com>
Date: Tue, 21 May 2024 20:16:38 +0200
Subject: [PATCH] Add and register toolchain

---
 BUILD                               |  6 ++++++
 MODULE.bazel                        |  2 ++
 MODULE.bazel.lock                   | 10 ++++++----
 docs/defs.md                        | 23 +++++++++++++++++++++++
 tests/current_toolchain/BUILD.bazel | 17 +++++++++++++++++
 5 files changed, 54 insertions(+), 4 deletions(-)
 create mode 100644 tests/current_toolchain/BUILD.bazel

diff --git a/BUILD b/BUILD
index e2c2f41..079f426 100644
--- a/BUILD
+++ b/BUILD
@@ -1,4 +1,5 @@
 load("@rules_license//rules:license.bzl", "license")
+load("//proto:defs.bzl", "proto_toolchain")
 
 license(
     name = "license",
@@ -8,3 +9,8 @@ license(
 licenses(["notice"])
 
 exports_files(["LICENSE"])
+
+proto_toolchain(
+    name = "proto_toolchain",
+    proto_compiler = "@com_google_protobuf//:protoc",
+)
diff --git a/MODULE.bazel b/MODULE.bazel
index d69b785..f2be98b 100644
--- a/MODULE.bazel
+++ b/MODULE.bazel
@@ -17,3 +17,5 @@ bazel_dep(name = "rules_cc", version = "0.0.1", dev_dependency = True)
 bazel_dep(name = "googletest", version = "1.11.0", dev_dependency = True, repo_name = "com_google_googletest")
 bazel_dep(name = "protobuf", version = "23.1", dev_dependency = True, repo_name = "com_google_protobuf")
 bazel_dep(name = "platforms", version = "0.0.8", dev_dependency = True)
+
+register_toolchains("//:proto_toolchain_toolchain", dev_dependency = True)
diff --git a/MODULE.bazel.lock b/MODULE.bazel.lock
index 5d86542..429f0c0 100644
--- a/MODULE.bazel.lock
+++ b/MODULE.bazel.lock
@@ -1,6 +1,6 @@
 {
   "lockFileVersion": 6,
-  "moduleFileHash": "7a83abe22db793fb1612f5cf942cc29bce39f91dcc76ce2f4ecc60a2f5f8a1e0",
+  "moduleFileHash": "1180f60115309a637d417b53b0188f1dcb65caf0cdbcb87d9c013c1b3b056d21",
   "flags": {
     "cmdRegistries": [
       "https://bcr.bazel.build/"
@@ -22,7 +22,9 @@
       "key": "<root>",
       "repoName": "rules_proto",
       "executionPlatformsToRegister": [],
-      "toolchainsToRegister": [],
+      "toolchainsToRegister": [
+        "//:proto_toolchain_toolchain"
+      ],
       "extensionUsages": [],
       "deps": {
         "rules_license": "rules_license@0.0.7",
@@ -1222,7 +1224,7 @@
     },
     "@@protobuf~//:non_module_deps.bzl%non_module_deps": {
       "general": {
-        "bzlTransitiveDigest": "aGnO/HqVtCmRLEQWGCuKp7jwX+lCh/nc3/hI3clfwD8=",
+        "bzlTransitiveDigest": "Ru/iB33/Fg7l06H1hBzJ1lPAZip3abmjbwD8z/MzBig=",
         "recordedFileInputs": {},
         "recordedDirentsInputs": {},
         "envVariables": {},
@@ -1250,7 +1252,7 @@
     },
     "@@rules_java~//java:extensions.bzl%toolchains": {
       "general": {
-        "bzlTransitiveDigest": "tJHbmWnq7m+9eUBnUdv7jZziQ26FmcGL9C5/hU3Q9UQ=",
+        "bzlTransitiveDigest": "0N5b5J9fUzo0sgvH4F3kIEaeXunz4Wy2/UtSFV/eXUY=",
         "recordedFileInputs": {},
         "recordedDirentsInputs": {},
         "envVariables": {},
diff --git a/docs/defs.md b/docs/defs.md
index 2f5dc92..c554646 100644
--- a/docs/defs.md
+++ b/docs/defs.md
@@ -2,6 +2,29 @@
 
 Starlark rules for building protocol buffers.
 
+<a id="current_proto_toolchain"></a>
+
+## current_proto_toolchain
+
+<pre>
+current_proto_toolchain(<a href="#current_proto_toolchain-name">name</a>)
+</pre>
+
+
+    This rule exists so that the current protoc toolchain can be used in the `toolchains` attribute of
+    other rules, such as genrule. It allows exposing a protoc toolchain after toolchain resolution has
+    happened, to a rule which expects a concrete implementation of a toolchain, rather than a
+    toolchain_type which could be resolved to that toolchain.
+    
+
+**ATTRIBUTES**
+
+
+| Name  | Description | Type | Mandatory | Default |
+| :------------- | :------------- | :------------- | :------------- | :------------- |
+| <a id="current_proto_toolchain-name"></a>name |  A unique name for this target.   | <a href="https://bazel.build/concepts/labels#target-names">Name</a> | required |  |
+
+
 <a id="proto_descriptor_set"></a>
 
 ## proto_descriptor_set
diff --git a/tests/current_toolchain/BUILD.bazel b/tests/current_toolchain/BUILD.bazel
new file mode 100644
index 0000000..4bc2cc2
--- /dev/null
+++ b/tests/current_toolchain/BUILD.bazel
@@ -0,0 +1,17 @@
+load("//proto:defs.bzl", "current_proto_toolchain")
+
+current_proto_toolchain(
+    name = "current_proto_toolchain",
+    visibility = ["//visibility:public"],
+)
+
+genrule(
+    name = "gen_protoc_version_from_current_proto_toolchain",
+    srcs = [":current_proto_toolchain"],
+    outs = ["protoc_version_from_current_proto_toolchain"],
+    cmd = """
+        v=$$($(PROTOC) --version)
+        echo $$v > $(OUTS)
+    """,
+    toolchains = [":current_proto_toolchain"],
+)