From 8dc12df71d21ac2b502e2bb89296f465d2088ca5 Mon Sep 17 00:00:00 2001
From: Jon Ross-Perkins <jperkins@google.com>
Date: Wed, 14 Dec 2022 14:27:30 -0800
Subject: [PATCH] Automate labeling of explorer and toolchain PRs (#2470)

Pixep has been doing this by hand, so offering up some automation.

This is derivative of other workflows for [path-filter](https://github.com/carbon-language/carbon-lang/blob/trunk/.github/workflows/assign_prs.yaml) and [using gh for labels](https://github.com/carbon-language/carbon-lang/blob/trunk/.github/workflows/proposal_labeled.yaml). It felt best to stick it in its own workflow rather than merging with assign_prs.yaml, just to make the boundary clearer (I believe the separate workflow is cheap).
---
 .github/workflows/label_prs.yaml | 37 ++++++++++++++++++++++++++++++++
 1 file changed, 37 insertions(+)
 create mode 100644 .github/workflows/label_prs.yaml

diff --git a/.github/workflows/label_prs.yaml b/.github/workflows/label_prs.yaml
new file mode 100644
index 000000000000..1fe0f408b03e
--- /dev/null
+++ b/.github/workflows/label_prs.yaml
@@ -0,0 +1,37 @@
+# Part of the Carbon Language project, under the Apache License v2.0 with LLVM
+# Exceptions. See /LICENSE for license information.
+# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+name: 'Auto label PRs'
+on:
+  pull_request_target:
+    types: [opened, ready_for_review]
+
+jobs:
+  assign_reviewer:
+    runs-on: ubuntu-latest
+    steps:
+      - id: filter
+        uses: dorny/paths-filter@v2
+        with:
+          filters: |
+            explorer:
+              - 'explorer/**'
+            toolchain:
+              - 'toolchain/**'
+
+      - id: explorer
+        if: steps.filter.outputs.explorer == 'true'
+        run: |
+          gh pr edit "${PR}" --add-label "explorer"
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          PR: ${{ github.event.pull_request.html_url }}
+
+      - id: assign-toolchain
+        if: steps.filter.outputs.toolchain == 'true'
+        run: |
+          gh pr edit "${PR}" --add-label "toolchain"
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          PR: ${{ github.event.pull_request.html_url }}