From d720770b0717af167d26ba123830b41fb9f316db Mon Sep 17 00:00:00 2001
From: John DiSanti <jdisanti@amazon.com>
Date: Wed, 24 Aug 2022 04:35:32 -0700
Subject: [PATCH] ci: add `cargo-check-external-types` check (#4914)

---
 .github/workflows/ci.yml  | 25 +++++++++++++++++++++++++
 tokio/external-types.toml | 16 ++++++++++++++++
 2 files changed, 41 insertions(+)
 create mode 100644 tokio/external-types.toml

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index ea9944bbd6b..3a5b83b7aa5 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -51,6 +51,7 @@ jobs:
       - test-hyper
       - wasm32-unknown-unknown
       - wasm32-wasi
+      - check-external-types
     steps:
       - run: exit 0
 
@@ -513,3 +514,27 @@ jobs:
         # TODO: this should become: `cargo hack wasi test --each-feature`
         run: cargo wasi test --test rt_yield --features wasi-rt
         working-directory: tests-integration
+
+  check-external-types:
+    name: check-external-types
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os:
+          - windows-latest
+          - ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+      - name: Install Rust ${{ env.rust_nightly }}
+        uses: actions-rs/toolchain@v1
+        with:
+          toolchain: ${{ env.rust_nightly }}
+          override: true
+      - uses: Swatinem/rust-cache@v1
+      - name: check-external-types
+        run: |
+          set -x
+          cargo install cargo-check-external-types --locked --version 0.1.3
+          cargo check-external-types --all-features --config external-types.toml
+        working-directory: tokio
+
diff --git a/tokio/external-types.toml b/tokio/external-types.toml
new file mode 100644
index 00000000000..fba14f532c3
--- /dev/null
+++ b/tokio/external-types.toml
@@ -0,0 +1,16 @@
+# This config file is for the `cargo-check-external-types` tool that is run in CI.
+
+# The following are types that are allowed to be exposed in Tokio's public API.
+# The standard library is allowed by default.
+allowed_external_types = [
+   "bytes::buf::buf_impl::Buf",
+   "bytes::buf::buf_mut::BufMut",
+
+   "tokio_macros::*",
+
+   # TODO(https://github.com/tokio-rs/tokio/issues/4916): Remove the libc types
+   "libc::unix::gid_t",
+   "libc::unix::pid_t",
+   "libc::unix::uid_t",
+]
+