fix new location of unstable assert_matches

.github/workflows/rust-stability.yml

@@ -2,6 +2,7 @@ name: Monthly stability checks
 
 on:
   workflow_dispatch:
+  workflow_call:
   pull_request:
   schedule:
     - cron: '0 3 6 * *'
@@ -15,7 +16,6 @@ env:
     RUSTC_BOOTSTRAP: 1
 
 jobs:
-
 
   test:
     strategy:
@@ -25,11 +25,10 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - uses: actions/checkout@v6
-    - uses: actions-rust-lang/setup-rust-toolchain@v1
-      with:
-        toolchain: ${{ matrix.channel }}
+    - name: update rust
+      run: rustup update
     - name: Run tests
-      run: cargo test --no-fail-fast
+      run: cargo +${{ matrix.channel }} test --no-fail-fast
 
   lint:
     strategy:
@@ -39,12 +38,10 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - uses: actions/checkout@v6
-    - uses: actions-rust-lang/setup-rust-toolchain@v1
-      with:
-        toolchain: ${{ matrix.channel }}
-        components: "clippy"
+    - name: update rust
+      run: rustup update && rustup component add --toolchain ${{ matrix.channel }} clippy
     - name: clippy
-      run: cargo clippy -- --deny warnings
+      run: cargo +${{ matrix.channel }} clippy -- --deny warnings
 
   report:
     if: ${{ always() }}

build.rs

@@ -1,6 +1,59 @@
+use autocfg::AutoCfg;
+
 extern crate autocfg;
 
 fn main() {
     let ac = autocfg::new();
-    ac.emit_path_cfg("std::assert_matches", "stable_assert_matches");
+    stable_feature(&ac, "assert_matches");
+    assert_matches_in_module(&ac);
+    assert_matches_in_root(&ac);
+}
+
+fn stable_feature(ac: &AutoCfg, feature: &'static str) {
+    let cfg = format!("stable_{feature}");
+    let code = format!(
+        r#"
+    #![deny(stable_features)]
+    #![feature({feature})]
+    "#
+    );
+
+    autocfg::emit_possibility(&cfg);
+    if ac.probe_raw(&code).is_err() {
+        autocfg::emit(&cfg);
+    }
+}
+
+fn assert_matches_in_root(ac: &AutoCfg) {
+    let cfg = "assert_matches_in_root";
+    let code = r#"
+    #![allow(stable_features)]
+    #![feature(assert_matches)]
+    use std::assert_matches;
+
+    fn main() {
+        assert_matches!(Some(4), Some(_));
+    }
+        "#;
+    autocfg::emit_possibility(cfg);
+    if ac.probe_raw(code).is_ok() {
+        autocfg::emit(cfg);
+    }
+}
+
+fn assert_matches_in_module(ac: &AutoCfg) {
+    let cfg = "assert_matches_in_module";
+    let code = r#"
+    #![allow(stable_features)]
+    #![feature(assert_matches)]
+    use std::assert_matches::assert_matches;
+
+    fn main() {
+        assert_matches!(Some(4), Some(_));
+    }
+        "#;
+    autocfg::emit_possibility(cfg);
+    if ac.probe_raw(code).is_ok() {
+        autocfg::emit(cfg);
+    }
 }

src/lib.rs

@@ -603,10 +603,10 @@ impl From<DiagnosticStream> for TokenStream1 {
 
 #[cfg(test)]
 mod tests {
-    #[cfg(not(stable_assert_matches))]
+    #[cfg(assert_matches_in_module)]
     use std::assert_matches::assert_matches;
 
-    #[cfg(stable_assert_matches)]
+    #[cfg(assert_matches_in_root)]
     use std::assert_matches;
 
     use super::*;