Make CI verify that error_generic_member_access works in latest nightly

Author: dtolnay

.github/workflows/ci.yml

@@ -35,6 +35,9 @@ jobs:
       - name: Enable type layout randomization
         run: echo RUSTFLAGS=${RUSTFLAGS}\ -Zrandomize-layout >> $GITHUB_ENV
         if: matrix.rust == 'nightly'
+      - name: Enable nightly-only tests
+        run: echo RUSTFLAGS=${RUSTFLAGS}\ --cfg=anyhow_nightly_testing >> $GITHUB_ENV
+        if: matrix.rust == 'nightly'
       - run: cargo test
       - run: cargo check --no-default-features
       - run: cargo check --features backtrace

src/lib.rs

@@ -237,6 +237,13 @@
     clippy::wrong_self_convention
 )]
 
+#[cfg(all(
+    anyhow_nightly_testing,
+    feature = "std",
+    not(error_generic_member_access)
+))]
+compile_error!("Build script probe failed to compile.");
+
 extern crate alloc;
 
 #[macro_use]