1 files changed, 37 insertions, 8 deletions

diff --git a/build.rs b/build.rs
index 004dfb0..7983a2b 100644
--- a/build.rs
+++ b/build.rs
@@ -4,27 +4,56 @@ use std::path::Path;
 use std::process::{Command, ExitStatus, Stdio};
 use std::str;
 
-// This code exercises the surface area that we expect of the Provider API. If
-// the current toolchain is able to compile it, then thiserror is able to use
-// providers for backtrace support.
+// This code exercises the surface area that we expect of the Error generic
+// member access API. If the current toolchain is able to compile it, then
+// thiserror is able to provide backtrace support.
 const PROBE: &str = r#"
-    #![feature(provide_any)]
+    #![feature(error_generic_member_access)]
 
-    use std::any::{Demand, Provider};
+    use std::error::{Error, Request};
+    use std::fmt::{self, Debug, Display};
 
-    fn _f<'a, P: Provider>(p: &'a P, demand: &mut Demand<'a>) {
-        p.provide(demand);
+    struct MyError(Thing);
+    struct Thing;
+
+    impl Debug for MyError {
+        fn fmt(&self, _formatter: &mut fmt::Formatter) -> fmt::Result {
+            unimplemented!()
+        }
+    }
+
+    impl Display for MyError {
+        fn fmt(&self, _formatter: &mut fmt::Formatter) -> fmt::Result {
+            unimplemented!()
+        }
+    }
+
+    impl Error for MyError {
+        fn provide<'a>(&'a self, request: &mut Request<'a>) {
+            request.provide_ref(&self.0);
+        }
     }
 "#;
 
 fn main() {
     match compile_probe() {
-        Some(status) if status.success() => println!("cargo:rustc-cfg=provide_any"),
+        Some(status) if status.success() => println!("cargo:rustc-cfg=error_generic_member_access"),
         _ => {}
     }
 }
 
 fn compile_probe() -> Option<ExitStatus> {
+    if env::var_os("RUSTC_STAGE").is_some() {
+        // We are running inside rustc bootstrap. This is a highly non-standard
+        // environment with issues such as:
+        //
+        //     https://github.com/rust-lang/cargo/issues/11138
+        //     https://github.com/rust-lang/rust/issues/114839
+        //
+        // Let's just not use nightly features here.
+        return None;
+    }
+
     let rustc = env::var_os("RUSTC")?;
     let out_dir = env::var_os("OUT_DIR")?;
     let probefile = Path::new(&out_dir).join("probe.rs");