Merge #9097

9097: feat: Implement per-edition preludes r=jonas-schievink a=jonas-schievink

Part of https://github.com/rust-analyzer/rust-analyzer/issues/9056

Our previous implementation was incorrect (presumably because of the misleading comment in libstd [here](https://github.com/rust-lang/rust/blob/a7890c7952bdc9445eb6c63dc671fa7a1ab0260d/library/std/src/lib.rs#L339-L343)). `#[prelude_import]` does not define the prelude, it can only override the implicit prelude for the current crate.

This PR fixes that, which also makes the prelude imports in `rustc_span` work. Closes https://github.com/rust-analyzer/rust-analyzer/issues/8815.

bors r+

Co-authored-by: Jonas Schievink <[email protected]>

1 files changed, 5 insertions, 4 deletions

diff --git a/crates/hir_ty/src/tests/regression.rs b/crates/hir_ty/src/tests/regression.rs
index ad9edf11c..1019e783b 100644
--- a/crates/hir_ty/src/tests/regression.rs
+++ b/crates/hir_ty/src/tests/regression.rs
@@ -426,11 +426,12 @@ fn test() {
 
 //- /std.rs crate:std
 #[prelude_import]
-use prelude::*;
-
+use self::prelude::rust_2018::*;
 pub mod prelude {
-    pub use crate::iter::Iterator;
-    pub use crate::option::Option;
+    pub mod rust_2018 {
+        pub use crate::iter::Iterator;
+        pub use crate::option::Option;
+    }
 }
 
 pub mod iter {