2 files changed, 50 insertions, 38 deletions

diff --git a/crates/hir_ty/src/tests/traits.rs b/crates/hir_ty/src/tests/traits.rs
index dd1ea817f..0b6a3a1e9 100644
--- a/crates/hir_ty/src/tests/traits.rs
+++ b/crates/hir_ty/src/tests/traits.rs
@@ -567,11 +567,11 @@ fn indexing_arrays() {
 fn infer_ops_index() {
     check_types(
         r#"
-//- /main.rs crate:main deps:std
+//- minicore: index
 struct Bar;
 struct Foo;
 
-impl std::ops::Index<u32> for Bar {
+impl core::ops::Index<u32> for Bar {
     type Output = Foo;
 }
 
@@ -580,15 +580,6 @@ fn test() {
     let b = a[1u32];
     b;
 } //^ Foo
-
-//- /std.rs crate:std
-#[prelude_import] use ops::*;
-mod ops {
-    #[lang = "index"]
-    pub trait Index<Idx> {
-        type Output;
-    }
-}
 "#,
     );
 }
@@ -597,16 +588,16 @@ mod ops {
 fn infer_ops_index_int() {
     check_types(
         r#"
-//- /main.rs crate:main deps:std
+//- minicore: index
 struct Bar;
 struct Foo;
 
-impl std::ops::Index<u32> for Bar {
+impl core::ops::Index<u32> for Bar {
     type Output = Foo;
 }
 
 struct Range;
-impl std::ops::Index<Range> for Bar {
+impl core::ops::Index<Range> for Bar {
     type Output = Bar;
 }
 
@@ -616,15 +607,6 @@ fn test() {
     b;
   //^ Foo
 }
-
-//- /std.rs crate:std
-#[prelude_import] use ops::*;
-mod ops {
-    #[lang = "index"]
-    pub trait Index<Idx> {
-        type Output;
-    }
-}
 "#,
     );
 }
@@ -633,25 +615,12 @@ mod ops {
 fn infer_ops_index_autoderef() {
     check_types(
         r#"
-//- /main.rs crate:main deps:std
+//- minicore: index, slice
 fn test() {
     let a = &[1u32, 2, 3];
-    let b = a[1u32];
+    let b = a[1];
     b;
 } //^ u32
-
-//- /std.rs crate:std
-impl<T> ops::Index<u32> for [T] {
-    type Output = T;
-}
-
-#[prelude_import] use ops::*;
-mod ops {
-    #[lang = "index"]
-    pub trait Index<Idx> {
-        type Output;
-    }
-}
 "#,
     );
 }
diff --git a/crates/test_utils/src/minicore.rs b/crates/test_utils/src/minicore.rs
index 769028580..71f07d38a 100644
--- a/crates/test_utils/src/minicore.rs
+++ b/crates/test_utils/src/minicore.rs
@@ -15,6 +15,7 @@
 //!     range:
 //!     deref: sized
 //!     deref_mut: deref
+//!     index: sized
 //!     fn:
 //!     pin:
 //!     future: pin
@@ -167,6 +168,48 @@ pub mod ops {
     };
     // endregion:deref
 
+    // region:index
+    mod index {
+        #[lang = "index"]
+        pub trait Index<Idx: ?Sized> {
+            type Output: ?Sized;
+            fn index(&self, index: Idx) -> &Self::Output;
+        }
+        #[lang = "index_mut"]
+        pub trait IndexMut<Idx: ?Sized>: Index<Idx> {
+            fn index_mut(&mut self, index: Idx) -> &mut Self::Output;
+        }
+
+        // region:slice
+        impl<T, I> Index<I> for [T]
+        where
+            I: SliceIndex<[T]>,
+        {
+            type Output = I::Output;
+            fn index(&self, index: I) -> &I::Output {
+                loop {}
+            }
+        }
+        impl<T, I> IndexMut<I> for [T]
+        where
+            I: SliceIndex<[T]>,
+        {
+            fn index_mut(&mut self, index: I) -> &mut I::Output {
+                loop {}
+            }
+        }
+
+        pub unsafe trait SliceIndex<T: ?Sized> {
+            type Output: ?Sized;
+        }
+        unsafe impl<T> SliceIndex<[T]> for usize {
+            type Output = T;
+        }
+        // endregion:slice
+    }
+    pub use self::index::{Index, IndexMut};
+    // endregion:index
+
     // region:range
     mod range {
         #[lang = "RangeFull"]