[Experiment] resolve: Check whether resolution insertion order is reproducible

src/librustc_resolve/lib.rs

@@ -56,6 +56,7 @@ use log::debug;
 use std::cell::{Cell, RefCell};
 use std::{cmp, fmt, iter, ptr};
 use std::collections::BTreeSet;
+use rustc_data_structures::fx::FxIndexMap;
 use rustc_data_structures::ptr_key::PtrKey;
 use rustc_data_structures::sync::Lrc;
 
@@ -431,7 +432,7 @@ impl ModuleKind {
     }
 }
 
-type Resolutions<'a> = RefCell<FxHashMap<(Ident, Namespace), &'a RefCell<NameResolution<'a>>>>;
+type Resolutions<'a> = RefCell<FxIndexMap<(Ident, Namespace), &'a RefCell<NameResolution<'a>>>>;
 
 /// One node in the tree of modules.
 pub struct ModuleData<'a> {
@@ -496,15 +497,10 @@ impl<'a> ModuleData<'a> {
         }
     }
 
-    fn for_each_child_stable<R, F>(&'a self, resolver: &mut R, mut f: F)
+    fn for_each_child_stable<R, F>(&'a self, resolver: &mut R, f: F)
         where R: AsMut<Resolver<'a>>, F: FnMut(&mut R, Ident, Namespace, &'a NameBinding<'a>)
     {
-        let resolutions = resolver.as_mut().resolutions(self).borrow();
-        let mut resolutions = resolutions.iter().collect::<Vec<_>>();
-        resolutions.sort_by_cached_key(|&(&(ident, ns), _)| (ident.as_str(), ns));
-        for &(&(ident, ns), &resolution) in resolutions.iter() {
-            resolution.borrow().binding.map(|binding| f(resolver, ident, ns, binding));
-        }
+        self.for_each_child(resolver, f)
     }
 
     fn res(&self) -> Option<Res> {

src/test/ui/did_you_mean/issue-43871-enum-instead-of-variant.stderr

@@ -5,10 +5,10 @@ LL |     let x = Option(1);
    |             ^^^^^^
 help: try using one of the enum's variants
    |
-LL |     let x = std::prelude::v1::Option::None(1);
-   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-LL |     let x = std::prelude::v1::Option::Some(1);
-   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+LL |     let x = std::option::Option::None(1);
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^
+LL |     let x = std::option::Option::Some(1);
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error[E0532]: expected tuple struct/variant, found enum `Option`
   --> $DIR/issue-43871-enum-instead-of-variant.rs:21:12
@@ -17,10 +17,10 @@ LL |     if let Option(_) = x {
    |            ^^^^^^
 help: try using one of the enum's variants
    |
-LL |     if let std::prelude::v1::Option::None(_) = x {
-   |            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-LL |     if let std::prelude::v1::Option::Some(_) = x {
-   |            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+LL |     if let std::option::Option::None(_) = x {
+   |            ^^^^^^^^^^^^^^^^^^^^^^^^^
+LL |     if let std::option::Option::Some(_) = x {
+   |            ^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error[E0532]: expected tuple struct/variant, found enum `Example`
   --> $DIR/issue-43871-enum-instead-of-variant.rs:27:12
@@ -47,14 +47,14 @@ LL |     let z = ManyVariants();
    |             ^^^^^^^^^^^^
 help: try using one of the enum's variants
    |
-LL |     let z = ManyVariants::Eight();
+LL |     let z = ManyVariants::One();
+   |             ^^^^^^^^^^^^^^^^^
+LL |     let z = ManyVariants::Two();
+   |             ^^^^^^^^^^^^^^^^^
+LL |     let z = ManyVariants::Three();
    |             ^^^^^^^^^^^^^^^^^^^
-LL |     let z = ManyVariants::Five();
-   |             ^^^^^^^^^^^^^^^^^^
 LL |     let z = ManyVariants::Four();
    |             ^^^^^^^^^^^^^^^^^^
-LL |     let z = ManyVariants::Nine();
-   |             ^^^^^^^^^^^^^^^^^^
 and 6 other candidates
 
 error: aborting due to 5 previous errors

src/test/ui/issues/issue-35675.stderr

@@ -63,7 +63,7 @@ LL | fn qux() -> Some {
    |             ^^^^
    |             |
    |             not a type
-   |             help: try using the variant's enum: `Option`
+   |             help: try using the variant's enum: `std::option::Option`
 
 error: aborting due to 7 previous errors