Auto merge of #65043 - Aaron1011:fix/reexport-determinism, r=petrochenkov

Make re-export collection deterministic

Fixes #65036

Previously, we were using an `FxHashMap` to collect module re-exports.
However, re-exports end up getting serialized into crate metadata, which
means that metadata generation was non-deterministic. This resulted in
spurious error messages changes (e.g. PR #64906) due to pretty-printing
implicitly depending on the order of re-exports when computing the
proper path to show to the user.

See #65042 for a long-term strategy to detect this kind of issue

Author: bors

src/librustc_resolve/diagnostics.rs

@@ -527,7 +527,7 @@ impl<'a> Resolver<'a> {
                         in_module_is_extern)) = worklist.pop() {
             // We have to visit module children in deterministic order to avoid
             // instabilities in reported imports (#43552).
-            in_module.for_each_child_stable(self, |this, ident, ns, name_binding| {
+            in_module.for_each_child(self, |this, ident, ns, name_binding| {
                 // avoid imports entirely
                 if name_binding.is_import() && !name_binding.is_extern_crate() { return; }
                 // avoid non-importable candidates as well

src/librustc_resolve/late/diagnostics.rs

@@ -728,7 +728,7 @@ impl<'a> LateResolutionVisitor<'a, '_> {
             // abort if the module is already found
             if result.is_some() { break; }
 
-            in_module.for_each_child_stable(self.r, |_, ident, _, name_binding| {
+            in_module.for_each_child(self.r, |_, ident, _, name_binding| {
                 // abort if the module is already found or if name_binding is private external
                 if result.is_some() || !name_binding.vis.is_visible_locally() {
                     return
@@ -760,7 +760,7 @@ impl<'a> LateResolutionVisitor<'a, '_> {
     fn collect_enum_variants(&mut self, def_id: DefId) -> Option<Vec<Path>> {
         self.find_module(def_id).map(|(enum_module, enum_import_suggestion)| {
             let mut variants = Vec::new();
-            enum_module.for_each_child_stable(self.r, |_, ident, _, name_binding| {
+            enum_module.for_each_child(self.r, |_, ident, _, name_binding| {
                 if let Res::Def(DefKind::Variant, _) = name_binding.res() {
                     let mut segms = enum_import_suggestion.path.segments.clone();
                     segms.push(ast::PathSegment::from_ident(ident));

src/librustc_resolve/lib.rs

@@ -57,6 +57,7 @@ use std::{cmp, fmt, iter, ptr};
 use std::collections::BTreeSet;
 use rustc_data_structures::ptr_key::PtrKey;
 use rustc_data_structures::sync::Lrc;
+use rustc_data_structures::fx::FxIndexMap;
 
 use diagnostics::{Suggestion, ImportSuggestion};
 use diagnostics::{find_span_of_binding_until_next_binding, extend_span_to_previous_binding};
@@ -430,7 +431,7 @@ 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> {
@@ -495,17 +496,6 @@ impl<'a> ModuleData<'a> {
         }
     }
 
-    fn for_each_child_stable<R, F>(&'a self, resolver: &mut R, mut 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));
-        }
-    }
-
     fn res(&self) -> Option<Res> {
         match self.kind {
             ModuleKind::Def(kind, def_id, _) => Some(Res::Def(kind, def_id)),

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