Ensure deterministic ordering for diagnostics

Author: roxelo

compiler/rustc_typeck/src/check/upvar.rs

@@ -96,7 +96,7 @@ type MigrationNeededForCapture = (Option<hir::HirId>, String, String);
 
 /// Intermediate format to store the hir id of the root variable and a HashSet containing
 /// information on why the root variable should be fully captured
-type MigrationDiagnosticInfo = (hir::HirId, FxHashSet<MigrationNeededForCapture>);
+type MigrationDiagnosticInfo = (hir::HirId, Vec<MigrationNeededForCapture>);
 
 struct InferBorrowKindVisitor<'a, 'tcx> {
     fcx: &'a FnCtxt<'a, 'tcx>,
@@ -861,7 +861,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
 
         // Perform auto-trait analysis
         for (&var_hir_id, _) in upvars.iter() {
-            let mut responsible_captured_hir_ids = FxHashSet::default();
+            let mut responsible_captured_hir_ids = Vec::new();
 
             let auto_trait_diagnostic = if let Some(diagnostics_info) =
                 self.compute_2229_migrations_for_trait(min_captures, var_hir_id, closure_clause)
@@ -891,6 +891,8 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 capture_diagnostic.insert(key.clone());
             }
 
+            let mut capture_diagnostic = capture_diagnostic.into_iter().collect::<Vec<_>>();
+            capture_diagnostic.sort();
             for captured_info in capture_diagnostic.iter() {
                 // Get the auto trait reasons of why migration is needed because of that capture, if there are any
                 let capture_trait_reasons =
@@ -907,7 +909,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 // auto trait implementation issues
                 auto_trait_migration_reasons.extend(capture_trait_reasons.clone());
 
-                responsible_captured_hir_ids.insert((
+                responsible_captured_hir_ids.push((
                     captured_info.0,
                     captured_info.1.clone(),
                     self.compute_2229_migrations_reasons(

src/test/ui/closures/2229_closure_analysis/migrations/multi_diagnostics.stderr

@@ -90,8 +90,8 @@ LL |         let _f_1 = f1.1;
 LL | }
    | -
    | |
-   | in Rust 2018, `f1` would be dropped here, but in Rust 2021, only `f1.1` would be dropped here alongside the closure
    | in Rust 2018, `f1` would be dropped here, but in Rust 2021, only `f1.0` would be dropped here alongside the closure
+   | in Rust 2018, `f1` would be dropped here, but in Rust 2021, only `f1.1` would be dropped here alongside the closure
    |
    = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/disjoint-capture-in-closures.html>
 help: add a dummy let to cause `f1` to be fully captured

src/test/ui/closures/2229_closure_analysis/migrations/precise.stderr

@@ -44,8 +44,8 @@ LL |         let _x = u.1.0;
 LL | }
    | -
    | |
-   | in Rust 2018, `u` would be dropped here, but in Rust 2021, only `u.0.1` would be dropped here alongside the closure
    | in Rust 2018, `u` would be dropped here, but in Rust 2021, only `u.0.0` would be dropped here alongside the closure
+   | in Rust 2018, `u` would be dropped here, but in Rust 2021, only `u.0.1` would be dropped here alongside the closure
    | in Rust 2018, `u` would be dropped here, but in Rust 2021, only `u.1.0` would be dropped here alongside the closure
    |
    = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/disjoint-capture-in-closures.html>