Don't hardcode the v1 prelude in diagnostics.

Instead of looking for `std::prelude::v1`, this changes it to look for
`std::prelude::<anything>`.

Author: m-ou-se

compiler/rustc_resolve/src/late/diagnostics.rs

@@ -324,7 +324,7 @@ impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> {
                 .lookup_import_candidates(ident, ns, &self.parent_scope, is_enum_variant)
                 .into_iter()
                 .map(|suggestion| import_candidate_to_enum_paths(&suggestion))
-                .filter(|(_, enum_ty_path)| enum_ty_path != "std::prelude::v1")
+                .filter(|(_, enum_ty_path)| !enum_ty_path.starts_with("std::prelude::"))
                 .collect();
             if !enum_candidates.is_empty() {
                 if let (PathSource::Type, Some(span)) =

compiler/rustc_typeck/src/check/demand.rs

@@ -200,7 +200,12 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                     if self.can_coerce(expr_ty, sole_field_ty) {
                         let variant_path = self.tcx.def_path_str(variant.def_id);
                         // FIXME #56861: DRYer prelude filtering
-                        Some(variant_path.trim_start_matches("std::prelude::v1::").to_string())
+                        if let Some(path) = variant_path.strip_prefix("std::prelude::") {
+                            if let Some((_, path)) = path.split_once("::") {
+                                return Some(path.to_string());
+                            }
+                        }
+                        Some(variant_path)
                     } else {
                         None
                     }