diff options
| -rw-r--r-- | compiler/rustc_hir_typeck/src/pat.rs | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/compiler/rustc_hir_typeck/src/pat.rs b/compiler/rustc_hir_typeck/src/pat.rs index d1153821e62..b60908ed210 100644 --- a/compiler/rustc_hir_typeck/src/pat.rs +++ b/compiler/rustc_hir_typeck/src/pat.rs @@ -215,6 +215,10 @@ impl MutblCap { } /// Variations on RFC 3627's Rule 4: when do reference patterns match against inherited references? +/// +/// "Inherited reference" designates the `&`/`&mut` types that arise from using match ergonomics, i.e. +/// from matching a reference type with a non-reference pattern. E.g. when `Some(x)` matches on +/// `&mut Option<&T>`, `x` gets type `&mut &T` and the outer `&mut` is considered "inherited". #[derive(Clone, Copy, Debug, PartialEq, Eq)] enum InheritedRefMatchRule { /// Reference patterns try to consume the inherited reference first. @@ -223,7 +227,7 @@ enum InheritedRefMatchRule { /// Reference patterns consume inherited references if matching against a non-reference type. /// This assumes reference patterns can always match against an inherited reference. EatInner, - /// Reference patterns consume both layers of reference. + /// Reference patterns consume both layers of reference, i.e. reset the binding mode when consuming a reference type. /// Currently, this assumes the stable Rust behavior of not allowing reference patterns to eat /// an inherited reference alone. This will need an additional field or variant to represent the /// planned edition <= 2021 behavior of experimental match ergonomics, which does allow that. |