Rollup merge of #119231 - aDotInTheVoid:PatKind-struct-bool-docs, r=compiler-errors

Clairify `ast::PatKind::Struct` presese of `..` by using an enum instead of a bool

The bool is mainly used for when a `..` is present, but it is also set on recovery to avoid errors. The doc comment not describes both of these cases.

See cee794ee98/compiler/rustc_parse/src/parser/pat.rs (L890-L897) for the only place this is constructed.

r? ``@compiler-errors``

compiler/rustc_ast/src/ast.rs

@@ -754,8 +754,7 @@ pub enum PatKind {
     Ident(BindingAnnotation, Ident, Option<P<Pat>>),
 
     /// A struct or struct variant pattern (e.g., `Variant {x, y, ..}`).
-    /// The `bool` is `true` in the presence of a `..`.
-    Struct(Option<P<QSelf>>, Path, ThinVec<PatField>, /* recovered */ bool),
+    Struct(Option<P<QSelf>>, Path, ThinVec<PatField>, PatFieldsRest),
 
     /// A tuple struct/variant pattern (`Variant(x, y, .., z)`).
     TupleStruct(Option<P<QSelf>>, Path, ThinVec<P<Pat>>),
@@ -812,6 +811,15 @@ pub enum PatKind {
     MacCall(P<MacCall>),
 }
 
+/// Whether the `..` is present in a struct fields pattern.
+#[derive(Clone, Copy, Encodable, Decodable, Debug, PartialEq)]
+pub enum PatFieldsRest {
+    /// `module::StructName { field, ..}`
+    Rest,
+    /// `module::StructName { field }`
+    None,
+}
+
 /// The kind of borrow in an `AddrOf` expression,
 /// e.g., `&place` or `&raw const place`.
 #[derive(Clone, Copy, PartialEq, Eq, Debug)]