Recover type casts in patterns

Author: ShE3py

compiler/rustc_parse/src/parser/pat.rs

@@ -383,11 +383,13 @@ impl<'a> Parser<'a> {
         // `|` is excluded as it is used in pattern alternatives and lambdas,
         // `?` is included for error propagation,
         // `[` is included for indexing operations,
-        // `[]` is excluded as `a[]` isn't an expression and should be recovered as `a, []` (cf. `tests/ui/parser/pat-lt-bracket-7.rs`)
+        // `[]` is excluded as `a[]` isn't an expression and should be recovered as `a, []` (cf. `tests/ui/parser/pat-lt-bracket-7.rs`),
+        // `as` is included for type casts
         let has_trailing_operator = matches!(self.token.kind, token::BinOp(op) if op != BinOpToken::Or)
             || self.token.kind == token::Question
             || (self.token.kind == token::OpenDelim(Delimiter::Bracket)
-                && self.look_ahead(1, |tok| tok.kind != token::CloseDelim(Delimiter::Bracket)));
+                && self.look_ahead(1, |tok| tok.kind != token::CloseDelim(Delimiter::Bracket)))
+            || self.token.is_keyword(kw::As);
 
         if !has_dot_expr && !has_trailing_operator {
             // Nothing to recover here.