From 88453aaccfe308a30a30dc4dee95fe51edc367e0 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Esteban=20K=C3=BCber?= <esteban@kuber.com.ar>
Date: Wed, 29 Nov 2023 18:45:36 +0000
Subject: [PATCH] Avoid unnecessary pattern parse errors on `ref box`

---
 compiler/rustc_parse/src/parser/pat.rs        |  6 +++---
 .../pattern/pattern-bad-ref-box-order.fixed   |  4 +---
 tests/ui/pattern/pattern-bad-ref-box-order.rs |  2 --
 .../pattern/pattern-bad-ref-box-order.stderr  | 20 +------------------
 4 files changed, 5 insertions(+), 27 deletions(-)

diff --git a/compiler/rustc_parse/src/parser/pat.rs b/compiler/rustc_parse/src/parser/pat.rs
index ec7c312d03f00..3d1d1ec8108c1 100644
--- a/compiler/rustc_parse/src/parser/pat.rs
+++ b/compiler/rustc_parse/src/parser/pat.rs
@@ -391,10 +391,10 @@ impl<'a> Parser<'a> {
             self.parse_pat_ident_mut(syntax_loc)?
         } else if self.eat_keyword(kw::Ref) {
             if self.check_keyword(kw::Box) {
-                // Suggest `box ref` and quit parsing pattern to prevent series of
-                // misguided diagnostics from later stages of the compiler.
+                // Suggest `box ref`.
                 let span = self.prev_token.span.to(self.token.span);
-                return Err(self.sess.create_err(SwitchRefBoxOrder { span }));
+                self.bump();
+                self.sess.emit_err(SwitchRefBoxOrder { span });
             }
             // Parse ref ident @ pat / ref mut ident @ pat
             let mutbl = self.parse_mutability();
diff --git a/tests/ui/pattern/pattern-bad-ref-box-order.fixed b/tests/ui/pattern/pattern-bad-ref-box-order.fixed
index e99ab449a6cfc..8825744a08b1d 100644
--- a/tests/ui/pattern/pattern-bad-ref-box-order.fixed
+++ b/tests/ui/pattern/pattern-bad-ref-box-order.fixed
@@ -5,10 +5,8 @@
 
 fn foo(f: Option<Box<i32>>) {
     match f {
-        Some(box ref, _i) => {},
+        Some(box ref _i) => {},
         //~^ ERROR switch the order of `ref` and `box`
-        //~| ERROR expected one of `)`, `,`, or `|`, found `_i`
-        //~| ERROR this pattern has 2 fields, but the corresponding tuple variant has 1 field
         None => {}
     }
 }
diff --git a/tests/ui/pattern/pattern-bad-ref-box-order.rs b/tests/ui/pattern/pattern-bad-ref-box-order.rs
index 3632bb438de0f..f3fcf0ceacf0b 100644
--- a/tests/ui/pattern/pattern-bad-ref-box-order.rs
+++ b/tests/ui/pattern/pattern-bad-ref-box-order.rs
@@ -7,8 +7,6 @@ fn foo(f: Option<Box<i32>>) {
     match f {
         Some(ref box _i) => {},
         //~^ ERROR switch the order of `ref` and `box`
-        //~| ERROR expected one of `)`, `,`, or `|`, found `_i`
-        //~| ERROR this pattern has 2 fields, but the corresponding tuple variant has 1 field
         None => {}
     }
 }
diff --git a/tests/ui/pattern/pattern-bad-ref-box-order.stderr b/tests/ui/pattern/pattern-bad-ref-box-order.stderr
index 0d3ab6394469c..a49f05c1028d8 100644
--- a/tests/ui/pattern/pattern-bad-ref-box-order.stderr
+++ b/tests/ui/pattern/pattern-bad-ref-box-order.stderr
@@ -4,23 +4,5 @@ error: switch the order of `ref` and `box`
 LL |         Some(ref box _i) => {},
    |              ^^^^^^^ help: swap them: `box ref`
 
-error: expected one of `)`, `,`, or `|`, found `_i`
-  --> $DIR/pattern-bad-ref-box-order.rs:8:22
-   |
-LL |         Some(ref box _i) => {},
-   |                     -^^ expected one of `)`, `,`, or `|`
-   |                     |
-   |                     help: missing `,`
-
-error[E0023]: this pattern has 2 fields, but the corresponding tuple variant has 1 field
-  --> $DIR/pattern-bad-ref-box-order.rs:8:22
-   |
-LL |         Some(ref box _i) => {},
-   |                      ^^ expected 1 field, found 2
-  --> $SRC_DIR/core/src/option.rs:LL:COL
-   |
-   = note: tuple variant has 1 field
-
-error: aborting due to 3 previous errors
+error: aborting due to 1 previous error
 
-For more information about this error, try `rustc --explain E0023`.