From 0f0276a858d7e481dfab88a46feeeb9de752ec49 Mon Sep 17 00:00:00 2001
From: Alyssa Haroldsen <kupiakos@gmail.com>
Date: Mon, 1 Jun 2026 14:17:45 -0700
Subject: [PATCH] Parse unnamed enum variants

As of writing, this is still rejected by rustc at a later stage.
---
 crates/parser/src/grammar/items/adt.rs        | 31 ++++++++++---------
 .../test_data/parser/ok/0019_enums.rast       | 10 ++++++
 .../parser/test_data/parser/ok/0019_enums.rs  |  1 +
 crates/syntax/rust.ungram                     |  2 +-
 crates/syntax/src/ast/generated/nodes.rs      |  2 ++
 5 files changed, 31 insertions(+), 15 deletions(-)

diff --git a/crates/parser/src/grammar/items/adt.rs b/crates/parser/src/grammar/items/adt.rs
index a030190ad34b..33e19f5725b3 100644
--- a/crates/parser/src/grammar/items/adt.rs
+++ b/crates/parser/src/grammar/items/adt.rs
@@ -87,24 +87,27 @@ pub(crate) fn variant_list(p: &mut Parser<'_>) {
         attributes::outer_attrs(p);
         if p.at(IDENT) {
             name(p);
-            match p.current() {
-                T!['{'] => record_field_list(p),
-                T!['('] => tuple_field_list(p),
-                _ => (),
-            }
-
-            // test variant_discriminant
-            // enum E { X(i32) = 10 }
-            if p.eat(T![=]) {
-                let m = p.start();
-                expressions::expr(p);
-                m.complete(p, CONST_ARG);
-            }
-            m.complete(p, VARIANT);
+        } else if p.at(T![_]) {
+            p.bump(T![_]);
         } else {
             m.abandon(p);
             p.err_and_bump("expected enum variant");
+            return;
+        }
+        match p.current() {
+            T!['{'] => record_field_list(p),
+            T!['('] => tuple_field_list(p),
+            _ => (),
+        }
+
+        // test variant_discriminant
+        // enum E { X(i32) = 10 }
+        if p.eat(T![=]) {
+            let m = p.start();
+            expressions::expr(p);
+            m.complete(p, CONST_ARG);
         }
+        m.complete(p, VARIANT);
     }
 }
 
diff --git a/crates/parser/test_data/parser/ok/0019_enums.rast b/crates/parser/test_data/parser/ok/0019_enums.rast
index 51837e5372a7..24256ea29436 100644
--- a/crates/parser/test_data/parser/ok/0019_enums.rast
+++ b/crates/parser/test_data/parser/ok/0019_enums.rast
@@ -151,6 +151,16 @@ SOURCE_FILE
           L_PAREN "("
           R_PAREN ")"
       COMMA ","
+      WHITESPACE "\n    "
+      VARIANT
+        UNDERSCORE "_"
+        WHITESPACE " "
+        EQ "="
+        WHITESPACE " "
+        CONST_ARG
+          RANGE_EXPR
+            DOT2 ".."
+      COMMA ","
       WHITESPACE "\n"
       R_CURLY "}"
   WHITESPACE "\n"
diff --git a/crates/parser/test_data/parser/ok/0019_enums.rs b/crates/parser/test_data/parser/ok/0019_enums.rs
index 7a1afa0e62f1..f548479e45d8 100644
--- a/crates/parser/test_data/parser/ok/0019_enums.rs
+++ b/crates/parser/test_data/parser/ok/0019_enums.rs
@@ -22,4 +22,5 @@ enum E5 {
     F {},
     D(u32,),
     E(),
+    _ = ..,
 }
diff --git a/crates/syntax/rust.ungram b/crates/syntax/rust.ungram
index 408f2f4b32c7..af50ed165619 100644
--- a/crates/syntax/rust.ungram
+++ b/crates/syntax/rust.ungram
@@ -305,7 +305,7 @@ VariantList =
 
 Variant =
   Attr* Visibility?
-  Name FieldList? ('=' ConstArg)?
+  (Name | '_') FieldList? ('=' ConstArg)?
 
 Union =
   Attr* Visibility?
diff --git a/crates/syntax/src/ast/generated/nodes.rs b/crates/syntax/src/ast/generated/nodes.rs
index c18311bfa3ad..71f23fe08750 100644
--- a/crates/syntax/src/ast/generated/nodes.rs
+++ b/crates/syntax/src/ast/generated/nodes.rs
@@ -2059,6 +2059,8 @@ impl Variant {
     pub fn field_list(&self) -> Option<FieldList> { support::child(&self.syntax) }
     #[inline]
     pub fn eq_token(&self) -> Option<SyntaxToken> { support::token(&self.syntax, T![=]) }
+    #[inline]
+    pub fn underscore_token(&self) -> Option<SyntaxToken> { support::token(&self.syntax, T![_]) }
 }
 pub struct VariantList {
     pub(crate) syntax: SyntaxNode,