From 49a9d2de3b145636690f7d192f2980b3459ef6ea Mon Sep 17 00:00:00 2001
From: Mitul Agrawal <mitulagr2@gmail.com>
Date: Thu, 21 Nov 2024 17:26:39 +0530
Subject: [PATCH 1/2] add record destructure spread test

---
 .../tests/snapshots/pass/record_destructure_spread.expr.roc     | 2 ++
 crates/compiler/test_syntax/tests/test_snapshots.rs             | 1 +
 2 files changed, 3 insertions(+)
 create mode 100644 crates/compiler/test_syntax/tests/snapshots/pass/record_destructure_spread.expr.roc

diff --git a/crates/compiler/test_syntax/tests/snapshots/pass/record_destructure_spread.expr.roc b/crates/compiler/test_syntax/tests/snapshots/pass/record_destructure_spread.expr.roc
new file mode 100644
index 00000000000..5a277f9cba9
--- /dev/null
+++ b/crates/compiler/test_syntax/tests/snapshots/pass/record_destructure_spread.expr.roc
@@ -0,0 +1,2 @@
+{ x, y, .. } = 5
+y = 6
diff --git a/crates/compiler/test_syntax/tests/test_snapshots.rs b/crates/compiler/test_syntax/tests/test_snapshots.rs
index 05bf4d7e6a9..d437cb24ef5 100644
--- a/crates/compiler/test_syntax/tests/test_snapshots.rs
+++ b/crates/compiler/test_syntax/tests/test_snapshots.rs
@@ -456,6 +456,7 @@ mod test_snapshots {
         pass/record_builder.expr,
         pass/record_builder_ignored_fields.expr,
         pass/record_destructure_def.expr,
+        pass/record_destructure_spread.expr,
         pass/record_func_type_decl.expr,
         pass/record_type_with_function.expr,
         pass/record_update.expr,

From c3f050887c4d80e29564193d6afab9902b1a6980 Mon Sep 17 00:00:00 2001
From: Mitul Agrawal <mitulagr2@gmail.com>
Date: Thu, 21 Nov 2024 17:28:58 +0530
Subject: [PATCH 2/2] parsing support for record spread destructure

---
 crates/compiler/parse/src/ast.rs     | 11 ++++++++
 crates/compiler/parse/src/pattern.rs | 39 +++++++++++++++++++++-------
 2 files changed, 41 insertions(+), 9 deletions(-)

diff --git a/crates/compiler/parse/src/ast.rs b/crates/compiler/parse/src/ast.rs
index f1860100470..59ded03c950 100644
--- a/crates/compiler/parse/src/ast.rs
+++ b/crates/compiler/parse/src/ast.rs
@@ -1687,6 +1687,10 @@ pub enum Pattern<'a> {
     /// In practice, these patterns will always be Identifier
     RecordDestructure(Collection<'a, Loc<Pattern<'a>>>),
 
+    /// A record spread pattern ".."
+    /// Can only occur inside of a [Pattern::Record]
+    RecordRest(Option<(&'a [CommentOrNewline<'a>])>),
+
     /// A required field pattern, e.g. { x: Just 0 } -> ...
     /// Can only occur inside of a RecordDestructure
     RequiredField(&'a str, &'a Loc<Pattern<'a>>),
@@ -1783,6 +1787,13 @@ impl<'a> Pattern<'a> {
                     false
                 }
             }
+            RecordRest(pattern_as) => match other {
+                RecordRest(other_pattern_as) => match (pattern_as, other_pattern_as) {
+                    (Some((_, a)), Some((_, b))) => a.equivalent(b),
+                    _ => false,
+                },
+                _ => false,
+            }
             RequiredField(x, inner_x) => {
                 if let RequiredField(y, inner_y) = other {
                     x == y && inner_x.value.equivalent(&inner_y.value)
diff --git a/crates/compiler/parse/src/pattern.rs b/crates/compiler/parse/src/pattern.rs
index 74e443a5157..fa4fa5ba66f 100644
--- a/crates/compiler/parse/src/pattern.rs
+++ b/crates/compiler/parse/src/pattern.rs
@@ -475,20 +475,41 @@ fn lowercase_ident_pattern<'a>() -> impl Parser<'a, &'a str, EPattern<'a>> {
 
 #[inline(always)]
 fn record_pattern_help<'a>() -> impl Parser<'a, Pattern<'a>, PRecord<'a>> {
-    map(record_pattern_fields(), Pattern::RecordDestructure)
+    map(
+        collection_trailing_sep_e(
+            byte(b'{', PRecord::Open),
+            record_element_pattern(),
+            byte(b',', PRecord::End),
+            byte(b'}', PRecord::End),
+            Pattern::SpaceBefore,
+        ),
+        Pattern::RecordDestructure
+    )
 }
 
-pub fn record_pattern_fields<'a>() -> impl Parser<'a, Collection<'a, Loc<Pattern<'a>>>, PRecord<'a>>
-{
-    collection_trailing_sep_e(
-        byte(b'{', PRecord::Open),
-        record_pattern_field(),
-        byte(b',', PRecord::End),
-        byte(b'}', PRecord::End),
-        Pattern::SpaceBefore,
+fn record_element_pattern<'a>() -> impl Parser<'a, Loc<Pattern<'a>>, PRecord<'a>> {
+    one_of!(
+        three_record_rest_pattern_error(),
+        record_rest_pattern(),
+        record_pattern_fields(),
     )
 }
 
+fn three_record_rest_pattern_error<'a>() -> impl Parser<'a, Loc<Pattern<'a>>, PRecord<'a>> {
+    fail_when(PRecord::Rest, loc(three_bytes(b'.', b'.', b'.', PRecord::Rest)))
+}
+
+fn record_rest_pattern<'a>() -> impl Parser<'a, Loc<Pattern<'a>>, PRecord<'a>> {
+    move |arena: &'a Bump, state: State<'a>, min_indent: u32| {
+        let (_, loc_word, state) =
+            loc(two_bytes(b'.', b'.', PRecord::Open)).parse(arena, state, min_indent)?;
+
+        let no_as = Loc::at(loc_word.region, Pattern::RecordRest(None));
+
+        Ok((MadeProgress, no_as, state))
+    }
+}
+
 fn record_pattern_field<'a>() -> impl Parser<'a, Loc<Pattern<'a>>, PRecord<'a>> {
     use crate::parser::Either::*;