Relax argument indentation requirements in closures

crates/compiler/load/tests/test_reporting.rs

@@ -6692,17 +6692,20 @@ All branches in an `if` must have the same type!
             )
             "
         ),
-        @r"
-    ── UNFINISHED FUNCTION in tmp/unfinished_closure_pattern_in_parens/Test.roc ────
+        @r###"
+    ── MISSING ARROW in tmp/unfinished_closure_pattern_in_parens/Test.roc ──────────
 
-    I was partway through parsing a function, but I got stuck here:
+    I am partway through parsing a function argument list, but I got stuck
+    here:
 
     4│      x = \( a
     5│      )
-             ^
+    6│
+    7│
+        ^
 
-    I just saw a pattern, so I was expecting to see a -> next.
-    "
+    I was expecting a -> next.
+    "###
     );
 
     test_report!(

crates/compiler/parse/src/expr.rs

@@ -2340,16 +2340,18 @@ pub fn parse_top_level_defs<'a>(
 
 fn closure_help<'a>(check_for_arrow: CheckForArrow) -> impl Parser<'a, Expr<'a>, EClosure<'a>> {
     one_of!(
-        closure_new_syntax_help(),
+        closure_new_syntax_help(check_for_arrow),
         closure_old_syntax_help(check_for_arrow),
     )
 }
 
-fn closure_new_syntax_help<'a>() -> impl Parser<'a, Expr<'a>, EClosure<'a>> {
+fn closure_new_syntax_help<'a>(
+    check_for_arrow: CheckForArrow,
+) -> impl Parser<'a, Expr<'a>, EClosure<'a>> {
     map_with_arena(
-        indented_seq_skip_first(
+        skip_first(
             error_on_pizza(byte_indent(b'|', EClosure::Bar), EClosure::Start),
-            and(
+            reset_min_indent(and(
                 sep_by1_e(
                     byte_indent(b',', EClosure::Comma),
                     space0_around_ee(
@@ -2363,14 +2365,9 @@ fn closure_new_syntax_help<'a>() -> impl Parser<'a, Expr<'a>, EClosure<'a>> {
                     // Parse the -> which separates params from body
                     byte(b'|', EClosure::Bar),
                     // Parse the body
-                    block(
-                        CheckForArrow(false),
-                        true,
-                        EClosure::IndentBody,
-                        EClosure::Body,
-                    ),
+                    block(check_for_arrow, true, EClosure::IndentBody, EClosure::Body),
                 ),
-            ),
+            )),
         ),
         |arena: &'a Bump, (params, body)| {
             let params: Vec<'a, Loc<Pattern<'a>>> = params;
@@ -2386,12 +2383,12 @@ fn closure_old_syntax_help<'a>(
     // closure_help_help(options)
     map_with_arena(
         // After the first token, all other tokens must be indented past the start of the line
-        indented_seq_skip_first(
+        skip_first(
             // All closures start with a '\' - e.g. (\x -> x + 1)
             byte_indent(b'\\', EClosure::Start),
             // Once we see the '\', we're committed to parsing this as a closure.
             // It may turn out to be malformed, but it is definitely a closure.
-            and(
+            reset_min_indent(and(
                 // Parse the params
                 // Params are comma-separated
                 sep_by1_e(
@@ -2409,7 +2406,7 @@ fn closure_old_syntax_help<'a>(
                     // Parse the body
                     block(check_for_arrow, true, EClosure::IndentBody, EClosure::Body),
                 ),
-            ),
+            )),
         ),
         |arena: &'a Bump, (params, body)| {
             let params: Vec<'a, Loc<Pattern<'a>>> = params;

crates/compiler/test_syntax/tests/snapshots/fail/unfinished_closure_pattern_in_parens.expr.result-ast

@@ -1 +1 @@
-Expr(Closure(IndentArrow(@10), @4), @0)
+Expr(Closure(Arrow(@11), @4), @0)

crates/compiler/test_syntax/tests/snapshots/pass/record_update_apply_closure_comments.expr.formatted.roc

@@ -0,0 +1,4 @@
+{ #
+    h &  } | #
+    i
+    | 0

crates/compiler/test_syntax/tests/snapshots/pass/record_update_apply_closure_comments.expr.result-ast

@@ -0,0 +1,41 @@
+@0-14 SpaceAfter(
+    Apply(
+        @0-6 RecordUpdate {
+            update: @3-4 SpaceBefore(
+                Var {
+                    module_name: "",
+                    ident: "h",
+                },
+                [
+                    LineComment(
+                        "",
+                    ),
+                ],
+            ),
+            fields: [],
+        },
+        [
+            @6-14 Closure(
+                [
+                    @10-11 SpaceBefore(
+                        Identifier {
+                            ident: "i",
+                        },
+                        [
+                            LineComment(
+                                "",
+                            ),
+                        ],
+                    ),
+                ],
+                @13-14 Num(
+                    "0",
+                ),
+            ),
+        ],
+        Space,
+    ),
+    [
+        Newline,
+    ],
+)

crates/compiler/test_syntax/tests/snapshots/pass/record_update_apply_closure_comments.expr.roc

@@ -0,0 +1,3 @@
+{#
+h&}\#
+ i->0

crates/compiler/test_syntax/tests/test_snapshots.rs

@@ -672,6 +672,7 @@ mod test_snapshots {
         pass/record_literal_field_bang.expr,
         pass/record_type_with_function.expr,
         pass/record_update.expr,
+        pass/record_update_apply_closure_comments.expr,
         pass/record_update_comment_before_ampersand.expr,
         pass/record_updater_closure_weirdness.expr,
         pass/record_updater_literal_apply.expr,