Fix multi-backpassing in top-level defs

Fixes #4821

crates/compiler/parse/src/expr.rs

@@ -924,7 +924,7 @@ macro_rules! join_alias_to_body {
 }
 
 fn parse_defs_end<'a>(
-    _options: ExprParseOptions,
+    options: ExprParseOptions,
     min_indent: u32,
     mut defs: Defs<'a>,
     arena: &'a Bump,
@@ -935,7 +935,7 @@ fn parse_defs_end<'a>(
     loop {
         let state = global_state;
 
-        global_state = match parse_single_def(_options, min_indent, arena, state) {
+        global_state = match parse_single_def(options, min_indent, arena, state) {
             Ok((_, Some(single_def), next_state)) => {
                 let region = single_def.region;
                 let spaces_before_current = single_def.spaces_before;
@@ -1953,7 +1953,7 @@ pub fn toplevel_defs<'a>() -> impl Parser<'a, Defs<'a>, EExpr<'a>> {
         let start_column = state.column();
 
         let options = ExprParseOptions {
-            accept_multi_backpassing: false,
+            accept_multi_backpassing: true,
             check_for_arrow: true,
         };
 

crates/compiler/test_syntax/tests/snapshots/pass/multi_backpassing_in_def.moduledefs.formatted.roc

@@ -0,0 +1,3 @@
+main =
+    arg1, arg2 <- f {}
+    "Roc <3 Zig!\n"

crates/compiler/test_syntax/tests/snapshots/pass/multi_backpassing_in_def.moduledefs.result-ast

@@ -0,0 +1,67 @@
+Defs {
+    tags: [
+        Index(2147483648),
+    ],
+    regions: [
+        @0-50,
+    ],
+    space_before: [
+        Slice(start = 0, length = 0),
+    ],
+    space_after: [
+        Slice(start = 0, length = 0),
+    ],
+    spaces: [],
+    type_defs: [],
+    value_defs: [
+        Body(
+            @0-4 Identifier(
+                "main",
+            ),
+            @12-50 SpaceBefore(
+                Backpassing(
+                    [
+                        @12-16 Identifier(
+                            "arg1",
+                        ),
+                        @18-22 Identifier(
+                            "arg2",
+                        ),
+                    ],
+                    @26-30 Apply(
+                        @26-27 Var {
+                            module_name: "",
+                            ident: "f",
+                        },
+                        [
+                            @28-30 Record(
+                                [],
+                            ),
+                        ],
+                        Space,
+                    ),
+                    @35-50 SpaceBefore(
+                        Str(
+                            Line(
+                                [
+                                    Plaintext(
+                                        "Roc <3 Zig!",
+                                    ),
+                                    EscapedChar(
+                                        Newline,
+                                    ),
+                                ],
+                            ),
+                        ),
+                        [
+                            Newline,
+                        ],
+                    ),
+                ),
+                [
+                    Newline,
+                ],
+            ),
+        ),
+    ],
+}

crates/compiler/test_syntax/tests/snapshots/pass/multi_backpassing_in_def.moduledefs.roc

@@ -0,0 +1,3 @@
+main = 
+    arg1, arg2 <- f {}
+    "Roc <3 Zig!\n"

crates/compiler/test_syntax/tests/test_snapshots.rs

@@ -309,6 +309,7 @@ mod test_snapshots {
         pass/mixed_docs.expr,
         pass/module_def_newline.moduledefs,
         pass/multi_backpassing.expr,
+        pass/multi_backpassing_in_def.moduledefs,
         pass/multi_backpassing_with_apply.expr,
         pass/multi_char_string.expr,
         pass/multiline_string.expr,