Fix formatter bug

CHANGELOG.md

@@ -8,6 +8,8 @@
 
 ### Bug fixes
 
+- Fixed a bug where long function headers with external implementations could
+  format incorrectly.
 - The `@deprecated` attribute can now be used to annotate module constants.
   This will cause a warning to be emitted when the constant is used.
 

compiler-core/src/format.rs

@@ -527,11 +527,12 @@ impl<'comments> Formatter<'comments> {
         let signature = match &function.return_annotation {
             Some(anno) => signature.append(" -> ").append(self.type_ast(anno)),
             None => signature,
-        };
+        }
+        .group();
 
         let body = &function.body;
         if body.len() == 1 && body.first().is_placeholder() {
-            return attributes.append(signature.group());
+            return attributes.append(signature);
         }
 
         let head = attributes.append(signature);
@@ -547,7 +548,6 @@ impl<'comments> Formatter<'comments> {
 
         // Stick it all together
         head.append(" {")
-            .group()
             .append(line().append(body).nest(INDENT).group())
             .append(line())
             .append("}")

compiler-core/src/format/tests.rs

@@ -711,21 +711,30 @@ fn statement_fn() {
 }
 "#
     );
+}
 
+#[test]
+fn statement_fn1() {
     assert_format!(
         r#"fn main(label_one one, label_two two, label_three three) {
   Nil
 }
 "#
     );
+}
 
+#[test]
+fn statement_fn2() {
     assert_format!(
         r#"fn main(label_one one: One, label_two two: Two) {
   Nil
 }
 "#
     );
+}
 
+#[test]
+fn statement_fn3() {
     assert_format!(
         r#"fn main(
   label_one one: One,
@@ -744,14 +753,20 @@ fn statement_fn() {
 }
 "#
     );
+}
 
+#[test]
+fn statement_fn4() {
     assert_format!(
         r#"fn main(label _discarded) {
   Nil
 }
 "#
     );
+}
 
+#[test]
+fn statement_fn5() {
     // https://github.com/gleam-lang/gleam/issues/613
     assert_format!(
         r#"fn main() {
@@ -760,7 +775,10 @@ fn statement_fn() {
 }
 "#
     );
+}
 
+#[test]
+fn statement_fn6() {
     //
     // Module function return annotations
     //
@@ -771,7 +789,10 @@ fn statement_fn() {
 }
 "#
     );
+}
 
+#[test]
+fn statement_fn7() {
     assert_format!(
         r#"fn main() -> Loooooooooooooooooooong(
   Looooooooooooooong,
@@ -783,7 +804,10 @@ fn statement_fn() {
 }
 "#
     );
+}
 
+#[test]
+fn statement_fn8() {
     assert_format!(
         r#"fn main() -> Loooooooooooooooooooong(
   Loooooooooooooooooooooooooooooooooooooooooong,
@@ -792,24 +816,33 @@ fn statement_fn() {
 }
 "#
     );
+}
 
+#[test]
+fn statement_fn9() {
     assert_format!(
         r#"fn main() -> program.Exit {
   Nil
 }
 "#
     );
+}
 
+#[test]
+fn statement_fn10() {
     assert_format!(
         "fn order(
   first: Set(member),
   second: Set(member),
-) -> #(Set(member), Set(member)) {
+) -> #(Set(member), Set(member), a) {
   Nil
 }
 "
     );
+}
 
+#[test]
+fn statement_fn11() {
     assert_format!(
         "///
 pub fn try_map(

compiler-core/src/format/tests/external_fn.rs

@@ -75,3 +75,18 @@ fn improper_list_append(
 "#
     );
 }
+
+// Bug found by Hayleigh
+#[test]
+fn long_long_external() {
+    assert_format!(
+        r#"@external(javascript, "./client-component.ffi.mjs", "register")
+pub fn register(
+  _app: App(WebComponent, Nil, model, msg),
+  _name: String,
+) -> Result(Nil, Error) {
+  Error(NotABrowser)
+}
+"#
+    );
+}

compiler-core/src/format/tests/function.rs

@@ -229,7 +229,7 @@ fn only_last_argument_can_be_broken() {
 fn function_that_is_a_little_over_the_limit() {
     assert_format!(
         r#"pub fn handle_request(
-  handler: aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa,
+  handler: aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa,
 ) -> Nil {
   todo
 }