From bdb7f7caf72e3f24c43586354044a7940c0e51a9 Mon Sep 17 00:00:00 2001
From: Spotandjake <40705786+spotandjake@users.noreply.github.com>
Date: Sun, 16 Feb 2025 17:49:39 -0500
Subject: [PATCH] fix(grainfmt): Correct formatting of nested constraints
 (#2245)

---
 compiler/src/formatting/fmt.re                 | 7 +++++++
 compiler/test/grainfmt/constraints.expected.gr | 5 +++++
 compiler/test/grainfmt/constraints.input.gr    | 5 +++++
 3 files changed, 17 insertions(+)

diff --git a/compiler/src/formatting/fmt.re b/compiler/src/formatting/fmt.re
index ad1bd25242..f64bfaf079 100644
--- a/compiler/src/formatting/fmt.re
+++ b/compiler/src/formatting/fmt.re
@@ -258,6 +258,13 @@ let needs_grouping = (~parent, ~side: infix_side, expr) => {
   | (PExpConstant(PConstNumber(PConstNumberRational(_))), _)
       when op_precedence('/') <= precedence(parent) =>
     ParenGrouping
+  | (PExpConstraint(_, _), _)
+      when
+        switch (parent.pexp_desc) {
+        | PExpConstraint(_, _) => true
+        | _ => false
+        } =>
+    ParenGrouping
   | _ => FormatterGrouping
   };
 };
diff --git a/compiler/test/grainfmt/constraints.expected.gr b/compiler/test/grainfmt/constraints.expected.gr
index 6f307c7fef..fb93f3e8e4 100644
--- a/compiler/test/grainfmt/constraints.expected.gr
+++ b/compiler/test/grainfmt/constraints.expected.gr
@@ -8,3 +8,8 @@ let test = test => {
     print(i)
   }, test: List<Number>)
 }
+
+// Regression #2244
+(1: Number): Number
+
+((1: Number): Number): Number
diff --git a/compiler/test/grainfmt/constraints.input.gr b/compiler/test/grainfmt/constraints.input.gr
index 6f307c7fef..fb93f3e8e4 100644
--- a/compiler/test/grainfmt/constraints.input.gr
+++ b/compiler/test/grainfmt/constraints.input.gr
@@ -8,3 +8,8 @@ let test = test => {
     print(i)
   }, test: List<Number>)
 }
+
+// Regression #2244
+(1: Number): Number
+
+((1: Number): Number): Number