From 33ed87cacb4d4761dfadcfc2a5a08e7b3b4798c6 Mon Sep 17 00:00:00 2001
From: Yuki Omoto <yukeomoto@gmail.com>
Date: Sun, 26 Mar 2023 21:04:26 +0900
Subject: [PATCH] Add missing parentheses of type annotation in docs

This commit adds parentheses for type annotation of nested function
as in `mapWithIndex : List a, (a, Nat -> b) -> List b`.

This resolves #4698
---
 crates/docs/src/lib.rs | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/crates/docs/src/lib.rs b/crates/docs/src/lib.rs
index d72239d66b..073c3418dc 100644
--- a/crates/docs/src/lib.rs
+++ b/crates/docs/src/lib.rs
@@ -540,6 +540,9 @@ fn type_annotation_to_html(
             type_annotation_to_html(indent_level, buf, extension, true);
         }
         TypeAnnotation::Function { args, output } => {
+            if needs_parens {
+                buf.push('(');
+            }
             let mut peekable_args = args.iter().peekable();
             while let Some(arg) = peekable_args.next() {
                 if is_multiline {
@@ -549,7 +552,11 @@ fn type_annotation_to_html(
                     indent(buf, indent_level + 1);
                 }
 
-                type_annotation_to_html(indent_level, buf, arg, false);
+                let child_needs_parens = match arg {
+                    TypeAnnotation::Function { args: _, output: _ } => true,
+                    _ => false,
+                };
+                type_annotation_to_html(indent_level, buf, arg, child_needs_parens);
 
                 if peekable_args.peek().is_some() {
                     buf.push_str(", ");
@@ -570,6 +577,9 @@ fn type_annotation_to_html(
             }
 
             type_annotation_to_html(next_indent_level, buf, output, false);
+            if needs_parens {
+                buf.push(')');
+            }
         }
         TypeAnnotation::Ability { members: _ } => {
             // TODO(abilities): fill me in