From 94cc7cbedb145ddc5e95442587f02186d3269789 Mon Sep 17 00:00:00 2001
From: Carson Full <carson_full@tsco.org>
Date: Mon, 3 Jun 2024 13:15:46 -0500
Subject: [PATCH] Fix `MadeEnum<'a'>` to be compatible with `MadeEnum<string>`

Disallow direct access to member values when referencing generically

```ts
let Color: MadeEnum<'red' | 'blue'>;
let AnEnum: MadeEnum<string>;
```
Without this change `Color` can't be assigned to `AnEnum`, because
the TS defines the member values as an index: `{ [x: string]: string }`.
So since one has an index accessor and one doesn't,
making them incompatible.

The `entry()` arg type change also allows them to be compatible.
Without it TS thinks something like `entry()` fn accepting any `string`
is not compatible with `entry()` fn only accepting `'red' | 'blue'`.
Using another generic at the function level somehow works around this,
while still maintaining all the strictness.
---
 src/common/make-enum.ts | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/src/common/make-enum.ts b/src/common/make-enum.ts
index 6f939080ec..637d6c8b58 100644
--- a/src/common/make-enum.ts
+++ b/src/common/make-enum.ts
@@ -12,13 +12,18 @@ export type MadeEnum<
   Values extends string,
   ValueDeclaration = EnumValueDeclarationShape,
   Extra = unknown,
-> = {
-  readonly [Value in Values & string]: Value;
-} & EnumHelpers<
+> = EnumHelpers<
   Values,
   ValueDeclaration & ImplicitValueDeclarationShape<Values>
 > &
-  Readonly<Extra>;
+  Readonly<Extra> &
+  // Allow direct access to the values if they're strict.
+  // For generic `string` we don't allow this.
+  // This allows strict values to be compatible with generic values.
+  // MadeEnum<string> = MadeEnum<X>
+  (string extends Values
+    ? unknown // ignore addition
+    : { readonly [Value in Values & string]: Value });
 
 interface EnumOptions<
   ValueDeclaration extends EnumValueDeclarationShape,
@@ -217,7 +222,7 @@ type NormalizedValueDeclaration<Declaration extends EnumValueDeclarationShape> =
 interface EnumHelpers<Values extends string, ValueDeclaration> {
   readonly values: ReadonlySet<Values>;
   readonly entries: ReadonlyArray<Readonly<ValueDeclaration>>;
-  readonly entry: (value: Values) => Readonly<ValueDeclaration>;
+  readonly entry: <V extends Values>(value: V) => Readonly<ValueDeclaration>;
   readonly has: <In extends string>(
     value: In & {},
   ) => value is In & Values & {};