From dcd5968a5fa793aea4b2b12751db5a5856922efd Mon Sep 17 00:00:00 2001
From: Maxime Mangel <mangel.maxime@protonmail.com>
Date: Tue, 7 May 2024 21:54:34 +0200
Subject: [PATCH] fix: don't generate U1 if an union is resolved as a single
 possible value

[converter]
---
 src/Glutinum.Converter/Transform.fs                  |  3 +++
 .../references/unionType/singleUnionResolved.d.ts    |  1 +
 .../references/unionType/singleUnionResolved.fsx     | 12 ++++++++++++
 3 files changed, 16 insertions(+)
 create mode 100644 tests/specs/references/unionType/singleUnionResolved.d.ts
 create mode 100644 tests/specs/references/unionType/singleUnionResolved.fsx

diff --git a/src/Glutinum.Converter/Transform.fs b/src/Glutinum.Converter/Transform.fs
index 72796b3..ea80926 100644
--- a/src/Glutinum.Converter/Transform.fs
+++ b/src/Glutinum.Converter/Transform.fs
@@ -200,6 +200,9 @@ let rec private transformType
 
         if isOptional && others.Length = 1 then
             FSharpType.Option(transformType context others.Head)
+        // Don't wrap in a U1 if there is only one case
+        else if others.Length = 1 then
+            transformType context others.Head
         else
             {
                 Attributes = []
diff --git a/tests/specs/references/unionType/singleUnionResolved.d.ts b/tests/specs/references/unionType/singleUnionResolved.d.ts
new file mode 100644
index 0000000..3fb116e
--- /dev/null
+++ b/tests/specs/references/unionType/singleUnionResolved.d.ts
@@ -0,0 +1 @@
+export type ColorInfo = number | false;
diff --git a/tests/specs/references/unionType/singleUnionResolved.fsx b/tests/specs/references/unionType/singleUnionResolved.fsx
new file mode 100644
index 0000000..fd50d1e
--- /dev/null
+++ b/tests/specs/references/unionType/singleUnionResolved.fsx
@@ -0,0 +1,12 @@
+module rec Glutinum
+
+open Fable.Core
+open Fable.Core.JsInterop
+open System
+
+type ColorInfo =
+    float
+
+(***)
+#r "nuget: Fable.Core"
+(***)