From a57c44e8f2e85de2527fd088de69a4047f659ee6 Mon Sep 17 00:00:00 2001
From: Jon Thompson <660222+jonthomp@users.noreply.github.com>
Date: Wed, 11 Nov 2026 00:23:21 +0000
Subject: [PATCH] fix(compiler): keep a custom property declared as 0

parseUnparsed returned nothing when its reduced token list was falsy, so
`--my-var: 0` compiled to no declaration. A var() reading it fell through to
the inherited value, the :root value or its fallback instead of 0.

The check now drops only an undefined result.
---
 src/__tests__/native/variables.test.tsx | 14 ++++++++++++++
 src/compiler/declarations.ts            |  2 +-
 2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/src/__tests__/native/variables.test.tsx b/src/__tests__/native/variables.test.tsx
index 25ac30f5..15a2c5c2 100644
--- a/src/__tests__/native/variables.test.tsx
+++ b/src/__tests__/native/variables.test.tsx
@@ -53,6 +53,20 @@ test("combined inline variables", () => {
   });
 });
 
+test("a custom property declared as 0 keeps its value", () => {
+  // Two definitions, so the compiler cannot inline `--my-var`.
+  registerCSS(`
+    .zero { --my-var: 0; }
+    .one { --my-var: 1; }
+    .test { opacity: var(--my-var, 0.5); }
+  `);
+
+  render(<View testID={testID} className="test zero" />);
+
+  const component = screen.getByTestId(testID);
+  expect(component.props.style).toStrictEqual({ opacity: 0 });
+});
+
 test("inherit variables", () => {
   registerCSS(`
     .my-class-1 { width: var(--my-var); }
diff --git a/src/compiler/declarations.ts b/src/compiler/declarations.ts
index 2f0b8a4a..efdd9a50 100644
--- a/src/compiler/declarations.ts
+++ b/src/compiler/declarations.ts
@@ -1198,7 +1198,7 @@ export function parseUnparsed(
       property,
       allowAuto,
     );
-    if (!args) return;
+    if (args === undefined) return;
     if (Array.isArray(args) && args.length === 1) {
       return args[0];
     } else if (