From 3cfa2010dc6aa4b19ee2394ad8db862150a018cf Mon Sep 17 00:00:00 2001
From: Isaac Rowntree <isaac@rowntree.me>
Date: Fri, 20 Mar 2026 13:04:16 +1100
Subject: [PATCH] fix(TextInput): fall back to theme fontWeight when style
 doesn't provide one
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Content-Type: text/plain; charset=UTF-8
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Both TextInputOutlined and TextInputFlat destructure `fontWeight` from the
user's `style` prop and spread it after the theme font object:

    const { fontWeight } = StyleSheet.flatten(style) || {};
    textStyle: { ...font, fontWeight }

When the user doesn't set `fontWeight` in their style, the destructured
value is `undefined`. Spreading `{ ...font, fontWeight: undefined }` then
overrides `font.fontWeight` (e.g. '400' from the theme) with `undefined`.

On React Native's Fabric renderer (New Architecture), this `undefined`
flows through as nil to the native `RCTGetFontWeight` function, which
passes it to `CFStringFind` → `CFStringGetLength` on a NULL pointer →
EXC_BAD_ACCESS (SIGSEGV).

The fix renames the destructured variable to `fontWeightStyle` and uses
nullish coalescing to fall back to the theme font's fontWeight:

    const fontWeight = fontWeightStyle ?? font.fontWeight;

This preserves the existing behavior when `fontWeight` IS provided in the
style prop, while preventing the nil crash when it isn't.
---
 src/components/TextInput/TextInputFlat.tsx     | 3 ++-
 src/components/TextInput/TextInputOutlined.tsx | 3 ++-
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/components/TextInput/TextInputFlat.tsx b/src/components/TextInput/TextInputFlat.tsx
index 378366e176..447bf810c2 100644
--- a/src/components/TextInput/TextInputFlat.tsx
+++ b/src/components/TextInput/TextInputFlat.tsx
@@ -88,12 +88,13 @@ const TextInputFlat = ({
   const {
     fontSize: fontSizeStyle,
     lineHeight: lineHeightStyle,
-    fontWeight,
+    fontWeight: fontWeightStyle,
     height,
     paddingHorizontal,
     textAlign,
     ...viewStyle
   } = (StyleSheet.flatten(style) || {}) as TextStyle;
+  const fontWeight = fontWeightStyle ?? font.fontWeight;
   const fontSize = fontSizeStyle || MAXIMIZED_LABEL_FONT_SIZE;
   const lineHeight =
     lineHeightStyle || (Platform.OS === 'web' ? fontSize * 1.2 : undefined);
diff --git a/src/components/TextInput/TextInputOutlined.tsx b/src/components/TextInput/TextInputOutlined.tsx
index 70b590fabb..03bc6732d4 100644
--- a/src/components/TextInput/TextInputOutlined.tsx
+++ b/src/components/TextInput/TextInputOutlined.tsx
@@ -90,13 +90,14 @@ const TextInputOutlined = ({
 
   const {
     fontSize: fontSizeStyle,
-    fontWeight,
+    fontWeight: fontWeightStyle,
     lineHeight: lineHeightStyle,
     height,
     backgroundColor = colors?.background,
     textAlign,
     ...viewStyle
   } = (StyleSheet.flatten(style) || {}) as TextStyle;
+  const fontWeight = fontWeightStyle ?? font.fontWeight;
   const fontSize = fontSizeStyle || MAXIMIZED_LABEL_FONT_SIZE;
   const lineHeight =
     lineHeightStyle || (Platform.OS === 'web' ? fontSize * 1.2 : undefined);