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A NaN length is not censored to 0: width: var(--n) over --n: calc(NaN * 1px) renders null or nothing #539
Description
Before submitting a new issue
- I tested using the latest version of the library, as the bug might be already fixed.
- I tested using a supported version of react native.
- I checked for possible duplicate issues, with possible answers.
Bug summary
A top-level calculation that is NaN is censored to 0 (css-values-4 §10.9.1). width: var(--n) over --n: calc(NaN * 1px) renders width: null with the variable inlined, from the overflowing length lightningcss prints for a NaN, and no width with it kept, where both should be width: 0.
Both fail:
inlineVariables=true: {"width":null}
inlineVariables=false: {}
lightningcss's half, printing a NaN calc() as 5.10424e38px, is parcel-bundler/lightningcss#1405; a NaN the compiler or the runtime receives still needs censoring here.
Library version
main at 2421ea7 (0.0.0-nightly.2421ea7)
Environment info
System:
OS: Windows 11 10.0.26300
CPU: "(32) x64 AMD Ryzen 9 9950X3D 16-Core Processor "
Memory: 155.26 GB / 255.67 GB
Binaries:
Node:
version: 26.12.1
path: C:\Program Files\nodejs\node.EXE
Yarn:
version: 4.9.2
path: C:\Users\<user>\AppData\Roaming\npm\yarn.CMD
npm:
version: 12.2.1
path: C:\Program Files\nodejs\npm.CMD
Watchman: Not Found
SDKs:
Android SDK:
API Levels:
- "33"
- "35"
- "35"
- "35"
- "36"
- "37"
Build Tools:
- 35.0.0
- 36.0.0
- 36.1.0
- 37.0.0
System Images:
- android-26 | Google APIs Intel x86_64 Atom
- android-28 | Google APIs Intel x86_64 Atom
- android-29 | Google APIs Intel x86_64 Atom
- android-30 | Google APIs Intel x86_64 Atom
- android-31 | Google APIs Intel x86_64 Atom
- android-32 | Google APIs Intel x86_64 Atom
- android-33 | Google APIs Intel x86_64 Atom
- android-34 | Google APIs Intel x86_64 Atom
- android-35 | Google APIs Intel x86_64 Atom
- android-36.1 | Google Play Intel x86_64 Atom
- android-36.1 | Pre-Release 16 KB Page Size Google Play Intel x86_64 Atom
- android-37.0 | Google APIs Intel x86_64 Atom
Android NDK: Not Found
Windows SDK: Not Found
IDEs:
Android Studio: AI-262.9437.185.2621.16467767
Visual Studio: Not Found
Languages:
Java:
version: 17.0.20.1
path: C:\Program Files\Microsoft\jdk-17.0.20.101-hotspot\bin\javac.EXE
Ruby: Not Found
npmPackages:
"@react-native-community/cli": Not Found
react:
installed: 19.2.3
wanted: 19.2.3
react-native:
installed: 0.86.3
wanted: 0.86.3
react-native-windows: Not Found
npmGlobalPackages:
"*react-native*": Not Found
Android:
hermesEnabled: Not found
newArchEnabled: Not found
iOS:
hermesEnabled: Not found
newArchEnabled: Not foundSteps to reproduce
- Clone the reproducer branch, which is
mainat 2421ea7 with one file added,src/__tests__/native/nan-length.test.tsx, and install:git clone --branch repro/539-calc-nan-and-range https://github.com/YevheniiKotyrlo/react-native-css cd react-native-css yarn install - Run
yarn jest src/__tests__/native/nan-length.test.tsx.
src/__tests__/native/nan-length.test.tsx:
import { render, screen } from "@testing-library/react-native";
import { View } from "react-native-css/components/View";
import { registerCSS, testID } from "react-native-css/jest";
test.each([true, false])(
"width: var(--n) over --n: calc(NaN * 1px) is 0 (inlineVariables: %s)",
(inlineVariables) => {
registerCSS(".a { --n: calc(NaN * 1px); width: var(--n); }", inlineVariables ? {} : { inlineVariables: false });
render(<View testID={testID} className="a" />);
const { style } = screen.getByTestId(testID).props;
console.log(`inlineVariables=${inlineVariables}: ${JSON.stringify(style)}`);
expect(style).toStrictEqual({ width: 0 });
},
);Expected: a NaN length is censored to width: 0, with the variable inlined or kept.
Actual: width: null with the variable inlined, and no width with it kept.
The run's output on main at 2421ea7, Windows 11, Node 26.12.1
console.log
inlineVariables=true: {"width":null}
at log (src/__tests__/native/nan-length.test.tsx:11:13)
console.log
inlineVariables=false: {}
at log (src/__tests__/native/nan-length.test.tsx:11:13)
FAIL src/__tests__/native/nan-length.test.tsx
× width: var(--n) over --n: calc(NaN * 1px) is 0 (inlineVariables: true) (26 ms)
× width: var(--n) over --n: calc(NaN * 1px) is 0 (inlineVariables: false) (7 ms)
● width: var(--n) over --n: calc(NaN * 1px) is 0 (inlineVariables: true)
expect(received).toStrictEqual(expected) // deep equality
- Expected - 1
+ Received + 1
Object {
- "width": 0,
+ "width": NaN,
}
10 | const { style } = screen.getByTestId(testID).props;
11 | console.log(`inlineVariables=${inlineVariables}: ${JSON.stringify(style)}`);
> 12 | expect(style).toStrictEqual({ width: 0 });
| ^
13 | },
14 | );
15 |
at toStrictEqual (src/__tests__/native/nan-length.test.tsx:12:19)
● width: var(--n) over --n: calc(NaN * 1px) is 0 (inlineVariables: false)
expect(received).toStrictEqual(expected) // deep equality
- Expected - 3
+ Received + 1
- Object {
- "width": 0,
- }
+ Object {}
10 | const { style } = screen.getByTestId(testID).props;
11 | console.log(`inlineVariables=${inlineVariables}: ${JSON.stringify(style)}`);
> 12 | expect(style).toStrictEqual({ width: 0 });
| ^
13 | },
14 | );
15 |
at toStrictEqual (src/__tests__/native/nan-length.test.tsx:12:19)
Test Suites: 1 failed, 1 total
Tests: 2 failed, 2 total
Snapshots: 0 total
Time: 1.06 s, estimated 2 s
Ran all test suites matching /src\\__tests__\\native\\nan-length.test.tsx/i.
Reproducible example repository
https://github.com/YevheniiKotyrlo/react-native-css/tree/repro/539-calc-nan-and-range
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