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A value the compiler can only partly convert is kept in part: --t: 10px 1cap renders translate: var(--t) as { translate: true } #523
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 declaration whose value does not match its property's grammar is invalid and ignored, and a var() that substitutes such a value makes the declaration invalid at computed-value time, so the property is unset. The compiler keeps the tokens it can convert and drops the rest: translate: 10px 1cap moves the element 10px, and the same value through a variable renders { translate: true }; font-family: Inter, Helvetica,, a stack with an empty entry, sets the array ["Inter", "Helvetica"] either way.
All four fail, the element receiving:
translate: {"transform": [{"translateX": 10}, {"translateY": undefined}]}
translate through a variable: {"transform": [{"translate": true}]}
font-family: {"fontFamily": ["Inter", "Helvetica"]}
font-family through a variable: {"fontFamily": ["Inter", "Helvetica"]}
reduceParseUnparsed (src/compiler/declarations.ts) maps every token through parseUnparsed and keeps what is not undefined; parseUnparsed returns undefined, with a warning, for a length whose unit it cannot convert, for inherit and initial, and for a token it does not read, and an empty entry between commas leaves no group. #389 and #417 ignore the written translate and font stack; a custom property's value goes through reduceParseUnparsed and keeps what it can convert.
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/custom-property-partial-value.test.tsx, and install:git clone --branch repro/523-custom-property-drops-what-it-cannot-take https://github.com/YevheniiKotyrlo/react-native-css cd react-native-css yarn install - Run
yarn jest src/__tests__/native/custom-property-partial-value.test.tsx.
src/__tests__/native/custom-property-partial-value.test.tsx:
import { render, screen } from "@testing-library/react-native";
import { Text } from "react-native-css/components/Text";
import { View } from "react-native-css/components/View";
import { registerCSS, testID } from "react-native-css/jest";
test.each([
["translate", ".a { translate: 10px 1cap; }"],
[
"translate through a variable",
":root { --t: 10px 1cap; } .a { translate: var(--t); }",
],
])("%s holding 10px 1cap leaves the element untranslated", (_, css) => {
registerCSS(css, { inlineVariables: false });
render(<View testID={testID} className="a" />);
expect(screen.getByTestId(testID).props.style).toBeUndefined();
});
test.each([
["font-family", ".a { font-family: Inter, Helvetica,; }"],
[
"font-family through a variable",
":root { --t: Inter, Helvetica,; } .a { font-family: var(--t); }",
],
])("%s holding Inter, Helvetica, sets no font", (_, css) => {
registerCSS(css, { inlineVariables: false });
render(<Text testID={testID} className="a" />);
expect(screen.getByTestId(testID).props.style).toBeUndefined();
});Expected: a value the compiler cannot convert whole leaves its property unset, written or read through a variable.
Actual: the parts it can convert are kept: translate: var(--t) over 10px 1cap renders { translate: true }, and font-family: Inter, Helvetica, sets ["Inter", "Helvetica"].
The run's output on main at 2421ea7, Windows 11, Node 26.12.1
FAIL src/__tests__/native/custom-property-partial-value.test.tsx
× translate holding 10px 1cap leaves the element untranslated (20 ms)
× translate through a variable holding 10px 1cap leaves the element untranslated (5 ms)
× font-family holding Inter, Helvetica, sets no font (2 ms)
× font-family through a variable holding Inter, Helvetica, sets no font (1 ms)
● translate holding 10px 1cap leaves the element untranslated
expect(received).toBeUndefined()
Received: {"transform": [{"translateX": 10}, {"translateY": undefined}]}
13 | registerCSS(css, { inlineVariables: false });
14 | render(<View testID={testID} className="a" />);
> 15 | expect(screen.getByTestId(testID).props.style).toBeUndefined();
| ^
16 | });
17 |
18 | test.each([
at toBeUndefined (src/__tests__/native/custom-property-partial-value.test.tsx:15:50)
● translate through a variable holding 10px 1cap leaves the element untranslated
expect(received).toBeUndefined()
Received: {"transform": [{"translate": true}]}
13 | registerCSS(css, { inlineVariables: false });
14 | render(<View testID={testID} className="a" />);
> 15 | expect(screen.getByTestId(testID).props.style).toBeUndefined();
| ^
16 | });
17 |
18 | test.each([
at toBeUndefined (src/__tests__/native/custom-property-partial-value.test.tsx:15:50)
● font-family holding Inter, Helvetica, sets no font
expect(received).toBeUndefined()
Received: {"fontFamily": ["Inter", "Helvetica"]}
25 | registerCSS(css, { inlineVariables: false });
26 | render(<Text testID={testID} className="a" />);
> 27 | expect(screen.getByTestId(testID).props.style).toBeUndefined();
| ^
28 | });
29 |
at toBeUndefined (src/__tests__/native/custom-property-partial-value.test.tsx:27:50)
● font-family through a variable holding Inter, Helvetica, sets no font
expect(received).toBeUndefined()
Received: {"fontFamily": ["Inter", "Helvetica"]}
25 | registerCSS(css, { inlineVariables: false });
26 | render(<Text testID={testID} className="a" />);
> 27 | expect(screen.getByTestId(testID).props.style).toBeUndefined();
| ^
28 | });
29 |
at toBeUndefined (src/__tests__/native/custom-property-partial-value.test.tsx:27:50)
Test Suites: 1 failed, 1 total
Tests: 4 failed, 4 total
Snapshots: 0 total
Time: 1.107 s, estimated 2 s
Ran all test suites matching /src\\__tests__\\native\\custom-property-partial-value.test.tsx/i.
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