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A keyword read through a variable keeps its case: `--v: ABSOLUTE; position: var(--v)` reaches React Native as `"ABSOLUTE"`

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Đánh giá

Độ khó
3/5
Thời gian dự kiến
1-2 ngày
Mức phù hợp với người mới
72/100
Loại issue
Lỗi
Độ rõ ràng
Đặc tả rõ ràng
Mức độ hoạt động
Sôi nổi
Công nghệ
javascript, react-native, typescript
Lĩnh vực
frontend, mobile

Hướng nghiên cứu

Start with parseUnparsed in src/compiler/declarations.ts, then trace how a resolved var() reaches the React Native style. Run the reproducer from src/__tests__/native/keyword-case.test.tsx on the linked branch; its output compares written keywords with variable values. Done when those routes produce the same lowercase keyword values for the reported properties.

Do mô hình lập chỉ mục viết ra từ nội dung của issue.

Mô tả

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

CSS keywords are ASCII case-insensitive, and lightningcss lowercases a written one: position: ABSOLUTE renders position: "absolute". The same keyword held in a variable the runtime keeps reaches React Native as written, position: "ABSOLUTE", which React Native does not read, and so do flex-direction, transition-timing-function and animation-direction.

position: ABSOLUTE
written: {"position":"absolute"}
kept:    {"position":"ABSOLUTE"}
flex-direction: Row
written: {"flexDirection":"row"}
kept:    {"flexDirection":"Row"}
transition-timing-function: EASE-IN
written: {"transitionTimingFunction":"ease-in"}
kept:    {"transitionTimingFunction":"EASE-IN"}
animation-direction: ALTERNATE
written: {"animationDirection":["alternate"]}
kept:    {"animationDirection":"ALTERNATE"}

Expected: the kept route renders the written route's lowercase keyword. parseUnparsed (src/compiler/declarations.ts) stores an ident token's value as written, and the runtime hands a resolved var() to the style as it is; only the typed route, through lightningcss, folds a keyword's case.

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 found
Steps to reproduce
  1. Clone the reproducer branch, which is main at 2421ea7 with one file added, src/__tests__/native/keyword-case.test.tsx, and install: 
    git clone --branch repro/529-keyword-through-a-variable-keeps-its-case https://github.com/YevheniiKotyrlo/react-native-css
cd react-native-css
yarn install
  2. Run yarn jest src/__tests__/native/keyword-case.test.tsx.

src/__tests__/native/keyword-case.test.tsx:

// Run from a react-native-css checkout: copy to src/__tests__/native/keyword-case.test.tsx, then `yarn jest` it.
import { StyleSheet } from "react-native";

import { render, screen } from "@testing-library/react-native";
import { View } from "react-native-css/components/View";
import { registerCSS, testID } from "react-native-css/jest";

jest.mock("../../native/reanimated", () => ({
  animatedComponentFamily: (component: unknown) => component,
}));

const styleOf = (css: string, inlineVariables: boolean) => {
  registerCSS(css, inlineVariables ? {} : { inlineVariables: false });
  render(<View testID={testID} className="a" />);
  const style = StyleSheet.flatten(screen.getByTestId(testID).props.style);
  screen.unmount();
  return JSON.stringify(style);
};

test.each([
  ["position", "ABSOLUTE"],
  ["display", "NONE"],
  ["flex-direction", "Row"],
  ["transition-timing-function", "EASE-IN"],
  ["animation-direction", "ALTERNATE"],
])("%s: %s written and through a variable", (property, value) => {
  console.log(
    `${property}: ${value}\n  written: ${styleOf(`.a { ${property}: ${value}; }`, true)}\n  kept:    ${styleOf(`.a { --v: ${value}; ${property}: var(--v); }`, false)}`,
  );
});

Expected: a keyword read through a variable is lowercased as a written one is: position: "absolute".

Actual: it reaches React Native as written, position: "ABSOLUTE", which React Native does not read, and so do the other keywords the test reads.

The run's output on main at 2421ea7, Windows 11, Node 26.12.1 
  console.log
    position: ABSOLUTE
      written: {"position":"absolute"}
      kept:    {"position":"ABSOLUTE"}
      at log (src/__tests__/native/keyword-case.test.tsx:27:11)
  console.log
    flex-direction: Row
      written: {"flexDirection":"row"}
      kept:    {"flexDirection":"Row"}
      at log (src/__tests__/native/keyword-case.test.tsx:27:11)
  console.log
    transition-timing-function: EASE-IN
      written: {"transitionTimingFunction":"ease-in"}
      kept:    {"transitionTimingFunction":"EASE-IN"}
      at log (src/__tests__/native/keyword-case.test.tsx:27:11)
  console.log
    animation-direction: ALTERNATE
      written: {"animationDirection":["alternate"]}
      kept:    {"animationDirection":"ALTERNATE"}
      at log (src/__tests__/native/keyword-case.test.tsx:27:11)
FAIL src/__tests__/native/keyword-case.test.tsx
  √ position: ABSOLUTE written and through a variable (30 ms)
  × display: NONE written and through a variable (4 ms)
  √ flex-direction: Row written and through a variable (4 ms)
  √ transition-timing-function: EASE-IN written and through a variable (2 ms)
  √ animation-direction: ALTERNATE written and through a variable (2 ms)
  ● display: NONE written and through a variable
    Unable to find an element with testID: react-native-css
    <View
      style={
        {
          "display": "none",
        }
      }
      testID="react-native-css"
    />
      13 |   registerCSS(css, inlineVariables ? {} : { inlineVariables: false });
      14 |   render(<View testID={testID} className="a" />);
    > 15 |   const style = StyleSheet.flatten(screen.getByTestId(testID).props.style);
         |                                           ^
      16 |   screen.unmount();
      17 |   return JSON.stringify(style);
      18 | };
      at getByTestId (src/__tests__/native/keyword-case.test.tsx:15:43)
      at styleOf (src/__tests__/native/keyword-case.test.tsx:28:42)
Test Suites: 1 failed, 1 total
Tests:       1 failed, 4 passed, 5 total
Snapshots:   0 total
Time:        1.124 s, estimated 3 s
Ran all test suites matching /src\\__tests__\\native\\keyword-case.test.tsx/i.
Reproducible example repository

https://github.com/YevheniiKotyrlo/react-native-css/tree/repro/529-keyword-through-a-variable-keeps-its-case

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