[Bug]: languageOptions.parserOptions.jsx related options (jsxPragma, jsxFragmentName) are ignored/broken

[swwind]

System Info

System:
  OS: Linux (x64)
npmPackages:
  @rslint/core: 0.6.5

Details

When configuring custom JSX pragmas (e.g., jsxPragma: 'h' and jsxFragmentName: 'Fragment' for Preact or custom JSX frameworks) under languageOptions.parserOptions, Rslint fails to respect them. This results in false-positive unused variable/import warnings (e.g. 'h' is defined but never used) because Rslint incorrectly defaults the JSX pragma name to 'React'.

We traced this behavior to two distinct issues in the codebase:

1. Scope Analyzer Option Drop (JS/TS worker):
   In packages/rslint/src/eslint-plugin/linter/ecma-language-plugin.ts (lines 271–284), the scope manager factory is instantiated without jsxPragma or jsxFragmentName:

   const scopeManagerFactory = (() => {
     const inner = makeScopeManagerFactory(ast, {
       filePath: req.filePath,
       sourceType: req.languageOptions?.sourceType ?? 'module',
       ecmaVersion: req.languageOptions?.ecmaVersion,
       globals,
       impliedStrict: ecmaFeatures?.impliedStrict,
       globalReturn: ecmaFeatures?.globalReturn,
       // missing jsxPragma and jsxFragmentName!
     });

   This causes ts-scope-manager in the Node/JS worker to fall back to 'React', which impacts any scope/variable checking rules running inside the worker (like react/jsx-uses-vars).

2. Go Config Merge Key Override:
   In internal/config/config.go (lines 569–583), mergeLanguageOptions only performs a shallow merge of the raw parserOptions map. If a base config configures parserOptions.project and a sub-config override configures parserOptions.jsxPragma, the parserOptions map is replaced entirely, throwing away project configurations on the wire:

   if len(override.Raw) > 0 {
       mergedRaw := make(map[string]any, len(base.Raw)+len(override.Raw))
       for k, v := range base.Raw {
           mergedRaw[k] = v
       }
       for k, v := range override.Raw {
           mergedRaw[k] = v // completely overwrites nested objects like parserOptions
       }
       merged.Raw = mergedRaw
   }

3. Fallback Program compiler options:
   In cmd/rslint/programs.go, the directory-scan/fallback compiler.Program options do not map jsxPragma or jsxFragmentName to core.CompilerOptions.JsxFactory. Go's native rules (like @typescript-eslint/no-unused-vars) therefore fall back to looking for React.

Reproduce Steps

1. Create a minimal project with a single JSX file src/index.jsx (no tsconfig.json present to ensure pure-linter config mapping is tested):

   // src/index.jsx
   import { h } from 'preact';
   
   export function App() {
     return <div>Hello Preact</div>;
   }

2. Create identical configurations for ESLint and Rslint targeting this file:

   • eslint.config.js:

     import tsParser from '@typescript-eslint/parser';
     import tsPlugin from '@typescript-eslint/eslint-plugin';
     
     export default [
       {
         files: ['src/**/*.jsx'],
         plugins: {
           '@typescript-eslint': tsPlugin,
         },
         languageOptions: {
           parser: tsParser,
           parserOptions: {
             ecmaFeatures: { jsx: true },
             jsxPragma: 'h',
             jsxFragmentName: 'Fragment',
           }
         },
         rules: {
           '@typescript-eslint/no-unused-vars': 'error'
         }
       }
     ];

   • rslint.config.mjs:

     import { defineConfig } from '@rslint/core';
     
     export default defineConfig([
       {
         files: ['src/**/*.jsx'],
         plugins: ['@typescript-eslint'],
         languageOptions: {
           parserOptions: {
             ecmaFeatures: { jsx: true },
             jsxPragma: 'h',
             jsxFragmentName: 'Fragment',
           }
         },
         rules: {
           '@typescript-eslint/no-unused-vars': 'error'
         }
       }
     ]);

3. Run ESLint:

   npx eslint src/index.jsx

   • Result: 0 problems (passes cleanly, because h is recognized as the JSX pragma).

4. Run Rslint:

   npx rslint --config rslint.config.mjs src/index.jsx

   • Result:

       @typescript-eslint/no-unused-vars  — [error] 'h' is defined but never used.
       ╭─┴──────────( src/index.jsx:1:10 )─────
       │ 1 │  import { h } from 'preact';
       │ 2 │  
       ╰────────────────────────────────