tsc --init update

[RyanCavanaugh]

Fixes #58420

Sample outputs

tsc --init

{
  // Visit https://aka.ms/tsconfig to read more about this file
  "compilerOptions": {
    // File Layout
    // "rootDir": "./src",
    // "outDir": "./dist",

    // Environment Settings
    // See also https://aka.ms/tsconfig_modules
    "module": "nodenext",
    "target": "esnext",
    "types": [],
    // For nodejs:
    // "lib": ["esnext"],
    // "types": ["node"],
    // and npm install -D @types/node

    // Other Outputs
    "sourceMap": true,
    "declaration": true,
    "declarationMap": true,

    // Stricter Typechecking Options
    "noUncheckedIndexedAccess": true,
    "exactOptionalPropertyTypes": true,

    // Style Options
    // "noImplicitReturns": true,
    // "noImplicitOverride": true,
    // "noUnusedLocals": true,
    // "noUnusedParameters": true,
    // "noFallthroughCasesInSwitch": true,
    // "noPropertyAccessFromIndexSignature": true,

    // Recommended Options
    "strict": true,
    "jsx": "react-jsx",
    "verbatimModuleSyntax": true,
    "isolatedModules": true,
    "noUncheckedSideEffectImports": true,
    "moduleDetection": "force",
    "skipLibCheck": true,
  }
}

tsc --init --noImplicitAny false --target es2022 --lib dom --rootDir src --types mocha --noImplicitReturns

{
  // Visit https://aka.ms/tsconfig to read more about this file
  "compilerOptions": {
    // File Layout
    "rootDir": "src",
    // "outDir": "./dist",

    // Environment Settings
    // See also https://aka.ms/tsconfig_modules
    "module": "nodenext",
    "target": "es2022",
    "types": ["mocha"],
    "lib": ["dom"],
    // For nodejs:
    // "lib": ["esnext"],
    // "types": ["node"],
    // and npm install -D @types/node

    // Other Outputs
    "sourceMap": true,
    "declaration": true,
    "declarationMap": true,

    // Stricter Typechecking Options
    "noUncheckedIndexedAccess": true,
    "exactOptionalPropertyTypes": true,

    // Style Options
    "noImplicitReturns": true,
    // "noImplicitOverride": true,
    // "noUnusedLocals": true,
    // "noUnusedParameters": true,
    // "noFallthroughCasesInSwitch": true,
    // "noPropertyAccessFromIndexSignature": true,

    // Recommended Options
    "strict": true,
    "jsx": "react-jsx",
    "verbatimModuleSyntax": true,
    "isolatedModules": true,
    "noUncheckedSideEffectImports": true,
    "moduleDetection": "force",
    "skipLibCheck": true,

    "noImplicitAny": false,
  }
}

[Copilot]

Pull Request Overview

Updates the --init logic to streamline how tsconfig.json is generated and simplify related tests and CLI handling. Key changes include:

• Refactored generateTSConfig signature and implementation to remove file list parameter and output clean, sectioned JSON.
• Updated writeConfigFile and test invocations to match new generateTSConfig signature.
• Added diagnostic message entries for each new section header.

Reviewed Changes

Copilot reviewed 15 out of 15 changed files in this pull request and generated 1 comment.

File	Description
src/compiler/commandLineParser.ts	Replaced old getCompilerOptionsDiffValue and rewritten generateTSConfig with new API.
src/compiler/executeCommandLine.ts	Updated writeConfigFile to call new generateTSConfig signature and cleaned output.
src/testRunner/unittests/config/initializeTSConfig.ts	Adjusted test helper to use new generateTSConfig(options, newLine) call.
src/compiler/diagnosticMessages.json	Inserted new diagnostic entries for section headers used in generated JSON.

Comments suppressed due to low confidence (1)

src/compiler/commandLineParser.ts:2930

• Consider appending a trailing newline to the generated config for consistency with existing baselines and editor tooling. For example: return result.join(newLine) + newLine;

    return result.join(newLine);

[jakebailey]

I was like "oh no, hope nobody calls this", but no, it's all callers from 5+ years ago (https://github.com/search?q=%2Fts%28+as+%5B%5E%28%5D%2B%5C%29%29%3F%5C.generateTSConfig%5C%28%2F+-path%3Atestrunner&type=code)

[sheetalkamat]

probably already discussed when i wasnt here, but declarationMap seems like overkill ? and additional cost?

[jakebailey]

I'd suggest we just comment it out.

[jakebailey]

Maybe a silly idea, but should we note the effect that this has?

[jakebailey]

Is this intentional? I assume so?

[jakebailey]

Outside what I commented, everything is looking great.

[jakebailey]

In any case, giving this another +1 since it's what was spec'd out, but if we do want to drop declarationMap that's fine too.

[robpalme]

There's a typo that caught my eye in the PR description. The code itself is fine.

 "target": "nodenext",

It should say "esnext"

[jakebailey]

Edited it. And it should also have said module=nodenext