Feature request: exclude outDir by default in tsconfig.json

[jsamr]

Scenario: As a user, I want typescript compiler to default-exclude output transpiled files to compilerOptions.outDir with compilerOptions.declaration property set to true. I would expect that outDir is excluded by default, because:

• it would prevent me from importing definitions from outDir by error, which is easy to do with intellisense
• it would prevent me from having TS5055 errors such as spotted in TypeScript complains about overwriting .d.ts files that are potentially known outputs #16749 and tsc generating TS5055 error when generating declaration files #6046
• tsc CLI has already implemented this behaviour, see PR exclude outDir and add more default excludes #8703

[mhegazy]

Not sure i understand the request, outDir is excluded by default from a compilation, e.g.:

c:\test\20108>tree /F
│   a.ts
│   tsconfig.json
│
└───outDir
        b.ts


c:\test\20108>type tsconfig.json
{
    "compilerOptions": {
        "target": "es5",
        "outDir": "./outDir"
    }
}

c:\test\20108>tsc --v
Version 2.7.0-dev.20171109

c:\test\20108>tsc --listFiles
C:/Users/mhegazy/AppData/Roaming/npm/node_modules/typescript/lib/lib.d.ts
c:/test/20108/a.ts

[jsamr]

I have a configuration where it doesn't. I'll work on a MWE and come back to you !

[jsamr]

@mhegazy I think I have found the reason : default excluded values are overwritten instead of merged when setting your own custom values.

[mhegazy]

If you define your own excludes we get out of the exclude business altogether. I recommmend using include instead.

[jsamr]

@mhegazy OK thanks for that clarification. However, exclude is difficult to avoid when implementing tests we don't want typescript to compile. I believe this scenario is so common that many users don't concretely benefit from default excludes...

[mhegazy]

I believe this scenario is so common that many users don't concretely benefit from default excludes...

I have not seen requests for this before to be frank. leaving this issue open to gather more user feedback.

[liron-navon]

@mhegazy
The "outDir" is not excluded by default, when I tried to enable js files in my project, typescript tried to compile the "dist" (which is registered as the outDir), the issue was resolved by adding:

 "exclude": [
   "node_modules",
   "dist"
 ]

But it really surprised me, since I expected the outdir to be excluded by default.

[leotm]

My scenario was I checked out react-native-template-typescript, ran yarn tsc, was greeted with error TS5053: Option 'noEmit' cannot be specified with option 'incremental', read the 3.4 release notes, decided to try incremental from the get-go. Cannot write file 'MyApp/index.js' made sense, so went with isolating the emitted files to "outDir": "./lib", only surprised to experience #8249 per compile because I expected it to be excluded by default, as I haven't gotten to structuring my project to the point of e.g. "include": [ "src" ]" just yet. Finding myself thinking alike #8249 (comment).