tsc: TS5053: Option 'noEmit' cannot be specified with option 'composite'

[dgadelha]

TypeScript Version: 3.9.0-dev.20200220 (broken in 3.8.2)

Search Terms: TS5053: Option 'noEmit' cannot be specified with option 'composite'

Code

{
  "compilerOptions": {
    "composite": true
  }
}

Expected behavior:

Run a type-check with no errors, as in 3.7 and previous versions.

Actual behavior:

# npx tsc --noEmit
tsconfig.json:3:5 - error TS5053: Option 'noEmit' cannot be specified with option 'composite'.

3     "composite": true,
      ~~~~~~~~~~~

Found 1 error.

Additional comments:

We use composite in our tsconfig.json to ensure the output directory structure is always the same.
We also use --noEmit in our CI pipelines to ensure type-checking before building a Docker image.

Is the --noEmit the best way to do type-checking without the overhead of running an entire build (with output files) or this breaking change should really be reverted?

Related Issues:
#36588 - attempt to remove the composite from tsconfig.json and use as CLI flag when building project

[weswigham]

Is the --noEmit the best way to do type-checking without the overhead of running an entire build (with output files) or this breaking change should really be reverted?

composite requires declaration output to actually do incremental work - use emitDeclarationsOnly instead of noEmit.

[dgadelha]

Is the --noEmit the best way to do type-checking without the overhead of running an entire build (with output files) or this breaking change should really be reverted?

composite requires declaration output to actually do incremental work - use emitDeclarationsOnly instead of noEmit.

Thanks for the quick answer! When using emitDeclarationOnly an entire build tree is created with the .d.ts files. We're looking for an alternative to use the composite flag when building (we can't use as CLI flag due to #36588) while using noEmit to do a quick type-checking without the I/O overhead.

[weswigham]

Those declaration files are the metadata that incremental and composite modes use to determine which files need to be checked in subsequent builds. Without them, no work is actually incremental.

[dgadelha]

I understand that composite needs metadata to work properly, but now there's no way to run a simple type-check within the CLI without actually building something.

composite was released in TypeScript 3.0 and worked with noEmit until 3.8.

I'm really not against that change, but as #36588 blocks us from removing composite from tsconfig.json and using it on compile-time, there's no way to run a type-check without build artifacts.

[dotupNET]

I understand that composite needs metadata to work properly, but now there's no way to run a simple type-check within the CLI without actually building something.

composite was released in TypeScript 3.0 and worked with noEmit until 3.8.

I'm really not against that change, but as #36588 blocks us from removing composite from tsconfig.json and using it on compile-time, there's no way to run a type-check without build artifacts.

I've the same problem in a mono repo. so that I can continue to work, I created a tsconfig.test.json

{ "extends": "./tsconfig.json", "compilerOptions": { "composite": false } }

to use it with --noEmit:

"lint": "tsc -p tsconfig.test.json --noEmit && eslint \"**/*.{ts,tsx}\" --quiet --fix",

So I can lint my packages at least

[hollg]

I have the same problem but with noEmit and incremental. Is there any other way to run a type-check without building anything?

[weswigham]

Don't use incremental? If you don't want anything built, you can't get any speedup from incremental; the built things are what incremental uses in place of normal inputs to save time.

[hollg]

Wesley Wigham (@weswigham) Sorry, to clarify: we have incremental set in our tsconfig, which until now we've used for our production builds, local environment builds and type-checks on commit. For the type-check on commit we've passed --noEmit as a CLI argument. As far as I can tell what we have to do now is add a separate tsconfig for type-checking as Peter Ullrich (@dotupNET) suggested.

So I'm wondering if there's a way to avoid having two config files.

[satya164]

We have a similar issue. We have a monorepo and use path references, which requires composite: true. We used to use --noEmit to perform type-checking on commit hook, but now it doesn't seem to be possible without actually building files.

[t7yang]

agree, --noEmit used to work perfectly with composite: true and incremental: true, pls bring it back.

[weswigham]

It did not "work perfectly" - it didn't do what it claimed to do (intelligently reuse build outputs as inputs where possible); the usage of noEmit completely negated what the composite and incremental flags were meant to achieve. You can get the same behavior (build performance-wise) by not having them set.

[weswigham]

Gary Holland (@hollg) you could pass --incremental false --noEmit rather than just --noEmit for the CI pass, no?