Improve type of RollupOutput.output

[MattiasBuelens]

This PR contains:

• bugfix
• feature
• refactor
• documentation
• other

Are tests included?

• yes (bugfixes and features will not be merged without tests)
• no

Breaking Changes?

• yes (breaking changes will not be merged unless absolutely necessary)
• no

List any relevant issue numbers:

Description

Now that microsoft/TypeScript#24897 has landed in TypeScript 3.2, we can more precisely define the type of RollupOutput.output to assert that the first element will be an OutputChunk.

[lukastaegert]

Nice one!

[lukastaegert]

Seems you broke the type check, though

[MattiasBuelens]

Seems you broke the type check, though

Woops! 😅

Right, so createOutput builds the output array by mapping over the keys of outputBundle which is a Record<string, OutputChunk | OutputAsset>. The compiler doesn't know that outputBundle will have at least one property that is an OutputChunk, and it also doesn't know that the subsequent sort() will move any OutputChunks to the front of the array.

Should we just put in a type cast? Something like:

Object.keys(outputBundle)
  .map(...)
  .sort(...) as [OutputChunk, ...(OutputChunk | OutputAsset)[]]

[lukastaegert]

Sounds good

[MattiasBuelens]

Very weird. Some unit tests are failing on Node 6 according to CircleCI:

  2759 passing (34s)
  1 pending
  14 failing

  1) rollup
       function
         export-global: any global variables in scope can be re-exported:
     Error: Export 'Buffer' is not defined
      at error (src/utils/error.ts:7:11)
      at Module.error (src/Module.ts:558:3)
      at tryParse (src/Module.ts:127:5)
      at Module.setSource (src/Module.ts:235:29)
      at /home/circleci/project/src/Graph.ts:545:10

  2) rollup
       form
         system-uninitialized: supports uninitialized binding exports:
     Error: Export 'globalVar' is not defined
      at error (src/utils/error.ts:7:11)
      at Module.error (src/Module.ts:558:3)
      at tryParse (src/Module.ts:127:5)
      at Module.setSource (src/Module.ts:235:29)
      at /home/circleci/project/src/Graph.ts:545:10

  ...

But I only changed some types! 😭

[lukastaegert]

Sorry for the wait, finally managed to address those test issues. Basically, it was caused by version drift on Node 6 (which should no longer happen) and a breaking change in a patch version of acorn.