warn.code for missing output.name of IIFE bundle that has export

[rail44]

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

Hi, I'm using rollup with typescript.
In my project, there are some modules built as iife, because they must assign some object into window when loaded .
But it also has export since its member's type definition was used by other modules.
In this case, rollup will warn that bundle is missing output.name.

This is request to add warn.code, useful for suppress by onwarn() .

[rail44]

writing test

[codecov]

Codecov Report

Merging #3372 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #3372   +/-   ##
=======================================
  Coverage   93.29%   93.29%           
=======================================
  Files         172      172           
  Lines        6114     6114           
  Branches     1823     1823           
=======================================
  Hits         5704     5704           
  Misses        218      218           
  Partials      192      192

Impacted Files	Coverage Δ
src/finalisers/iife.ts	100% <ø> (ø)	⬆️

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[lukastaegert]

A code should definitely be added, but I think it should be aligned with the corresponding error for UMD bundles 'You must supply "output.name" for UMD bundles.', because it is about the same issue. This one is using INVALID_OPTION, though, which I am not really happy about as not passing a name IS valid if there are no exports. Would you consider changing the code in umd.ts to MISSING_NAME_FOR_EXPORT? You might also slightly tune the error message, e.g. You must supply "output.name" for UMD bundles that have exports.

[rail44]

@lukastaegert
Thank you for your suggestion!

Then, should IIFE bundles also publish error, instead of warning?
And, when this PR will include such changes, it will become breaking change for people already having onwarn() with INVALID_OPTION won't it?

[lukastaegert]

You are somewhat right about the breaking change. Maybe we should make a separate PR for changing the error code to the release-2.0.0 branch. Then I would actually just merge this one as it is. Note though that since it is an error, not a warning, it will not get passed to onwarn handlers. The only way to see the code for errors is to use the JavaScript API and catch the call to bundle.generate.

Then, should IIFE bundles also publish error, instead of warning?

If it produces working code, no reason to make it an error IMO. It's always possible someone depends on this...

[rail44]

@lukastaegert

Sorry for late reply. I was under busy.
I also create #3393 for UMD bundle.

[lukastaegert]

Let's wait how the discussion in #3393 pans out before merging