Exclude 'babel-plugin-compact-reexports' during Stage 1 build

[charlespierce]

Info

• The plugin babel-plugin-compact-reexports, included by ember-engines, translates an ES Modules re-export statement (export { foo } from './bar') into a single-line AMD declaration, which saves space compared to the multiple lines an explicit import & export would use.
• However, during the Stage 1 Embroider build, we want to leave the ES Modules exports as they are, so that they can be properly parsed during Stage 3.

Changes

• Analogous to the existing code that removes other invalid plugins during Stage 1, added a section to detect and exclude babel-plugin-compact-reexports during a stage 1 build.

Tested

• Performed a STAGE1_ONLY build and confirmed that the reexport statements are not translated and are left as-is

[rwjblue]

ember-engines doesn't use this plugin if module transpilation is disabled (see here). Have you looked into why that flag isn't set (therefore preventing this plugin from being added in the first place)?

[ef4]

We disable module compilation in stage1 here and stage2 here.

But some addons insist on invoking babel or rollup directly and eliminate modules before we get a chance to stop them. Maybe that is the case here.

[charlespierce]

I think the issue here is actually just one of timing. It looks like the check for compileModules is performed within the init() method of the ember-engines mixin, so it happens before embroider is invoked at all, and well before it gets the chance to update the configuration. At that point, it's adding compact-reexports to the babel plugins.

Then later on when Embroider updates compileModules, it's too late since the plugin was already added.

I'm definitely open to a different approach for avoiding that plugin if there's a cleaner way forward.

[rwjblue]

This seems good to me, I don't see how we can modify ember-engines to avoid adding the babel plugin. As @charlespierce mentioned above ember-engines does this in its init:

https://github.com/ember-engines/ember-engines/blob/2a7a46a821db2ffc635dd144b25972722be533ad/packages/ember-engines/lib/engine-addon.js#L481-L491

When this is ran (at addon init) Embroider hasn't started loading, and there is no way to introspect that we will eventually be in an Embroider build.

[rwjblue]

@charlespierce - Ready for a rebase (should fix canary failures).