As of TypeScript 3.9, the tsc emit is not compatible with Closure
Compiler due to
https://github.com/microsoft/TypeScript/pull/32011.
There is some hope that this will be fixed by a solution like the one
proposed in
https://github.com/microsoft/TypeScript/issues/38374 but currently it's
unclear if / when that will
happen.
Since the Closure support has been somewhat already broken, and the
tsickle pass has been a source
of headaches for some time for Angular packages, we are removing it for
now while we rethink our
strategy to make Angular Closure compatible outside of Google.
This change has no effect on our Closure compatibility within Google
which work well because all the
code is compiled from sources and passed through tsickle.
This change only disables the tsickle pass but doesn't remove it.
A follow up PR should either remove all the traces of tscikle or
re-enable the fixed version.
BREAKING CHANGE: Angular npm packages no longer contain jsdoc comments
to support Closure Compiler's advanced optimizations
The support for Closure compiler in Angular packages has been
experimental and broken for quite some
time.
As of TS3.9 Closure is unusable with the JavaScript emit. Please follow
https://github.com/microsoft/TypeScript/issues/38374 for more
information and updates.
If you used Closure compiler with Angular in the past, you will likely
be better off consuming
Angular packages built from sources directly rather than consuming the
version we publish on npm
which is primarily optimized for Webpack/Rollup + Terser build pipeline.
As a temporary workaround you might consider using your current build
pipeline with Closure flag
`--compilation_level=SIMPLE`. This flag will ensure that your build
pipeline produces buildable and
runnable artifacts, at the cost of increased payload size due to
advanced optimizations being disabled.
If you were affected by this change, please help us understand your
needs by leaving a comment on https://github.com/angular/angular/issues/37234.
PR Close#37221
