As part of the Bazel toolchain migration we noticed that implicit types
generated by the TypeScript compiler sometimes end up referencing types
from other packages (i.e. cross-package imports).
These imports currently work just because the Bazel `ts_library` and
`ng_module` rules automatically inserted a `<amd-module
name="@angular/x" />` into `.d.ts` of packages. This helped TS figure
out how to import a given file. Notably this is custom logic that is not
occuring in vanilla TS or Angular compilations—so we will drop this
magic as part of the toolchain cleanup!
To improve code quality and keep the existing behavior working, we are
doing the following:
- adding a lint rule that reduces the risk of such imports breaking. The
failure scenario without the rule is that API goldens show unexpected
diffs, and types might be duplicated in a different package!
- keeping the `<amd-module` headers, but we manually insert them into
the package entry-points. This should ensure we don't regress
anywhere; while we also improved general safety around this above.
Long-term, isolated declarations or a lint rule from eslint-typescript
can make this even more robust.
PR Close#61312
Instead of relying on Microsoft's API extractor for `d.ts` bundling,
we are switching to Rollup-based `.d.ts` bundling.
This allows us to support code spliting, even for `.d.ts` files,
allowing for relative imports to be used between entry-points, without
ending up duplicating `.d.ts` definitions in two files. This would otherwise cause
problems with assignability of types.
It also nicely integrates into our existing rollup configuration, and
overall simplifies the `ng_package` rule even further!
Notably `tsup` also uses this rollup plugin, and it seems to work well.
Keep in mind that Microsoft's API extractor is pretty hard to integrate,
caused many problems in the past, and isn't capable of code splitting.
This aligns our d.ts bundling with the .mjs bundling (great alignment).
PR Close#60321
