This lets projects like Material change ng_package "bundle index" files to non-conflicting paths
Currently packages like @angular/core ship with the generated metadata
in a path like 'core.js' which overwrites one of the inputs.
Angular material puts the generated file in a path like 'index.js'
Either way these files generated by ng_module rules have the potential
to collide with inputs given by the user, which results in an error.
Instead, give users the freedom to choose a different non-conflicting name.
Also this refactors the ng_package rule, removing the redundant
secondary_entry_points attribute.
Instead, we assume that any ng_module in the deps with a module_name
attribute is a secondary entry point.
PR Close#22814
This produces a directory following the Angular Package layout spec.
Includes integration test coverage by making a minimal ng_package in integration/bazel.
Unit tests verify the content of the @angular/core and @angular/common packages.
This doesn't totally match our current output, but is good enough to unblock some
early adopters.
It re-uses logic from the rollup_bundle rule in rules_nodejs. It should also
eventually have the .pack and .publish secondary targets like npm_package rule.
PR Close#22221
Greg Magolan
Alex Eagle