With the update to TypeScript 3.2.x, a big issue seems to have appeared for downstream Bazel users. If the downstream user still uses a lower TypeScript version, normal Bazel targets using the `ng_module` rule are still compiled with the correct/old TypeScript version (assuming they set the `node_modules` attribute properly).
But, if they build the previous Bazel targets by specifying them within a `ng_package` rule, the TypeScript version from the Angular `workspace` is being used for the replayed ESM5 compilation. This is because we resolve the replay compiler to `ngc_wrapped` or `tsc_wrapped` Bazel executables which are defined as part of the `angular` workspace. This means that the compilers are different if the downstream user uses `ngc-wrapped` from the `@npm` repository because the replayed compilation would use the compiler with `@ngdeps//typescript`.
In order to fix this, we should just use the compiler that is defined in the `@angular//BUILD.bazel` file. This target by defaults to the "@npm" workspace which is working for downstream users. This is similar to how it is handled for `tsc-wrapped`. `tsc-wrapped` works as expected for downstream users.
**Note**: This is not the ideal solution because ideally we would
completely respect the `compiler` option from the base `ng_module`, but
this is not possible in a hermetic way, unless we somehow accept the
`compiler` as an attribute that builds all transitive deps. This is
something we should explore in the future. For now, we just fix this in
a reasonable way that is also used for `tsc_wrapped` from the TypeScript
rules.
PR Close#28053
cd0451305a