a87951a28f
When ngcc creates an entry-point program, the `allowJs` option is enabled in order to operate on the JavaScript source files of the entry-point. A side-effect of this approach is that external modules that don't ship declaration files will also have their JavaScript source files loaded into the program, as the `allowJs` flag allows for them to be imported. This may pose an issue in certain edge cases, where ngcc would inadvertently operate on these external modules. This can introduce all sorts of undesirable behavior and incompatibilities, e.g. the reflection host that is selected for the entry-point's format could be incompatible with that of the external module's JavaScript bundles. To avoid these kinds of issues, module resolution that would resolve to a JavaScript file located outside of the package will instead be rejected, as if the file would not exist. This would have been the behavior when `allowJs` is set to false, which is the case in typical Angular compilations. Fixes #37508 PR Close #37596
Angular Compatibility Compiler (ngcc)
This compiler will convert node_modules compiled with ngc, into node_modules which
appear to have been compiled with ngtsc.
This conversion will allow such "legacy" packages to be used by the Ivy rendering engine.
Building
The project is built using Bazel:
yarn bazel build //packages/compiler-cli/ngcc
Unit Testing
The unit tests are built and run using Bazel:
yarn bazel test //packages/compiler-cli/ngcc/test
Integration Testing
There are tests that check the behavior of the overall executable:
yarn bazel test //packages/compiler-cli/ngcc/test:integration