The cached file-system was implemented to speed up ngcc processing, but in reality most files are not accessed many times and there is no noticeable degradation in speed by removing it. Benchmarking `ngcc -l debug` for AIO on a local machine gave a range of 196-236 seconds with the cache and 197-224 seconds without the cache. Moreover, when running in parallel mode, ngcc has a separate file cache for each process. This results in excess memory usage. Notably the master process, which only does analysis of entry-points holds on to up to 500Mb for AIO when using the cache compared to only around 30Mb when not using the cache. Finally, the file-system cache being incorrectly primed with file contents before being processed has been the cause of a number of bugs. For example https://github.com/angular/angular-cli/issues/16860#issuecomment-614694269. PR Close #36687
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