Previously, when we needed to detect whether a file is external to a package, we only checked whether the relative path to the file from the package's root started with `..`. This would detect external imports when the packages were siblings (e.g. peer dependencies or hoisted to the top of `node_modules/` by the package manager), but would fail to detect imports from packages located in nested `node_modules/` as external. For example, importing `node_modules/foo/node_modules/bar` from a file in `node_modules/foo/` would be considered internal to the `foo` package. This could result in processing/analyzing more files than necessary. More importantly it could lead to errors due to trying to analyze non-Angular packages that were direct dependencies of Angular packages. This commit fixes it by also verifying that the relative path to a file does not start with `node_modules/`. Jira issue: [FW-2068](https://angular-team.atlassian.net/browse/FW-2068) Fixes #36526 PR Close #36559
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