angular-docs-cn/modules/@angular/compiler-cli/integrationtest/third_party_src/README.md

This folder emulates consuming precompiled modules and components. It is compiled separately from the other sources under src to only generate *.js / *.d.ts / *.metadata.json files, but no *.ngfactory.ts files.

** WARNING ** Do not import components/directives from here directly as we want to test that ngc still compiles them when they are not imported.