Closure Compiler by default will report diagnostics from type checks in
any JavaScript code, including code emitted by the Angular compiler.
Disabling `checkTypes` substantially reduces warning spam for users, and
allows them to run with stricter compiler flags (e.g. treating actual
diagnostics from user code as errors).
Closure Compiler will still type check the code and use types (where
found and correct) for optimizations.
PR Close#20828
If no user files changed:
- only type check the changed generated files
Never emit non changed generated files
- we still calculate them, but don’t send them through
TypeScript to emit them but cache the written files instead.
PR Close#19646
For now, we always create all generated files, but diff them
before we pass them to TypeScript.
For the user files, we compare the programs and only emit changed
TypeScript files.
This also adds more diagnostic messages if the `—diagnostics` flag
is passed to the command line.
