The mirrors library does not understand extensions

[lrhn]

The dart:mirrors library has no notion of extensions.

It doesn't expose an extension declaration as a member of the library it's declared in. Instead it exposes the synthetic top-level declarations that the extension is desugared into. Exposing those is definitely wrong.

Example:

library name;
import"dart:mirrors";

extension Foo<T> on T {
  static int foo() => 42;
  T get log {
    print(this); 
    return this;
  }
}

main() {
 var library = reflectClass(Hook).owner as LibraryMirror;
 print("Library name: ${library.simpleName}"); // Sanity check, it's the current library.
 print("Library declares Foo: ${library.declarations[#Foo]}"); // No
 print("Library leaks Foo.log: ${library.declarations[#Foo.log]}"); // Yes, it does.
 print("Library leaks Foo.foo: ${library.declarations[#Foo.foo]}"); // Yes, it does.
}
class Hook {}

The mirrors library should either be deprecated or be made compatible with new language features.

[a-siva]

At this point we have no plans for enhancing the dart:mirrors library to account for new language features.
Please see #44489 which is investigating a path towards discontinuing support for dart:mirrors