Restrict dart:mirrors on DDC

[vsmenon]

We're no longer supporting dart:mirrors on the web. We have limited support for it right now and the emit-metadata flag is required to preserve some annotation info.

We should:

• Disallow importing except via special flag (maybe emit-metadata) - minimum bar for milestone
• Remove more static metadata that can't be read without mirrors (e.g., constructor / static method type info)
• Eventually (once pageloader is removed) delete mirrors code.

@jmesserly

[jmesserly]

I'm working on a CL for this. There are a few tests in tests/*_2 that import dart:mirrors, so that needs triage. I'm also running internal tests to look for any breakage caused by restricting the import.

[jmesserly]

I've got a ways to go before the CL is ready (because status files), but this CL fixes the tests: https://dart-review.googlesource.com/c/sdk/+/49624

[dgrove]

any updates on this?

[jmesserly]

Slowly making progress.

This CL reduces signature data DDC stores: https://dart-review.googlesource.com/c/sdk/+/48455. More things will not be reflectable unless emit-metadata is enabled. I'm waiting on a code review.

I fixed the language tests to reflect correct behavior in https://dart-review.googlesource.com/c/sdk/+/49624 (moving dart:mirrors tests into lib_2/mirrors, fixing tests that don't need to use mirrors, splitting a few other tests that legitimately tested both mirrors and non-mirrors functionality). However I can't send that CL out because it needs more status file fixes. Those are very difficult/time consuming so I'm not sure how long it will take.

Once that lands, and we've got internal code fixed too, we can land a CL that restricts dart:mirrors import. I'll send you a message offline regarding internal repository details.

[jmesserly]

this is the CL that disables mirrors (in DDC, need DDK as well) https://dart-review.googlesource.com/c/sdk/+/53163 ... I'm going to see if this can be rolled into internal code or if we need fixes there.

[jmesserly]

Sent out test CL https://dart-review.googlesource.com/c/sdk/+/49624

[jmesserly]

https://dart.googlesource.com/sdk/+/3002e47e36e7072831c2e0ff061f56522480f493 landed, and sent out https://dart-review.googlesource.com/c/sdk/+/53163 for review, which will fix this bug.