Migrate pkg/compiler to null safety

[devoncarew]

This issues tracks migrating dart2js (pkg/compiler) to null safety; see #49169 for the general dart-lang repo tracking meta issue.

[devoncarew]

(post migration tasks can be tracked using #48820)

[sigmundch]

Status as of 9/30/22 (files under pkg/compiler/lib/)

	migrated	total	%
Files	246	330	74.55%
Lines	92845	164412	56.47%
Bytes	3170147	5720789	55.41%

[khyati82]

@sigmundch - Is there a tentative eta on when this might be done?

[sigmundch]

ETA is unclear at the moment.

Our initial goal was to complete this by November, however, recent high-priority internal demands on my team are taking our attention away from this. Our plan was to hold a team fixit once we reduce the pressure on the internal demands. Meanwhile, I only expect steady incremental progress.

Today's status:

	migrated	total	%
Files	255	333	76.58%
Lines	95922	164865	58.18%
Bytes	3282311	5737107	57.21%

[sigmundch]

Update: we continue to focus on other areas at the moment, but have made some progress. Current status:

	migrated	total	%
Files	270	342	78.95%
Lines	103498	166045	62.33%
Bytes	3550347	5779222	61.43%

Most remaining items are in the following subfolders: inferrer*, ssa, js_backend, js_emitter

[sigmundch]

inferrer folder is now migrated, ssa, js_backend, and js_emitter remain:

	migrated	total	%
Files	263	325	80.92%
Lines	111538	164707	67.72%
Bytes	3841046	5734266	66.98%

[sigmundch]

Lots of activity last week, updated stats on the pkg/compiler/lib/ folder:

	migrated	total	%
Files	287	324	88.58%
Lines	129623	164394	78.85%
Bytes	4459214	5728895	77.84%

[sigmundch]

Current status of the lib/ folder:

	migrated	total	%
Files	310	324	95.68%
Lines	145806	164884	88.43%
Bytes	5048289	5748555	87.82%

Most remaining work are a couple big cycles in the SSA folder and a few entry point files before we start triaging runtime failures with sound null safety and before we start migrating unit tests.

[sigmundch]

Current lib status:

	migrated	total	%
Files	314	323	97.21%
Lines	153633	166104	92.49%
Bytes	5339523	5796163	92.12%

[mit-mit]

Hey @sigmundch got any updates?

[sigmundch]

yes! @natebiggs pushed through and the lib migration is complete (100%) and the tests and tool folders are nearly complete (98% including data files that are likely to be kept unmigrated for test coverage purposes).

@natebiggs has a couple CLs in flight to enable sound null-safety for running the compiler both internally and in the sdk. He is on PTO this week, so I expect we will land them sometime in the next couple weeks.

[mit-mit]

Very cool, thanks!

[mit-mit]

Any updates @natebiggs ?

[biggs0125]

Ah yes forgot to update this bug, this is done!

[mit-mit]

WOOHOO 🥳, thanks!