Version 3.0.4 can't be compiled with dart2js server mode

[simolus3]

This is a regression in version 3.0.4, compiling this package works fine with 3.0.3:

../../../../.pub-cache/hosted/pub.dev/crypto-3.0.4/lib/src/sha512_fastsinks.dart:197:3:
Error: The integer literal 0x428a2f98d728ae22 can't be represented exactly in JavaScript.
  0x428a2f98d728ae22,
  ^^^^^^^^^^^^^^^^^^

There are many more such errors in that file.

[devoncarew]

Is this a regression? related to dart-archive/crypto#165? cc @kevmoo

[kevmoo]

Ah shoot. Hrm...

[kevmoo]

@simolus3 – which version of Flutter/Dart are you using?

[simolus3]

Dart SDK version: 3.5.0 (stable) (Tue Jul 30 02:17:59 2024 -0700) on "linux_x64"

[kevmoo]

SO WEIRD! Can you try running the crypto tests locally @simolus3 ?

dart test -p chrome,vm --compiler dart2wasm,dart2js -j 1

[simolus3]

Oh wait I think I know what's happening haha, I'm running dart2js in server mode because my only test that is affected by this is @TestOn('node'). That doesn't have dart:html, normal dart2js does.
I suppose this will make it pretty hard to detect JS being targeted in conditional imports?

[kevmoo]

@simolus3 – ah! We can fix that I think.

[kevmoo]

@sigmundch is looking into this now!

[sigmundch]

@kevmoo - ideally both dart.library.js and dart.library.js_util should be false in a conditional imports in dart2wasm, but it's not today (cc @srujzs @mkustermann).

I recall there were recent changes around what libraries are exposed by the wasm backend, and found a recent change it to make dart.library.ffi false. According to https://dart-review.googlesource.com/c/sdk/+/370880, this should be the case starting from 3.4.4 in the stable channel.

Given that this is already available, I'd suggest to use that for now:

import 'fast.dart'
  if (dart.library.ffi) 'fast.dart' // force wasm to go down this path.
  if (dart.library.js) 'slow.dart';

And later revisit to make it more precise. Ideally, we should allow conditional imports that directly describe the platform (e.g. dart.tool.dart2wasm), rather than the libraries available to that platform (see dart-lang/sdk#54785).

[sigmundch]

My bad, the example above is incorrect - the change to dart.library.ffi precisely makes this harder: it made dart2wasm harder to distinguish from dart2js, not the other way around. It gives us a secondary way to distinguish VM from wasm, but not a way to divide between JS and Wasm backends.

[sigmundch]

For now, I'd suggest revert the original change until we land something. We have dart-lang/sdk#55266 to track the underlying issue.