dart2native --enable-asserts doesn't work

[nex3]

dart2native's help documentation mentions an --enable-asserts flag:

$ dart2native --help
Usage: dart2native <main-dart-file> [<options>]

Generates an executable or an AOT snapshot from <main-dart-file>.

-D, --define=<key=value>       Set values of environment variables. To specify multiple variables, use multiple options or use commas
                               to separate key-value pairs.
                               E.g.: dart2native -Da=1,b=2 main.dart

    --enable-asserts           Enable assert statements.
-h, --help                     Display this help message.
-k, --output-kind=<aot|exe>    
          [aot]                Generate an AOT snapshot.
          [exe] (default)      Generate a standalone executable.

-o, --output=<path>            Set the output filename. <path> can be relative or absolute.
                               E.g.: dart2native main.dart -o ../bin/my_app.exe

-p, --packages=<path>          Get package locations from the specified file instead of .packages. <path> can be relative or absolute.
                               E.g.: dart2native --packages=/tmp/pkgs main.dart

-v, --verbose                  Show verbose output.

However, when I try to compile a Dart executable with the --enable-asserts flag, I get an error:

$ dart2native --enable-asserts --output=test test.dart

Setting VM flags failed: Unrecognized flags: enable-asserts

Failed to generate native files:
Generating AOT snapshot failed!

I need to run my executable with asserts enabled for testing purposes, and I want to do AOT compilation so my tests run quickly.

(Tested with Dart 2.7.0)

[a-siva]

dart2native is meant for creating AOT apps for deployment and we build them in product mode which does not support asserts, there is a bug in the output from '--help' which lists '--enable-asserts' as a supported option.

For testing purposes you should run your app using regular dart "dart test.dart".

We will use this bug to fix the message output by the '--help' option.

[nex3]

What's the technical reasoning behind not supporting this? Why not make dart2native consistent with every other way of invoking an executable?

For testing purposes you should run your app using regular dart "dart test.dart".

The VM on its own is way too slow for this to be feasible. In Dart Sass, dart bin/sass.dart --help takes 1.5 to 2 seconds to run on my laptop, and we invoke our executable many many times throughout our test suite.

Test iteration time directly blocks engineer productivity, and every second counts. It's very user-unfriendly to say that the only way to run Dart executables with quick startup time is unsuitable for testing.

[a-siva]

What's the technical reasoning behind not supporting this? Why not make dart2native consistent with every other way of invoking an executable?

The reasoning was probably derived from the flutter model where-in asserts are used only during development and not in the deployed app (code size and startup times are key factors here).
It is tecnically possible to support both modes at the extra cost of including additional artifacts in the dart sdk which is already quite bloated.

Test iteration time directly blocks engineer productivity, and every second counts. It's very user-unfriendly to say that the only way to run Dart executables with quick startup time is unsuitable for testing.

One could still run tests on the app we don't prevent that, just that assert based testing would be hampered.

[nex3]

If there's no technical reason not to support this, please add support for it—you have a major user requesting it with a clear use-case.

One could still run tests on the app we don't prevent that, just that assert based testing would be hampered.

But it's not suitable for testing if it's not running in a mode with asserts enabled.

[jamesderlin]

dartaotruntime has the same problem of documenting --enable-asserts but not recognizing it.

It is disappointing that AOT snapshots cannot be created with enabled assertions.

[a-siva]

It is disappointing that AOT snapshots cannot be created with enabled assertions.

This is now enabled for AOT snapshots, see #53343