[dartdev] Fails to report VM service URL on Windows when run from different drive

[dnys1]

Starting with Dart 3.4.0, dart run fails to report the VM service URL on Windows when the command is run from a separate drive.

Assuming the dart executable lives on the C:\ drive and this simple Dart program (example.dart):

void main() => print('Hello, World');

1. Running dart run from C:\ drive (base case)

PS C:\workspace> dart run --enable-vm-service=0 .\example.dart
The Dart VM service is listening on http://127.0.0.1:50153/cbhV5WcNEvU=/
The Dart DevTools debugger and profiler is available at: http://127.0.0.1:50153/cbhV5WcNEvU=/devtools?uri=ws://127.0.0.1:50153/cbhV5WcNEvU=/ws
Hello, World!

2. Running from the D:\ drive

PS D:\workspace> dart run --enable-vm-service=0 .\example.dart
Hello, World!

Interestingly, the VM service does seem to be starting, though, since the following prints a URL.

PS D:\workspace> dart run --observe=0 .\example.dart
Hello, World!
vm-service: isolate(5632243645610243)  'main' has no debugger attached and is paused at exit.  Connect to the Dart VM service at http://127.0.0.1:50164/5eI1O7H6CDg=/ to debug.

There doesn't seem to be a good workaround for this, either:

• --enable-vm-service=<open port> does not spawn on the provided port
• --write-service-info does not create the file (tried different drive letter, relative/absolute combos)

[mit-mit]

cc @bkonyi @kenzieschmoll

[dnys1]

Seems to be an issue in DDS. I haven't looked into the code at all, but I found that passing --no-dds produces the expected output.

[bkonyi]

Thanks for the details @dnys1! I'll take a look to see if I can reproduce.

[bkonyi]

I'm unable to reproduce this on the main branch (Dart 3.5.0-edge.4692937341db70e60ee6b58bb75c6a0c621e14b0). @dnys1 can you run dart info and share the output here?

[dnys1]

Thanks, @bkonyi. The above was discovered on the Dart stable branch (3.4.1).

Trying with flutter master, I get the following output:

PS D:\workspace\dev_test> dart run --enable-vm-service=0 .\example.dart
Hello, World!
Could not start the VM service:
DartDevelopmentServiceException: Failed to start Dart Development Service

dart info

PS D:\workspace\dev_test> dart info

If providing this information as part of reporting a bug, please review the information
below to ensure it only contains things you're comfortable posting publicly.

#### General info

- Dart 3.5.0-219.0.dev (dev) (Mon Jun 3 17:02:15 2024 -0700) on "windows_x64"
- on windows / "Windows 10 Pro" 10.0 (Build 22631)
- locale is en-US

#### Project info

- sdk constraint: '^3.4.1'
- dependencies:
- dev_dependencies: lints, test

#### Process info

| Memory | CPU | Elapsed time | Command line |
| -----: | --: | -----------: | ------------ |
| 133 MB |  -- |              | dart.exe     |
|  95 MB |  -- |              | dart.exe     |

Although it says Windows 10, this is Windows 11, running commands in new Terminal program. Not sure if that makes a difference.

[bkonyi]

Thanks for the response @dnys1.

I've tried to run using the Dart SDK shipped with Flutter, but I'm still unable to reproduce:

PS D:\> dart --version
Dart SDK version: 3.5.0-234.0.dev (dev) (Thu Jun 6 17:03:02 2024 -0700) on "windows_x64"
PS D:\> dart run --enable-vm-service=0 .\foo.dart
The Dart VM service is listening on http://127.0.0.1:50415/efUSziJRNGI=/
The Dart DevTools debugger and profiler is available at: http://127.0.0.1:50415/efUSziJRNGI=/devtools?uri=ws://127.0.0.1:50415/efUSziJRNGI=/ws
hello world!

Is there anything special about your drive configuration by any chance? I know we've had some issues with Dev Drives before, although I'm a bit fuzzy on what was actually impacted.

Would it be possible for you to try moving your SDK (or creating a new copy of it) on your D:\ drive and seeing if you can reproduce?

[dnys1]

Welp.. I went to dive in and debug this but as soon as I started, I was no longer able to consistently reproduce it. Not sure what to make of it!

I'll close this for now and chalk it up to something being wrong with my dev setup.

I appreciate the quick help, @bkonyi!