Fix running dart_dev in mixed-version packages opted into null safety

[greglittlefield-wf]

Motivation

dart_dev currently fails to run in mixed-version packages that have opted into null safety but have some non-null-safe dependencies.

This is because, in those packages, the bootstrap script is run in sound null safety mode by default, which fails because dart_dev (and potentially other packages pulled in via the config) are not themselves null-safe.

This is what those errors look like:

$ ddev format
Error: Cannot run with sound null safety, because the following dependencies
don't support null safety:

 - package:dart_dev

For solutions, see https://dart.dev/go/unsound-null-safety

When using a config.dart that's also opted out of null-safety via a language comment:

$ ddev format
tool/dart_dev/config.dart:1:1: Error: A library can't opt out of null safety by default, when using sound null safety.
// @dart=2.9
^^^^^^^^^^^^
Error: Cannot run with sound null safety, because the following dependencies
don't support null safety:

 - package:dart_dev

For solutions, see https://dart.dev/go/unsound-null-safety

Solution

• While dart_dev is null safe, opt the run script out of null safety using a version comment (this could also be achieved via a --no-sound-null-safety flag, but this seemed more straightforward)
• If there's a language version comment in config.dart, copy that over to the run script. This will ensure that non-null-safe configs will continue to work even after dart_dev itself is migrated to null safety,
• Add functional tests that fail unless this new logic is in place

Testing

• CI passes

[aviary-wf]

Security Insights

No security relevant content was detected by automated scans.

Action Items

• Review PR for security impact; comment "security review required" if needed or unsure
• Verify aviary.yaml coverage of security relevant code

---

Questions or Comments? Reach out on Slack: #support-infosec.

[evanweible-wf]

LGTM - thanks for adding this @greglittlefield-wf! Would you mind adding a changelog entry for this? I think it makes sense as a patch, so the next version would be 3.8.4

[greglittlefield-wf]

@evanweible-wf Np, thanks for reviewing! Can do!

[evanweible-wf]

QA +1

• CI passes

@Workiva/release-management-p

[rmconsole-wf]

+1 from RM