rustc_mir_dataflow tests fail with debug-assertions enabled

[ehuss]

The rustc_mir_dataflow tests forward_cursor and backward_cursor are failing when built with debug-assertions.

This is related to the bootstrap bump in #90042. This brings in a change in cargo where tests now inherit profile settings from the dev/release profiles. When debug-assertions is enabled in config.toml, tests are now built with debug-assertions enabled where they previously didn't.

These tests seem to intentionally create a mir body with disconnected basic blocks. However in #74169 a debug assertion was added to prevent API consumers from visiting those basic blocks by accident. That assertion is now triggering in the test.

I don't have any particular ideas on how to resolve this, since the test seems to be fundamentally going against that assertion.

[Mark-Simulacrum]

cc @ecstatic-morse @pnkfelix we'll likely just disable the mir dataflow tests for the 1.57 bootstrap bump, but a more complete fix seems in order as well. Would you be able to put up a PR which fixes the tests to not trigger debug asserts here?

[ecstatic-morse]

I can do it. The fix is pretty simple. Feel free to disable the test in the meantime, since the cursor logic doesn't change often.

[Mark-Simulacrum]

Thanks!