Ensure that an artifact is indeed no_std

[gnzlbg]

It would be good if cargo build would have a --nostd option that would ensure that the resulting artifact doesn't indeed link against the std library and fails if this is the case.

To check this, it needs to at least check that rustc is not called with the std feature enabled. A bonus point would be to use nm on Linux and MacOSX (and its equivalent on windows) to check that the artifact does not contain any std symbols.

[stale]

As there hasn't been any activity here in over 6 months I've marked this as stale and if no further activity happens for 7 days I will close it.

I'm a bot so this may be in error! If this issue should remain open, could someone (the author, a team member, or any interested party) please comment to that effect?

The team would be especially grateful if such a comment included details such as:

• Is this still relevant?
• If so, what is blocking it?
• Is it known what could be done to help move this forward?

Thank you for contributing!

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[gnzlbg]

Is this still relevant?

Yes.

If so, what is blocking it?

Nothing.

[hobofan]

For the meantime I built cargo nono to help with this.

[epage]

rust-lang/rfcs#3875 will elevate no_std into the dependency tree for analysis, like #8798.