Fix bound checking in the NorFlash::erase implementation of FlashRegion

[wzhd]

Submission Checklist 📝

• I have updated existing examples or added new ones.
• I have used cargo xtask fmt-packages command to ensure that all changed code is formatted correctly.
• My changes were added to the CHANGELOG.md in the proper section.
• I have added necessary changes to user code to the Migration Guide.
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Extra:

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Pull Request Details 📖

Description

address_to could be just past the range, being exactly equal to the end that is exclusive.

Testing

I configured littlefs to use partition size / erase size blocks, and got an OutOfBounds error when it tried to erase the last block.

[bjoernQ]

needs to be !(address_to <= self.range().end) or even better address_to > self.range().end

[wzhd]

my bad

[bjoernQ]

Thanks!

Ideally, we would add tests for this but that would require implementing NorFlash for MockFlash

the ! takes precedence so you need braces

[bugadani]

According to the documentation:

Erase the given storage range, clearing all data within [from..to].

That's a closed-closed interval. Is our current check really incorrect?

[wzhd]

The check_erase helper function only rejects to > flash.capacity(), I think it's consistent with the way ranges are usually passed. Perhaps the documentation isn't using mathematical notation.

[bugadani]

Maybe we should then ask for clarification on the documentation, instead of guessing something and risking doing the wrong thing. This may be a case where the rest of our implementation is wrong, but the documentation is right. If we don't know, we shouldn't change behaviour.

I guess the helper is a good hint, IMO we still should be sure.