Mismatch between documentation and implementation of debug_assert_eq macro

[est31]

The documentation for the debug_assert_eq macro claims:

Asserts that two expressions are equal to each other, testing equality in both directions.

But if you read the implementation of debug_assert_eq, you see that it tests equality in one direction only. Also see the example: http://is.gd/YGKAOj

[durka]

What does "equality in both directions" even mean?

[sfackler]

It used to check if left == right && right == left.

[est31]

The commit that introduced this mismatch was
5cf126a

debug_assert_eq internally uses assert_eq, and when assert_eq was changed to check equality in one direction only (in above commit), the documentation for debug_assert_eq wasn't adjusted.

[est31]

As the macro was stabilized when it checked equality in one direction only. I guess it makes most sense to adjust the documentation, and not the code?

[sfackler]

Yep, this is a docs issue.