1.36 borrow checker warns about possible undefined behavior

[nicodemus26]

Rust 1.36 (stable) raises a warning from the new borrow checker that will be come an error in the future, and represents potentially undefined behavior. Maybe related to this issue: #561

See also: https://blog.rust-lang.org/2019/07/04/Rust-1.36.0.html#nll-for-rust-2015

warning[E0502]: cannot borrow `*self` as immutable because it is also borrowed as mutable
   --> /usr/local/cargo/registry/src/github.com-1ecc6299db9ec823/nalgebra-0.16.13/src/base/cg.rs:291:44
    |
291 |                 self[(j, i)] += shift[j] * self[(D::dim() - 1, i)];
    |                 ---------------------------^^^^-------------------
    |                 |                          |
    |                 |                          immutable borrow occurs here
    |                 mutable borrow occurs here
    |                 mutable borrow later used here
    |
    = warning: this error has been downgraded to a warning for backwards compatibility with previous releases
    = warning: this represents potential undefined behavior in your code and this warning will become a hard error in the future

[est31]

Yes, this is a dupe of #561 .

You are using nalgebra 0.16.13 which is ancient. This bug is fixed since the 0.18.0 release in March 31, 2019.