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sparsemat / sprs

sparse linear algebra library for rust
Apache License 2.0
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fix borrow warning on nightly #162

Closed pmarks closed 5 years ago

pmarks commented 5 years ago

this line is giving the following warning on the nightly compiler. This patch fixes the warning:

warning[E0502]: cannot borrow `indptr` as immutable because it is also borrowed as mutable
   --> src/sparse/triplet_iter.rs:122:26
    |
122 |             indptr[i] += indptr[i - 1];
    |             -------------^^^^^^-------
    |             |            |
    |             |            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
vbarrielle commented 5 years ago

Yes I've also had this issue in my branch porting to the 2018 edition. This seems related to order of evaluation that's not the same for a generic index type and for a primitive type https://internals.rust-lang.org/t/rust-expression-order-of-evaluation/2605/30

This fix is fine. Just wondering why the nightly CI doesn't pass, I thought the dyn keyword wasn't there until the crate was on the 2018 edition.

vbarrielle commented 5 years ago

So it turns out the dyn keyword was also stabilized in the 2015 edition, so I've pushed a fixed and I'm rebasing and merging your changes. Thanks!