Top rust issues

It is not intuitive which loop is broken out from in `loop { while break {} }`

Confusing error message when attempting to &mut a mutable reference

A-diagnostics C-enhancement T-compiler

Targets filtered out too early

A-frontend C-enhancement

Using tuples as arguments

Room for optimization improvement on reference counting

A-codegen C-enhancement E-easy I-slow T-libs

Tracking issue for sorting by expensive-to-compute keys (feature slice_sort_by_cached_key)

C-enhancement I-slow T-libs

std::iter::Chain should implement ExactSizeIterator when possible

Allow generating a C header representing the exported symbols of a lib

A-ffi C-enhancement

DWARF for enums could be improved

A-debuginfo C-enhancement

"raw pointers cannot be cast to integers in statics" justification is incorrect