consistent naming for Rhs type parameter in libcore/ops
Rename RHS type parameter occurrences RHS->Rhs to make it consistent throughout files and follow naming conventions.
Added warning for unused arithmetic expressions
The compiler now displays a warning when a binary arithmetic operation is evaluated but not used. This resolves#50124 by following the instructions outlined in the issue. The changes are as follows:
- Added new pattern matching for unused arithmetic expressions in `src/librustc_lint/unused.rs`
- Added `#[must_use]` attributes to the binary operation methods in `src/libcore/internal_macros.rs`
- Added `#[must_use]` attributes to the non-assigning binary operators in `src/libcore/ops/arith.rs`
- filter error on the evaluated value of `Self`
- filter error on the evaluated value of the type arguments
- add argument to include custom note in diagnostic
- allow the parser to parse `Self` when processing attributes
- add custom message to binops
* fixed link typos and copy-paster errors
* rewrote Fn* explanations
* `RHS = Self` -> `RHS` is `Self` (added that to all applicable places as
well)
* fixed up some links
* s/MutDeref/DerefMut
* removed remaining superfluous `fn main()`s
* fixed some minor phrasings and factual errors and inaccuracies
std::ops docs: Fix phrasing and factual errors/inaccuracies
Part of #29365.
* Replaced examples for Mul-/Div-/RemAssign with more illustrative ones
* Made summary senteces for the trait methods use third person singular
* Moved some explanations from Examples section to main explanation
* Switched around argument order for the vector-scalar multiplication
example such that the vector is on the left side (as it would be expected
if one were to switch from `*` to `*=`)
* Replaced mostly redundant example introductions with headings in traits
with more than one example (where it made sense)
* Cleaned up some examples to derive `PartialEq` instead of implementing it
manually when that wasn't needed
* Removed explicit `fn main()`s in examples where they weren't necessary
* Rephrased some things
* Added some missing periods
* Fixed some formatting/punctuation in examples
