Avoid O(n^2) performance by reconsidering the full set of obligations only when we are about to report an error (#18208). I found it is still important to consider the full set in order to make tests like `let x: Vec<_> = obligations.iter().collect()` work.
auto merge of #18386 : nikomatsakis/rust/issue-18208, r=pnkfelix

Avoid O(n^2) performance by reconsidering the full set of obligations only when we are about to report an error (#18208). I found it is still important to consider the full set in order to make tests like `let x: Vec<_> = obligations.iter().collect()` work.

I think we lack the infrastructure to write a regression test for this, but when I did manual testing I found a massive reduction in type-checking time for extreme examples like those found in #18208 vs stage0.

f? @dotdash
Remove double negation from sqrt's doc comment
auto merge of #18273 : gamazeps/rust/issue18218, r=steveklabnik

Closes #18218
Fix the output of negative duration

Technically speaking, negative duration is not valid ISO 8601, but we need to
print it anyway. If `d` is a positive duration with the output `xxxxxxx`, then
the expected output of negative `-d` value is `-xxxxxxx`. I.e. the idea is to
print negative durations as positive with a leading minus sign.

Closes #18181.
Add ptr::RawMutPtr to prelude

Closes https://github.com/rust-lang/rust/issues/18196
Guide: Fix use of sqrt() in example
Remove unnecessary clone in ascii.rs
Update code with new lint names
Turn on warning for use of deprecated lint names
Add regression test for lint deprecation
Describe doc attribute in the reference

FIxes #7963.
Remove ty_bot from the type system

We now instead use a fresh variable for expressions that diverge.
Update tests with the new error messages
Long lines
Address review comments
auto merge of #17851 : brson/rust/rustup, r=alexcrichton

Just to have it somewhere to point to. Updating it will not
automatically update the one on static.rust-lang.org.
Guide: Iterators: …are always lazy + rewrap as per request
update keyword list

Fixes #17969
Fix example for BufferedReader

Fixes #18197