This ended up being a bigger refactoring than I thought, as I also cleaned a few ugly points in rustc. There are still a few areas that need improvements.
Performance numbers:
```
Before:
572.70user 5.52system 7:33.21elapsed 127%CPU (0avgtext+0avgdata 1173368maxresident)k
llvm-time: 385.858
After:
545.27user 5.49system 7:10.22elapsed 128%CPU (0avgtext+0avgdata 1145348maxresident)k
llvm-time: 387.119
```
A good 5% perf improvement. Note that after this patch >70% of the time is spent in LLVM - Amdahl's law is in full effect.
Passes make check locally.
r? @nikomatsakis
With the latter is provided by the `From` conversion trait, the former is now completely redundant. Their code is identical. Let’s deprecate now and plan to remove in the next cycle. (It’s `#[unstable]`.)
r? @alexcrichton
CC @nagisa
rustdoc: Associated type fixes
The first commit fixes a bug with "dud" items in the search index from
misrepresented `type` items in trait impl blocks.
For a trait *implementation* there are typedefs which are the types for
that particular trait and implementor. Skip these in the search index.
There were lots of dud items in the search index due to this (search for
Item, Iterator's associated type).
Add a boolean to clean::TypedefItem so that it tracks whether the it is
a type alias on its own, or if it's a `type` item in a trait impl.
The second commit fixes a bug that made signatures and where bounds
using associated types (if they were not on `Self`) incorrect.
The third commit fixes so that where clauses in type alias definititons
are shown.
Fixes#22442Fixes#24417Fixes#25769
Functions such as `fn foo<I: Iterator>(x: I::Item)` would not
render correctly and displayed `I` instead of `I::Item`. Same thing
with `I::Item` appearing in where bounds.
This fixes the bug by using paths for generics.
Fixes#24417
- add feature gate
- add basic tests
- adjust parser to eliminate conflict between `const fn` and associated
constants
- allow `const fn` in traits/trait-impls, but forbid later in type check
- correct some merge conflicts
For a trait *implementation* there are typedefs which are the types for
that particular trait and implementor. Skip these in the search index.
There were lots of dud items in the search index due to this (search for
Item, Iterator's associated type).
Add a boolean to clean::TypedefItem so that it tracks whether the it is
a type alias on its own, or if it's a `type` item in a trait impl.
Fixes#22442
The loop to load all the known impls from external crates seems to have been used because `ty::populate_implementations_for_trait_if_necessary` wasn't doing its job, and solely relying on it resulted in loading only impls in the same crate as the trait.
Coherence for `librustc` was reduced from 18.310s to 0.610s, from stage1 to stage2.
Interestingly, type checking also went from 46.232s to 42.003s, though that could be noise or unrelated improvements.
On a smaller scale, `fn main() {}` now spends 0.003s in coherence instead of 0.368s, which fixes#22068.
It also peaks at only 1.2MB, instead of 16MB of heap usage.
There were still some mentions of `~[T]` and `~T`, mostly in comments and debugging statements. I tried to do my best to preserve meaning, but I might have gotten some wrong-- I'm happy to fix anything :)
