I did a read through of the manual. This commit corrects various small points and expands some sections, while avoiding too much detail.
r? @steveklabnik
At the moment, http://doc.rust-lang.org/error-index.html isn't linked to from anywhere (except Reddit). This should allow search engines to find error codes!
I also capitalised "The Standard Library" and neatened a few bits of grammar.
Also fixed: `#[main]` inside one of the error descriptions.
Add diagnostic message for E0317, E0154, E0259 and E0260; part of #24407.
About E0317, I was unsure if I should add an example of what could be wrong, such as `struct i64`, `enum char { A, B }` or `type isize = i64`. I decided against it, since the diagnostic message looks clear enough to me.
What do you think?
I corrected some pretty obvious textual mistakes. One thing requires more attention - the paragraph at line 133 in Ownership. It was confusing, so I changed it, but I am no sure if this is what the author had in mind.
core::slice was originally written to tolerate overflow (notably, with
slices of zero-sized elements), but it was never updated to use wrapping
arithmetic when overflow traps were added.
Also correctly handle the case of calling .nth() on an Iter with a
zero-sized element type. The iterator was assuming that the pointer
value of the returned reference was meaningful, but that's not true for
zero-sized elements.
Fixes#25016.
It is currently broken to use syntax such as `<T as Foo>::U::static_method()` where `<T as Foo>::U` is an associated type. I was able to fix this and simplify the parser a bit at the same time.
This also fixes the corresponding issue with associated types (#22139), but that's somewhat irrelevant because #22519 is still open, so this syntax still causes an error in type checking.
Similarly, although this fix applies to associated consts, #25046 forbids associated constants from using type parameters or `Self`, while #19559 means that associated types have to always have one of those two. Therefore, I think that you can't use an associated const from an associated type anyway.
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.
A few errors slipped through my filter. Markdown formatting is especially important now that http://doc.rust-lang.org/error-index.html is live!
Speaking of, the error index should probably be linked to from somewhere. It doesn't quite fit under any of the sections in the index, but I could create a new one for it? Or add it under "tools" despite it not exactly being an executable tool.
The functions BitSet::{iter,union,symmetric_difference} each had docs that claimed u32s were output when their actual output each end up being usizes.
r? @steveklabnik
Adds long diagnostic messages for:
- E0184
- E0204
- E0205
- E0206
- E0243
- E0244
- E0249
- E0250
This PR also adds some comments to the error codes in `librustc_typeck/diagnostics.rs`.
cc #24407
They're only enabled in debug builds, but a panic is usually more
welcome than UB in debug builds.
Previous review at https://github.com/rust-lang/rust/pull/22069
r? @Gankro
cc @huon
