Make FileMap::{lines, multibyte_chars, non_narrow_chars} non-mutable.
This PR removes most of the interior mutability from `FileMap`, which should be beneficial, especially in a multithreaded setting. This is achieved by initializing the state in question when the filemap is constructed instead of during lexing. Hopefully this doesn't degrade performance.
cc @wesleywiser
The method relied on the FileMap still being under construction in
order for it to do what the name promises. It's now independent of
the current state.
Add existential type definitions
Note: this does not allow creating named existential types, it just desugars `impl Trait` to a less (but still very) hacky version of actual `existential type` items.
r? @nikomatsakis
Implement edition hygiene for keywords
Determine "keywordness" of an identifier in its hygienic context.
cc https://github.com/rust-lang/rust/pull/49611
I've resurrected `proc` as an Edition-2015-only keyword for testing purposes, but it should probably be buried again. EDIT: `proc` is removed again.
Improve format string errors
Point at format string position inside the formatting string:
```
error: invalid format string: unmatched `}` found
--> $DIR/format-string-error.rs:21:22
|
LL | let _ = format!("}");
| ^ unmatched `}` in format string
```
Explain that argument names can't start with an underscore:
```
error: invalid format string: invalid argument name `_foo`
--> $DIR/format-string-error.rs:15:23
|
LL | let _ = format!("{_foo}", _foo = 6usize);
| ^^^^ invalid argument name in format string
|
= note: argument names cannot start with an underscore
```
Fix#23476.
The more accurate spans will only be seen when using `format!` directly, when using `println!` the diagnostics machinery makes the span be the entire statement.
It only has a single use, within code handling indented block comments.
We can replace that with the new `FileMap::col_pos()`, which computes
the col position (BytePos instead of CharPos) based on the record of the
last newline char (which we already record).
This is actually an improvement, because
`trim_whitespace_prefix_and_push_line()` was using `col`, which is a
`CharPos`, as a slice index, which is a byte/char confusion.
Add some utilities to `libsyntax`
Adds a few functions to `Mark` and `Span` that I found useful in an upcoming refactor of NLL region error reporting. Also includes some new documentation based on my discussion with @jseyfried on IRC.
r? @jseyfried
Provide better names for builtin deriving-generated attributes
First attempt at fixing #49967
Not in love with any choices here, don't be shy if you aren't happy with anything :)
I've tested that this produces nicer names in documentation, and that it no longer has issues conflicting with constants with the same name. (I guess we _could_ make a test for that... unsure if that would be valuable)
In all cases I took the names from the methods as declared in the relevant trait.
In some cases I had to prepend the names with _ otherwise there were errors about un-used variables. I'm uneasy with the inconsistency... do they all need to be like that? Is there a way to generate an alternate impl or use a different name (`_`?) in the cases where the arguments are not used?
Lastly the gensym addition to Ident I implemented largely as suggested, but I want to point out it's a little circuitous (at least, as far as I understand it). `cx.ident_of(name)` is just `Ident::from_str`, so we create an Ident then another Ident from it. `Ident::with_empty_ctxt(Symbol::gensym(string))` may or may not be equivalent, I don't know if it's important to intern it _then_ gensym it. It seems like either we could use that, or if we do want a new method to make this convenient, it could be on Ident instead (`from_str_gensymed`?)
