Modify message for keyword as identifier name
This is a temporary solution to #46311.
The message is generic enough to cover both cases and is probably a fine enough solution to the specific problem described in the task. However, the underlying reason for this to be wrong is that `next_token_inner` returns `Lifetime` even if the token is a label. That's not simple, as the syntax for both can be quite similar and it may need to take a look to the next token to make a decision. I'm not sure I have enough knowledge about the project to be able to solve that (yet!), so I thought I'll fix the immediate problem first.
It's just not useful. It also makes it hard to have tests that probe
internal state, since the interning number is very sensitive.
Dumping the number in the case of gensym is not ideal but will do for
now.
Display `\t` in diagnostics code as four spaces
Follow up to #44386 using the unicode variable width machinery from #45711 to replace tabs in the source code when displaying a diagnostic error with four spaces (instead of only one), while properly accounting for this when calculating underlines.
Partly addresses #44618.
The previous method ran into problems because ICH would treat Spans
as (file,line,col) but the cache contained byte offsets and its
possible for the latter to change while the former stayed stable.
Implement CompilerDesugaringKind enum
This is the first step outlined in #35946. I think that the variants of `CompilerDesugaringKind` should be changed, I didn't know what the official names for `...` and `<-` are.
I'm not to sure how tests for the compiler work, but I would imagine that tests should be added such that
`Symbol::intern(s) == CompilerDesugaringKind::from(s).as_symbol()` for valid `s`.
Fix quadratic performance with lots of use statements
This fixes 2 problems that caused quadratic performance when lots of use-statements were present. After this patch, performance is linear (and very fast) even with 1M uses.
Fixes#43572.
Fixes#43573.
r? @eddyb
We already had a cache for file contents, but we read the source-file
before testing the cache, causing obvious slowness, so this just avoids
loading the source-file when the cache already has the contents.
