Don't emit the same compiler diagnostic twice.
This PR makes the compiler filter out diagnostic messages that have already been emitted during the same compilation session.
Make fields of `Span` private
I actually tried to intern spans and benchmark the result<sup>*</sup>, and this was a prerequisite.
This kind of encapsulation will be a prerequisite for any other attempt to compress span's representation, so I decided to submit this change alone.
The issue https://github.com/rust-lang/rust/issues/43088 seems relevant, but it looks like `SpanId` won't be able to reuse this interface, unless the tables are global (like interner that I tried) and are not a part of HIR.
r? @michaelwoerister anyway
<sup>*</sup> Interning means 2-3 times more space is required for a single span, but duplicates are free. In practice it turned out that duplicates are not *that* common, so more memory was wasted by interning rather than saved.
rustc: Start moving toward "try_get is a bug" for incremental
This PR is an effort to burn down some of the work items on #42633. The basic change here was to leave the `try_get` function exposed but have it return a `DiagnosticBuilder` instead of a `CycleError`. This means that it should be a compiler bug to *not* handle the error as dropping a diagnostic should result in a complier panic.
After that change it was then necessary to update the compiler's callsites of `try_get` to handle the error coming out. These were handled as:
* The `sized_constraint` and `needs_drop_raw` checks take the diagnostic and defer it as a compiler bug. This was a new piece of functionality added to the error handling infrastructure, and the idea is that for both these checks a "real" compiler error should be emitted elsewhere, so it's only a bug if we don't actually emit the complier error elsewhere.
* MIR inlining was updated to just ignore the diagnostic. This is being tracked by https://github.com/rust-lang/rust/issues/43542 which sounded like it either already had some work underway or was planning to change regardless.
* The final case, `item_path`, is still sort of up for debate. At the time of this writing this PR simply removes the invocations of `try_get` there, assuming that the query will always succeed. This turns out to be true for the test suite anyway! It sounds like, though, that this logic was intended to assist in "weird" situations like `RUST_LOG` where debug implementations can trigger at any time. This PR would therefore, however, break those implementations.
I'm unfortunately sort of out of ideas on how to handle `item_path`, but other thoughts would be welcome!
Closes#42633
This adds a function to `DiagnosticBuilder` to delay the entire diagnostic as a
bug to be emitted at a later time. This'll end up getting used in the compiler
in the subsequent commits...
This commit alters the `rustc::ty::maps` implementation to ensure that all
output diagnostics from the compiler are tracked for the duration of each query.
These are then intended to be replayed back the first time a cached value is
loaded, and otherwise the cache should operate the same as it does today.
Closes#42513
Now there's a way to add suggestions that hide the suggested code when
presented inline, to avoid weird wording when short code snippets are
added at the end.
* The lazy loading mechanism has been moved to a more appropriate place.
* Return values from the functions invoked there are properly used.
* Documentation has gotten some minor improvements.
* Possibly some larger restructuring will need to take place still.
We now fetch source lines from the `external_src` member as a secondary
fallback if no regular source is present, that is, if the file map
belongs to an external crate and the source has been fetched from disk.
They are now handled in their own member to prevent mutating access to
the `src` member. This way, we can safely load external sources, while
keeping the mutation of local source strings off-limits.
Minimize single span suggestions into a label
changes
```
14 | println!("☃{}", tup[0]);
| ^^^^^^
|
help: to access tuple elements, use tuple indexing syntax as shown
| println!("☃{}", tup.0);
```
into
```
14 | println!("☃{}", tup[0]);
| ^^^^^^ to access tuple elements, use `tup.0`
```
Also makes suggestions explicit in the backend in preparation of adding multiple suggestions to a single diagnostic. Currently that's already possible, but results in a full help message + modified code snippet per suggestion, and has no rate limit (might show 100+ suggestions).
`try_index_step` does not resolve type variables by itself and would
fail otherwise. Also harden the failure path in `confirm` to cause less
confusing errors.
