Turn on new errors and json mode
This PR is a big-switch, but on a well-worn path:
* Turns on new errors by default (and removes old skool)
* Moves json output from behind a flag
The RFC for new errors [landed](https://github.com/rust-lang/rfcs/pull/1644) and as part of that we wanted some bake time. It's now had a few weeks + all the time leading up to the RFC of people banging on it. We've also had [editors updating to the new format](https://github.com/saviorisdead/RustyCode/pull/159) and expect more to follow.
We also have an [issue on old skool](https://github.com/rust-lang/rust/issues/35330) that needs to be fixed as more errors are switched to the new style, but it seems silly to fix old skool errors when we fully intend to throw the switch in the near future.
This makes it lean towards "why not just throw the switch now, rather than waiting a couple more weeks?" I only know of vim that wanted to try to parse the new format but were not sure how, and I think we can reach out to them and work out something in the 8 weeks before this would appear in a stable release.
We've [hashed out](https://github.com/rust-lang/rust/issues/35330) stabilizing JSON output, and it seems like people are relatively happy making what we have v1 and then likely adding to it in the future. The idea is that we'd maintain backward compatibility and just add new fields as needed. We'll also work on a separate output format that'd be better suited for interactive tools like IDES (since JSON message can get a little long depending on the error).
This PR stabilizes JSON mode, allowing its use without `-Z unstable-options`
Combined, this gives editors two ways to support errors going forward: parsing the new error format or using the JSON mode. By moving JSON to stable, we can also add support to Cargo, which plugin authors tell us does help simplify their support story.
r? @nikomatsakis
cc @rust-lang/tools
Closes https://github.com/rust-lang/rust/issues/34826
Address ICEs running w/ incremental compilation and building glium
Fixes for various ICEs I encountered trying to build glium with incremental compilation enabled. Building glium now works. Of the 4 ICEs, I have test cases for 3 of them -- I didn't isolate a test for the last commit and kind of want to go do other things -- most notably, figuring out why incremental isn't saving much *effort*.
But if it seems worthwhile and I can come back and try to narrow down the problem.
r? @michaelwoerister
Fixes#34991Fixes#32015
Centralize and clean type error reporting
Refactors the code that handles type errors to be cleaner and fixes various edge cases.
This made the already-bad "type mismatch resolving" error message somewhat uglier. I want to fix that in another commit before this PR is merged.
Fixes#31173
r? @jonathandturner, cc @nikomatsakis
Refactor constant evaluation to use a single error reporting function
that reports a type-error-like message.
Also, unify all error codes with the "constant evaluation error" message
to just E0080, and similarly for a few other duplicate codes. The old
situation was a total mess, and now that we have *something* we can
further iterate on the UX.
Revert "skip double negation in const eval"
This reverts commit 735c018974e5570ea13fd887aa70a011a5b8e7b8.
fixes#34395
The original commit was based on a mis-understanding of the overflowing literal lint.
This needs to be ported to beta.
r? @eddyb
Support 16-bit pointers as well as i/usize
I'm opening this pull request to get some feedback from the community.
Although Rust doesn't support any platforms with a native 16-bit pointer at the moment, the [AVR-Rust][ar] fork is working towards that goal. Keeping this forked logic up-to-date with the changes in master has been onerous so I'd like to merge these changes so that they get carried along when refactoring happens. I do not believe this should increase the maintenance burden.
This is based on the original work of Dylan McKay (@dylanmckay).
[ar]: https://github.com/avr-rust/rust
fix various const eval errors
These were found after const_evaluating arbitrary expressions and linting if the const evaluator failed
fixes#33275 (int -> float casts for negative ints)
fixes#33291 (int -> char casts (new! wasn't allowed in constants until this PR))
r? @eddyb
cc @bluss @japaric
There was no span available in the cast function, but we need to infer the `x` in `x as char` to `u8`.
The spans are now removed from all functions using `infer` and instead added in `eval_const_expr_partial`
