stop using BytePos for computing spans in librustc_parse/parser/mod.rs
Computing spans using logic such as `self.token.span.lo() + BytePos(1)` can cause internal compiler errors like #68730 when non-ascii characters are given as input.
#68735 partially addressed this problem, but only for one case. Moreover, its usage of `next_point()` does not actually align with what `bump_with()` expects. For example, given the token `>>=`, we should pass the span consisting of the final two characters `>=`, but `next_point()` advances the span beyond the end of the `=`.
This pull request instead computes the start of the new span by doing `start_point(self.token.span).hi()`. This matches `self.token.span.lo() + BytePos(1)` in the common case where the characters are ascii, and it gracefully handles multibyte characters.
Fixes#68783.
parser: syntactically allow `self` in all `fn` contexts
Part of https://github.com/rust-lang/rust/pull/68728.
`self` parameters are now *syntactically* allowed as the first parameter irrespective of item context (and in function pointers). Instead, semantic validation (`ast_validation`) is used.
r? @petrochenkov
Suggest path separator for single-colon typos
This commit adds guidance for when a user means to type a path, but ends
up typing a single colon, such as `<<Impl as T>:Ty>`.
This change seemed pertinent as the current error message is
particularly misleading, emitting `error: unmatched angle bracket`,
despite the angle bracket being matched later on, leaving the user to
track down the typo'd colon.
Address inconsistency in using "is" with "declared here"
"is" was generally used for NLL diagnostics, but not other diagnostics. Using "is" makes the diagnostics sound more natural and readable, so it seems sensible to commit to them throughout.
r? @Centril
This commit adds guidance for when a user means to type a path, but ends
up typing a single colon, such as `<<Impl as T>:Ty>`.
This change seemed pertinent as the current error message is
particularly misleading, emitting `error: unmatched angle bracket`,
despite the angle bracket being matched later on, leaving the user to
track down the typo'd colon.
This doesn't mention that using an existing lifetime is possible, but
that would hopefully be clear as always being an option. The intention
of this is to teach newcomers what the lifetime syntax is.
Add suggestions when encountering chained comparisons
Ideally, we'd also prevent the type error, which is just extra noise, but that will require moving the error from the parser, and I think the suggestion makes things clear enough for now.
Fixes https://github.com/rust-lang/rust/issues/65659.
parser: reduce diversity in error handling mechanisms
Instead of having e.g. `span_err`, `fatal`, etc., we prefer to move towards uniformly using `struct_span_err` thus making it harder to emit fatal and/or unstructured diagnostics.
This PR also de-fatalizes some diagnostics.
r? @estebank
Refactor type & bounds parsing thoroughly
PR is based on https://github.com/rust-lang/rust/pull/67131 with first one from this PR being ` extract parse_ty_tuple_or_parens`.
Also fixes#67146.
r? @estebank
Make GATs less ICE-prone.
After this PR simple lifetime-generic associated types can now be used in a compiling program. There are two big limitations:
* #30472 has not been addressed in any way (see src/test/ui/generic-associated-types/iterable.rs)
* Using type- and const-generic associated types errors because bound types and constants aren't handled by trait solving.
* The errors are technically non-fatal, but they happen in a [part of the compiler](4abb0ad273/src/librustc_typeck/lib.rs (L298)) that fairly aggressively stops compiling on errors.
closes#47206closes#49362closes#62521closes#63300closes#64755closes#67089
* Make some run-pass or check-pass
* Use `#![allow(incomplete_features)]`
* Update FIXMEs now that some of the issues have been addressed
* Add regression tests
