unused_must_use: Don't warn on `Result<(), Uninhabited>` or `ControlFlow<Uninhabited, ()>`
This suppresses warnings on things like `Result<(), !>`, which helps simplify code using the common pattern of having an `Error` associated type: code will only have to check the error if there is a possibility of error.
This will, for instance, help with future refactorings of `write!` in the standard library.
As this is a user-visible change to lint behavior, it'll require a lang FCP.
---
My proposal, here, is that we handle this simple case to make common patterns more usable. This does not rule out the possibility of adding more cases in the future, including general trait-based cases. However, I don't think we should make this common case wait on the more general cases. In particular, this solution does not close any doors on replacing this special case with a general case.
This would unblock some planned work in the standard library to make `write!` more usable for infallible cases (e.g. writing into a `Vec` or `String`).
Issue-125323: ICE non-ADT in struct pattern when long time constant evaluation is in for loop
This PR fixes#125323
## Context
According to the issue, the ICE happens since #121206.
In the PR, some error methods were reorganized. For example, has_errors() was renamed to has_errors_exclude_lint_errors(). However, some codes which used the original has_errors() were not switched to has_errors_exclude_lint_errors(). I finally found that report_error() in writeback.rs causes this ICE. Currently the method uses tainted_by_errors() to get guar (ErrorGuaranteed), but originally it used dcx().has_errors() but it wasn't changed to has_errors_exclude_lint_errors() when changes in #121206 were merged. I don't think I fully understand how an error is propagated, but I suppose that the error from long time constant evaluation is unexpectedly propagated other parts (in this ICE, for loop), then cause the non-ADT in struct pattern ICE.
## Change
- Fix report_error() in writeback.rs: use dcx().has_errors_exclude_lint_errors() instead of tainted_by_errors() to prevent error propagation from constant evaluation.
- Add test for the ICE
- Modify some tests to align the change: Due to this fix, E0282 error happens (or not happen anymore) in some tests.
## NOTE
The 4th commit aims to revert the fix in #123516 because I confirmed that the ICE solved by the PR doesn't happen if I modify report_error(). I think the root cause of that ICE is the same as #125323 . But I can discard this commit since we can fix#125323 without it.
Result/Option layout guarantee clarifications
- It seems worth spelling out that this guarantee allows particular transmutes.
- After the `Result` section was written, the `Option` section it referenced gained *more* guarantees, saying that `None` is represented as `[0u8; N]`. Those guarantees were not meant to apply to `Result`. Make the `Result` section more self-contained to make this more clear.
- "Type has no fields" is unclear since there is no general definition of what the fields of some arbitrary type are. Replace that by a more accurate description of the actual check implemented [here](https://github.com/rust-lang/rust/blob/e379c7758667f900aaf5551c4553c7d4c121e3e1/compiler/rustc_lint/src/types.rs#L828-L838).
r? `@traviscross`
mismatched_lifetime_syntax lint refactors and optimizations
I found several opportunities to return early so I'm hoping those will have a perf improvement. Otherwise, it's various refactors for simplicity.
error from const eval lint causes ICE at check_pat in late_lint, because the function expects the typeck result isn't tainted by error but it is.
To avoid the ICE, check_pat returns earlier if the typeck_result is tainted.
check_mod_deathness also has an issue from the same reason. visit_body for making live symbols expects the typeck result has no error.
So this commit adds a check in visit_nested_body to avoid the ICE.
However, if visit_nested_body just returns without doing anything, all codes with the error are marked as dead, because live_symbols is empty.
To avoid this side effect, visit_nested_body and other visit_* functions in MarkSymbolVistior should return appropriate error.
If a function returns ControlFlow::Break, live_symbols_and_ignore_derived_traits returns earlier with error,
then check_mod_deathness, the caller of the function returns earlier without pushing everything into dead_codes.
Restrict sysroot crate imports to those defined in this repo.
It's common to import dependencies from the sysroot via `extern crate` rather than use an explicit cargo dependency, when it's necessary to use the same dependency version as used by rustc itself. However, this is dangerous for crates.io crates, since rustc may not pull in the dependency on some targets, or may pull in multiple versions. In both cases, the `extern crate` fails to resolve.
To address this, re-export all such dependencies from the appropriate `rustc_*` crates, and use this alias from crates which would otherwise need to use `extern crate`.
See https://github.com/rust-lang/rust/pull/143492 for an example of the kind of issue that can occur.
It's common to import dependencies from the sysroot via `extern crate`
rather than use an explicit cargo dependency, when it's necessary to use
the same dependency version as used by rustc itself. However, this is
dangerous for crates.io crates, since rustc may not pull in the
dependency on some targets, or may pull in multiple versions. In both
cases, the `extern crate` fails to resolve.
To address this, re-export all such dependencies from the appropriate
`rustc_*` crates, and use this alias from crates which would otherwise
need to use `extern crate`.
This suppresses warnings on things like `Result<(), !>`, which helps
simplify code using the common pattern of having an `Error` associated
type: code will only have to check the error if there is a possibility
of error.
ignore power alignment rule on unions
fixes https://github.com/rust-lang/rust/issues/147348
The power alignment rule only applies to the non-first field of a struct, and so should not apply to unions at all.
The current code also does not consider enums (whose fields might be, morally, structs). Given that C does not actually have ADTs like this it's probably fine from a compatibility perspective, but I'll leave that to the powerpc folks.
cc `@daltenty` `@gilamn5tr`
r? compiler
Clean up `ty::Dynamic`
1. As a follow-up to PR rust-lang/rust#143036, remove `DynKind` entirely.
2. Inside HIR ty lowering, consolidate modules `dyn_compatibility` and `lint` into `dyn_trait`
* `dyn_compatibility` wasn't about dyn compatibility itself, it's about lowering trait object types
* `lint` contained dyn-Trait-specific diagnostics+lints only
Keep space if arg does not follow punctuation when lint unused parens
Fixesrust-lang/rust#138234
If the arg follows punctuation, still pass `left_pos` with `None` and no space will be added, else then pass `left_pos` with `Some(arg.span.lo())`, so that we can add the space as expected.
And `emit_unused_delims` can make sure no more space will be added if the expr follows space.
---
Edited:
Directly use the `value_span` to check whether the expr removed parens will follow identifier or be followed by identifier.
No changes should be visible by rustc users
This is just some architecture changes to the type checking to
facilitate FFI-safety decisions that depend on how the type is used
(the change here is not complete, there are still bits of "legacy" state
passing for this, but since this is a retconned commit, I can tell you
those bits will disappear before the end of the commit chain)
(there is at least one bit where the decision making code is weird, but
that this is because we do not want to change the lint's behaviour this
early in the chain)
no visible changes to rust users, just making the inner architecture of
the ImproperCTypes lints more sensible, with a clean separation between
the struct (now singular) that interacts with the linting system
and the struct (now singular) that visits the types to check FFI-safety
Mainly, we realise that the non-null assumption on a Box<_> argument
does not depend on what side of the FFI boundary the function is on.
And anyway, this is not the way to deal with this assumption being maybe violated.
This was done in #145740 and #145947. It is causing problems for people
using r-a on anything that uses the rustc-dev rustup package, e.g. Miri,
clippy.
This repository has lots of submodules and subtrees and various
different projects are carved out of pieces of it. It seems like
`[workspace.dependencies]` will just be more trouble than it's worth.
Stuart Cook