Add initial implementation of HIR-based WF checking for diagnostics
During well-formed checking, we walk through all types 'nested' in
generic arguments. For example, WF-checking `Option<MyStruct<u8>>`
will cause us to check `MyStruct<u8>` and `u8`. However, this is done
on a `rustc_middle::ty::Ty`, which has no span information. As a result,
any errors that occur will have a very general span (e.g. the
definintion of an associated item).
This becomes a problem when macros are involved. In general, an
associated type like `type MyType = Option<MyStruct<u8>>;` may
have completely different spans for each nested type in the HIR. Using
the span of the entire associated item might end up pointing to a macro
invocation, even though a user-provided span is available in one of the
nested types.
This PR adds a framework for HIR-based well formed checking. This check
is only run during error reporting, and is used to obtain a more precise
span for an existing error. This is accomplished by individually
checking each 'nested' type in the HIR for the type, allowing us to
find the most-specific type (and span) that produces a given error.
The majority of the changes are to the error-reporting code. However,
some of the general trait code is modified to pass through more
information.
Since this has no soundness implications, I've implemented a minimal
version to begin with, which can be extended over time. In particular,
this only works for HIR items with a corresponding `DefId` (e.g. it will
not work for WF-checking performed within function bodies).
During well-formed checking, we walk through all types 'nested' in
generic arguments. For example, WF-checking `Option<MyStruct<u8>>`
will cause us to check `MyStruct<u8>` and `u8`. However, this is done
on a `rustc_middle::ty::Ty`, which has no span information. As a result,
any errors that occur will have a very general span (e.g. the
definintion of an associated item).
This becomes a problem when macros are involved. In general, an
associated type like `type MyType = Option<MyStruct<u8>>;` may
have completely different spans for each nested type in the HIR. Using
the span of the entire associated item might end up pointing to a macro
invocation, even though a user-provided span is available in one of the
nested types.
This PR adds a framework for HIR-based well formed checking. This check
is only run during error reporting, and is used to obtain a more precise
span for an existing error. This is accomplished by individually
checking each 'nested' type in the HIR for the type, allowing us to
find the most-specific type (and span) that produces a given error.
The majority of the changes are to the error-reporting code. However,
some of the general trait code is modified to pass through more
information.
Since this has no soundness implications, I've implemented a minimal
version to begin with, which can be extended over time. In particular,
this only works for HIR items with a corresponding `DefId` (e.g. it will
not work for WF-checking performed within function bodies).
TAIT: Infer all inference variables in opaque type substitutions via InferCx
The previous algorithm was correct for the example given in its
documentation, but when the TAIT was declared as a free item
instead of an associated item, the generic parameters were the
wrong ones.
cc `@spastorino`
r? `@nikomatsakis`
Loop over all opaque types instead of looking at just the first one with the same DefId
This exposed a bug in VecMap and is needed for https://github.com/rust-lang/rust/pull/86410 anyway
r? ``@spastorino``
cc ``@nikomatsakis``
The previous algorithm was correct for the example given in its
documentation, but when the TAIT was declared as a free item
instead of an associated item, the generic parameters were the
wrong ones.
Remove refs from Pat slices
Changes `PatKind::Or(&'hir [&'hir Pat<'hir>])` to `PatKind::Or(&'hir [Pat<'hir>])` and others. This is more consistent with `ExprKind`, saves a little memory, and is a little easier to use.
RFC2229: Use the correct place type
Closes https://github.com/rust-lang/rust/issues/87097
The ICE occurred because instead of looking at the type of the place after all the projections are applied, we instead looked at the `base_ty` of the Place to decide whether a discriminant should be read of not. This lead to two issues:
1. the kind of the type is not necessarily `Adt` since we only look at the `base_ty`, it could be instead `Ref` for example
2. if the kind of the type is `Adt` you could still be looking at the wrong variant to make a decision on whether the discriminant should be read or not
r? `@nikomatsakis`
Replace associated item bound vars with placeholders when projecting
Fixes#76407Fixes#76826
Similar, but more limited, to #85499. This allows us to handle things like `for<'a> <T as Trait>::Assoc<'a>` but not `for<'a> <T as Trait<'a>>::Assoc`, unblocking GATs.
r? `@nikomatsakis`
Report an error if resolution of closure call functions failed
This pull request fixes#86238. The current implementation seems to assume that resolution of closure call functions (I'm not sure what the proper term is; I mean `call` of `Fn` etc.) can never fail:
60f1a2fc4b/compiler/rustc_typeck/src/check/callee.rs (L590-L595)
But actually, it can, if the `fn`/`fn_mut`/`fn_once` lang items are not defined, or don't have an associated `call`/`call_mut`/`call_once` function, leading to the ICE described in #86238. I have therefore turned the `span_bug!()` into an error message, which prevents the ICE.
Do not suggest adding a semicolon after `?`
Fixes#87051. I have only modified `report_return_mismatched_types()`, i.e. my changes only affect suggestions to add `;` for return type mismatches, but this never makes sense after `?`, because the function cannot return `()` if `?` is used (it has to return a `Result` or an `Option`), and a semicolon won't help if the expected and actual `Err` types differ, even if the expected one is `()`.
Improves migrations lint for RFC2229
This PR improves the current disjoint capture migration lint by providing more information on why drop order or auto trait implementation for a closure is impacted by the use of the new feature.
The drop order migration lint will now look something like this:
```
error: changes to closure capture in Rust 2021 will affect drop order
--> $DIR/significant_drop.rs:163:21
|
LL | let c = || {
| ^^
...
LL | tuple.0;
| ------- in Rust 2018, closure captures all of `tuple`, but in Rust 2021, it only captures `tuple.0`
...
LL | }
| - in Rust 2018, `tuple` would be dropped here, but in Rust 2021, only `tuple.0` would be dropped here alongside the closure
```
The auto trait migration lint will now look something like this:
```
error: changes to closure capture in Rust 2021 will affect `Send` trait implementation for closure
--> $DIR/auto_traits.rs:14:19
|
LL | thread::spawn(move || unsafe {
| ^^^^^^^^^^^^^^ in Rust 2018, this closure would implement `Send` as `fptr` implements `Send`, but in Rust 2021, this closure would no longer implement `Send` as `fptr.0` does not implement `Send`
...
LL | *fptr.0 = 20;
| ------- in Rust 2018, closure captures all of `fptr`, but in Rust 2021, it only captures `fptr.0`
```
r? `@nikomatsakis`
Closes https://github.com/rust-lang/project-rfc-2229/issues/54
Support forwarding caller location through trait object method call
Since PR #69251, the `#[track_caller]` attribute has been supported on
traits. However, it only has an effect on direct (monomorphized) method
calls. Calling a `#[track_caller]` method on a trait object will *not*
propagate caller location information - instead, `Location::caller()` will
return the location of the method definition.
This PR forwards caller location information when `#[track_caller]` is
present on the method definition in the trait. This is possible because
`#[track_caller]` in this position is 'inherited' by any impls of that
trait, so all implementations will have the same ABI.
This PR does *not* change the behavior in the case where
`#[track_caller]` is present only on the impl of a trait.
While all implementations of the method might have an explicit
`#[track_caller]`, we cannot know this at codegen time, since other
crates may have impls of the trait. Therefore, we keep the current
behavior of not forwarding the caller location, ensuring that all
implementations of the trait will have the correct ABI.
See the modified test for examples of how this works
only check cg defaults wf once instantiated
the previous fixmes here didn't make too much sense as I didn't yet fully understand the code further below.
That code only runs if the predicates using our generic param default are fully concrete after substituting our default, which never happens if our default is generic.
r? `@oli-obk` `@BoxyUwU`
Account for capture kind in auto traits migration
Modifies the current auto traits migration for RFC2229 so it takes into account capture kind
Closes https://github.com/rust-lang/project-rfc-2229/issues/51
r? `@nikomatsakis`
2229: Reduce the size of closures with `capture_disjoint_fields`
One key observation while going over the closure size profile of rustc
was that we are disjointly capturing one or more fields starting at an
immutable reference.
Disjoint capture over immutable reference doesn't add too much value
because the fields can either be borrowed immutably or copied.
One possible edge case of the optimization is when a fields of a struct
have a longer lifetime than the structure, therefore we can't completely
get rid of all the accesses on top of sharef refs, only the rightmost
one. Here is a possible example:
```rust
struct MyStruct<'a> {
a: &'static A,
b: B,
c: C<'a>,
}
fn foo<'a, 'b>(m: &'a MyStruct<'b>) -> impl FnMut() + 'static {
let c = || drop(&*m.a.field_of_a);
// Here we really do want to capture `*m.a` because that outlives `'static`
// If we capture `m`, then the closure no longer outlives `'static'
// it is constrained to `'a`
}
```
r? `@nikomatsakis`
- Add `:Sized` assertion in interpreter impl
- Use `Scalar::from_bool` instead of `ScalarInt: From<bool>`
- Remove unneeded comparison in intrinsic typeck
- Make this UB to call with undef, not just return undef in that case
Use diagnostic items instead of lang items for rfc2229 migrations
This PR removes the `Send`, `UnwindSafe` and `RefUnwindSafe` lang items introduced in https://github.com/rust-lang/rust/pull/84730, and uses diagnostic items instead to check for `Send`, `UnwindSafe` and `RefUnwindSafe` traits for RFC2229 migrations.
r? ```@nikomatsakis```
