Rollup merge of #118146 - compiler-errors:deref-into-dyn-regions, r=lcnr

Rework supertrait lint once again

I accidentally pushed the wrong commits because I totally didn't check I was on the right computer when updating #118026.
Sorry, this should address all the nits in #118026.

r? lcnr
This commit is contained in:
Matthias Krüger 2023-11-23 07:06:30 +01:00 committed by GitHub
commit add423bcf7
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
10 changed files with 125 additions and 25 deletions

View File

@ -491,8 +491,9 @@ lint_requested_level = requested on the command line with `{$level} {$lint_name}
lint_span_use_eq_ctxt = use `.eq_ctxt()` instead of `.ctxt() == .ctxt()`
lint_supertrait_as_deref_target = this `Deref` implementation is covered by an implicit supertrait coercion
.label = `{$self_ty}` implements `Deref<Target = dyn {$target_principal}>` which conflicts with supertrait `{$supertrait_principal}`
.label2 = target type is a supertrait of `{$self_ty}`
.help = consider removing this implementation or replacing it with a method instead
.label = target type is a supertrait of `{$t}`
lint_suspicious_double_ref_clone =
using `.clone()` on a double reference, which returns `{$ty}` instead of cloning the inner type

View File

@ -53,35 +53,43 @@ impl<'tcx> LateLintPass<'tcx> for DerefIntoDynSupertrait {
let tcx = cx.tcx;
// `Deref` is being implemented for `t`
if let hir::ItemKind::Impl(impl_) = item.kind
// the trait is a `Deref` implementation
&& let Some(trait_) = &impl_.of_trait
&& let t = tcx.type_of(item.owner_id).instantiate_identity()
&& let opt_did @ Some(did) = trait_.trait_def_id()
&& opt_did == tcx.lang_items().deref_trait()
// `t` is `dyn t_principal`
&& let ty::Dynamic(data, _, ty::Dyn) = t.kind()
&& let Some(t_principal) = data.principal()
&& let Some(did) = trait_.trait_def_id()
&& Some(did) == tcx.lang_items().deref_trait()
// the self type is `dyn t_principal`
&& let self_ty = tcx.type_of(item.owner_id).instantiate_identity()
&& let ty::Dynamic(data, _, ty::Dyn) = self_ty.kind()
&& let Some(self_principal) = data.principal()
// `<T as Deref>::Target` is `dyn target_principal`
&& let Some(target) = cx.get_associated_type(t, did, "Target")
&& let Some(target) = cx.get_associated_type(self_ty, did, "Target")
&& let ty::Dynamic(data, _, ty::Dyn) = target.kind()
&& let Some(target_principal) = data.principal()
// `target_principal` is a supertrait of `t_principal`
&& supertraits(tcx, t_principal.with_self_ty(tcx, tcx.types.trait_object_dummy_self))
.any(|sup| {
tcx.erase_regions(
sup.map_bound(|x| ty::ExistentialTraitRef::erase_self_ty(tcx, x)),
) == tcx.erase_regions(target_principal)
})
&& let Some(supertrait_principal) = supertraits(tcx, self_principal.with_self_ty(tcx, self_ty))
.find(|supertrait| supertrait.def_id() == target_principal.def_id())
{
let t = tcx.erase_regions(t);
let label = impl_
// erase regions in self type for better diagnostic presentation
let (self_ty, target_principal, supertrait_principal) =
tcx.erase_regions((self_ty, target_principal, supertrait_principal));
let label2 = impl_
.items
.iter()
.find_map(|i| (i.ident.name == sym::Target).then_some(i.span))
.map(|label| SupertraitAsDerefTargetLabel { label });
let span = tcx.def_span(item.owner_id.def_id);
cx.emit_spanned_lint(
DEREF_INTO_DYN_SUPERTRAIT,
tcx.def_span(item.owner_id.def_id),
SupertraitAsDerefTarget { t, label },
span,
SupertraitAsDerefTarget {
self_ty,
supertrait_principal: supertrait_principal.map_bound(|trait_ref| {
ty::ExistentialTraitRef::erase_self_ty(tcx, trait_ref)
}),
target_principal,
label: span,
label2,
},
);
}
}

View File

@ -10,7 +10,9 @@ use rustc_errors::{
};
use rustc_hir::def_id::DefId;
use rustc_macros::{LintDiagnostic, Subdiagnostic};
use rustc_middle::ty::{inhabitedness::InhabitedPredicate, Clause, Ty, TyCtxt};
use rustc_middle::ty::{
inhabitedness::InhabitedPredicate, Clause, PolyExistentialTraitRef, Ty, TyCtxt,
};
use rustc_session::parse::ParseSess;
use rustc_span::{edition::Edition, sym, symbol::Ident, Span, Symbol};
@ -556,13 +558,17 @@ pub enum BuiltinSpecialModuleNameUsed {
#[diag(lint_supertrait_as_deref_target)]
#[help]
pub struct SupertraitAsDerefTarget<'a> {
pub t: Ty<'a>,
pub self_ty: Ty<'a>,
pub supertrait_principal: PolyExistentialTraitRef<'a>,
pub target_principal: PolyExistentialTraitRef<'a>,
#[label]
pub label: Span,
#[subdiagnostic]
pub label: Option<SupertraitAsDerefTargetLabel>,
pub label2: Option<SupertraitAsDerefTargetLabel>,
}
#[derive(Subdiagnostic)]
#[label(lint_label)]
#[label(lint_label2)]
pub struct SupertraitAsDerefTargetLabel {
#[primary_span]
pub label: Span,

View File

@ -2,7 +2,7 @@ warning: this `Deref` implementation is covered by an implicit supertrait coerci
--> $DIR/deref-lint-regions.rs:8:1
|
LL | impl<'a> Deref for dyn Foo<'a> {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `dyn Foo<'_>` implements `Deref<Target = dyn Bar<'_>>` which conflicts with supertrait `Bar<'_>`
LL |
LL | type Target = dyn Bar<'a>;
| -------------------------- target type is a supertrait of `dyn Foo<'_>`

View File

@ -8,6 +8,7 @@ trait B: A {}
impl<'a> Deref for dyn 'a + B {
//~^ WARN this `Deref` implementation is covered by an implicit supertrait coercion
type Target = dyn A;
fn deref(&self) -> &Self::Target {
todo!()

View File

@ -2,8 +2,8 @@ warning: this `Deref` implementation is covered by an implicit supertrait coerci
--> $DIR/deref-lint.rs:9:1
|
LL | impl<'a> Deref for dyn 'a + B {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
LL |
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `dyn B` implements `Deref<Target = dyn A>` which conflicts with supertrait `A`
...
LL | type Target = dyn A;
| -------------------- target type is a supertrait of `dyn B`
|

View File

@ -0,0 +1,34 @@
#![deny(deref_into_dyn_supertrait)]
use std::ops::Deref;
trait Bar<T> {}
impl<T, U> Bar<U> for T {}
trait Foo: Bar<i32> {
fn as_dyn_bar_u32<'a>(&self) -> &(dyn Bar<u32> + 'a);
}
impl Foo for () {
fn as_dyn_bar_u32<'a>(&self) -> &(dyn Bar<u32> + 'a) {
self
}
}
impl<'a> Deref for dyn Foo + 'a {
type Target = dyn Bar<u32> + 'a;
fn deref(&self) -> &Self::Target {
self.as_dyn_bar_u32()
}
}
fn take_dyn<T>(x: &dyn Bar<T>) -> T {
todo!()
}
fn main() {
let x: &dyn Foo = &();
let y = take_dyn(x);
let z: u32 = y;
//~^ ERROR mismatched types
}

View File

@ -0,0 +1,16 @@
error[E0308]: mismatched types
--> $DIR/deref-upcast-behavioral-change.rs:32:18
|
LL | let z: u32 = y;
| --- ^ expected `u32`, found `i32`
| |
| expected due to this
|
help: you can convert an `i32` to a `u32` and panic if the converted value doesn't fit
|
LL | let z: u32 = y.try_into().unwrap();
| ++++++++++++++++++++
error: aborting due to previous error
For more information about this error, try `rustc --explain E0308`.

View File

@ -0,0 +1,20 @@
// check-pass
use std::ops::Deref;
trait Bar<T> {}
trait Foo: Bar<i32> {
fn as_dyn_bar_u32<'a>(&self) -> &(dyn Bar<u32> + 'a);
}
impl<'a> Deref for dyn Foo + 'a {
//~^ WARN this `Deref` implementation is covered by an implicit supertrait coercion
type Target = dyn Bar<u32> + 'a;
fn deref(&self) -> &Self::Target {
self.as_dyn_bar_u32()
}
}
fn main() {}

View File

@ -0,0 +1,14 @@
warning: this `Deref` implementation is covered by an implicit supertrait coercion
--> $DIR/migrate-lint-different-substs.rs:11:1
|
LL | impl<'a> Deref for dyn Foo + 'a {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `dyn Foo` implements `Deref<Target = dyn Bar<u32>>` which conflicts with supertrait `Bar<i32>`
LL |
LL | type Target = dyn Bar<u32> + 'a;
| -------------------------------- target type is a supertrait of `dyn Foo`
|
= help: consider removing this implementation or replacing it with a method instead
= note: `#[warn(deref_into_dyn_supertrait)]` on by default
warning: 1 warning emitted