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Rollup merge of rust-lang#100500 - cjgillot:verify-self-predicate, r=…
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…lcnr

Ban references to `Self` in trait object substs for projection predicates too.

Fixes rust-lang#100484
Fixes rust-lang#100485

r? `@lcnr`
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matthiaskrgr authored Aug 20, 2022
2 parents 80fa648 + 72acd94 commit 2038658
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Showing 5 changed files with 67 additions and 22 deletions.
57 changes: 36 additions & 21 deletions compiler/rustc_typeck/src/astconv/mod.rs
Original file line number Diff line number Diff line change
Expand Up @@ -35,7 +35,7 @@ use rustc_session::lint::builtin::{AMBIGUOUS_ASSOCIATED_ITEMS, BARE_TRAIT_OBJECT
use rustc_span::edition::Edition;
use rustc_span::lev_distance::find_best_match_for_name;
use rustc_span::symbol::{kw, Ident, Symbol};
use rustc_span::{Span, DUMMY_SP};
use rustc_span::Span;
use rustc_target::spec::abi;
use rustc_trait_selection::traits;
use rustc_trait_selection::traits::astconv_object_safety_violations;
Expand Down Expand Up @@ -1453,21 +1453,15 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
.enumerate()
.skip(1) // Remove `Self` for `ExistentialPredicate`.
.map(|(index, arg)| {
if let ty::GenericArgKind::Type(ty) = arg.unpack() {
debug!(?ty);
if ty == dummy_self {
let param = &generics.params[index];
missing_type_params.push(param.name);
tcx.ty_error().into()
} else if ty.walk().any(|arg| arg == dummy_self.into()) {
references_self = true;
tcx.ty_error().into()
} else {
arg
}
} else {
arg
if arg == dummy_self.into() {
let param = &generics.params[index];
missing_type_params.push(param.name);
return tcx.ty_error().into();
} else if arg.walk().any(|arg| arg == dummy_self.into()) {
references_self = true;
return tcx.ty_error().into();
}
arg
})
.collect();
let substs = tcx.intern_substs(&substs[..]);
Expand Down Expand Up @@ -1506,13 +1500,34 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
});

let existential_projections = bounds.projection_bounds.iter().map(|(bound, _)| {
bound.map_bound(|b| {
if b.projection_ty.self_ty() != dummy_self {
tcx.sess.delay_span_bug(
DUMMY_SP,
&format!("trait_ref_to_existential called on {:?} with non-dummy Self", b),
);
bound.map_bound(|mut b| {
assert_eq!(b.projection_ty.self_ty(), dummy_self);

// Like for trait refs, verify that `dummy_self` did not leak inside default type
// parameters.
let references_self = b.projection_ty.substs.iter().skip(1).any(|arg| {
if arg.walk().any(|arg| arg == dummy_self.into()) {
return true;
}
false
});
if references_self {
tcx.sess
.delay_span_bug(span, "trait object projection bounds reference `Self`");
let substs: Vec<_> = b
.projection_ty
.substs
.iter()
.map(|arg| {
if arg.walk().any(|arg| arg == dummy_self.into()) {
return tcx.ty_error().into();
}
arg
})
.collect();
b.projection_ty.substs = tcx.intern_substs(&substs[..]);
}

ty::ExistentialProjection::erase_self_ty(tcx, b)
})
});
Expand Down
12 changes: 12 additions & 0 deletions src/test/ui/traits/alias/self-in-const-generics.rs
Original file line number Diff line number Diff line change
@@ -0,0 +1,12 @@
#![allow(incomplete_features)]
#![feature(generic_const_exprs)]
#![feature(trait_alias)]

trait Bar<const N: usize> {}

trait BB = Bar<{ 2 + 1 }>;

fn foo(x: &dyn BB) {}
//~^ ERROR the trait alias `BB` cannot be made into an object [E0038]

fn main() {}
11 changes: 11 additions & 0 deletions src/test/ui/traits/alias/self-in-const-generics.stderr
Original file line number Diff line number Diff line change
@@ -0,0 +1,11 @@
error[E0038]: the trait alias `BB` cannot be made into an object
--> $DIR/self-in-const-generics.rs:9:16
|
LL | fn foo(x: &dyn BB) {}
| ^^
|
= note: it cannot use `Self` as a type parameter in a supertrait or `where`-clause

error: aborting due to previous error

For more information about this error, try `rustc --explain E0038`.
7 changes: 7 additions & 0 deletions src/test/ui/traits/alias/self-in-generics.rs
Original file line number Diff line number Diff line change
@@ -1,3 +1,10 @@
// astconv uses `FreshTy(0)` as a dummy `Self` type when instanciating trait objects.
// This `FreshTy(0)` can leak into substs, causing ICEs in several places.
// Using `save-analysis` triggers type-checking `f` that would be normally skipped
// as `type_of` emitted an error.
//
// compile-flags: -Zsave-analysis

#![feature(trait_alias)]

pub trait SelfInput = Fn(&mut Self);
Expand Down
2 changes: 1 addition & 1 deletion src/test/ui/traits/alias/self-in-generics.stderr
Original file line number Diff line number Diff line change
@@ -1,5 +1,5 @@
error[E0038]: the trait alias `SelfInput` cannot be made into an object
--> $DIR/self-in-generics.rs:5:19
--> $DIR/self-in-generics.rs:12:19
|
LL | pub fn f(_f: &dyn SelfInput) {}
| ^^^^^^^^^
Expand Down

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