From 4b162141631e900f760752eacdd6d5e510ac4e42 Mon Sep 17 00:00:00 2001
From: Camille GILLOT <gillot.camille@gmail.com>
Date: Sat, 13 Aug 2022 18:39:30 +0200
Subject: [PATCH 1/3] Ban references to `Self` in trait object substs for
projection predicates too.
---
compiler/rustc_typeck/src/astconv/mod.rs | 46 +++++++++++++------
src/test/ui/traits/alias/self-in-generics.rs | 7 +++
.../ui/traits/alias/self-in-generics.stderr | 2 +-
3 files changed, 41 insertions(+), 14 deletions(-)
diff --git a/compiler/rustc_typeck/src/astconv/mod.rs b/compiler/rustc_typeck/src/astconv/mod.rs
index 1e6cb53f3eeae..ff81747cafe6f 100644
--- a/compiler/rustc_typeck/src/astconv/mod.rs
+++ b/compiler/rustc_typeck/src/astconv/mod.rs
@@ -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;
@@ -1458,16 +1458,13 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
if ty == dummy_self {
let param = &generics.params[index];
missing_type_params.push(param.name);
- tcx.ty_error().into()
+ return tcx.ty_error().into();
} else if ty.walk().any(|arg| arg == dummy_self.into()) {
references_self = true;
- tcx.ty_error().into()
- } else {
- arg
+ return tcx.ty_error().into();
}
- } else {
- arg
}
+ arg
})
.collect();
let substs = tcx.intern_substs(&substs[..]);
@@ -1506,13 +1503,36 @@ 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 let ty::GenericArgKind::Type(ty) = arg.unpack() {
+ if ty == dummy_self || ty.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 let ty::GenericArgKind::Type(_) = arg.unpack() {
+ return tcx.ty_error().into();
+ }
+ arg
+ })
+ .collect();
+ b.projection_ty.substs = tcx.intern_substs(&substs[..]);
}
+
ty::ExistentialProjection::erase_self_ty(tcx, b)
})
});
diff --git a/src/test/ui/traits/alias/self-in-generics.rs b/src/test/ui/traits/alias/self-in-generics.rs
index 6b99431f5bbcf..0bb6335f91e4b 100644
--- a/src/test/ui/traits/alias/self-in-generics.rs
+++ b/src/test/ui/traits/alias/self-in-generics.rs
@@ -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);
diff --git a/src/test/ui/traits/alias/self-in-generics.stderr b/src/test/ui/traits/alias/self-in-generics.stderr
index a1056872ea641..110d60e6e9116 100644
--- a/src/test/ui/traits/alias/self-in-generics.stderr
+++ b/src/test/ui/traits/alias/self-in-generics.stderr
@@ -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) {}
| ^^^^^^^^^
From be2641a61f2d34fe4f937a49dacfcb82bf0b9075 Mon Sep 17 00:00:00 2001
From: Camille GILLOT <gillot.camille@gmail.com>
Date: Wed, 17 Aug 2022 20:22:52 +0200
Subject: [PATCH 2/3] Fortify check for const generics.
---
compiler/rustc_typeck/src/astconv/mod.rs | 25 ++++++++++--------------
1 file changed, 10 insertions(+), 15 deletions(-)
diff --git a/compiler/rustc_typeck/src/astconv/mod.rs b/compiler/rustc_typeck/src/astconv/mod.rs
index ff81747cafe6f..5bb02bc246caf 100644
--- a/compiler/rustc_typeck/src/astconv/mod.rs
+++ b/compiler/rustc_typeck/src/astconv/mod.rs
@@ -1453,16 +1453,13 @@ 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);
- return tcx.ty_error().into();
- } else if ty.walk().any(|arg| arg == dummy_self.into()) {
- references_self = true;
- return tcx.ty_error().into();
- }
+ 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
})
@@ -1509,10 +1506,8 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
// 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 let ty::GenericArgKind::Type(ty) = arg.unpack() {
- if ty == dummy_self || ty.walk().any(|arg| arg == dummy_self.into()) {
- return true;
- }
+ if arg.walk().any(|arg| arg == dummy_self.into()) {
+ return true;
}
false
});
@@ -1524,7 +1519,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
.substs
.iter()
.map(|arg| {
- if let ty::GenericArgKind::Type(_) = arg.unpack() {
+ if arg.walk().any(|arg| arg == dummy_self.into()) {
return tcx.ty_error().into();
}
arg
From 72acd94117e784d4e7425e827c60d6a6748d7a88 Mon Sep 17 00:00:00 2001
From: Camille GILLOT <gillot.camille@gmail.com>
Date: Wed, 17 Aug 2022 21:50:59 +0200
Subject: [PATCH 3/3] Add const-generics test.
---
src/test/ui/traits/alias/self-in-const-generics.rs | 12 ++++++++++++
.../ui/traits/alias/self-in-const-generics.stderr | 11 +++++++++++
2 files changed, 23 insertions(+)
create mode 100644 src/test/ui/traits/alias/self-in-const-generics.rs
create mode 100644 src/test/ui/traits/alias/self-in-const-generics.stderr
diff --git a/src/test/ui/traits/alias/self-in-const-generics.rs b/src/test/ui/traits/alias/self-in-const-generics.rs
new file mode 100644
index 0000000000000..b0de8ccd67847
--- /dev/null
+++ b/src/test/ui/traits/alias/self-in-const-generics.rs
@@ -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() {}
diff --git a/src/test/ui/traits/alias/self-in-const-generics.stderr b/src/test/ui/traits/alias/self-in-const-generics.stderr
new file mode 100644
index 0000000000000..61cc217cfbce6
--- /dev/null
+++ b/src/test/ui/traits/alias/self-in-const-generics.stderr
@@ -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`.