diff options
6 files changed, 85 insertions, 25 deletions
diff --git a/compiler/rustc_ast_passes/src/ast_validation.rs b/compiler/rustc_ast_passes/src/ast_validation.rs index 1a4c60087c3..f42aca685f6 100644 --- a/compiler/rustc_ast_passes/src/ast_validation.rs +++ b/compiler/rustc_ast_passes/src/ast_validation.rs @@ -38,6 +38,13 @@ enum SelfSemantic { No, } +/// What is the context that prevents using `~const`? +enum DisallowTildeConstContext<'a> { + TraitObject, + ImplTrait, + Fn(FnKind<'a>), +} + struct AstValidator<'a> { session: &'a Session, @@ -56,7 +63,7 @@ struct AstValidator<'a> { /// e.g., `impl Iterator<Item = impl Debug>`. outer_impl_trait: Option<Span>, - is_tilde_const_allowed: bool, + disallow_tilde_const: Option<DisallowTildeConstContext<'a>>, /// Used to ban `impl Trait` in path projections like `<impl Iterator>::Item` /// or `Foo::Bar<impl Trait>` @@ -93,18 +100,26 @@ impl<'a> AstValidator<'a> { self.is_impl_trait_banned = old; } - fn with_tilde_const(&mut self, allowed: bool, f: impl FnOnce(&mut Self)) { - let old = mem::replace(&mut self.is_tilde_const_allowed, allowed); + fn with_tilde_const( + &mut self, + disallowed: Option<DisallowTildeConstContext<'a>>, + f: impl FnOnce(&mut Self), + ) { + let old = mem::replace(&mut self.disallow_tilde_const, disallowed); f(self); - self.is_tilde_const_allowed = old; + self.disallow_tilde_const = old; } fn with_tilde_const_allowed(&mut self, f: impl FnOnce(&mut Self)) { - self.with_tilde_const(true, f) + self.with_tilde_const(None, f) } - fn with_banned_tilde_const(&mut self, f: impl FnOnce(&mut Self)) { - self.with_tilde_const(false, f) + fn with_banned_tilde_const( + &mut self, + ctx: DisallowTildeConstContext<'a>, + f: impl FnOnce(&mut Self), + ) { + self.with_tilde_const(Some(ctx), f) } fn with_let_management( @@ -172,7 +187,7 @@ impl<'a> AstValidator<'a> { fn with_impl_trait(&mut self, outer: Option<Span>, f: impl FnOnce(&mut Self)) { let old = mem::replace(&mut self.outer_impl_trait, outer); if outer.is_some() { - self.with_banned_tilde_const(f); + self.with_banned_tilde_const(DisallowTildeConstContext::ImplTrait, f); } else { f(self); } @@ -197,7 +212,10 @@ impl<'a> AstValidator<'a> { TyKind::ImplTrait(..) => { self.with_impl_trait(Some(t.span), |this| visit::walk_ty(this, t)) } - TyKind::TraitObject(..) => self.with_banned_tilde_const(|this| visit::walk_ty(this, t)), + TyKind::TraitObject(..) => self + .with_banned_tilde_const(DisallowTildeConstContext::TraitObject, |this| { + visit::walk_ty(this, t) + }), TyKind::Path(ref qself, ref path) => { // We allow these: // - `Option<impl Trait>` @@ -1411,13 +1429,15 @@ impl<'a> Visitor<'a> for AstValidator<'a> { ); err.emit(); } - (_, TraitBoundModifier::MaybeConst) => { - if !self.is_tilde_const_allowed { - self.err_handler() - .struct_span_err(bound.span(), "`~const` is not allowed here") - .note("only allowed on bounds on functions, traits' associated types and functions, const impls and its associated functions") - .emit(); - } + (_, TraitBoundModifier::MaybeConst) if let Some(reason) = &self.disallow_tilde_const => { + let mut err = self.err_handler().struct_span_err(bound.span(), "`~const` is not allowed here"); + match reason { + DisallowTildeConstContext::TraitObject => err.note("trait objects cannot have `~const` trait bounds"), + DisallowTildeConstContext::ImplTrait => err.note("`impl Trait`s cannot have `~const` trait bounds"), + DisallowTildeConstContext::Fn(FnKind::Closure(..)) => err.note("closures cannot have `~const` trait bounds"), + DisallowTildeConstContext::Fn(FnKind::Fn(_, ident, ..)) => err.span_note(ident.span, "this function is not `const`, so it cannot have `~const` trait bounds"), + }; + err.emit(); } (_, TraitBoundModifier::MaybeConstMaybe) => { self.err_handler() @@ -1523,10 +1543,13 @@ impl<'a> Visitor<'a> for AstValidator<'a> { }); } - let tilde_const_allowed = matches!(fk.header(), Some(FnHeader { .. })) - || matches!(fk.ctxt(), Some(FnCtxt::Assoc(_))); + let tilde_const_allowed = + matches!(fk.header(), Some(FnHeader { constness: ast::Const::Yes(_), .. })) + || matches!(fk.ctxt(), Some(FnCtxt::Assoc(_))); + + let disallowed = (!tilde_const_allowed).then(|| DisallowTildeConstContext::Fn(fk)); - self.with_tilde_const(tilde_const_allowed, |this| visit::walk_fn(this, fk)); + self.with_tilde_const(disallowed, |this| visit::walk_fn(this, fk)); } fn visit_assoc_item(&mut self, item: &'a AssocItem, ctxt: AssocCtxt) { @@ -1770,7 +1793,7 @@ pub fn check_crate(session: &Session, krate: &Crate, lints: &mut LintBuffer) -> in_const_trait_impl: false, has_proc_macro_decls: false, outer_impl_trait: None, - is_tilde_const_allowed: false, + disallow_tilde_const: None, is_impl_trait_banned: false, is_assoc_ty_bound_banned: false, forbidden_let_reason: Some(ForbiddenLetReason::GenericForbidden), diff --git a/src/test/ui/rfc-2632-const-trait-impl/issue-90052.rs b/src/test/ui/rfc-2632-const-trait-impl/issue-90052.rs new file mode 100644 index 00000000000..21ddf4ab4e5 --- /dev/null +++ b/src/test/ui/rfc-2632-const-trait-impl/issue-90052.rs @@ -0,0 +1,9 @@ +#![feature(const_trait_impl)] + +#[const_trait] +trait Bar {} + +fn foo<T>() where T: ~const Bar {} +//~^ ERROR `~const` is not allowed + +fn main() {} diff --git a/src/test/ui/rfc-2632-const-trait-impl/issue-90052.stderr b/src/test/ui/rfc-2632-const-trait-impl/issue-90052.stderr new file mode 100644 index 00000000000..b2a9365378b --- /dev/null +++ b/src/test/ui/rfc-2632-const-trait-impl/issue-90052.stderr @@ -0,0 +1,14 @@ +error: `~const` is not allowed here + --> $DIR/issue-90052.rs:6:22 + | +LL | fn foo<T>() where T: ~const Bar {} + | ^^^^^^^^^^ + | +note: this function is not `const`, so it cannot have `~const` trait bounds + --> $DIR/issue-90052.rs:6:4 + | +LL | fn foo<T>() where T: ~const Bar {} + | ^^^ + +error: aborting due to previous error + diff --git a/src/test/ui/rfc-2632-const-trait-impl/tilde-const-and-const-params.rs b/src/test/ui/rfc-2632-const-trait-impl/tilde-const-and-const-params.rs index b29b633cff6..78a64b9018a 100644 --- a/src/test/ui/rfc-2632-const-trait-impl/tilde-const-and-const-params.rs +++ b/src/test/ui/rfc-2632-const-trait-impl/tilde-const-and-const-params.rs @@ -1,4 +1,3 @@ -// check-pass #![feature(const_trait_impl)] #![feature(generic_arg_infer)] #![feature(generic_const_exprs)] @@ -24,6 +23,7 @@ impl const Add42 for () { } fn bar<A: ~const Add42, const N: usize>(_: Foo<N>) -> Foo<{ A::add(N) }> { + //~^ ERROR `~const` is not allowed here Foo } diff --git a/src/test/ui/rfc-2632-const-trait-impl/tilde-const-and-const-params.stderr b/src/test/ui/rfc-2632-const-trait-impl/tilde-const-and-const-params.stderr new file mode 100644 index 00000000000..aae72f36e57 --- /dev/null +++ b/src/test/ui/rfc-2632-const-trait-impl/tilde-const-and-const-params.stderr @@ -0,0 +1,14 @@ +error: `~const` is not allowed here + --> $DIR/tilde-const-and-const-params.rs:25:11 + | +LL | fn bar<A: ~const Add42, const N: usize>(_: Foo<N>) -> Foo<{ A::add(N) }> { + | ^^^^^^^^^^^^ + | +note: this function is not `const`, so it cannot have `~const` trait bounds + --> $DIR/tilde-const-and-const-params.rs:25:4 + | +LL | fn bar<A: ~const Add42, const N: usize>(_: Foo<N>) -> Foo<{ A::add(N) }> { + | ^^^ + +error: aborting due to previous error + diff --git a/src/test/ui/rfc-2632-const-trait-impl/tilde-const-invalid-places.stderr b/src/test/ui/rfc-2632-const-trait-impl/tilde-const-invalid-places.stderr index 5d213315634..84867cb4a53 100644 --- a/src/test/ui/rfc-2632-const-trait-impl/tilde-const-invalid-places.stderr +++ b/src/test/ui/rfc-2632-const-trait-impl/tilde-const-invalid-places.stderr @@ -4,7 +4,7 @@ error: `~const` is not allowed here LL | fn rpit() -> impl ~const T { S } | ^^^^^^^^ | - = note: only allowed on bounds on functions, traits' associated types and functions, const impls and its associated functions + = note: `impl Trait`s cannot have `~const` trait bounds error: `~const` is not allowed here --> $DIR/tilde-const-invalid-places.rs:12:17 @@ -12,7 +12,7 @@ error: `~const` is not allowed here LL | fn apit(_: impl ~const T) {} | ^^^^^^^^ | - = note: only allowed on bounds on functions, traits' associated types and functions, const impls and its associated functions + = note: `impl Trait`s cannot have `~const` trait bounds error: `~const` is not allowed here --> $DIR/tilde-const-invalid-places.rs:15:50 @@ -20,7 +20,7 @@ error: `~const` is not allowed here LL | fn rpit_assoc_bound() -> impl IntoIterator<Item: ~const T> { Some(S) } | ^^^^^^^^ | - = note: only allowed on bounds on functions, traits' associated types and functions, const impls and its associated functions + = note: `impl Trait`s cannot have `~const` trait bounds error: `~const` is not allowed here --> $DIR/tilde-const-invalid-places.rs:18:48 @@ -28,7 +28,7 @@ error: `~const` is not allowed here LL | fn apit_assoc_bound(_: impl IntoIterator<Item: ~const T>) {} | ^^^^^^^^ | - = note: only allowed on bounds on functions, traits' associated types and functions, const impls and its associated functions + = note: `impl Trait`s cannot have `~const` trait bounds error: `~const` and `?` are mutually exclusive --> $DIR/tilde-const-invalid-places.rs:21:25 |