Handle fresh lifetimes on bare trait objects.
This commit is contained in:
Camille GILLOT
parent
d5354eb48e
commit
21a12e8ab7
6 changed files with 53 additions and 71 deletions
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@ -1174,6 +1174,33 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
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param_mode: ParamMode,
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itctx: ImplTraitContext,
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) -> hir::Ty<'hir> {
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// Check whether we should interpret this as a bare trait object.
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// This check mirrors the one in late resolution. We only introduce this special case in
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// the rare occurence we need to lower `Fresh` anonymous lifetimes.
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// The other cases when a qpath should be opportunistically made a trait object are handled
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// by `ty_path`.
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if qself.is_none()
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&& let Some(partial_res) = self.resolver.get_partial_res(t.id)
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&& partial_res.unresolved_segments() == 0
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&& let Res::Def(DefKind::Trait | DefKind::TraitAlias, _) = partial_res.base_res()
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{
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let (bounds, lifetime_bound) = self.with_dyn_type_scope(true, |this| {
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let bound = this.lower_poly_trait_ref(
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&PolyTraitRef {
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bound_generic_params: vec![],
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trait_ref: TraitRef { path: path.clone(), ref_id: t.id },
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span: t.span
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},
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itctx,
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);
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let bounds = this.arena.alloc_from_iter([bound]);
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let lifetime_bound = this.elided_dyn_bound(t.span);
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(bounds, lifetime_bound)
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});
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let kind = hir::TyKind::TraitObject(bounds, lifetime_bound, TraitObjectSyntax::None);
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return hir::Ty { kind, span: self.lower_span(t.span), hir_id: self.next_id() };
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}
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let id = self.lower_node_id(t.id);
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let qpath = self.lower_qpath(t.id, qself, path, param_mode, itctx);
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self.ty_path(id, t.span, qpath)
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@ -611,6 +611,30 @@ impl<'a: 'ast, 'ast> Visitor<'ast> for LateResolutionVisitor<'a, '_, 'ast> {
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TyKind::Path(ref qself, ref path) => {
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self.diagnostic_metadata.current_type_path = Some(ty);
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self.smart_resolve_path(ty.id, qself.as_ref(), path, PathSource::Type);
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// Check whether we should interpret this as a bare trait object.
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if qself.is_none()
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&& let Some(partial_res) = self.r.partial_res_map.get(&ty.id)
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&& partial_res.unresolved_segments() == 0
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&& let Res::Def(DefKind::Trait | DefKind::TraitAlias, _) = partial_res.base_res()
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{
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// This path is actually a bare trait object. In case of a bare `Fn`-trait
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// object with anonymous lifetimes, we need this rib to correctly place the
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// synthetic lifetimes.
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let span = ty.span.shrink_to_lo().to(path.span.shrink_to_lo());
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self.with_generic_param_rib(
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&[],
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NormalRibKind,
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LifetimeRibKind::Generics {
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binder: ty.id,
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kind: LifetimeBinderKind::PolyTrait,
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span,
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},
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|this| this.visit_path(&path, ty.id),
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);
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self.diagnostic_metadata.current_type_path = prev_ty;
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return;
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}
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}
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TyKind::ImplicitSelf => {
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let self_ty = Ident::with_dummy_span(kw::SelfUpper);
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@ -1,5 +1,5 @@
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#![allow(bare_trait_objects)]
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// check-pass
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pub struct FormatWith<'a, I, F> {
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sep: &'a str,
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/// FormatWith uses interior mutability because Display::fmt takes &self.
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@ -21,7 +21,4 @@ where
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fn main() {
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let _ = new_format(0..32, " | ", |i, f| f(&format_args!("0x{:x}", i)));
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//~^ ERROR temporary value dropped while borrowed
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//~| ERROR temporary value dropped while borrowed
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//~| ERROR `i` does not live long enough
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}
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@ -1,43 +0,0 @@
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error[E0716]: temporary value dropped while borrowed
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--> $DIR/bare-trait-object-borrowck.rs:23:48
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LL | let _ = new_format(0..32, " | ", |i, f| f(&format_args!("0x{:x}", i)));
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| - ---^^^^^^^^^^^^^^^^^^^^^^^^^-
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| | | | |
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| | | | temporary value is freed at the end of this statement
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| | | creates a temporary which is freed while still in use
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| | argument requires that borrow lasts for `'1`
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| has type `&mut dyn FnMut(&'1 (dyn std::fmt::Display + '1)) -> Result<(), std::fmt::Error>`
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= note: this error originates in the macro `format_args` (in Nightly builds, run with -Z macro-backtrace for more info)
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error[E0716]: temporary value dropped while borrowed
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--> $DIR/bare-trait-object-borrowck.rs:23:48
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LL | let _ = new_format(0..32, " | ", |i, f| f(&format_args!("0x{:x}", i)));
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| - ---^^^^^^^^^^^^^^^^^^^^^^^^^-
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| | | | |
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| | | | temporary value is freed at the end of this statement
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| | | creates a temporary which is freed while still in use
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| | argument requires that borrow lasts for `'1`
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| has type `&mut dyn FnMut(&'1 (dyn std::fmt::Display + '1)) -> Result<(), std::fmt::Error>`
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= note: this error originates in the macro `format_args` (in Nightly builds, run with -Z macro-backtrace for more info)
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error[E0597]: `i` does not live long enough
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--> $DIR/bare-trait-object-borrowck.rs:23:71
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LL | let _ = new_format(0..32, " | ", |i, f| f(&format_args!("0x{:x}", i)));
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| - --------------------------^--
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| | | | |
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| | | | `i` dropped here while still borrowed
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| | | borrowed value does not live long enough
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| | argument requires that `i` is borrowed for `'1`
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| has type `&mut dyn FnMut(&'1 (dyn std::fmt::Display + '1)) -> Result<(), std::fmt::Error>`
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= note: this error originates in the macro `format_args` (in Nightly builds, run with -Z macro-backtrace for more info)
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error: aborting due to 3 previous errors
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Some errors have detailed explanations: E0597, E0716.
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For more information about an error, try `rustc --explain E0597`.
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@ -1,5 +1,5 @@
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// Verify that lifetime resolution correctly accounts for `Fn` bare trait objects.
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// check-pass
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#![allow(bare_trait_objects)]
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// This should work as: fn next_u32(fill_buf: &mut dyn FnMut(&mut [u8]))
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@ -15,10 +15,8 @@ fn explicit(fill_buf: &mut dyn FnMut(&mut [u8])) {
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fn main() {
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let _: fn(&mut FnMut(&mut [u8])) = next_u32;
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//~^ ERROR mismatched types
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let _: &dyn Fn(&mut FnMut(&mut [u8])) = &next_u32;
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let _: fn(&mut FnMut(&mut [u8])) = explicit;
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//~^ ERROR mismatched types
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let _: &dyn Fn(&mut FnMut(&mut [u8])) = &explicit;
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let _: fn(&mut dyn FnMut(&mut [u8])) = next_u32;
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let _: &dyn Fn(&mut dyn FnMut(&mut [u8])) = &next_u32;
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@ -1,21 +0,0 @@
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error[E0308]: mismatched types
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--> $DIR/bare-trait-object.rs:17:40
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LL | let _: fn(&mut FnMut(&mut [u8])) = next_u32;
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| ^^^^^^^^ one type is more general than the other
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= note: expected fn pointer `for<'r, 's> fn(&'r mut (dyn for<'s> FnMut(&'s mut [u8]) + 'r))`
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found fn item `for<'r> fn(&'r mut (dyn for<'r> FnMut(&'r mut [u8]) + 'r)) {next_u32}`
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error[E0308]: mismatched types
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--> $DIR/bare-trait-object.rs:20:40
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LL | let _: fn(&mut FnMut(&mut [u8])) = explicit;
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| ^^^^^^^^ one type is more general than the other
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= note: expected fn pointer `for<'r, 's> fn(&'r mut (dyn for<'s> FnMut(&'s mut [u8]) + 'r))`
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found fn item `for<'r> fn(&'r mut (dyn for<'r> FnMut(&'r mut [u8]) + 'r)) {explicit}`
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error: aborting due to 2 previous errors
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For more information about this error, try `rustc --explain E0308`.
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