diff options
4 files changed, 88 insertions, 2 deletions
diff --git a/compiler/rustc_typeck/src/astconv/generics.rs b/compiler/rustc_typeck/src/astconv/generics.rs index 956696546da..05ff7f818c7 100644 --- a/compiler/rustc_typeck/src/astconv/generics.rs +++ b/compiler/rustc_typeck/src/astconv/generics.rs @@ -445,7 +445,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o { let named_type_param_count = param_counts.types - has_self as usize - synth_type_param_count; let infer_lifetimes = - gen_pos != GenericArgPosition::Type && !gen_args.has_lifetime_params(); + (gen_pos != GenericArgPosition::Type || infer_args) && !gen_args.has_lifetime_params(); if gen_pos != GenericArgPosition::Type && !gen_args.bindings.is_empty() { Self::prohibit_assoc_ty_binding(tcx, gen_args.bindings[0].span); diff --git a/compiler/rustc_typeck/src/astconv/mod.rs b/compiler/rustc_typeck/src/astconv/mod.rs index 17cf3667611..71444d8a8af 100644 --- a/compiler/rustc_typeck/src/astconv/mod.rs +++ b/compiler/rustc_typeck/src/astconv/mod.rs @@ -482,7 +482,20 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o { ) -> subst::GenericArg<'tcx> { let tcx = self.astconv.tcx(); match param.kind { - GenericParamDefKind::Lifetime => tcx.lifetimes.re_static.into(), + GenericParamDefKind::Lifetime => self + .astconv + .re_infer(Some(param), self.span) + .unwrap_or_else(|| { + debug!(?param, "unelided lifetime in signature"); + + // This indicates an illegal lifetime in a non-assoc-trait position + tcx.sess.delay_span_bug(self.span, "unelided lifetime in signature"); + + // Supply some dummy value. We don't have an + // `re_error`, annoyingly, so use `'static`. + tcx.lifetimes.re_static + }) + .into(), GenericParamDefKind::Type { has_default, .. } => { if !infer_args && has_default { // No type parameter provided, but a default exists. diff --git a/src/test/ui/generic-associated-types/elided-in-expr-position.rs b/src/test/ui/generic-associated-types/elided-in-expr-position.rs new file mode 100644 index 00000000000..482d0d5c00a --- /dev/null +++ b/src/test/ui/generic-associated-types/elided-in-expr-position.rs @@ -0,0 +1,38 @@ +#![feature(generic_associated_types)] +#![allow(unused)] + +pub trait Trait { + type Assoc<'a> where Self: 'a; + + fn f(&self) -> Self::Assoc<'_>; + + // Disallow elision in return position, for now + fn g(&self) -> Self::Assoc; + //~^ ERROR missing generics for associated type `Trait::Assoc` +} + +pub struct Struct { + item: f32 +} + +pub struct GenericStruct<'a> { + ref_item: &'a f32 +} + +impl Trait for Struct { + type Assoc<'a> = GenericStruct<'a>; + + fn f(&self) -> Self::Assoc<'_> { + Self::Assoc { + ref_item: &self.item + } + } + + // Disallow elision in return position, for now + fn g(&self) -> Self::Assoc { + //~^ ERROR missing generics for associated type `Trait::Assoc` + todo!() + } +} + +fn main() {} diff --git a/src/test/ui/generic-associated-types/elided-in-expr-position.stderr b/src/test/ui/generic-associated-types/elided-in-expr-position.stderr new file mode 100644 index 00000000000..9263f3d67e3 --- /dev/null +++ b/src/test/ui/generic-associated-types/elided-in-expr-position.stderr @@ -0,0 +1,35 @@ +error[E0107]: missing generics for associated type `Trait::Assoc` + --> $DIR/elided-in-expr-position.rs:10:26 + | +LL | fn g(&self) -> Self::Assoc; + | ^^^^^ expected 1 lifetime argument + | +note: associated type defined here, with 1 lifetime parameter: `'a` + --> $DIR/elided-in-expr-position.rs:5:10 + | +LL | type Assoc<'a> where Self: 'a; + | ^^^^^ -- +help: add missing lifetime argument + | +LL | fn g(&self) -> Self::Assoc<'_>; + | ~~~~~~~~~ + +error[E0107]: missing generics for associated type `Trait::Assoc` + --> $DIR/elided-in-expr-position.rs:32:26 + | +LL | fn g(&self) -> Self::Assoc { + | ^^^^^ expected 1 lifetime argument + | +note: associated type defined here, with 1 lifetime parameter: `'a` + --> $DIR/elided-in-expr-position.rs:5:10 + | +LL | type Assoc<'a> where Self: 'a; + | ^^^^^ -- +help: add missing lifetime argument + | +LL | fn g(&self) -> Self::Assoc<'_> { + | ~~~~~~~~~ + +error: aborting due to 2 previous errors + +For more information about this error, try `rustc --explain E0107`. |