diff --git a/compiler/rustc_infer/messages.ftl b/compiler/rustc_infer/messages.ftl index 7a5e71599203e..c279195a7e99c 100644 --- a/compiler/rustc_infer/messages.ftl +++ b/compiler/rustc_infer/messages.ftl @@ -225,6 +225,8 @@ infer_outlives_content = lifetime of reference outlives lifetime of borrowed con infer_precise_capturing_existing = add `{$new_lifetime}` to the `use<...>` bound to explicitly capture it infer_precise_capturing_new = add a `use<...>` bound to explicitly capture `{$new_lifetime}` +infer_precise_capturing_new_but_apit = add a `use<...>` bound to explicitly capture `{$new_lifetime}` after turning all argument-position `impl Trait` into type parameters, noting that this possibly affects the API of this crate + infer_prlf_defined_with_sub = the lifetime `{$sub_symbol}` defined here... infer_prlf_defined_without_sub = the lifetime defined here... infer_prlf_known_limitation = this is a known limitation that will be removed in the future (see issue #100013 for more information) @@ -387,6 +389,9 @@ infer_type_annotations_needed = {$source_kind -> .label = type must be known at this point infer_types_declared_different = these two types are declared with different lifetimes... + +infer_warn_removing_apit_params = you could use a `use<...>` bound to explicitly capture `{$new_lifetime}`, but argument-position `impl Trait`s are not nameable + infer_where_copy_predicates = copy the `where` clause predicates from the trait infer_where_remove = remove the `where` clause diff --git a/compiler/rustc_infer/src/errors/mod.rs b/compiler/rustc_infer/src/errors/mod.rs index ce1b0f86d0341..e86c96fe4d73c 100644 --- a/compiler/rustc_infer/src/errors/mod.rs +++ b/compiler/rustc_infer/src/errors/mod.rs @@ -1610,3 +1610,25 @@ pub enum AddPreciseCapturing { post: &'static str, }, } + +pub struct AddPreciseCapturingAndParams { + pub suggs: Vec<(Span, String)>, + pub new_lifetime: Symbol, + pub apit_spans: Vec, +} + +impl Subdiagnostic for AddPreciseCapturingAndParams { + fn add_to_diag_with>( + self, + diag: &mut Diag<'_, G>, + _f: &F, + ) { + diag.arg("new_lifetime", self.new_lifetime); + diag.multipart_suggestion_verbose( + fluent::infer_precise_capturing_new_but_apit, + self.suggs, + Applicability::MaybeIncorrect, + ); + diag.span_note(self.apit_spans, fluent::infer_warn_removing_apit_params); + } +} diff --git a/compiler/rustc_infer/src/infer/error_reporting/region.rs b/compiler/rustc_infer/src/infer/error_reporting/region.rs index 191cb23184da1..9e5f032f2d521 100644 --- a/compiler/rustc_infer/src/infer/error_reporting/region.rs +++ b/compiler/rustc_infer/src/infer/error_reporting/region.rs @@ -1269,9 +1269,13 @@ fn suggest_precise_capturing<'tcx>( captured_lifetime: ty::Region<'tcx>, diag: &mut Diag<'_>, ) { - let hir::OpaqueTy { bounds, .. } = + let hir::OpaqueTy { bounds, origin, .. } = tcx.hir_node_by_def_id(opaque_def_id).expect_item().expect_opaque_ty(); + let hir::OpaqueTyOrigin::FnReturn(fn_def_id) = *origin else { + return; + }; + let new_lifetime = Symbol::intern(&captured_lifetime.to_string()); if let Some((args, span)) = bounds.iter().find_map(|bound| match bound { @@ -1306,6 +1310,7 @@ fn suggest_precise_capturing<'tcx>( let variances = tcx.variances_of(opaque_def_id); let mut generics = tcx.generics_of(opaque_def_id); + let mut synthetics = vec![]; loop { for param in &generics.own_params { if variances[param.index as usize] == ty::Bivariant { @@ -1317,9 +1322,7 @@ fn suggest_precise_capturing<'tcx>( captured_lifetimes.insert(param.name); } ty::GenericParamDefKind::Type { synthetic: true, .. } => { - // FIXME: We can't provide a good suggestion for - // `use<...>` if we have an APIT. Bail for now. - return; + synthetics.push((tcx.def_span(param.def_id), param.name)); } ty::GenericParamDefKind::Type { .. } | ty::GenericParamDefKind::Const { .. } => { @@ -1340,17 +1343,86 @@ fn suggest_precise_capturing<'tcx>( return; } - let concatenated_bounds = captured_lifetimes - .into_iter() - .chain(captured_non_lifetimes) - .map(|sym| sym.to_string()) - .collect::>() - .join(", "); - - diag.subdiagnostic(errors::AddPreciseCapturing::New { - span: tcx.def_span(opaque_def_id).shrink_to_hi(), - new_lifetime, - concatenated_bounds, - }); + if synthetics.is_empty() { + let concatenated_bounds = captured_lifetimes + .into_iter() + .chain(captured_non_lifetimes) + .map(|sym| sym.to_string()) + .collect::>() + .join(", "); + + diag.subdiagnostic(errors::AddPreciseCapturing::New { + span: tcx.def_span(opaque_def_id).shrink_to_hi(), + new_lifetime, + concatenated_bounds, + }); + } else { + let mut next_fresh_param = || { + ["T", "U", "V", "W", "X", "Y", "A", "B", "C"] + .into_iter() + .map(Symbol::intern) + .chain((0..).map(|i| Symbol::intern(&format!("T{i}")))) + .find(|s| captured_non_lifetimes.insert(*s)) + .unwrap() + }; + + let mut new_params = String::new(); + let mut suggs = vec![]; + let mut apit_spans = vec![]; + + for (i, (span, name)) in synthetics.into_iter().enumerate() { + apit_spans.push(span); + + let fresh_param = next_fresh_param(); + + // Suggst renaming. + suggs.push((span, fresh_param.to_string())); + + // Super jank. Turn `impl Trait` into `T: Trait`. + // + // This currently involves stripping the `impl` from the name of + // the parameter, since APITs are always named after how they are + // rendered in the AST. This sucks! But to recreate the bound list + // from the APIT itself would be miserable, so we're stuck with + // this for now! + if i > 0 { + new_params += ", "; + } + let name_as_bounds = name.as_str().trim_start_matches("impl").trim_start(); + new_params += fresh_param.as_str(); + new_params += ": "; + new_params += name_as_bounds; + } + + let Some(generics) = tcx.hir().get_generics(fn_def_id) else { + // This shouldn't happen, but don't ICE. + return; + }; + + // Add generics or concatenate to the end of the list. + suggs.push(if let Some(params_span) = generics.span_for_param_suggestion() { + (params_span, format!(", {new_params}")) + } else { + (generics.span, format!("<{new_params}>")) + }); + + let concatenated_bounds = captured_lifetimes + .into_iter() + .chain(captured_non_lifetimes) + .map(|sym| sym.to_string()) + .collect::>() + .join(", "); + + suggs.push(( + tcx.def_span(opaque_def_id).shrink_to_hi(), + format!(" + use<{concatenated_bounds}>"), + )); + + diag.subdiagnostic(errors::AddPreciseCapturingAndParams { + suggs, + new_lifetime, + apit_spans, + }); + } } } diff --git a/tests/ui/impl-trait/precise-capturing/hidden-type-suggestion.rs b/tests/ui/impl-trait/precise-capturing/hidden-type-suggestion.rs index e0b115b0ce412..b50780643f1cc 100644 --- a/tests/ui/impl-trait/precise-capturing/hidden-type-suggestion.rs +++ b/tests/ui/impl-trait/precise-capturing/hidden-type-suggestion.rs @@ -27,4 +27,16 @@ fn missing<'a, 'captured, 'not_captured, Captured>(x: &'a ()) -> impl Captures<' //~^ ERROR hidden type for } +fn no_params_yet(_: impl Sized, y: &()) -> impl Sized { +//~^ HELP add a `use<...>` bound + y +//~^ ERROR hidden type for +} + +fn yes_params_yet<'a, T>(_: impl Sized, y: &'a ()) -> impl Sized { +//~^ HELP add a `use<...>` bound + y +//~^ ERROR hidden type for +} + fn main() {} diff --git a/tests/ui/impl-trait/precise-capturing/hidden-type-suggestion.stderr b/tests/ui/impl-trait/precise-capturing/hidden-type-suggestion.stderr index 391f16d012e4b..1007a835894e1 100644 --- a/tests/ui/impl-trait/precise-capturing/hidden-type-suggestion.stderr +++ b/tests/ui/impl-trait/precise-capturing/hidden-type-suggestion.stderr @@ -62,6 +62,48 @@ help: add a `use<...>` bound to explicitly capture `'a` LL | fn missing<'a, 'captured, 'not_captured, Captured>(x: &'a ()) -> impl Captures<'captured> + use<'captured, 'a, Captured> { | ++++++++++++++++++++++++++++++ -error: aborting due to 4 previous errors +error[E0700]: hidden type for `impl Sized` captures lifetime that does not appear in bounds + --> $DIR/hidden-type-suggestion.rs:32:5 + | +LL | fn no_params_yet(_: impl Sized, y: &()) -> impl Sized { + | --- ---------- opaque type defined here + | | + | hidden type `&()` captures the anonymous lifetime defined here +LL | +LL | y + | ^ + | +note: you could use a `use<...>` bound to explicitly capture `'_`, but argument-position `impl Trait`s are not nameable + --> $DIR/hidden-type-suggestion.rs:30:21 + | +LL | fn no_params_yet(_: impl Sized, y: &()) -> impl Sized { + | ^^^^^^^^^^ +help: add a `use<...>` bound to explicitly capture `'_` after turning all argument-position `impl Trait` into type parameters, noting that this possibly affects the API of this crate + | +LL | fn no_params_yet(_: T, y: &()) -> impl Sized + use<'_, T> { + | ++++++++++ ~ ++++++++++++ + +error[E0700]: hidden type for `impl Sized` captures lifetime that does not appear in bounds + --> $DIR/hidden-type-suggestion.rs:38:5 + | +LL | fn yes_params_yet<'a, T>(_: impl Sized, y: &'a ()) -> impl Sized { + | -- ---------- opaque type defined here + | | + | hidden type `&'a ()` captures the lifetime `'a` as defined here +LL | +LL | y + | ^ + | +note: you could use a `use<...>` bound to explicitly capture `'a`, but argument-position `impl Trait`s are not nameable + --> $DIR/hidden-type-suggestion.rs:36:29 + | +LL | fn yes_params_yet<'a, T>(_: impl Sized, y: &'a ()) -> impl Sized { + | ^^^^^^^^^^ +help: add a `use<...>` bound to explicitly capture `'a` after turning all argument-position `impl Trait` into type parameters, noting that this possibly affects the API of this crate + | +LL | fn yes_params_yet<'a, T, U: Sized>(_: U, y: &'a ()) -> impl Sized + use<'a, T, U> { + | ++++++++++ ~ +++++++++++++++ + +error: aborting due to 6 previous errors For more information about this error, try `rustc --explain E0700`.