diff options
3 files changed, 50 insertions, 17 deletions
diff --git a/compiler/rustc_hir_analysis/src/hir_ty_lowering/lint.rs b/compiler/rustc_hir_analysis/src/hir_ty_lowering/lint.rs index 43348791fa5..e78801dd601 100644 --- a/compiler/rustc_hir_analysis/src/hir_ty_lowering/lint.rs +++ b/compiler/rustc_hir_analysis/src/hir_ty_lowering/lint.rs @@ -78,13 +78,16 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ { } if self_ty.span.edition().at_least_rust_2021() { - let msg = "expected a type, found a trait"; - let label = "you can add the `dyn` keyword if you want a trait object"; - let mut diag = - rustc_errors::struct_span_code_err!(self.dcx(), self_ty.span, E0782, "{}", msg); + let mut diag = rustc_errors::struct_span_code_err!( + self.dcx(), + self_ty.span, + E0782, + "{}", + "expected a type, found a trait" + ); if self_ty.span.can_be_used_for_suggestions() && !self.maybe_suggest_impl_trait(self_ty, &mut diag) - && !self.maybe_suggest_dyn_trait(self_ty, label, sugg, &mut diag) + && !self.maybe_suggest_dyn_trait(self_ty, sugg, &mut diag) { self.maybe_suggest_add_generic_impl_trait(self_ty, &mut diag); } @@ -131,8 +134,6 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ { diag: &mut Diag<'_>, ) -> bool { let tcx = self.tcx(); - let msg = "you might be missing a type parameter"; - let mut sugg = vec![]; let parent_hir_id = tcx.parent_hir_id(self_ty.hir_id); let parent_item = tcx.hir_get_parent_item(self_ty.hir_id).def_id; @@ -160,13 +161,27 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ { _ => return false, }; - // FIXME: `T` may already be taken. - sugg.push(( - generics.where_clause_span, - format!("<T: {}>", self.tcx().sess.source_map().span_to_snippet(self_ty.span).unwrap()), - )); - sugg.push((self_ty.span, "T".to_string())); - diag.multipart_suggestion_verbose(msg, sugg, Applicability::MachineApplicable); + let Ok(rendered_ty) = tcx.sess.source_map().span_to_snippet(self_ty.span) else { + return false; + }; + + let param = "TUV" + .chars() + .map(|c| c.to_string()) + .chain((0..).map(|i| format!("P{i}"))) + .find(|s| !generics.params.iter().any(|param| param.name.ident().as_str() == s)) + .expect("we definitely can find at least one param name to generate"); + let mut sugg = vec![(self_ty.span, param.to_string())]; + if let Some(insertion_span) = generics.span_for_param_suggestion() { + sugg.push((insertion_span, format!(", {param}: {}", rendered_ty))); + } else { + sugg.push((generics.where_clause_span, format!("<{param}: {}>", rendered_ty))); + } + diag.multipart_suggestion_verbose( + "you might be missing a type parameter", + sugg, + Applicability::MachineApplicable, + ); true } /// Make sure that we are in the condition to suggest the blanket implementation. @@ -227,7 +242,6 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ { fn maybe_suggest_dyn_trait( &self, self_ty: &hir::Ty<'_>, - label: &str, sugg: Vec<(Span, String)>, diag: &mut Diag<'_>, ) -> bool { @@ -270,7 +284,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ { // FIXME: Only emit this suggestion if the trait is dyn-compatible. diag.multipart_suggestion_verbose( - label.to_string(), + "you can add the `dyn` keyword if you want a trait object", sugg, Applicability::MachineApplicable, ); diff --git a/tests/ui/dyn-keyword/suggest-struct-or-union-add-generic-impl-trait.rs b/tests/ui/dyn-keyword/suggest-struct-or-union-add-generic-impl-trait.rs index dcbed027c74..4d573b90d60 100644 --- a/tests/ui/dyn-keyword/suggest-struct-or-union-add-generic-impl-trait.rs +++ b/tests/ui/dyn-keyword/suggest-struct-or-union-add-generic-impl-trait.rs @@ -31,4 +31,11 @@ where Trait:, {} //~^ ERROR expected a type, found a trait +struct HasGenerics<T> { + f: Trait, + //~^ ERROR expected a type, found a trait + t: T, +} + + fn main() {} diff --git a/tests/ui/dyn-keyword/suggest-struct-or-union-add-generic-impl-trait.stderr b/tests/ui/dyn-keyword/suggest-struct-or-union-add-generic-impl-trait.stderr index 16e48ef3a12..9584147bbc7 100644 --- a/tests/ui/dyn-keyword/suggest-struct-or-union-add-generic-impl-trait.stderr +++ b/tests/ui/dyn-keyword/suggest-struct-or-union-add-generic-impl-trait.stderr @@ -47,6 +47,18 @@ LL ~ B(T), | error[E0782]: expected a type, found a trait + --> $DIR/suggest-struct-or-union-add-generic-impl-trait.rs:35:8 + | +LL | f: Trait, + | ^^^^^ + | +help: you might be missing a type parameter + | +LL ~ struct HasGenerics<T, U: Trait> { +LL ~ f: U, + | + +error[E0782]: expected a type, found a trait --> $DIR/suggest-struct-or-union-add-generic-impl-trait.rs:31:5 | LL | Trait:, {} @@ -57,6 +69,6 @@ help: you can add the `dyn` keyword if you want a trait object LL | dyn Trait:, {} | +++ -error: aborting due to 5 previous errors +error: aborting due to 6 previous errors For more information about this error, try `rustc --explain E0782`. |