diff --git a/compiler/rustc_hir_typeck/src/fn_ctxt/suggestions.rs b/compiler/rustc_hir_typeck/src/fn_ctxt/suggestions.rs index 719f44f9f665a..407d6ac8544c2 100644 --- a/compiler/rustc_hir_typeck/src/fn_ctxt/suggestions.rs +++ b/compiler/rustc_hir_typeck/src/fn_ctxt/suggestions.rs @@ -13,7 +13,9 @@ use rustc_hir_analysis::astconv::AstConv; use rustc_infer::infer; use rustc_infer::traits::{self, StatementAsExpression}; use rustc_middle::lint::in_external_macro; -use rustc_middle::ty::{self, Binder, DefIdTree, IsSuggestable, Ty}; +use rustc_middle::ty::{ + self, suggest_constraining_type_params, Binder, DefIdTree, IsSuggestable, ToPredicate, Ty, +}; use rustc_session::errors::ExprParenthesesNeeded; use rustc_span::symbol::sym; use rustc_span::Span; @@ -1276,15 +1278,13 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { && !results.expr_adjustments(callee_expr).iter().any(|adj| matches!(adj.kind, ty::adjustment::Adjust::Deref(..))) // Check that we're in fact trying to clone into the expected type && self.can_coerce(*pointee_ty, expected_ty) + && let trait_ref = ty::Binder::dummy(self.tcx.mk_trait_ref(clone_trait_did, [expected_ty])) // And the expected type doesn't implement `Clone` && !self.predicate_must_hold_considering_regions(&traits::Obligation::new( self.tcx, traits::ObligationCause::dummy(), self.param_env, - ty::Binder::dummy(self.tcx.mk_trait_ref( - clone_trait_did, - [expected_ty], - )), + trait_ref, )) { diag.span_note( @@ -1293,6 +1293,19 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { "`{expected_ty}` does not implement `Clone`, so `{found_ty}` was cloned instead" ), ); + let owner = self.tcx.hir().enclosing_body_owner(expr.hir_id); + if let ty::Param(param) = expected_ty.kind() + && let Some(generics) = self.tcx.hir().get_generics(owner) + { + suggest_constraining_type_params( + self.tcx, + generics, + diag, + vec![(param.name.as_str(), "Clone", Some(clone_trait_did))].into_iter(), + ); + } else { + self.suggest_derive(diag, &[(trait_ref.to_predicate(self.tcx), None, None)]); + } } } diff --git a/compiler/rustc_hir_typeck/src/method/suggest.rs b/compiler/rustc_hir_typeck/src/method/suggest.rs index 5c0d5f32f0fd0..6b3cc26fd761f 100644 --- a/compiler/rustc_hir_typeck/src/method/suggest.rs +++ b/compiler/rustc_hir_typeck/src/method/suggest.rs @@ -1848,7 +1848,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { self.suggest_derive(err, &preds); } - fn suggest_derive( + pub fn suggest_derive( &self, err: &mut Diagnostic, unsatisfied_predicates: &[( diff --git a/src/test/ui/suggestions/clone-on-unconstrained-borrowed-type-param.fixed b/src/test/ui/suggestions/clone-on-unconstrained-borrowed-type-param.fixed new file mode 100644 index 0000000000000..4f9e93a47ed1c --- /dev/null +++ b/src/test/ui/suggestions/clone-on-unconstrained-borrowed-type-param.fixed @@ -0,0 +1,16 @@ +// run-rustfix +fn wat(t: &T) -> T { + t.clone() //~ ERROR E0308 +} + +#[derive(Clone)] +struct Foo; + +fn wut(t: &Foo) -> Foo { + t.clone() //~ ERROR E0308 +} + +fn main() { + wat(&42); + wut(&Foo); +} diff --git a/src/test/ui/suggestions/clone-on-unconstrained-borrowed-type-param.rs b/src/test/ui/suggestions/clone-on-unconstrained-borrowed-type-param.rs new file mode 100644 index 0000000000000..89b077d671a51 --- /dev/null +++ b/src/test/ui/suggestions/clone-on-unconstrained-borrowed-type-param.rs @@ -0,0 +1,15 @@ +// run-rustfix +fn wat(t: &T) -> T { + t.clone() //~ ERROR E0308 +} + +struct Foo; + +fn wut(t: &Foo) -> Foo { + t.clone() //~ ERROR E0308 +} + +fn main() { + wat(&42); + wut(&Foo); +} diff --git a/src/test/ui/suggestions/clone-on-unconstrained-borrowed-type-param.stderr b/src/test/ui/suggestions/clone-on-unconstrained-borrowed-type-param.stderr new file mode 100644 index 0000000000000..26ab515d9b4b6 --- /dev/null +++ b/src/test/ui/suggestions/clone-on-unconstrained-borrowed-type-param.stderr @@ -0,0 +1,43 @@ +error[E0308]: mismatched types + --> $DIR/clone-on-unconstrained-borrowed-type-param.rs:3:5 + | +LL | fn wat(t: &T) -> T { + | - - expected `T` because of return type + | | + | this type parameter +LL | t.clone() + | ^^^^^^^^^ expected type parameter `T`, found `&T` + | + = note: expected type parameter `T` + found reference `&T` +note: `T` does not implement `Clone`, so `&T` was cloned instead + --> $DIR/clone-on-unconstrained-borrowed-type-param.rs:3:5 + | +LL | t.clone() + | ^ +help: consider restricting type parameter `T` + | +LL | fn wat(t: &T) -> T { + | +++++++ + +error[E0308]: mismatched types + --> $DIR/clone-on-unconstrained-borrowed-type-param.rs:9:5 + | +LL | fn wut(t: &Foo) -> Foo { + | --- expected `Foo` because of return type +LL | t.clone() + | ^^^^^^^^^ expected struct `Foo`, found `&Foo` + | +note: `Foo` does not implement `Clone`, so `&Foo` was cloned instead + --> $DIR/clone-on-unconstrained-borrowed-type-param.rs:9:5 + | +LL | t.clone() + | ^ +help: consider annotating `Foo` with `#[derive(Clone)]` + | +LL | #[derive(Clone)] + | + +error: aborting due to 2 previous errors + +For more information about this error, try `rustc --explain E0308`. diff --git a/src/test/ui/typeck/explain_clone_autoref.stderr b/src/test/ui/typeck/explain_clone_autoref.stderr index faac680ea1931..ff36e18d28301 100644 --- a/src/test/ui/typeck/explain_clone_autoref.stderr +++ b/src/test/ui/typeck/explain_clone_autoref.stderr @@ -12,6 +12,10 @@ note: `NotClone` does not implement `Clone`, so `&NotClone` was cloned instead | LL | nc.clone() | ^^ +help: consider annotating `NotClone` with `#[derive(Clone)]` + | +LL | #[derive(Clone)] + | error: aborting due to previous error