From 5d2a935e6cf25e0bc86354962929ee02513549b7 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Esteban=20K=C3=BCber?= Date: Tue, 18 Aug 2020 16:44:45 -0700 Subject: [PATCH] Make suggestion more complete --- .../src/infer/error_reporting/mod.rs | 2 +- compiler/rustc_typeck/src/check/coercion.rs | 21 +++++++- src/test/ui/impl-trait/equality.stderr | 2 +- ...trait-in-return-position-impl-trait.stderr | 10 +++- ...type-err-cause-on-impl-trait-return.stderr | 54 ++++++++++++++++--- 5 files changed, 75 insertions(+), 14 deletions(-) diff --git a/compiler/rustc_infer/src/infer/error_reporting/mod.rs b/compiler/rustc_infer/src/infer/error_reporting/mod.rs index fe53ccdbad5..ca6f4243c28 100644 --- a/compiler/rustc_infer/src/infer/error_reporting/mod.rs +++ b/compiler/rustc_infer/src/infer/error_reporting/mod.rs @@ -749,7 +749,7 @@ fn suggest_boxing_for_return_impl_trait( }) .collect::>(); err.multipart_suggestion( - "if you change the return type to expect trait objects box the returned expressions", + "if you change the return type to expect trait objects, box the returned expressions", sugg, Applicability::MaybeIncorrect, ); diff --git a/compiler/rustc_typeck/src/check/coercion.rs b/compiler/rustc_typeck/src/check/coercion.rs index b669476483b..4addee1a4c9 100644 --- a/compiler/rustc_typeck/src/check/coercion.rs +++ b/compiler/rustc_typeck/src/check/coercion.rs @@ -1459,7 +1459,7 @@ fn report_return_mismatched_types<'a>( } } if let (Some(sp), Some(fn_output)) = (fcx.ret_coercion_span.borrow().as_ref(), fn_output) { - self.add_impl_trait_explanation(&mut err, fcx, expected, *sp, fn_output); + self.add_impl_trait_explanation(&mut err, cause, fcx, expected, *sp, fn_output); } err } @@ -1467,6 +1467,7 @@ fn report_return_mismatched_types<'a>( fn add_impl_trait_explanation<'a>( &self, err: &mut DiagnosticBuilder<'a>, + cause: &ObligationCause<'tcx>, fcx: &FnCtxt<'a, 'tcx>, expected: Ty<'tcx>, sp: Span, @@ -1531,6 +1532,22 @@ fn add_impl_trait_explanation<'a>( ], Applicability::MachineApplicable, ); + let sugg = vec![sp, cause.span] + .into_iter() + .flat_map(|sp| { + vec![ + (sp.shrink_to_lo(), "Box::new(".to_string()), + (sp.shrink_to_hi(), ")".to_string()), + ] + .into_iter() + }) + .collect::>(); + err.multipart_suggestion( + "if you change the return type to expect trait objects, box the returned \ + expressions", + sugg, + Applicability::MaybeIncorrect, + ); } else { err.help(&format!( "if the trait `{}` were object safe, you could return a boxed trait object", @@ -1539,7 +1556,7 @@ fn add_impl_trait_explanation<'a>( } err.note(trait_obj_msg); } - err.help("alternatively, create a new `enum` with a variant for each returned type"); + err.help("you could instead create a new `enum` with a variant for each returned type"); } fn is_return_ty_unsized(&self, fcx: &FnCtxt<'a, 'tcx>, blk_id: hir::HirId) -> bool { diff --git a/src/test/ui/impl-trait/equality.stderr b/src/test/ui/impl-trait/equality.stderr index 9667a9785dc..cdaa61ac323 100644 --- a/src/test/ui/impl-trait/equality.stderr +++ b/src/test/ui/impl-trait/equality.stderr @@ -23,7 +23,7 @@ LL | 0_u32 = note: for information on `impl Trait`, see = help: if the trait `Foo` were object safe, you could return a boxed trait object = note: for information on trait objects, see - = help: alternatively, create a new `enum` with a variant for each returned type + = help: you could instead create a new `enum` with a variant for each returned type error[E0277]: cannot add `impl Foo` to `u32` --> $DIR/equality.rs:24:11 diff --git a/src/test/ui/impl-trait/object-unsafe-trait-in-return-position-impl-trait.stderr b/src/test/ui/impl-trait/object-unsafe-trait-in-return-position-impl-trait.stderr index 9abebeff95a..66043267f91 100644 --- a/src/test/ui/impl-trait/object-unsafe-trait-in-return-position-impl-trait.stderr +++ b/src/test/ui/impl-trait/object-unsafe-trait-in-return-position-impl-trait.stderr @@ -14,7 +14,7 @@ LL | B = note: for information on `impl Trait`, see = help: if the trait `NotObjectSafe` were object safe, you could return a boxed trait object = note: for information on trait objects, see - = help: alternatively, create a new `enum` with a variant for each returned type + = help: you could instead create a new `enum` with a variant for each returned type error[E0308]: mismatched types --> $DIR/object-unsafe-trait-in-return-position-impl-trait.rs:43:5 @@ -31,11 +31,17 @@ LL | B = note: to return `impl Trait`, all returned values must be of the same type = note: for information on `impl Trait`, see = note: for information on trait objects, see - = help: alternatively, create a new `enum` with a variant for each returned type + = help: you could instead create a new `enum` with a variant for each returned type help: you could change the return type to be a boxed trait object | LL | fn cat() -> Box { | ^^^^^^^ ^ +help: if you change the return type to expect trait objects, box the returned expressions + | +LL | return Box::new(A); +LL | } +LL | Box::new(B) + | error: aborting due to 2 previous errors diff --git a/src/test/ui/point-to-type-err-cause-on-impl-trait-return.stderr b/src/test/ui/point-to-type-err-cause-on-impl-trait-return.stderr index 66d9ff307d9..4265381eb40 100644 --- a/src/test/ui/point-to-type-err-cause-on-impl-trait-return.stderr +++ b/src/test/ui/point-to-type-err-cause-on-impl-trait-return.stderr @@ -13,11 +13,17 @@ LL | 1u32 = note: to return `impl Trait`, all returned values must be of the same type = note: for information on `impl Trait`, see = note: for information on trait objects, see - = help: alternatively, create a new `enum` with a variant for each returned type + = help: you could instead create a new `enum` with a variant for each returned type help: you could change the return type to be a boxed trait object | LL | fn foo() -> Box { | ^^^^^^^ ^ +help: if you change the return type to expect trait objects, box the returned expressions + | +LL | return Box::new(0i32); +LL | } +LL | Box::new(1u32) + | error[E0308]: mismatched types --> $DIR/point-to-type-err-cause-on-impl-trait-return.rs:12:16 @@ -34,11 +40,17 @@ LL | return 1u32; = note: to return `impl Trait`, all returned values must be of the same type = note: for information on `impl Trait`, see = note: for information on trait objects, see - = help: alternatively, create a new `enum` with a variant for each returned type + = help: you could instead create a new `enum` with a variant for each returned type help: you could change the return type to be a boxed trait object | LL | fn bar() -> Box { | ^^^^^^^ ^ +help: if you change the return type to expect trait objects, box the returned expressions + | +LL | return Box::new(0i32); +LL | } else { +LL | return Box::new(1u32); + | error[E0308]: mismatched types --> $DIR/point-to-type-err-cause-on-impl-trait-return.rs:20:9 @@ -55,11 +67,17 @@ LL | 1u32 = note: to return `impl Trait`, all returned values must be of the same type = note: for information on `impl Trait`, see = note: for information on trait objects, see - = help: alternatively, create a new `enum` with a variant for each returned type + = help: you could instead create a new `enum` with a variant for each returned type help: you could change the return type to be a boxed trait object | LL | fn baz() -> Box { | ^^^^^^^ ^ +help: if you change the return type to expect trait objects, box the returned expressions + | +LL | return Box::new(0i32); +LL | } else { +LL | Box::new(1u32) + | error[E0308]: `if` and `else` have incompatible types --> $DIR/point-to-type-err-cause-on-impl-trait-return.rs:28:9 @@ -77,7 +95,7 @@ help: you could change the return type to be a boxed trait object | LL | fn qux() -> Box { | ^^^^^^^ ^ -help: if you change the return type to expect trait objects box the returned expressions +help: if you change the return type to expect trait objects, box the returned expressions | LL | Box::new(0i32) LL | } else { @@ -98,11 +116,16 @@ LL | _ => 1u32, = note: to return `impl Trait`, all returned values must be of the same type = note: for information on `impl Trait`, see = note: for information on trait objects, see - = help: alternatively, create a new `enum` with a variant for each returned type + = help: you could instead create a new `enum` with a variant for each returned type help: you could change the return type to be a boxed trait object | LL | fn bat() -> Box { | ^^^^^^^ ^ +help: if you change the return type to expect trait objects, box the returned expressions + | +LL | 0 => return Box::new(0i32), +LL | _ => Box::new(1u32), + | error[E0308]: mismatched types --> $DIR/point-to-type-err-cause-on-impl-trait-return.rs:40:5 @@ -120,11 +143,19 @@ LL | | } = note: to return `impl Trait`, all returned values must be of the same type = note: for information on `impl Trait`, see = note: for information on trait objects, see - = help: alternatively, create a new `enum` with a variant for each returned type + = help: you could instead create a new `enum` with a variant for each returned type help: you could change the return type to be a boxed trait object | LL | fn can() -> Box { | ^^^^^^^ ^ +help: if you change the return type to expect trait objects, box the returned expressions + | +LL | Box::new(match 13 { +LL | 0 => return Box::new(0i32), +LL | 1 => 1u32, +LL | _ => 2u32, +LL | }) + | error[E0308]: mismatched types --> $DIR/point-to-type-err-cause-on-impl-trait-return.rs:53:13 @@ -141,11 +172,18 @@ LL | 1u32 = note: to return `impl Trait`, all returned values must be of the same type = note: for information on `impl Trait`, see = note: for information on trait objects, see - = help: alternatively, create a new `enum` with a variant for each returned type + = help: you could instead create a new `enum` with a variant for each returned type help: you could change the return type to be a boxed trait object | LL | fn cat() -> Box { | ^^^^^^^ ^ +help: if you change the return type to expect trait objects, box the returned expressions + | +LL | return Box::new(0i32); +LL | } +LL | _ => { +LL | Box::new(1u32) + | error[E0308]: `match` arms have incompatible types --> $DIR/point-to-type-err-cause-on-impl-trait-return.rs:61:14 @@ -163,7 +201,7 @@ help: you could change the return type to be a boxed trait object | LL | fn dog() -> Box { | ^^^^^^^ ^ -help: if you change the return type to expect trait objects box the returned expressions +help: if you change the return type to expect trait objects, box the returned expressions | LL | 0 => Box::new(0i32), LL | 1 => Box::new(1u32),