From e324919ec57954adaa49884e5894bc7d615d413e Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Esteban=20K=C3=BCber?= Date: Wed, 31 May 2017 23:14:43 -0700 Subject: [PATCH] Show trait method signature when impl differs When the trait's span is available, it is already being used, add a `note` for the cases where the span isn't available: ``` error[E0053]: method `fmt` has an incompatible type for trait --> $DIR/trait_type.rs:17:4 | 17 | fn fmt(&self, x: &str) -> () { } | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ types differ in mutability | = note: expected type `fn(&MyType, &mut std::fmt::Formatter<'_>) -> std::result::Result<(), std::fmt::Error>` found type `fn(&MyType, &str)` error[E0050]: method `fmt` has 1 parameter but the declaration in trait `std::fmt::Display::fmt` has 2 --> $DIR/trait_type.rs:21:11 | 21 | fn fmt(&self) -> () { } | ^^^^^ expected 2 parameters, found 1 | = note: `fmt` from trait: `fn(&Self, &mut std::fmt::Formatter<'_>) -> std::result::Result<(), std::fmt::Error>` error[E0186]: method `fmt` has a `&self` declaration in the trait, but not in the impl --> $DIR/trait_type.rs:25:4 | 25 | fn fmt() -> () { } | ^^^^^^^^^^^^^^^^^^ expected `&self` in impl | = note: `fmt` from trait: `fn(&Self, &mut std::fmt::Formatter<'_>) -> std::result::Result<(), std::fmt::Error>` error[E0046]: not all trait items implemented, missing: `fmt` --> $DIR/trait_type.rs:28:1 | 28 | impl std::fmt::Display for MyType4 {} | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ missing `fmt` in implementation | = note: `fmt` from trait: `fn(&Self, &mut std::fmt::Formatter<'_>) -> std::result::Result<(), std::fmt::Error>` ``` --- src/librustc/ty/mod.rs | 16 ++++++++++ src/librustc_errors/diagnostic.rs | 8 +++++ src/librustc_typeck/check/compare_method.rs | 6 ++++ src/librustc_typeck/check/mod.rs | 17 ++-------- src/test/ui/impl-trait/trait_type.rs | 30 ++++++++++++++++++ src/test/ui/impl-trait/trait_type.stderr | 35 +++++++++++++++++++++ 6 files changed, 97 insertions(+), 15 deletions(-) create mode 100644 src/test/ui/impl-trait/trait_type.rs create mode 100644 src/test/ui/impl-trait/trait_type.stderr diff --git a/src/librustc/ty/mod.rs b/src/librustc/ty/mod.rs index b495b5ee81a9a..3fedf947fb8b0 100644 --- a/src/librustc/ty/mod.rs +++ b/src/librustc/ty/mod.rs @@ -221,6 +221,22 @@ impl AssociatedItem { AssociatedKind::Method => !self.method_has_self_argument, } } + + pub fn signature<'a, 'tcx>(&self, tcx: &TyCtxt<'a, 'tcx, 'tcx>) -> String { + match self.kind { + ty::AssociatedKind::Method => { + // We skip the binder here because the binder would deanonymize all + // late-bound regions, and we don't want method signatures to show up + // `as for<'r> fn(&'r MyType)`. Pretty-printing handles late-bound + // regions just fine, showing `fn(&MyType)`. + format!("{}", tcx.type_of(self.def_id).fn_sig().skip_binder()) + } + ty::AssociatedKind::Type => format!("type {};", self.name.to_string()), + ty::AssociatedKind::Const => { + format!("const {}: {:?};", self.name.to_string(), tcx.type_of(self.def_id)) + } + } + } } #[derive(Clone, Debug, PartialEq, Eq, Copy, RustcEncodable, RustcDecodable)] diff --git a/src/librustc_errors/diagnostic.rs b/src/librustc_errors/diagnostic.rs index 861880aa265ec..7a64cdeee65c7 100644 --- a/src/librustc_errors/diagnostic.rs +++ b/src/librustc_errors/diagnostic.rs @@ -157,6 +157,14 @@ impl Diagnostic { self } + pub fn note_trait_signature(&mut self, name: String, signature: String) -> &mut Self { + self.highlighted_note(vec![ + (format!("`{}` from trait: `", name), Style::NoStyle), + (signature, Style::Highlight), + ("`".to_string(), Style::NoStyle)]); + self + } + pub fn note(&mut self, msg: &str) -> &mut Self { self.sub(Level::Note, msg, MultiSpan::new(), None); self diff --git a/src/librustc_typeck/check/compare_method.rs b/src/librustc_typeck/check/compare_method.rs index 3121f4948504e..5eb7b3de8deae 100644 --- a/src/librustc_typeck/check/compare_method.rs +++ b/src/librustc_typeck/check/compare_method.rs @@ -543,6 +543,9 @@ fn compare_self_type<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, format!("expected `{}` in impl", self_descr)); if let Some(span) = tcx.hir.span_if_local(trait_m.def_id) { err.span_label(span, format!("`{}` used in trait", self_descr)); + } else { + err.note_trait_signature(trait_m.name.to_string(), + trait_m.signature(&tcx)); } err.emit(); return Err(ErrorReported); @@ -690,6 +693,9 @@ fn compare_number_of_method_arguments<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, } else { format!("{} parameter", trait_number_args) })); + } else { + err.note_trait_signature(trait_m.name.to_string(), + trait_m.signature(&tcx)); } err.span_label(impl_span, format!("expected {}, found {}", diff --git a/src/librustc_typeck/check/mod.rs b/src/librustc_typeck/check/mod.rs index 32c3f5c8a5edd..683a1d13a5f97 100644 --- a/src/librustc_typeck/check/mod.rs +++ b/src/librustc_typeck/check/mod.rs @@ -1334,18 +1334,6 @@ fn check_impl_items_against_trait<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, } } - let signature = |item: &ty::AssociatedItem| { - match item.kind { - ty::AssociatedKind::Method => { - format!("{}", tcx.type_of(item.def_id).fn_sig().0) - } - ty::AssociatedKind::Type => format!("type {};", item.name.to_string()), - ty::AssociatedKind::Const => { - format!("const {}: {:?};", item.name.to_string(), tcx.type_of(item.def_id)) - } - } - }; - if !missing_items.is_empty() { let mut err = struct_span_err!(tcx.sess, impl_span, E0046, "not all trait items implemented, missing: `{}`", @@ -1360,9 +1348,8 @@ fn check_impl_items_against_trait<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, if let Some(span) = tcx.hir.span_if_local(trait_item.def_id) { err.span_label(span, format!("`{}` from trait", trait_item.name)); } else { - err.note(&format!("`{}` from trait: `{}`", - trait_item.name, - signature(&trait_item))); + err.note_trait_signature(trait_item.name.to_string(), + trait_item.signature(&tcx)); } } err.emit(); diff --git a/src/test/ui/impl-trait/trait_type.rs b/src/test/ui/impl-trait/trait_type.rs new file mode 100644 index 0000000000000..3507dcfbe172a --- /dev/null +++ b/src/test/ui/impl-trait/trait_type.rs @@ -0,0 +1,30 @@ +// Copyright 2017 The Rust Project Developers. See the COPYRIGHT +// file at the top-level directory of this distribution and at +// http://rust-lang.org/COPYRIGHT. +// +// Licensed under the Apache License, Version 2.0 or the MIT license +// , at your +// option. This file may not be copied, modified, or distributed +// except according to those terms. + +struct MyType; +struct MyType2; +struct MyType3; +struct MyType4; + +impl std::fmt::Display for MyType { + fn fmt(&self, x: &str) -> () { } +} + +impl std::fmt::Display for MyType2 { + fn fmt(&self) -> () { } +} + +impl std::fmt::Display for MyType3 { + fn fmt() -> () { } +} + +impl std::fmt::Display for MyType4 {} + +fn main() {} diff --git a/src/test/ui/impl-trait/trait_type.stderr b/src/test/ui/impl-trait/trait_type.stderr new file mode 100644 index 0000000000000..cc7a7153a3859 --- /dev/null +++ b/src/test/ui/impl-trait/trait_type.stderr @@ -0,0 +1,35 @@ +error[E0053]: method `fmt` has an incompatible type for trait + --> $DIR/trait_type.rs:17:4 + | +17 | fn fmt(&self, x: &str) -> () { } + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ types differ in mutability + | + = note: expected type `fn(&MyType, &mut std::fmt::Formatter<'_>) -> std::result::Result<(), std::fmt::Error>` + found type `fn(&MyType, &str)` + +error[E0050]: method `fmt` has 1 parameter but the declaration in trait `std::fmt::Display::fmt` has 2 + --> $DIR/trait_type.rs:21:11 + | +21 | fn fmt(&self) -> () { } + | ^^^^^ expected 2 parameters, found 1 + | + = note: `fmt` from trait: `fn(&Self, &mut std::fmt::Formatter<'_>) -> std::result::Result<(), std::fmt::Error>` + +error[E0186]: method `fmt` has a `&self` declaration in the trait, but not in the impl + --> $DIR/trait_type.rs:25:4 + | +25 | fn fmt() -> () { } + | ^^^^^^^^^^^^^^^^^^ expected `&self` in impl + | + = note: `fmt` from trait: `fn(&Self, &mut std::fmt::Formatter<'_>) -> std::result::Result<(), std::fmt::Error>` + +error[E0046]: not all trait items implemented, missing: `fmt` + --> $DIR/trait_type.rs:28:1 + | +28 | impl std::fmt::Display for MyType4 {} + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ missing `fmt` in implementation + | + = note: `fmt` from trait: `fn(&Self, &mut std::fmt::Formatter<'_>) -> std::result::Result<(), std::fmt::Error>` + +error: aborting due to previous error(s) +