diff options
Diffstat (limited to 'compiler')
| -rw-r--r-- | compiler/rustc_typeck/src/astconv/errors.rs | 18 | ||||
| -rw-r--r-- | compiler/rustc_typeck/src/structured_errors/wrong_number_of_generic_args.rs | 45 |
2 files changed, 49 insertions, 14 deletions
diff --git a/compiler/rustc_typeck/src/astconv/errors.rs b/compiler/rustc_typeck/src/astconv/errors.rs index 1a10b07cc27..38cc74a5e37 100644 --- a/compiler/rustc_typeck/src/astconv/errors.rs +++ b/compiler/rustc_typeck/src/astconv/errors.rs @@ -10,7 +10,6 @@ use rustc_span::symbol::{sym, Ident}; use rustc_span::{Span, DUMMY_SP}; use std::collections::BTreeSet; -use std::iter; impl<'o, 'tcx> dyn AstConv<'tcx> + 'o { /// On missing type parameters, emit an E0393 error and provide a structured suggestion using @@ -323,6 +322,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o { let mut suggestions = vec![]; let mut types_count = 0; let mut where_constraints = vec![]; + let mut already_has_generics_args_suggestion = false; for (span, assoc_items) in &associated_types { let mut names: FxHashMap<_, usize> = FxHashMap::default(); for item in assoc_items { @@ -343,16 +343,10 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o { } } if potential_assoc_types.len() == assoc_items.len() { - // Only suggest when the amount of missing associated types equals the number of - // extra type arguments present, as that gives us a relatively high confidence - // that the user forgot to give the associated type's name. The canonical - // example would be trying to use `Iterator<isize>` instead of - // `Iterator<Item = isize>`. - for (potential, item) in iter::zip(&potential_assoc_types, assoc_items) { - if let Ok(snippet) = tcx.sess.source_map().span_to_snippet(*potential) { - suggestions.push((*potential, format!("{} = {}", item.name, snippet))); - } - } + // When the amount of missing associated types equals the number of + // extra type arguments present. A suggesting to replace the generic args with + // associated types is already emitted. + already_has_generics_args_suggestion = true; } else if let (Ok(snippet), false) = (tcx.sess.source_map().span_to_snippet(*span), dupes) { @@ -382,7 +376,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o { // the same associated type name. err.help(where_msg); } - if suggestions.len() != 1 { + if suggestions.len() != 1 || already_has_generics_args_suggestion { // We don't need this label if there's an inline suggestion, show otherwise. for (span, assoc_items) in &associated_types { let mut names: FxHashMap<_, usize> = FxHashMap::default(); diff --git a/compiler/rustc_typeck/src/structured_errors/wrong_number_of_generic_args.rs b/compiler/rustc_typeck/src/structured_errors/wrong_number_of_generic_args.rs index 1b1a2037d9e..5cd7a7d578e 100644 --- a/compiler/rustc_typeck/src/structured_errors/wrong_number_of_generic_args.rs +++ b/compiler/rustc_typeck/src/structured_errors/wrong_number_of_generic_args.rs @@ -6,9 +6,10 @@ use rustc_errors::{ use rustc_hir as hir; use rustc_middle::hir::map::fn_sig; use rustc_middle::middle::resolve_lifetime::LifetimeScopeForPath; -use rustc_middle::ty::{self as ty, TyCtxt}; +use rustc_middle::ty::{self as ty, AssocItems, AssocKind, TyCtxt}; use rustc_session::Session; use rustc_span::def_id::DefId; +use std::iter; use GenericArgsInfo::*; @@ -334,6 +335,22 @@ impl<'a, 'tcx> WrongNumberOfGenericArgs<'a, 'tcx> { .join(", ") } + fn get_unbound_associated_types(&self) -> Vec<String> { + if self.tcx.is_trait(self.def_id) { + let items: &AssocItems<'_> = self.tcx.associated_items(self.def_id); + items + .in_definition_order() + .filter(|item| item.kind == AssocKind::Type) + .filter(|item| { + !self.gen_args.bindings.iter().any(|binding| binding.ident.name == item.name) + }) + .map(|item| item.name.to_ident_string()) + .collect() + } else { + Vec::default() + } + } + fn create_error_message(&self) -> String { let def_path = self.tcx.def_path_str(self.def_id); let def_kind = self.tcx.def_kind(self.def_id).descr(self.def_id); @@ -618,6 +635,7 @@ impl<'a, 'tcx> WrongNumberOfGenericArgs<'a, 'tcx> { fn suggest_removing_args_or_generics(&self, err: &mut Diagnostic) { let num_provided_lt_args = self.num_provided_lifetime_args(); let num_provided_type_const_args = self.num_provided_type_or_const_args(); + let unbound_types = self.get_unbound_associated_types(); let num_provided_args = num_provided_lt_args + num_provided_type_const_args; assert!(num_provided_args > 0); @@ -629,6 +647,8 @@ impl<'a, 'tcx> WrongNumberOfGenericArgs<'a, 'tcx> { let redundant_type_or_const_args = num_redundant_type_or_const_args > 0; let remove_entire_generics = num_redundant_args >= self.gen_args.args.len(); + let provided_args_matches_unbound_traits = + unbound_types.len() == num_redundant_type_or_const_args; let remove_lifetime_args = |err: &mut Diagnostic| { let mut lt_arg_spans = Vec::new(); @@ -713,7 +733,28 @@ impl<'a, 'tcx> WrongNumberOfGenericArgs<'a, 'tcx> { ); }; - if remove_entire_generics { + // If there is a single unbound associated type and a single excess generic param + // suggest replacing the generic param with the associated type bound + if provided_args_matches_unbound_traits && !unbound_types.is_empty() { + let mut suggestions = vec![]; + let unused_generics = &self.gen_args.args[self.num_expected_type_or_const_args()..]; + for (potential, name) in iter::zip(unused_generics, &unbound_types) { + if let Ok(snippet) = self.tcx.sess.source_map().span_to_snippet(potential.span()) { + suggestions.push((potential.span(), format!("{} = {}", name, snippet))); + } + } + + if !suggestions.is_empty() { + err.multipart_suggestion( + &format!( + "replace the generic bound{s} with the associated type{s}", + s = pluralize!(unbound_types.len()) + ), + suggestions, + Applicability::MaybeIncorrect, + ); + } + } else if remove_entire_generics { let span = self .path_segment .args |