Point at method call when type annotations are needed
This commit is contained in:
Esteban Küber
parent
7dbfb0a8ca
commit
12af2561e9
13 changed files with 108 additions and 44 deletions
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@ -6,6 +6,7 @@ use crate::infer::type_variable::TypeVariableOriginKind;
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use crate::ty::{self, Ty, Infer, TyVar};
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use crate::ty::print::Print;
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use syntax::source_map::DesugaringKind;
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use syntax::symbol::kw;
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use syntax_pos::Span;
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use errors::{Applicability, DiagnosticBuilder};
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@ -19,6 +20,7 @@ struct FindLocalByTypeVisitor<'a, 'tcx> {
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found_arg_pattern: Option<&'tcx Pat>,
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found_ty: Option<Ty<'tcx>>,
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found_closure: Option<&'tcx ExprKind>,
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found_method_call: Option<&'tcx ExprKind>,
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}
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impl<'a, 'tcx> FindLocalByTypeVisitor<'a, 'tcx> {
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@ -35,6 +37,7 @@ impl<'a, 'tcx> FindLocalByTypeVisitor<'a, 'tcx> {
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found_arg_pattern: None,
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found_ty: None,
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found_closure: None,
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found_method_call: None,
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}
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}
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@ -93,11 +96,12 @@ impl<'a, 'tcx> Visitor<'tcx> for FindLocalByTypeVisitor<'a, 'tcx> {
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}
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fn visit_expr(&mut self, expr: &'tcx Expr) {
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if let (ExprKind::Closure(_, _fn_decl, _id, _sp, _), Some(_)) = (
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&expr.kind,
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self.node_matches_type(expr.hir_id),
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) {
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self.found_closure = Some(&expr.kind);
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if self.node_matches_type(expr.hir_id).is_some() {
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match expr.kind {
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ExprKind::Closure(..) => self.found_closure = Some(&expr.kind),
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ExprKind::MethodCall(..) => self.found_method_call = Some(&expr.kind),
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_ => {}
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}
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}
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intravisit::walk_expr(self, expr);
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}
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@ -157,7 +161,9 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
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let ty_vars = self.type_variables.borrow();
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let var_origin = ty_vars.var_origin(ty_vid);
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if let TypeVariableOriginKind::TypeParameterDefinition(name) = var_origin.kind {
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return (name.to_string(), Some(var_origin.span));
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if name != kw::SelfUpper {
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return (name.to_string(), Some(var_origin.span));
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}
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}
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}
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@ -175,6 +181,7 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
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body_id: Option<hir::BodyId>,
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span: Span,
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ty: Ty<'tcx>,
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is_projection: bool,
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) -> DiagnosticBuilder<'tcx> {
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let ty = self.resolve_vars_if_possible(&ty);
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let (name, name_sp) = self.extract_type_name(&ty, None);
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@ -210,6 +217,20 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
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// 3 | let _ = x.sum() as f64;
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// | ^^^ cannot infer type for `S`
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span
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} else if let Some(ExprKind::MethodCall(_, call_span, _)) = local_visitor.found_method_call {
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// Point at the call instead of the whole expression:
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// error[E0284]: type annotations needed
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// --> file.rs:2:5
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// |
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// 2 | vec![Ok(2)].into_iter().collect()?;
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// | ^^^^^^^ cannot infer type
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// |
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// = note: cannot resolve `<_ as std::ops::Try>::Ok == _`
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if span.contains(*call_span) {
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*call_span
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} else {
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span
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}
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} else {
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span
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};
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@ -247,13 +268,11 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
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// | consider giving `b` the explicit type `std::result::Result<i32, E>`, where
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// | the type parameter `E` is specified
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// ```
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let mut err = struct_span_err!(
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self.tcx.sess,
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err_span,
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E0282,
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"type annotations needed{}",
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ty_msg,
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);
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let mut err = if is_projection {
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struct_span_err!(self.tcx.sess, err_span, E0284, "type annotations needed{}", ty_msg)
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} else {
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struct_span_err!(self.tcx.sess, err_span, E0282, "type annotations needed{}", ty_msg)
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};
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let suffix = match local_visitor.found_ty {
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Some(ty::TyS { kind: ty::Closure(def_id, substs), .. }) => {
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@ -334,6 +353,18 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
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format!("consider giving this pattern {}", suffix)
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};
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err.span_label(pattern.span, msg);
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} else if let Some(ExprKind::MethodCall(segment, ..)) = local_visitor.found_method_call {
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if let Ok(snippet) = self.tcx.sess.source_map().span_to_snippet(segment.ident.span) {
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if segment.args.is_none() {
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err.span_suggestion(
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segment.ident.span,
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"consider specifying the type argument in the method call",
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// FIXME: we don't know how many type arguments should be set here.
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format!("{}::<_>", snippet),
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Applicability::HasPlaceholders,
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);
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}
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}
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}
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// Instead of the following:
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// error[E0282]: type annotations needed
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@ -351,7 +382,7 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
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// | ^^^ cannot infer type for `S`
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// |
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// = note: type must be known at this point
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let span = name_sp.unwrap_or(span);
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let span = name_sp.unwrap_or(err_span);
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if !err.span.span_labels().iter().any(|span_label| {
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span_label.label.is_some() && span_label.span == span
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}) && local_visitor.found_arg_pattern.is_none()
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@ -1989,7 +1989,7 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
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self.tcx.lang_items().sized_trait()
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.map_or(false, |sized_id| sized_id == trait_ref.def_id())
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{
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self.need_type_info_err(body_id, span, self_ty).emit();
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self.need_type_info_err(body_id, span, self_ty, false).emit();
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} else {
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let mut err = struct_span_err!(
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self.tcx.sess,
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@ -2007,7 +2007,9 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
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// Same hacky approach as above to avoid deluging user
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// with error messages.
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if !ty.references_error() && !self.tcx.sess.has_errors() {
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self.need_type_info_err(body_id, span, ty).emit();
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let mut err = self.need_type_info_err(body_id, span, ty, false);
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self.note_obligation_cause(&mut err, obligation);
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err.emit();
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}
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}
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@ -2018,21 +2020,33 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
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let &SubtypePredicate { a_is_expected: _, a, b } = data.skip_binder();
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// both must be type variables, or the other would've been instantiated
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assert!(a.is_ty_var() && b.is_ty_var());
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self.need_type_info_err(body_id,
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obligation.cause.span,
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a).emit();
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let mut err = self.need_type_info_err(body_id, span, a, false);
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self.note_obligation_cause(&mut err, obligation);
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err.emit();
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}
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}
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ty::Predicate::Projection(ref data) => {
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let trait_ref = data.to_poly_trait_ref(self.tcx);
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let self_ty = trait_ref.self_ty();
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if predicate.references_error() {
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return;
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}
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let mut err = self.need_type_info_err(body_id, span, self_ty, true);
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err.note(&format!("cannot resolve `{}`", predicate));
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self.note_obligation_cause(&mut err, obligation);
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err.emit();
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}
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_ => {
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if !self.tcx.sess.has_errors() {
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let mut err = struct_span_err!(
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self.tcx.sess,
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obligation.cause.span,
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span,
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E0284,
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"type annotations needed: cannot resolve `{}`",
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predicate,
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);
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err.span_label(span, &format!("cannot resolve `{}`", predicate));
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self.note_obligation_cause(&mut err, obligation);
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err.emit();
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}
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