Auto merge of #45069 - sinkuu:tuple_arg, r=nikomatsakis
Better error for missing tuple pattern in args #44150 Before: ``` error[E0593]: closure takes 2 arguments but 1 argument is required --> test.rs:5:40 | 5 | let it = v.into_iter().enumerate().map(|i, x| i); | ^^^ -------- takes 2 arguments | | | expected closure that takes 1 argument ``` After: ``` error[E0593]: closure takes 2 arguments but a 2-tuple is required --> test.rs:5:40 | 5 | let it = v.into_iter().enumerate().map(|i, x| i); | ^^^ ------ takes 2 arguments | | | expected closure that takes a 2-tuple ```
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02a24dbdd8
@ -711,41 +711,105 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
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}
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}
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OutputTypeParameterMismatch(ref expected_trait_ref, ref actual_trait_ref, _) => {
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OutputTypeParameterMismatch(ref found_trait_ref, ref expected_trait_ref, _) => {
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let found_trait_ref = self.resolve_type_vars_if_possible(&*found_trait_ref);
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let expected_trait_ref = self.resolve_type_vars_if_possible(&*expected_trait_ref);
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let actual_trait_ref = self.resolve_type_vars_if_possible(&*actual_trait_ref);
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if actual_trait_ref.self_ty().references_error() {
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if expected_trait_ref.self_ty().references_error() {
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return;
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}
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let expected_trait_ty = expected_trait_ref.self_ty();
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let found_span = expected_trait_ty.ty_to_def_id().and_then(|did| {
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let found_trait_ty = found_trait_ref.self_ty();
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let found_did = found_trait_ty.ty_to_def_id();
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let found_span = found_did.and_then(|did| {
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self.tcx.hir.span_if_local(did)
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});
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let self_ty_count =
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let found_ty_count =
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match found_trait_ref.skip_binder().substs.type_at(1).sty {
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ty::TyTuple(ref tys, _) => tys.len(),
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_ => 1,
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};
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let (expected_tys, expected_ty_count) =
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match expected_trait_ref.skip_binder().substs.type_at(1).sty {
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ty::TyTuple(ref tys, _) => tys.len(),
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_ => 1,
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ty::TyTuple(ref tys, _) =>
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(tys.iter().map(|t| &t.sty).collect(), tys.len()),
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ref sty => (vec![sty], 1),
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};
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let arg_ty_count =
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match actual_trait_ref.skip_binder().substs.type_at(1).sty {
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ty::TyTuple(ref tys, _) => tys.len(),
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_ => 1,
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};
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if self_ty_count == arg_ty_count {
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if found_ty_count == expected_ty_count {
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self.report_closure_arg_mismatch(span,
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found_span,
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expected_trait_ref,
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actual_trait_ref)
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found_trait_ref,
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expected_trait_ref)
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} else {
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// Expected `|| { }`, found `|x, y| { }`
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// Expected `fn(x) -> ()`, found `|| { }`
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let expected_tuple = if expected_ty_count == 1 {
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expected_tys.first().and_then(|t| {
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if let &&ty::TyTuple(ref tuptys, _) = t {
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Some(tuptys.len())
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} else {
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None
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}
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})
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} else {
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None
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};
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// FIXME(#44150): Expand this to "N args expected but a N-tuple found."
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// Type of the 1st expected argument is somehow provided as type of a
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// found one in that case.
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//
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// ```
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// [1i32, 2, 3].sort_by(|(a, b)| ..)
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// // ^^^^^^^^
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// // expected_trait_ref: std::ops::FnMut<(&i32, &i32)>
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// // found_trait_ref: std::ops::FnMut<(&i32,)>
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// ```
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let (closure_span, closure_args) = found_did
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.and_then(|did| self.tcx.hir.get_if_local(did))
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.and_then(|node| {
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if let hir::map::NodeExpr(
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&hir::Expr {
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node: hir::ExprClosure(_, ref decl, id, span, _),
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..
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}) = node
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{
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let ty_snips = decl.inputs.iter()
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.map(|ty| {
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self.tcx.sess.codemap().span_to_snippet(ty.span).ok()
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.and_then(|snip| {
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// filter out dummy spans
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if snip == "," || snip == "|" {
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None
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} else {
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Some(snip)
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}
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})
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})
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.collect::<Vec<Option<String>>>();
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let body = self.tcx.hir.body(id);
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let pat_snips = body.arguments.iter()
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.map(|arg|
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self.tcx.sess.codemap().span_to_snippet(arg.pat.span).ok())
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.collect::<Option<Vec<String>>>();
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Some((span, pat_snips, ty_snips))
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} else {
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None
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}
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})
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.map(|(span, pat, ty)| (Some(span), Some((pat, ty))))
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.unwrap_or((None, None));
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let closure_args = closure_args.and_then(|(pat, ty)| Some((pat?, ty)));
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self.report_arg_count_mismatch(
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span,
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found_span,
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arg_ty_count,
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self_ty_count,
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expected_trait_ty.is_closure()
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closure_span.or(found_span),
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expected_ty_count,
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expected_tuple,
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found_ty_count,
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closure_args,
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found_trait_ty.is_closure()
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)
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}
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}
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@ -767,32 +831,97 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
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err.emit();
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}
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fn report_arg_count_mismatch(&self,
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span: Span,
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found_span: Option<Span>,
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expected: usize,
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found: usize,
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is_closure: bool)
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-> DiagnosticBuilder<'tcx>
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{
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let mut err = struct_span_err!(self.tcx.sess, span, E0593,
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"{} takes {} argument{} but {} argument{} {} required",
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if is_closure { "closure" } else { "function" },
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found,
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if found == 1 { "" } else { "s" },
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expected,
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if expected == 1 { "" } else { "s" },
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if expected == 1 { "is" } else { "are" });
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fn report_arg_count_mismatch(
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&self,
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span: Span,
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found_span: Option<Span>,
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expected: usize,
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expected_tuple: Option<usize>,
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found: usize,
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closure_args: Option<(Vec<String>, Vec<Option<String>>)>,
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is_closure: bool
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) -> DiagnosticBuilder<'tcx> {
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use std::borrow::Cow;
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let kind = if is_closure { "closure" } else { "function" };
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let args_str = |n, distinct| format!(
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"{} {}argument{}",
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n,
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if distinct && n >= 2 { "distinct " } else { "" },
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if n == 1 { "" } else { "s" },
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);
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let expected_str = if let Some(n) = expected_tuple {
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assert!(expected == 1);
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if closure_args.as_ref().map(|&(ref pats, _)| pats.len()) == Some(n) {
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Cow::from("a single tuple as argument")
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} else {
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// be verbose when numbers differ
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Cow::from(format!("a single {}-tuple as argument", n))
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}
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} else {
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Cow::from(args_str(expected, false))
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};
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let found_str = if expected_tuple.is_some() {
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args_str(found, true)
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} else {
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args_str(found, false)
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};
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let mut err = struct_span_err!(self.tcx.sess, span, E0593,
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"{} is expected to take {}, but it takes {}",
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kind,
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expected_str,
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found_str,
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);
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err.span_label(
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span,
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format!(
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"expected {} that takes {}",
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kind,
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expected_str,
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)
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);
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err.span_label(span, format!("expected {} that takes {} argument{}",
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if is_closure { "closure" } else { "function" },
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expected,
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if expected == 1 { "" } else { "s" }));
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if let Some(span) = found_span {
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err.span_label(span, format!("takes {} argument{}",
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found,
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if found == 1 { "" } else { "s" }));
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if let (Some(expected_tuple), Some((pats, tys))) = (expected_tuple, closure_args) {
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if expected_tuple != found || pats.len() != found {
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err.span_label(span, format!("takes {}", found_str));
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} else {
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let sugg = format!(
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"|({}){}|",
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pats.join(", "),
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// add type annotations if available
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if tys.iter().any(|ty| ty.is_some()) {
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Cow::from(format!(
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": ({})",
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tys.into_iter().map(|ty| if let Some(ty) = ty {
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ty
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} else {
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"_".to_string()
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}).collect::<Vec<String>>().join(", ")
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))
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} else {
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Cow::from("")
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},
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);
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err.span_suggestion(
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span,
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"consider changing the closure to accept a tuple",
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sugg
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);
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}
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} else {
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err.span_label(span, format!("takes {}", found_str));
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}
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}
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err
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}
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@ -16,4 +16,8 @@ fn main() {
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[1, 2, 3].sort_by(|tuple| panic!());
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[1, 2, 3].sort_by(|(tuple, tuple2)| panic!());
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f(|| panic!());
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let _it = vec![1, 2, 3].into_iter().enumerate().map(|i, x| i);
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let _it = vec![1, 2, 3].into_iter().enumerate().map(|i: usize, x| i);
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let _it = vec![1, 2, 3].into_iter().enumerate().map(|i, x, y| i);
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}
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@ -1,16 +1,16 @@
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error[E0593]: closure takes 0 arguments but 2 arguments are required
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error[E0593]: closure is expected to take 2 arguments, but it takes 0 arguments
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--> $DIR/closure-arg-count.rs:15:15
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15 | [1, 2, 3].sort_by(|| panic!());
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| ^^^^^^^ ----------- takes 0 arguments
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| ^^^^^^^ -- takes 0 arguments
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| |
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| expected closure that takes 2 arguments
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error[E0593]: closure takes 1 argument but 2 arguments are required
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error[E0593]: closure is expected to take 2 arguments, but it takes 1 argument
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--> $DIR/closure-arg-count.rs:16:15
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16 | [1, 2, 3].sort_by(|tuple| panic!());
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| ^^^^^^^ ---------------- takes 1 argument
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| ^^^^^^^ ------- takes 1 argument
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| |
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| expected closure that takes 2 arguments
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@ -23,23 +23,47 @@ error[E0308]: mismatched types
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= note: expected type `&{integer}`
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found type `(_, _)`
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error[E0593]: closure takes 1 argument but 2 arguments are required
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error[E0593]: closure is expected to take 2 arguments, but it takes 1 argument
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--> $DIR/closure-arg-count.rs:17:15
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17 | [1, 2, 3].sort_by(|(tuple, tuple2)| panic!());
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| ^^^^^^^ -------------------------- takes 1 argument
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| ^^^^^^^ ----------------- takes 1 argument
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| |
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| expected closure that takes 2 arguments
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error[E0593]: closure takes 0 arguments but 1 argument is required
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error[E0593]: closure is expected to take 1 argument, but it takes 0 arguments
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--> $DIR/closure-arg-count.rs:18:5
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18 | f(|| panic!());
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| ^ ----------- takes 0 arguments
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| ^ -- takes 0 arguments
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| |
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| expected closure that takes 1 argument
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= note: required by `f`
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error: aborting due to 5 previous errors
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error[E0593]: closure is expected to take a single tuple as argument, but it takes 2 distinct arguments
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--> $DIR/closure-arg-count.rs:20:53
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20 | let _it = vec![1, 2, 3].into_iter().enumerate().map(|i, x| i);
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| ^^^ ------ help: consider changing the closure to accept a tuple: `|(i, x)|`
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| |
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| expected closure that takes a single tuple as argument
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error[E0593]: closure is expected to take a single tuple as argument, but it takes 2 distinct arguments
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--> $DIR/closure-arg-count.rs:21:53
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21 | let _it = vec![1, 2, 3].into_iter().enumerate().map(|i: usize, x| i);
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| ^^^ ------------- help: consider changing the closure to accept a tuple: `|(i, x): (usize, _)|`
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| |
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| expected closure that takes a single tuple as argument
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error[E0593]: closure is expected to take a single 2-tuple as argument, but it takes 3 distinct arguments
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--> $DIR/closure-arg-count.rs:22:53
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22 | let _it = vec![1, 2, 3].into_iter().enumerate().map(|i, x, y| i);
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| ^^^ --------- takes 3 distinct arguments
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| |
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| expected closure that takes a single 2-tuple as argument
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error: aborting due to 8 previous errors
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