1 files changed, 15 insertions, 20 deletions

diff --git a/compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs b/compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs
index 59d017545c0..53ce8f368e2 100644
--- a/compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs
+++ b/compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs
@@ -70,7 +70,7 @@ pub trait InferCtxtExt<'tcx> {
     /// returns a span and `ArgKind` information that describes the
     /// arguments it expects. This can be supplied to
     /// `report_arg_count_mismatch`.
-    fn get_fn_like_arguments(&self, node: Node<'_>) -> Option<(Span, Vec<ArgKind>)>;
+    fn get_fn_like_arguments(&self, node: Node<'_>) -> Option<(Span, Option<Span>, Vec<ArgKind>)>;
 
     /// Reports an error when the number of arguments needed by a
     /// trait match doesn't match the number that the expression
@@ -82,6 +82,7 @@ pub trait InferCtxtExt<'tcx> {
         expected_args: Vec<ArgKind>,
         found_args: Vec<ArgKind>,
         is_closure: bool,
+        closure_pipe_span: Option<Span>,
     ) -> DiagnosticBuilder<'tcx, ErrorGuaranteed>;
 
     /// Checks if the type implements one of `Fn`, `FnMut`, or `FnOnce`
@@ -134,15 +135,16 @@ impl<'tcx> InferCtxtExt<'tcx> for InferCtxt<'tcx> {
     /// returns a span and `ArgKind` information that describes the
     /// arguments it expects. This can be supplied to
     /// `report_arg_count_mismatch`.
-    fn get_fn_like_arguments(&self, node: Node<'_>) -> Option<(Span, Vec<ArgKind>)> {
+    fn get_fn_like_arguments(&self, node: Node<'_>) -> Option<(Span, Option<Span>, Vec<ArgKind>)> {
         let sm = self.tcx.sess.source_map();
         let hir = self.tcx.hir();
         Some(match node {
             Node::Expr(&hir::Expr {
-                kind: hir::ExprKind::Closure(&hir::Closure { body, fn_decl_span, .. }),
+                kind: hir::ExprKind::Closure(&hir::Closure { body, fn_decl_span, fn_arg_span, .. }),
                 ..
             }) => (
                 fn_decl_span,
+                fn_arg_span,
                 hir.body(body)
                     .params
                     .iter()
@@ -173,6 +175,7 @@ impl<'tcx> InferCtxtExt<'tcx> for InferCtxt<'tcx> {
                 kind: hir::TraitItemKind::Fn(ref sig, _), ..
             }) => (
                 sig.span,
+                None,
                 sig.decl
                     .inputs
                     .iter()
@@ -187,7 +190,7 @@ impl<'tcx> InferCtxtExt<'tcx> for InferCtxt<'tcx> {
             ),
             Node::Ctor(ref variant_data) => {
                 let span = variant_data.ctor_hir_id().map_or(DUMMY_SP, |id| hir.span(id));
-                (span, vec![ArgKind::empty(); variant_data.fields().len()])
+                (span, None, vec![ArgKind::empty(); variant_data.fields().len()])
             }
             _ => panic!("non-FnLike node found: {:?}", node),
         })
@@ -203,6 +206,7 @@ impl<'tcx> InferCtxtExt<'tcx> for InferCtxt<'tcx> {
         expected_args: Vec<ArgKind>,
         found_args: Vec<ArgKind>,
         is_closure: bool,
+        closure_arg_span: Option<Span>,
     ) -> DiagnosticBuilder<'tcx, ErrorGuaranteed> {
         let kind = if is_closure { "closure" } else { "function" };
 
@@ -240,24 +244,13 @@ impl<'tcx> InferCtxtExt<'tcx> for InferCtxt<'tcx> {
         if let Some(found_span) = found_span {
             err.span_label(found_span, format!("takes {}", found_str));
 
-            // move |_| { ... }
-            // ^^^^^^^^-- def_span
-            //
-            // move |_| { ... }
-            // ^^^^^-- prefix
-            let prefix_span = self.tcx.sess.source_map().span_until_non_whitespace(found_span);
-            // move |_| { ... }
-            //      ^^^-- pipe_span
-            let pipe_span =
-                if let Some(span) = found_span.trim_start(prefix_span) { span } else { found_span };
-
             // Suggest to take and ignore the arguments with expected_args_length `_`s if
             // found arguments is empty (assume the user just wants to ignore args in this case).
             // For example, if `expected_args_length` is 2, suggest `|_, _|`.
             if found_args.is_empty() && is_closure {
                 let underscores = vec!["_"; expected_args.len()].join(", ");
                 err.span_suggestion_verbose(
-                    pipe_span,
+                    closure_arg_span.unwrap_or(found_span),
                     &format!(
                         "consider changing the closure to take and ignore the expected argument{}",
                         pluralize!(expected_args.len())
@@ -1251,13 +1244,14 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
                         obligation.cause.code(),
                     )
                 } else {
-                    let (closure_span, found) = found_did
+                    let (closure_span, closure_arg_span, found) = found_did
                         .and_then(|did| {
                             let node = self.tcx.hir().get_if_local(did)?;
-                            let (found_span, found) = self.get_fn_like_arguments(node)?;
-                            Some((Some(found_span), found))
+                            let (found_span, closure_arg_span, found) =
+                                self.get_fn_like_arguments(node)?;
+                            Some((Some(found_span), closure_arg_span, found))
                         })
-                        .unwrap_or((found_span, found));
+                        .unwrap_or((found_span, None, found));
 
                     self.report_arg_count_mismatch(
                         span,
@@ -1265,6 +1259,7 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
                         expected,
                         found,
                         found_trait_ty.is_closure(),
+                        closure_arg_span,
                     )
                 }
             }