Rollup merge of #88123 - camelid:tup-pat-precise-spans, r=estebank

Make spans for tuple patterns in E0023 more precise

As suggested in #86307. Closes #86307.

r? ````@estebank````

compiler/rustc_hir/src/hir.rs

@@ -3183,6 +3183,20 @@ pub enum Node<'hir> {
 }
 
 impl<'hir> Node<'hir> {
+    /// Get the identifier of this `Node`, if applicable.
+    ///
+    /// # Edge cases
+    ///
+    /// Calling `.ident()` on a [`Node::Ctor`] will return `None`
+    /// because `Ctor`s do not have identifiers themselves.
+    /// Instead, call `.ident()` on the parent struct/variant, like so:
+    ///
+    /// ```ignore (illustrative)
+    /// ctor
+    ///     .ctor_hir_id()
+    ///     .and_then(|ctor_id| tcx.hir().find(tcx.hir().get_parent_node(ctor_id)))
+    ///     .and_then(|parent| parent.ident())
+    /// ```
     pub fn ident(&self) -> Option<Ident> {
         match self {
             Node::TraitItem(TraitItem { ident, .. })
@@ -3191,8 +3205,25 @@ impl<'hir> Node<'hir> {
             | Node::Field(FieldDef { ident, .. })
             | Node::Variant(Variant { ident, .. })
             | Node::MacroDef(MacroDef { ident, .. })
-            | Node::Item(Item { ident, .. }) => Some(*ident),
-            _ => None,
+            | Node::Item(Item { ident, .. })
+            | Node::PathSegment(PathSegment { ident, .. }) => Some(*ident),
+            Node::Lifetime(lt) => Some(lt.name.ident()),
+            Node::GenericParam(p) => Some(p.name.ident()),
+            Node::Param(..)
+            | Node::AnonConst(..)
+            | Node::Expr(..)
+            | Node::Stmt(..)
+            | Node::Block(..)
+            | Node::Ctor(..)
+            | Node::Pat(..)
+            | Node::Binding(..)
+            | Node::Arm(..)
+            | Node::Local(..)
+            | Node::Visibility(..)
+            | Node::Crate(..)
+            | Node::Ty(..)
+            | Node::TraitRef(..)
+            | Node::Infer(..) => None,
         }
     }
 

compiler/rustc_ty_utils/src/ty.rs

@@ -223,7 +223,18 @@ fn associated_items(tcx: TyCtxt<'_>, def_id: DefId) -> ty::AssocItems<'_> {
 }
 
 fn def_ident_span(tcx: TyCtxt<'_>, def_id: DefId) -> Option<Span> {
-    tcx.hir().get_if_local(def_id).and_then(|node| node.ident()).map(|ident| ident.span)
+    tcx.hir()
+        .get_if_local(def_id)
+        .and_then(|node| match node {
+            // A `Ctor` doesn't have an identifier itself, but its parent
+            // struct/variant does. Compare with `hir::Map::opt_span`.
+            hir::Node::Ctor(ctor) => ctor
+                .ctor_hir_id()
+                .and_then(|ctor_id| tcx.hir().find(tcx.hir().get_parent_node(ctor_id)))
+                .and_then(|parent| parent.ident()),
+            _ => node.ident(),
+        })
+        .map(|ident| ident.span)
 }
 
 /// If the given `DefId` describes an item belonging to a trait,

compiler/rustc_typeck/src/check/pat.rs

@@ -15,7 +15,7 @@ use rustc_span::hygiene::DesugaringKind;
 use rustc_span::lev_distance::find_best_match_for_name;
 use rustc_span::source_map::{Span, Spanned};
 use rustc_span::symbol::Ident;
-use rustc_span::{BytePos, DUMMY_SP};
+use rustc_span::{BytePos, MultiSpan, DUMMY_SP};
 use rustc_trait_selection::autoderef::Autoderef;
 use rustc_trait_selection::traits::{ObligationCause, Pattern};
 use ty::VariantDef;
@@ -990,10 +990,25 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
     ) {
         let subpats_ending = pluralize!(subpats.len());
         let fields_ending = pluralize!(fields.len());
+
+        let subpat_spans = if subpats.is_empty() {
+            vec![pat_span]
+        } else {
+            subpats.iter().map(|p| p.span).collect()
+        };
+        let last_subpat_span = *subpat_spans.last().unwrap();
         let res_span = self.tcx.def_span(res.def_id());
+        let def_ident_span = self.tcx.def_ident_span(res.def_id()).unwrap_or(res_span);
+        let field_def_spans = if fields.is_empty() {
+            vec![res_span]
+        } else {
+            fields.iter().map(|f| f.ident.span).collect()
+        };
+        let last_field_def_span = *field_def_spans.last().unwrap();
+
         let mut err = struct_span_err!(
             self.tcx.sess,
-            pat_span,
+            MultiSpan::from_spans(subpat_spans.clone()),
             E0023,
             "this pattern has {} field{}, but the corresponding {} has {} field{}",
             subpats.len(),
@@ -1003,10 +1018,22 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             fields_ending,
         );
         err.span_label(
-            pat_span,
-            format!("expected {} field{}, found {}", fields.len(), fields_ending, subpats.len(),),
-        )
-        .span_label(res_span, format!("{} defined here", res.descr()));
+            last_subpat_span,
+            &format!("expected {} field{}, found {}", fields.len(), fields_ending, subpats.len()),
+        );
+        if self.tcx.sess.source_map().is_multiline(qpath.span().between(last_subpat_span)) {
+            err.span_label(qpath.span(), "");
+        }
+        if self.tcx.sess.source_map().is_multiline(def_ident_span.between(last_field_def_span)) {
+            err.span_label(def_ident_span, format!("{} defined here", res.descr()));
+        }
+        for span in &field_def_spans[..field_def_spans.len() - 1] {
+            err.span_label(*span, "");
+        }
+        err.span_label(
+            last_field_def_span,
+            &format!("{} has {} field{}", res.descr(), fields.len(), fields_ending),
+        );
 
         // Identify the case `Some(x, y)` where the expected type is e.g. `Option<(T, U)>`.
         // More generally, the expected type wants a tuple variant with one field of an