Migrate borrow of moved value diagnostic

Author: lzcunt

compiler/rustc_error_messages/locales/en-US/mir_build.ftl

@@ -287,3 +287,9 @@ mir_build_irrefutable_let_patterns_while_let = irrefutable `while let` {$count -
         *[other] these patterns
     } will always match, so the loop will never exit
     .help = consider instead using a `loop {"{"} ... {"}"}` with a `let` inside it
+
+mir_build_borrow_of_moved_value = borrow of moved value
+    .label = value moved into `{$name}` here
+    .occurs_because_label = move occurs because `{$name}` has type `{$ty}` which does not implement the `Copy` trait
+    .value_borrowed_label = value borrowed here after move
+    .suggest_borrowing = borrow this binding in the pattern to avoid moving the value

compiler/rustc_mir_build/src/errors.rs

@@ -562,3 +562,19 @@ pub struct IrrefutableLetPatternsLetElse {
 pub struct IrrefutableLetPatternsWhileLet {
     pub count: usize,
 }
+
+#[derive(SessionDiagnostic)]
+#[diag(mir_build::borrow_of_moved_value)]
+pub struct BorrowOfMovedValue<'tcx> {
+    #[primary_span]
+    pub span: Span,
+    #[label]
+    #[label(mir_build::occurs_because_label)]
+    pub binding_span: Span,
+    #[label(mir_build::value_borrowed_label)]
+    pub conflicts_ref: Vec<Span>,
+    pub name: Ident,
+    pub ty: Ty<'tcx>,
+    #[suggestion(code = "ref ", applicability = "machine-applicable")]
+    pub suggest_borrowing: Option<Span>,
+}

compiler/rustc_mir_build/src/thir/pattern/check_match.rs

@@ -962,24 +962,14 @@ fn check_borrow_conflicts_in_at_patterns(cx: &MatchVisitor<'_, '_, '_>, pat: &Pa
                 }
             });
             if !conflicts_ref.is_empty() {
-                let occurs_because = format!(
-                    "move occurs because `{}` has type `{}` which does not implement the `Copy` trait",
+                sess.emit_err(BorrowOfMovedValue {
+                    span: pat.span,
+                    binding_span,
+                    conflicts_ref,
                     name,
-                    typeck_results.node_type(pat.hir_id),
-                );
-                let mut err = sess.struct_span_err(pat.span, "borrow of moved value");
-                err.span_label(binding_span, format!("value moved into `{}` here", name))
-                    .span_label(binding_span, occurs_because)
-                    .span_labels(conflicts_ref, "value borrowed here after move");
-                if pat.span.contains(binding_span) {
-                    err.span_suggestion_verbose(
-                        binding_span.shrink_to_lo(),
-                        "borrow this binding in the pattern to avoid moving the value",
-                        "ref ".to_string(),
-                        Applicability::MachineApplicable,
-                    );
-                }
-                err.emit();
+                    ty: typeck_results.node_type(pat.hir_id),
+                    suggest_borrowing: pat.span.contains(binding_span).then(|| binding_span.shrink_to_lo()),
+                });
             }
             return;
         }