3 files changed, 26 insertions, 23 deletions
diff --git a/compiler/rustc_mir_build/src/errors.rs b/compiler/rustc_mir_build/src/errors.rs
index 42be7f9402e..00f65e0c7d0 100644
--- a/compiler/rustc_mir_build/src/errors.rs
+++ b/compiler/rustc_mir_build/src/errors.rs
@@ -983,6 +983,8 @@ pub(crate) struct Rust2024IncompatiblePat {
 
 pub(crate) struct Rust2024IncompatiblePatSugg {
     pub(crate) suggestion: Vec<(Span, String)>,
+    /// Whether the incompatibility is a hard error because a relevant span is in edition 2024.
+    pub(crate) is_hard_error: bool,
 }
 
 impl Subdiagnostic for Rust2024IncompatiblePatSugg {
diff --git a/compiler/rustc_mir_build/src/thir/cx/expr.rs b/compiler/rustc_mir_build/src/thir/cx/expr.rs
index abf486af962..5995d60e7e0 100644
--- a/compiler/rustc_mir_build/src/thir/cx/expr.rs
+++ b/compiler/rustc_mir_build/src/thir/cx/expr.rs
@@ -808,21 +808,11 @@ impl<'tcx> Cx<'tcx> {
                 });
                 ExprKind::Loop { body }
             }
-            hir::ExprKind::Field(source, ..) => {
-                let mut kind = ExprKind::Field {
-                    lhs: self.mirror_expr(source),
-                    variant_index: FIRST_VARIANT,
-                    name: self.typeck_results.field_index(expr.hir_id),
-                };
-                let nested_field_tys_and_indices =
-                    self.typeck_results.nested_field_tys_and_indices(expr.hir_id);
-                for &(ty, idx) in nested_field_tys_and_indices {
-                    let expr = Expr { temp_lifetime, ty, span: source.span, kind };
-                    let lhs = self.thir.exprs.push(expr);
-                    kind = ExprKind::Field { lhs, variant_index: FIRST_VARIANT, name: idx };
-                }
-                kind
-            }
+            hir::ExprKind::Field(source, ..) => ExprKind::Field {
+                lhs: self.mirror_expr(source),
+                variant_index: FIRST_VARIANT,
+                name: self.typeck_results.field_index(expr.hir_id),
+            },
             hir::ExprKind::Cast(source, cast_ty) => {
                 // Check for a user-given type annotation on this `cast`
                 let user_provided_types = self.typeck_results.user_provided_types();
diff --git a/compiler/rustc_mir_build/src/thir/pattern/mod.rs b/compiler/rustc_mir_build/src/thir/pattern/mod.rs
index 04e921ecc2e..56e5156a91f 100644
--- a/compiler/rustc_mir_build/src/thir/pattern/mod.rs
+++ b/compiler/rustc_mir_build/src/thir/pattern/mod.rs
@@ -25,6 +25,7 @@ use tracing::{debug, instrument};
 
 pub(crate) use self::check_match::check_match;
 use crate::errors::*;
+use crate::fluent_generated as fluent;
 use crate::thir::util::UserAnnotatedTyHelpers;
 
 struct PatCtxt<'a, 'tcx> {
@@ -48,18 +49,28 @@ pub(super) fn pat_from_hir<'a, 'tcx>(
         typeck_results,
         rust_2024_migration_suggestion: typeck_results
             .rust_2024_migration_desugared_pats()
-            .contains(pat.hir_id)
-            .then_some(Rust2024IncompatiblePatSugg { suggestion: Vec::new() }),
+            .get(pat.hir_id)
+            .map(|&is_hard_error| Rust2024IncompatiblePatSugg {
+                suggestion: Vec::new(),
+                is_hard_error,
+            }),
     };
     let result = pcx.lower_pattern(pat);
     debug!("pat_from_hir({:?}) = {:?}", pat, result);
     if let Some(sugg) = pcx.rust_2024_migration_suggestion {
-        tcx.emit_node_span_lint(
-            lint::builtin::RUST_2024_INCOMPATIBLE_PAT,
-            pat.hir_id,
-            pat.span,
-            Rust2024IncompatiblePat { sugg },
-        );
+        if sugg.is_hard_error {
+            let mut err =
+                tcx.dcx().struct_span_err(pat.span, fluent::mir_build_rust_2024_incompatible_pat);
+            err.subdiagnostic(sugg);
+            err.emit();
+        } else {
+            tcx.emit_node_span_lint(
+                lint::builtin::RUST_2024_INCOMPATIBLE_PAT,
+                pat.hir_id,
+                pat.span,
+                Rust2024IncompatiblePat { sugg },
+            );
+        }
     }
     result
 }