downgrade mutable-ptr-in-final-value from hard-error to future-incompat lint to address issue 121610.

2 files changed, 13 insertions, 6 deletions

diff --git a/compiler/rustc_const_eval/src/errors.rs b/compiler/rustc_const_eval/src/errors.rs
index 249c02b75f7..46790264359 100644
--- a/compiler/rustc_const_eval/src/errors.rs
+++ b/compiler/rustc_const_eval/src/errors.rs
@@ -25,10 +25,13 @@ pub(crate) struct DanglingPtrInFinal {
     pub kind: InternKind,
 }
 
-#[derive(Diagnostic)]
+#[derive(LintDiagnostic)]
 #[diag(const_eval_mutable_ptr_in_final)]
 pub(crate) struct MutablePtrInFinal {
-    #[primary_span]
+    // rust-lang/rust#122153: This was marked as `#[primary_span]` under
+    // `derive(Diagnostic)`. Since we expect we may hard-error in future, we are
+    // keeping the field (and skipping it under `derive(LintDiagnostic)`).
+    #[skip_arg]
     pub span: Span,
     pub kind: InternKind,
 }
diff --git a/compiler/rustc_const_eval/src/interpret/intern.rs b/compiler/rustc_const_eval/src/interpret/intern.rs
index 55d4b9edd59..0994ace814c 100644
--- a/compiler/rustc_const_eval/src/interpret/intern.rs
+++ b/compiler/rustc_const_eval/src/interpret/intern.rs
@@ -23,6 +23,7 @@ use rustc_middle::query::TyCtxtAt;
 use rustc_middle::ty::layout::TyAndLayout;
 use rustc_span::def_id::LocalDefId;
 use rustc_span::sym;
+use rustc_session::lint;
 
 use super::{AllocId, Allocation, InterpCx, MPlaceTy, Machine, MemoryKind, PlaceTy};
 use crate::const_eval;
@@ -262,10 +263,13 @@ pub fn intern_const_alloc_recursive<
         })?);
     }
     if found_bad_mutable_pointer {
-        return Err(ecx
-            .tcx
-            .dcx()
-            .emit_err(MutablePtrInFinal { span: ecx.tcx.span, kind: intern_kind }));
+        let err_diag = MutablePtrInFinal { span: ecx.tcx.span, kind: intern_kind };
+        ecx.tcx.emit_node_span_lint(
+            lint::builtin::CONST_EVAL_MUTABLE_PTR_IN_FINAL_VALUE,
+            ecx.best_lint_scope(),
+            err_diag.span,
+            err_diag,
+        )
     }
 
     Ok(())