do not use stringly typed diagnostics

compiler/rustc_lint/messages.ftl

@@ -478,13 +478,11 @@ lint_requested_level = requested on the command line with `{$level} {$lint_name}
 lint_supertrait_as_deref_target = `{$t}` implements `Deref` with supertrait `{$target_principal}` as target
     .label = target type is set here
 
-lint_suspicious_double_ref_op =
+lint_suspicious_double_ref_clone =
-    using `.{$call}()` on a double reference, which returns `{$ty}` instead of {$op ->
+    using `.clone()` on a double reference, which returns `{$ty}` instead of cloning the inner type
-        *[should_not_happen] [{$op}]
+
-        [deref] dereferencing
+lint_suspicious_double_ref_deref =
-        [borrow] borrowing
+    using `.deref()` on a double reference, which returns `{$ty}` instead of dereferencing the inner type
-        [clone] cloning
-    } the inner type
 
 lint_trivial_untranslatable_diag = diagnostic with static strings only
 

compiler/rustc_lint/src/lints.rs

@@ -1231,11 +1231,15 @@ pub struct NoopMethodCallDiag<'a> {
 }
 
 #[derive(LintDiagnostic)]
-#[diag(lint_suspicious_double_ref_op)]
+#[diag(lint_suspicious_double_ref_deref)]
-pub struct SuspiciousDoubleRefDiag<'a> {
+pub struct SuspiciousDoubleRefDerefDiag<'a> {
-    pub call: Symbol,
+    pub ty: Ty<'a>,
+}
+
+#[derive(LintDiagnostic)]
+#[diag(lint_suspicious_double_ref_clone)]
+pub struct SuspiciousDoubleRefCloneDiag<'a> {
     pub ty: Ty<'a>,
-    pub op: &'static str,
 }
 
 // pass_by_value.rs

compiler/rustc_lint/src/noop_method_call.rs

@@ -1,5 +1,7 @@
 use crate::context::LintContext;
-use crate::lints::{NoopMethodCallDiag, SuspiciousDoubleRefDiag};
+use crate::lints::{
+    NoopMethodCallDiag, SuspiciousDoubleRefCloneDiag, SuspiciousDoubleRefDerefDiag,
+};
 use crate::LateContext;
 use crate::LateLintPass;
 use rustc_hir::def::DefKind;
@@ -102,13 +104,6 @@ impl<'tcx> LateLintPass<'tcx> for NoopMethodCall {
         // (Re)check that it implements the noop diagnostic.
         let Some(name) = cx.tcx.get_diagnostic_name(i.def_id()) else { return };
 
-        let op = match name {
-            sym::noop_method_borrow => "borrow",
-            sym::noop_method_clone => "clone",
-            sym::noop_method_deref => "deref",
-            _ => return,
-        };
-
         let receiver_ty = cx.typeck_results().expr_ty(receiver);
         let expr_ty = cx.typeck_results().expr_ty_adjusted(expr);
         let arg_adjustments = cx.typeck_results().expr_adjustments(receiver);
@@ -129,14 +124,22 @@ impl<'tcx> LateLintPass<'tcx> for NoopMethodCall {
                 NoopMethodCallDiag { method: call.ident.name, receiver_ty, label: span },
             );
         } else {
-            if op == "borrow" {
+            match name {
-                return;
+                // If `type_of(x) == T` and `x.borrow()` is used to get `&T`,
-            }
+                // then that should be allowed
-            cx.emit_spanned_lint(
+                sym::noop_method_borrow => return,
+                sym::noop_method_clone => cx.emit_spanned_lint(
                     SUSPICIOUS_DOUBLE_REF_OP,
                     span,
-                SuspiciousDoubleRefDiag { call: call.ident.name, ty: expr_ty, op },
+                    SuspiciousDoubleRefCloneDiag { ty: expr_ty },
-            )
+                ),
+                sym::noop_method_deref => cx.emit_spanned_lint(
+                    SUSPICIOUS_DOUBLE_REF_OP,
+                    span,
+                    SuspiciousDoubleRefDerefDiag { ty: expr_ty },
+                ),
+                _ => return,
+            }
         }
     }
 }