From 729d92cf0405ef8ee06e76b9e59b4892caa173f0 Mon Sep 17 00:00:00 2001
From: Ada Alakbarova <ada.alakbarova@proton.me>
Date: Mon, 4 Aug 2025 00:12:47 +0200
Subject: [PATCH] sugg on ty

---
 clippy_lints/src/mut_mut.rs       | 16 +++++++++++-----
 tests/ui/mut_mut.stderr           | 16 ++++++++--------
 tests/ui/mut_mut_unfixable.stderr |  4 ++--
 3 files changed, 21 insertions(+), 15 deletions(-)

diff --git a/clippy_lints/src/mut_mut.rs b/clippy_lints/src/mut_mut.rs
index 376d7214c267..7d7d4fa542c1 100644
--- a/clippy_lints/src/mut_mut.rs
+++ b/clippy_lints/src/mut_mut.rs
@@ -1,5 +1,6 @@
-use clippy_utils::diagnostics::{span_lint, span_lint_hir_and_then};
+use clippy_utils::diagnostics::{span_lint_and_sugg, span_lint_hir_and_then};
 use clippy_utils::higher;
+use clippy_utils::source::snippet_with_applicability;
 use clippy_utils::sugg::Sugg;
 use rustc_errors::Applicability;
 use rustc_hir::{self as hir, AmbigArg, intravisit};
@@ -37,15 +38,20 @@ impl<'tcx> LateLintPass<'tcx> for MutMut {
     fn check_ty(&mut self, cx: &LateContext<'tcx>, ty: &'tcx hir::Ty<'_, AmbigArg>) {
         if let hir::TyKind::Ref(_, mty) = ty.kind
             && mty.mutbl == hir::Mutability::Mut
-            && let hir::TyKind::Ref(_, mty) = mty.ty.kind
-            && mty.mutbl == hir::Mutability::Mut
+            && let hir::TyKind::Ref(_, mty2) = mty.ty.kind
+            && mty2.mutbl == hir::Mutability::Mut
             && !ty.span.in_external_macro(cx.sess().source_map())
         {
-            span_lint(
+            let mut applicability = Applicability::MaybeIncorrect;
+            let sugg = snippet_with_applicability(cx.sess(), mty.ty.span, "..", &mut applicability);
+            span_lint_and_sugg(
                 cx,
                 MUT_MUT,
                 ty.span,
-                "generally you want to avoid `&mut &mut _` if possible",
+                "a type of form `&mut &mut _`",
+                "remove the extra `&mut`",
+                sugg.to_string(),
+                applicability,
             );
         }
     }
diff --git a/tests/ui/mut_mut.stderr b/tests/ui/mut_mut.stderr
index 5f7c9b4fe23f..341ac643417c 100644
--- a/tests/ui/mut_mut.stderr
+++ b/tests/ui/mut_mut.stderr
@@ -1,8 +1,8 @@
-error: generally you want to avoid `&mut &mut _` if possible
+error: a type of form `&mut &mut _`
   --> tests/ui/mut_mut.rs:15:11
    |
 LL | fn fun(x: &mut &mut u32) {
-   |           ^^^^^^^^^^^^^
+   |           ^^^^^^^^^^^^^ help: remove the extra `&mut`: `&mut u32`
    |
    = note: `-D clippy::mut-mut` implied by `-D warnings`
    = help: to override `-D warnings` add `#[allow(clippy::mut_mut)]`
@@ -25,11 +25,11 @@ error: an expression of form `&mut &mut _`
 LL |         let y: &mut &mut u32 = &mut &mut 2;
    |                                ^^^^^^^^^^^ help: remove the extra `&mut`: `&mut 2`
 
-error: generally you want to avoid `&mut &mut _` if possible
+error: a type of form `&mut &mut _`
   --> tests/ui/mut_mut.rs:40:16
    |
 LL |         let y: &mut &mut u32 = &mut &mut 2;
-   |                ^^^^^^^^^^^^^
+   |                ^^^^^^^^^^^^^ help: remove the extra `&mut`: `&mut u32`
 
 error: an expression of form `&mut &mut _`
   --> tests/ui/mut_mut.rs:46:37
@@ -37,17 +37,17 @@ error: an expression of form `&mut &mut _`
 LL |         let y: &mut &mut &mut u32 = &mut &mut &mut 2;
    |                                     ^^^^^^^^^^^^^^^^ help: remove the extra `&mut`: `&mut &mut 2`
 
-error: generally you want to avoid `&mut &mut _` if possible
+error: a type of form `&mut &mut _`
   --> tests/ui/mut_mut.rs:46:16
    |
 LL |         let y: &mut &mut &mut u32 = &mut &mut &mut 2;
-   |                ^^^^^^^^^^^^^^^^^^
+   |                ^^^^^^^^^^^^^^^^^^ help: remove the extra `&mut`: `&mut &mut u32`
 
-error: generally you want to avoid `&mut &mut _` if possible
+error: a type of form `&mut &mut _`
   --> tests/ui/mut_mut.rs:46:21
    |
 LL |         let y: &mut &mut &mut u32 = &mut &mut &mut 2;
-   |                     ^^^^^^^^^^^^^
+   |                     ^^^^^^^^^^^^^ help: remove the extra `&mut`: `&mut u32`
 
 error: aborting due to 8 previous errors
 
diff --git a/tests/ui/mut_mut_unfixable.stderr b/tests/ui/mut_mut_unfixable.stderr
index 129e5b24387e..da820f766d02 100644
--- a/tests/ui/mut_mut_unfixable.stderr
+++ b/tests/ui/mut_mut_unfixable.stderr
@@ -1,8 +1,8 @@
-error: generally you want to avoid `&mut &mut _` if possible
+error: a type of form `&mut &mut _`
   --> tests/ui/mut_mut_unfixable.rs:9:11
    |
 LL | fn fun(x: &mut &mut u32) -> bool {
-   |           ^^^^^^^^^^^^^
+   |           ^^^^^^^^^^^^^ help: remove the extra `&mut`: `&mut u32`
    |
    = note: `-D clippy::mut-mut` implied by `-D warnings`
    = help: to override `-D warnings` add `#[allow(clippy::mut_mut)]`