Auto merge of #12794 - J-ZhengLi:issue9251, r=blyxyas

improve [`match_same_arms`] messages, enable rustfix test

closes: #9251

don't worry about the commit size, most of them are generated

---

changelog: improve [`match_same_arms`] lint messages

8 files changed, 533 insertions, 209 deletions

diff --git a/clippy_lints/src/matches/match_same_arms.rs b/clippy_lints/src/matches/match_same_arms.rs
index cd61e733694..da8c918a62b 100644
--- a/clippy_lints/src/matches/match_same_arms.rs
+++ b/clippy_lints/src/matches/match_same_arms.rs
@@ -1,5 +1,5 @@
 use clippy_utils::diagnostics::span_lint_hir_and_then;
-use clippy_utils::source::snippet;
+use clippy_utils::source::snippet_with_applicability;
 use clippy_utils::{is_lint_allowed, path_to_local, search_same, SpanlessEq, SpanlessHash};
 use core::cmp::Ordering;
 use core::{iter, slice};
@@ -9,9 +9,9 @@ use rustc_errors::Applicability;
 use rustc_hir::def_id::DefId;
 use rustc_hir::{Arm, Expr, ExprKind, HirId, HirIdMap, HirIdMapEntry, HirIdSet, Pat, PatKind, RangeEnd};
 use rustc_lint::builtin::NON_EXHAUSTIVE_OMITTED_PATTERNS;
-use rustc_lint::LateContext;
+use rustc_lint::{LateContext, LintContext};
 use rustc_middle::ty;
-use rustc_span::{ErrorGuaranteed, Symbol};
+use rustc_span::{ErrorGuaranteed, Span, Symbol};
 
 use super::MATCH_SAME_ARMS;
 
@@ -110,20 +110,22 @@ pub(super) fn check<'tcx>(cx: &LateContext<'tcx>, arms: &'tcx [Arm<'_>]) {
             && check_same_body()
     };
 
+    let mut appl = Applicability::MaybeIncorrect;
     let indexed_arms: Vec<(usize, &Arm<'_>)> = arms.iter().enumerate().collect();
     for (&(i, arm1), &(j, arm2)) in search_same(&indexed_arms, hash, eq) {
         if matches!(arm2.pat.kind, PatKind::Wild) {
             if !cx.tcx.features().non_exhaustive_omitted_patterns_lint
                 || is_lint_allowed(cx, NON_EXHAUSTIVE_OMITTED_PATTERNS, arm2.hir_id)
             {
+                let arm_span = adjusted_arm_span(cx, arm1.span);
                 span_lint_hir_and_then(
                     cx,
                     MATCH_SAME_ARMS,
                     arm1.hir_id,
-                    arm1.span,
+                    arm_span,
                     "this match arm has an identical body to the `_` wildcard arm",
                     |diag| {
-                        diag.span_suggestion(arm1.span, "try removing the arm", "", Applicability::MaybeIncorrect)
+                        diag.span_suggestion(arm_span, "try removing the arm", "", appl)
                             .help("or try changing either arm body")
                             .span_note(arm2.span, "`_` wildcard arm here");
                     },
@@ -144,23 +146,36 @@ pub(super) fn check<'tcx>(cx: &LateContext<'tcx>, arms: &'tcx [Arm<'_>]) {
                 keep_arm.span,
                 "this match arm has an identical body to another arm",
                 |diag| {
-                    let move_pat_snip = snippet(cx, move_arm.pat.span, "<pat2>");
-                    let keep_pat_snip = snippet(cx, keep_arm.pat.span, "<pat1>");
+                    let move_pat_snip = snippet_with_applicability(cx, move_arm.pat.span, "<pat2>", &mut appl);
+                    let keep_pat_snip = snippet_with_applicability(cx, keep_arm.pat.span, "<pat1>", &mut appl);
 
                     diag.span_suggestion(
                         keep_arm.pat.span,
-                        "try merging the arm patterns",
+                        "or try merging the arm patterns",
                         format!("{keep_pat_snip} | {move_pat_snip}"),
-                        Applicability::MaybeIncorrect,
+                        appl,
                     )
-                    .help("or try changing either arm body")
-                    .span_note(move_arm.span, "other arm here");
+                    .span_suggestion(
+                        adjusted_arm_span(cx, move_arm.span),
+                        "and remove this obsolete arm",
+                        "",
+                        appl,
+                    )
+                    .help("try changing either arm body");
                 },
             );
         }
     }
 }
 
+/// Extend arm's span to include the comma and whitespaces after it.
+fn adjusted_arm_span(cx: &LateContext<'_>, span: Span) -> Span {
+    let source_map = cx.sess().source_map();
+    source_map
+        .span_extend_while(span, |c| c == ',' || c.is_ascii_whitespace())
+        .unwrap_or(span)
+}
+
 #[derive(Clone, Copy)]
 enum NormalizedPat<'a> {
     Wild,
diff --git a/tests/ui/match_same_arms.stderr b/tests/ui/match_same_arms.stderr
index a926570b60a..3c0382767c3 100644
--- a/tests/ui/match_same_arms.stderr
+++ b/tests/ui/match_same_arms.stderr
@@ -2,7 +2,7 @@ error: this match arm has an identical body to the `_` wildcard arm
   --> tests/ui/match_same_arms.rs:12:9
    |
 LL |         Abc::A => 0,
-   |         ^^^^^^^^^^^ help: try removing the arm
+   |         ^^^^^^^^^^^^^ help: try removing the arm
    |
    = help: or try changing either arm body
 note: `_` wildcard arm here
@@ -17,106 +17,114 @@ error: this match arm has an identical body to another arm
   --> tests/ui/match_same_arms.rs:18:9
    |
 LL |         (1, .., 3) => 42,
-   |         ----------^^^^^^
-   |         |
-   |         help: try merging the arm patterns: `(1, .., 3) | (.., 3)`
+   |         ^^^^^^^^^^^^^^^^
    |
-   = help: or try changing either arm body
-note: other arm here
-  --> tests/ui/match_same_arms.rs:19:9
+   = help: try changing either arm body
+help: or try merging the arm patterns
+   |
+LL |         (1, .., 3) | (.., 3) => 42,
+   |         ~~~~~~~~~~~~~~~~~~~~
+help: and remove this obsolete arm
+   |
+LL -         (.., 3) => 42,
    |
-LL |         (.., 3) => 42,
-   |         ^^^^^^^^^^^^^
 
 error: this match arm has an identical body to another arm
   --> tests/ui/match_same_arms.rs:25:9
    |
 LL |         51 => 1,
-   |         --^^^^^
-   |         |
-   |         help: try merging the arm patterns: `51 | 42`
+   |         ^^^^^^^
    |
-   = help: or try changing either arm body
-note: other arm here
-  --> tests/ui/match_same_arms.rs:24:9
+   = help: try changing either arm body
+help: or try merging the arm patterns
+   |
+LL |         51 | 42 => 1,
+   |         ~~~~~~~
+help: and remove this obsolete arm
+   |
+LL -         42 => 1,
    |
-LL |         42 => 1,
-   |         ^^^^^^^
 
 error: this match arm has an identical body to another arm
   --> tests/ui/match_same_arms.rs:26:9
    |
 LL |         41 => 2,
-   |         --^^^^^
-   |         |
-   |         help: try merging the arm patterns: `41 | 52`
+   |         ^^^^^^^
    |
-   = help: or try changing either arm body
-note: other arm here
-  --> tests/ui/match_same_arms.rs:27:9
+   = help: try changing either arm body
+help: or try merging the arm patterns
+   |
+LL |         41 | 52 => 2,
+   |         ~~~~~~~
+help: and remove this obsolete arm
+   |
+LL -         52 => 2,
    |
-LL |         52 => 2,
-   |         ^^^^^^^
 
 error: this match arm has an identical body to another arm
   --> tests/ui/match_same_arms.rs:33:9
    |
 LL |         2 => 2,
-   |         -^^^^^
-   |         |
-   |         help: try merging the arm patterns: `2 | 1`
+   |         ^^^^^^
    |
-   = help: or try changing either arm body
-note: other arm here
-  --> tests/ui/match_same_arms.rs:32:9
+   = help: try changing either arm body
+help: or try merging the arm patterns
+   |
+LL |         2 | 1 => 2,
+   |         ~~~~~
+help: and remove this obsolete arm
+   |
+LL -         1 => 2,
    |
-LL |         1 => 2,
-   |         ^^^^^^
 
 error: this match arm has an identical body to another arm
   --> tests/ui/match_same_arms.rs:35:9
    |
 LL |         3 => 2,
-   |         -^^^^^
-   |         |
-   |         help: try merging the arm patterns: `3 | 1`
+   |         ^^^^^^
    |
-   = help: or try changing either arm body
-note: other arm here
-  --> tests/ui/match_same_arms.rs:32:9
+   = help: try changing either arm body
+help: or try merging the arm patterns
+   |
+LL |         3 | 1 => 2,
+   |         ~~~~~
+help: and remove this obsolete arm
+   |
+LL -         1 => 2,
    |
-LL |         1 => 2,
-   |         ^^^^^^
 
 error: this match arm has an identical body to another arm
   --> tests/ui/match_same_arms.rs:33:9
    |
 LL |         2 => 2,
-   |         -^^^^^
-   |         |
-   |         help: try merging the arm patterns: `2 | 3`
+   |         ^^^^^^
    |
-   = help: or try changing either arm body
-note: other arm here
-  --> tests/ui/match_same_arms.rs:35:9
+   = help: try changing either arm body
+help: or try merging the arm patterns
+   |
+LL |         2 | 3 => 2,
+   |         ~~~~~
+help: and remove this obsolete arm
+   |
+LL -         3 => 2,
+LL +
    |
-LL |         3 => 2,
-   |         ^^^^^^
 
 error: this match arm has an identical body to another arm
   --> tests/ui/match_same_arms.rs:52:17
    |
 LL |                 CommandInfo::External { name, .. } => name.to_string(),
-   |                 ----------------------------------^^^^^^^^^^^^^^^^^^^^
-   |                 |
-   |                 help: try merging the arm patterns: `CommandInfo::External { name, .. } | CommandInfo::BuiltIn { name, .. }`
+   |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
-   = help: or try changing either arm body
-note: other arm here
-  --> tests/ui/match_same_arms.rs:51:17
+   = help: try changing either arm body
+help: or try merging the arm patterns
+   |
+LL |                 CommandInfo::External { name, .. } | CommandInfo::BuiltIn { name, .. } => name.to_string(),
+   |                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+help: and remove this obsolete arm
+   |
+LL -                 CommandInfo::BuiltIn { name, .. } => name.to_string(),
    |
-LL |                 CommandInfo::BuiltIn { name, .. } => name.to_string(),
-   |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: aborting due to 8 previous errors
 
diff --git a/tests/ui/match_same_arms2.fixed b/tests/ui/match_same_arms2.fixed
new file mode 100644
index 00000000000..fba0cf33b3c
--- /dev/null
+++ b/tests/ui/match_same_arms2.fixed
@@ -0,0 +1,241 @@
+#![warn(clippy::match_same_arms)]
+#![allow(
+    clippy::disallowed_names,
+    clippy::diverging_sub_expression,
+    clippy::uninlined_format_args,
+    clippy::match_single_binding,
+    clippy::match_like_matches_macro
+)]
+fn bar<T>(_: T) {}
+fn foo() -> bool {
+    unimplemented!()
+}
+
+fn match_same_arms() {
+    let _ = match 42 {
+        _ => {
+            foo();
+            let mut a = 42 + [23].len() as i32;
+            if true {
+                a += 7;
+            }
+            a = -31 - a;
+            a
+        },
+    };
+    //~^^^^^^^^^^^^^^^^^^^ ERROR: this match arm has an identical body to the `_` wildcard arm
+
+    let _ = match 42 {
+        51 | 42 => foo(), //~ ERROR: this match arm has an identical body to another arm
+        _ => true,
+    };
+
+    let _ = match Some(42) {
+        None | Some(_) => 24, //~ ERROR: this match arm has an identical body to another arm
+    };
+
+    let _ = match Some(42) {
+        Some(foo) => 24,
+        None => 24,
+    };
+
+    let _ = match Some(42) {
+        Some(42) => 24,
+        Some(a) => 24, // bindings are different
+        None => 0,
+    };
+
+    let _ = match Some(42) {
+        Some(a) if a > 0 => 24,
+        Some(a) => 24, // one arm has a guard
+        None => 0,
+    };
+
+    match (Some(42), Some(42)) {
+        (None, Some(a)) | (Some(a), None) => bar(a), //~ ERROR: this match arm has an identical body to another arm
+        _ => (),
+    }
+
+    // No warning because guards are different
+    let _ = match Some(42) {
+        Some(a) if a == 42 => a,
+        Some(a) if a == 24 => a,
+        Some(_) => 24,
+        None => 0,
+    };
+
+    let _ = match (Some(42), Some(42)) {
+        (None, Some(a)) | (Some(a), None) if a == 42 => a, //~ ERROR: this match arm has an identical body to another arm
+        _ => 0,
+    };
+
+    match (Some(42), Some(42)) {
+        (Some(a), ..) | (.., Some(a)) => bar(a), //~ ERROR: this match arm has an identical body to another arm
+        _ => (),
+    }
+
+    let _ = match Some(()) {
+        Some(()) => 0.0,
+        None => -0.0,
+    };
+
+    match (Some(42), Some("")) {
+        (Some(a), None) => bar(a),
+        (None, Some(a)) => bar(a), // bindings have different types
+        _ => (),
+    }
+
+    let x: Result<i32, &str> = Ok(3);
+
+    // No warning because of the guard.
+    match x {
+        Ok(x) if x * x == 64 => println!("ok"),
+        Ok(_) => println!("ok"),
+        Err(_) => println!("err"),
+    }
+
+    // This used to be a false positive; see issue #1996.
+    match x {
+        Ok(3) => println!("ok"),
+        Ok(x) if x * x == 64 => println!("ok 64"),
+        Ok(_) => println!("ok"),
+        Err(_) => println!("err"),
+    }
+
+    match (x, Some(1i32)) {
+        (Ok(x), Some(_)) | (Ok(_), Some(x)) => println!("ok {}", x), //~ ERROR: this match arm has an identical body to another arm
+        _ => println!("err"),
+    }
+
+    // No warning; different types for `x`.
+    match (x, Some(1.0f64)) {
+        (Ok(x), Some(_)) => println!("ok {}", x),
+        (Ok(_), Some(x)) => println!("ok {}", x),
+        _ => println!("err"),
+    }
+
+    // False negative #2251.
+    match x {
+        Ok(_tmp) => println!("ok"),
+        Ok(_) | Ok(3) => println!("ok"), //~ ERROR: this match arm has an identical body to another arm
+        Err(_) => {
+            unreachable!();
+        },
+    }
+
+    // False positive #1390
+    macro_rules! empty {
+        ($e:expr) => {};
+    }
+    match 0 {
+        0 => {
+            empty!(0);
+        },
+        1 => {
+            empty!(1);
+        },
+        x => {
+            empty!(x);
+        },
+    };
+
+    // still lint if the tokens are the same
+    match 0 {
+        1 | 0 => {
+            empty!(0);
+        },
+        x => {
+            empty!(x);
+        },
+    }
+    //~^^^^^^^ ERROR: this match arm has an identical body to another arm
+
+    match_expr_like_matches_macro_priority();
+}
+
+fn match_expr_like_matches_macro_priority() {
+    enum E {
+        A,
+        B,
+        C,
+    }
+    let x = E::A;
+    let _ans = match x {
+        E::A => false,
+        E::B => false,
+        _ => true,
+    };
+}
+
+fn main() {
+    let _ = match Some(0) {
+        Some(0) => 0,
+        Some(1) => 1,
+        #[cfg(feature = "foo")]
+        Some(2) => 2,
+        _ => 1,
+    };
+
+    enum Foo {
+        X(u32),
+        Y(u32),
+        Z(u32),
+    }
+
+    // Don't lint. `Foo::X(0)` and `Foo::Z(_)` overlap with the arm in between.
+    let _ = match Foo::X(0) {
+        Foo::X(0) => 1,
+        Foo::X(_) | Foo::Y(_) | Foo::Z(0) => 2,
+        Foo::Z(_) => 1,
+        _ => 0,
+    };
+
+    // Suggest moving `Foo::Z(_)` up.
+    let _ = match Foo::X(0) {
+        Foo::X(0) | Foo::Z(_) => 1, //~ ERROR: this match arm has an identical body to another arm
+        Foo::X(_) | Foo::Y(_) => 2,
+        _ => 0,
+    };
+
+    // Suggest moving `Foo::X(0)` down.
+    let _ = match Foo::X(0) {
+        Foo::Y(_) | Foo::Z(0) => 2,
+        Foo::Z(_) | Foo::X(0) => 1, //~ ERROR: this match arm has an identical body to another arm
+        _ => 0,
+    };
+
+    // Don't lint.
+    let _ = match 0 {
+        -2 => 1,
+        -5..=50 => 2,
+        -150..=88 => 1,
+        _ => 3,
+    };
+
+    struct Bar {
+        x: u32,
+        y: u32,
+        z: u32,
+    }
+
+    // Lint.
+    let _ = match None {
+        Some(Bar { y: 10, z: 0, .. }) => 2,
+        None => 50,
+        Some(Bar { y: 0, x: 5, .. }) | Some(Bar { x: 0, y: 5, .. }) => 1, //~ ERROR: this match arm has an identical body to another arm
+        _ => 200,
+    };
+
+    let _ = match 0 {
+        0 => todo!(),
+        1 => todo!(),
+        2 => core::convert::identity::<u32>(todo!()),
+        3 => core::convert::identity::<u32>(todo!()),
+        _ => 5,
+    };
+
+    let _ = match 0 {
+        1 | 0 => cfg!(not_enable),
+        _ => false,
+    };
+}
diff --git a/tests/ui/match_same_arms2.rs b/tests/ui/match_same_arms2.rs
index 85ad0962eb4..8a4e3b325bb 100644
--- a/tests/ui/match_same_arms2.rs
+++ b/tests/ui/match_same_arms2.rs
@@ -2,9 +2,10 @@
 #![allow(
     clippy::disallowed_names,
     clippy::diverging_sub_expression,
-    clippy::uninlined_format_args
+    clippy::uninlined_format_args,
+    clippy::match_single_binding,
+    clippy::match_like_matches_macro
 )]
-//@no-rustfix
 fn bar<T>(_: T) {}
 fn foo() -> bool {
     unimplemented!()
diff --git a/tests/ui/match_same_arms2.stderr b/tests/ui/match_same_arms2.stderr
index f4c38c1af89..3d15176ccf9 100644
--- a/tests/ui/match_same_arms2.stderr
+++ b/tests/ui/match_same_arms2.stderr
@@ -1,18 +1,18 @@
 error: this match arm has an identical body to the `_` wildcard arm
-  --> tests/ui/match_same_arms2.rs:15:9
+  --> tests/ui/match_same_arms2.rs:16:9
    |
 LL | /         42 => {
 LL | |             foo();
 LL | |             let mut a = 42 + [23].len() as i32;
 LL | |             if true {
 ...  |
-LL | |             a
 LL | |         },
-   | |_________^ help: try removing the arm
+LL | |         _ => {
+   | |________^ help: try removing the arm
    |
    = help: or try changing either arm body
 note: `_` wildcard arm here
-  --> tests/ui/match_same_arms2.rs:24:9
+  --> tests/ui/match_same_arms2.rs:25:9
    |
 LL | /         _ => {
 LL | |             foo();
@@ -26,203 +26,200 @@ LL | |         },
    = help: to override `-D warnings` add `#[allow(clippy::match_same_arms)]`
 
 error: this match arm has an identical body to another arm
-  --> tests/ui/match_same_arms2.rs:38:9
+  --> tests/ui/match_same_arms2.rs:39:9
    |
 LL |         51 => foo(),
-   |         --^^^^^^^^^
-   |         |
-   |         help: try merging the arm patterns: `51 | 42`
+   |         ^^^^^^^^^^^
    |
-   = help: or try changing either arm body
-note: other arm here
-  --> tests/ui/match_same_arms2.rs:37:9
+   = help: try changing either arm body
+help: or try merging the arm patterns
+   |
+LL |         51 | 42 => foo(),
+   |         ~~~~~~~
+help: and remove this obsolete arm
+   |
+LL -         42 => foo(),
    |
-LL |         42 => foo(),
-   |         ^^^^^^^^^^^
 
 error: this match arm has an identical body to another arm
-  --> tests/ui/match_same_arms2.rs:44:9
+  --> tests/ui/match_same_arms2.rs:45:9
    |
 LL |         None => 24,
-   |         ----^^^^^^
-   |         |
-   |         help: try merging the arm patterns: `None | Some(_)`
+   |         ^^^^^^^^^^
    |
-   = help: or try changing either arm body
-note: other arm here
-  --> tests/ui/match_same_arms2.rs:43:9
+   = help: try changing either arm body
+help: or try merging the arm patterns
+   |
+LL |         None | Some(_) => 24,
+   |         ~~~~~~~~~~~~~~
+help: and remove this obsolete arm
+   |
+LL -         Some(_) => 24,
    |
-LL |         Some(_) => 24,
-   |         ^^^^^^^^^^^^^
 
 error: this match arm has an identical body to another arm
-  --> tests/ui/match_same_arms2.rs:66:9
+  --> tests/ui/match_same_arms2.rs:67:9
    |
 LL |         (None, Some(a)) => bar(a),
-   |         ---------------^^^^^^^^^^
-   |         |
-   |         help: try merging the arm patterns: `(None, Some(a)) | (Some(a), None)`
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^
    |
-   = help: or try changing either arm body
-note: other arm here
-  --> tests/ui/match_same_arms2.rs:65:9
+   = help: try changing either arm body
+help: or try merging the arm patterns
+   |
+LL |         (None, Some(a)) | (Some(a), None) => bar(a),
+   |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+help: and remove this obsolete arm
+   |
+LL -         (Some(a), None) => bar(a),
    |
-LL |         (Some(a), None) => bar(a),
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: this match arm has an identical body to another arm
-  --> tests/ui/match_same_arms2.rs:80:9
+  --> tests/ui/match_same_arms2.rs:81:9
    |
 LL |         (None, Some(a)) if a == 42 => a,
-   |         ---------------^^^^^^^^^^^^^^^^
-   |         |
-   |         help: try merging the arm patterns: `(None, Some(a)) | (Some(a), None)`
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
-   = help: or try changing either arm body
-note: other arm here
-  --> tests/ui/match_same_arms2.rs:79:9
+   = help: try changing either arm body
+help: or try merging the arm patterns
+   |
+LL |         (None, Some(a)) | (Some(a), None) if a == 42 => a,
+   |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+help: and remove this obsolete arm
+   |
+LL -         (Some(a), None) if a == 42 => a,
    |
-LL |         (Some(a), None) if a == 42 => a,
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: this match arm has an identical body to another arm
-  --> tests/ui/match_same_arms2.rs:85:9
+  --> tests/ui/match_same_arms2.rs:86:9
    |
 LL |         (Some(a), ..) => bar(a),
-   |         -------------^^^^^^^^^^
-   |         |
-   |         help: try merging the arm patterns: `(Some(a), ..) | (.., Some(a))`
+   |         ^^^^^^^^^^^^^^^^^^^^^^^
    |
-   = help: or try changing either arm body
-note: other arm here
-  --> tests/ui/match_same_arms2.rs:86:9
+   = help: try changing either arm body
+help: or try merging the arm patterns
+   |
+LL |         (Some(a), ..) | (.., Some(a)) => bar(a),
+   |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+help: and remove this obsolete arm
+   |
+LL -         (.., Some(a)) => bar(a),
    |
-LL |         (.., Some(a)) => bar(a),
-   |         ^^^^^^^^^^^^^^^^^^^^^^^
 
 error: this match arm has an identical body to another arm
-  --> tests/ui/match_same_arms2.rs:119:9
+  --> tests/ui/match_same_arms2.rs:120:9
    |
 LL |         (Ok(x), Some(_)) => println!("ok {}", x),
-   |         ----------------^^^^^^^^^^^^^^^^^^^^^^^^
-   |         |
-   |         help: try merging the arm patterns: `(Ok(x), Some(_)) | (Ok(_), Some(x))`
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
-   = help: or try changing either arm body
-note: other arm here
-  --> tests/ui/match_same_arms2.rs:120:9
+   = help: try changing either arm body
+help: or try merging the arm patterns
+   |
+LL |         (Ok(x), Some(_)) | (Ok(_), Some(x)) => println!("ok {}", x),
+   |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+help: and remove this obsolete arm
+   |
+LL -         (Ok(_), Some(x)) => println!("ok {}", x),
    |
-LL |         (Ok(_), Some(x)) => println!("ok {}", x),
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: this match arm has an identical body to another arm
-  --> tests/ui/match_same_arms2.rs:135:9
+  --> tests/ui/match_same_arms2.rs:136:9
    |
 LL |         Ok(_) => println!("ok"),
-   |         -----^^^^^^^^^^^^^^^^^^
-   |         |
-   |         help: try merging the arm patterns: `Ok(_) | Ok(3)`
+   |         ^^^^^^^^^^^^^^^^^^^^^^^
    |
-   = help: or try changing either arm body
-note: other arm here
-  --> tests/ui/match_same_arms2.rs:134:9
+   = help: try changing either arm body
+help: or try merging the arm patterns
+   |
+LL |         Ok(_) | Ok(3) => println!("ok"),
+   |         ~~~~~~~~~~~~~
+help: and remove this obsolete arm
+   |
+LL -         Ok(3) => println!("ok"),
    |
-LL |         Ok(3) => println!("ok"),
-   |         ^^^^^^^^^^^^^^^^^^^^^^^
 
 error: this match arm has an identical body to another arm
-  --> tests/ui/match_same_arms2.rs:162:9
+  --> tests/ui/match_same_arms2.rs:163:9
    |
-LL |           1 => {
-   |           ^ help: try merging the arm patterns: `1 | 0`
-   |  _________|
-   | |
+LL | /         1 => {
 LL | |             empty!(0);
 LL | |         },
    | |_________^
    |
-   = help: or try changing either arm body
-note: other arm here
-  --> tests/ui/match_same_arms2.rs:159:9
+   = help: try changing either arm body
+help: or try merging the arm patterns
+   |
+LL |         1 | 0 => {
+   |         ~~~~~
+help: and remove this obsolete arm
+   |
+LL -         0 => {
+LL -             empty!(0);
+LL -         },
    |
-LL | /         0 => {
-LL | |             empty!(0);
-LL | |         },
-   | |_________^
-
-error: match expression looks like `matches!` macro
-  --> tests/ui/match_same_arms2.rs:181:16
-   |
-LL |       let _ans = match x {
-   |  ________________^
-LL | |         E::A => false,
-LL | |         E::B => false,
-LL | |         _ => true,
-LL | |     };
-   | |_____^ help: try: `!matches!(x, E::A | E::B)`
-   |
-   = note: `-D clippy::match-like-matches-macro` implied by `-D warnings`
-   = help: to override `-D warnings` add `#[allow(clippy::match_like_matches_macro)]`
 
 error: this match arm has an identical body to another arm
-  --> tests/ui/match_same_arms2.rs:213:9
+  --> tests/ui/match_same_arms2.rs:214:9
    |
 LL |         Foo::X(0) => 1,
-   |         ---------^^^^^
-   |         |
-   |         help: try merging the arm patterns: `Foo::X(0) | Foo::Z(_)`
+   |         ^^^^^^^^^^^^^^
    |
-   = help: or try changing either arm body
-note: other arm here
-  --> tests/ui/match_same_arms2.rs:215:9
+   = help: try changing either arm body
+help: or try merging the arm patterns
+   |
+LL |         Foo::X(0) | Foo::Z(_) => 1,
+   |         ~~~~~~~~~~~~~~~~~~~~~
+help: and remove this obsolete arm
+   |
+LL -         Foo::Z(_) => 1,
    |
-LL |         Foo::Z(_) => 1,
-   |         ^^^^^^^^^^^^^^
 
 error: this match arm has an identical body to another arm
-  --> tests/ui/match_same_arms2.rs:223:9
+  --> tests/ui/match_same_arms2.rs:224:9
    |
 LL |         Foo::Z(_) => 1,
-   |         ---------^^^^^
-   |         |
-   |         help: try merging the arm patterns: `Foo::Z(_) | Foo::X(0)`
+   |         ^^^^^^^^^^^^^^
    |
-   = help: or try changing either arm body
-note: other arm here
-  --> tests/ui/match_same_arms2.rs:221:9
+   = help: try changing either arm body
+help: or try merging the arm patterns
+   |
+LL |         Foo::Z(_) | Foo::X(0) => 1,
+   |         ~~~~~~~~~~~~~~~~~~~~~
+help: and remove this obsolete arm
+   |
+LL -         Foo::X(0) => 1,
    |
-LL |         Foo::X(0) => 1,
-   |         ^^^^^^^^^^^^^^
 
 error: this match arm has an identical body to another arm
-  --> tests/ui/match_same_arms2.rs:246:9
+  --> tests/ui/match_same_arms2.rs:247:9
    |
 LL |         Some(Bar { y: 0, x: 5, .. }) => 1,
-   |         ----------------------------^^^^^
-   |         |
-   |         help: try merging the arm patterns: `Some(Bar { y: 0, x: 5, .. }) | Some(Bar { x: 0, y: 5, .. })`
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
-   = help: or try changing either arm body
-note: other arm here
-  --> tests/ui/match_same_arms2.rs:243:9
+   = help: try changing either arm body
+help: or try merging the arm patterns
+   |
+LL |         Some(Bar { y: 0, x: 5, .. }) | Some(Bar { x: 0, y: 5, .. }) => 1,
+   |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+help: and remove this obsolete arm
+   |
+LL -         Some(Bar { x: 0, y: 5, .. }) => 1,
    |
-LL |         Some(Bar { x: 0, y: 5, .. }) => 1,
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: this match arm has an identical body to another arm
-  --> tests/ui/match_same_arms2.rs:260:9
+  --> tests/ui/match_same_arms2.rs:261:9
    |
 LL |         1 => cfg!(not_enable),
-   |         -^^^^^^^^^^^^^^^^^^^^
-   |         |
-   |         help: try merging the arm patterns: `1 | 0`
+   |         ^^^^^^^^^^^^^^^^^^^^^
    |
-   = help: or try changing either arm body
-note: other arm here
-  --> tests/ui/match_same_arms2.rs:259:9
+   = help: try changing either arm body
+help: or try merging the arm patterns
+   |
+LL |         1 | 0 => cfg!(not_enable),
+   |         ~~~~~
+help: and remove this obsolete arm
+   |
+LL -         0 => cfg!(not_enable),
    |
-LL |         0 => cfg!(not_enable),
-   |         ^^^^^^^^^^^^^^^^^^^^^
 
-error: aborting due to 14 previous errors
+error: aborting due to 13 previous errors
 
diff --git a/tests/ui/match_same_arms_non_exhaustive.fixed b/tests/ui/match_same_arms_non_exhaustive.fixed
new file mode 100644
index 00000000000..804c0a869a9
--- /dev/null
+++ b/tests/ui/match_same_arms_non_exhaustive.fixed
@@ -0,0 +1,61 @@
+#![feature(non_exhaustive_omitted_patterns_lint)]
+#![warn(clippy::match_same_arms)]
+#![no_main]
+use std::sync::atomic::Ordering; // #[non_exhaustive] enum
+
+fn repeat() -> ! {
+    panic!()
+}
+
+pub fn f(x: Ordering) {
+    #[deny(non_exhaustive_omitted_patterns)]
+    match x {
+        Ordering::Relaxed => println!("relaxed"),
+        Ordering::Release => println!("release"),
+        Ordering::Acquire => println!("acquire"),
+        Ordering::AcqRel | Ordering::SeqCst => repeat(),
+        _ => repeat(),
+    }
+}
+
+mod f {
+    #![deny(non_exhaustive_omitted_patterns)]
+
+    use super::*;
+
+    pub fn f(x: Ordering) {
+        match x {
+            Ordering::Relaxed => println!("relaxed"),
+            Ordering::Release => println!("release"),
+            Ordering::Acquire => println!("acquire"),
+            Ordering::AcqRel | Ordering::SeqCst => repeat(),
+            _ => repeat(),
+        }
+    }
+}
+
+// Below should still lint
+
+pub fn g(x: Ordering) {
+    match x {
+        Ordering::Relaxed => println!("relaxed"),
+        Ordering::Release => println!("release"),
+        Ordering::Acquire => println!("acquire"),
+        //~^ ERROR: this match arm has an identical body to the `_` wildcard arm
+        _ => repeat(),
+    }
+}
+
+mod g {
+    use super::*;
+
+    pub fn g(x: Ordering) {
+        match x {
+            Ordering::Relaxed => println!("relaxed"),
+            Ordering::Release => println!("release"),
+            Ordering::Acquire => println!("acquire"),
+            //~^ ERROR: this match arm has an identical body to the `_` wildcard arm
+            _ => repeat(),
+        }
+    }
+}
diff --git a/tests/ui/match_same_arms_non_exhaustive.rs b/tests/ui/match_same_arms_non_exhaustive.rs
index 5c277f925a8..e50663932a1 100644
--- a/tests/ui/match_same_arms_non_exhaustive.rs
+++ b/tests/ui/match_same_arms_non_exhaustive.rs
@@ -1,7 +1,6 @@
 #![feature(non_exhaustive_omitted_patterns_lint)]
 #![warn(clippy::match_same_arms)]
 #![no_main]
-//@no-rustfix
 use std::sync::atomic::Ordering; // #[non_exhaustive] enum
 
 fn repeat() -> ! {
diff --git a/tests/ui/match_same_arms_non_exhaustive.stderr b/tests/ui/match_same_arms_non_exhaustive.stderr
index cf2a75354e1..aa7f8c95dce 100644
--- a/tests/ui/match_same_arms_non_exhaustive.stderr
+++ b/tests/ui/match_same_arms_non_exhaustive.stderr
@@ -1,12 +1,13 @@
 error: this match arm has an identical body to the `_` wildcard arm
-  --> tests/ui/match_same_arms_non_exhaustive.rs:45:9
+  --> tests/ui/match_same_arms_non_exhaustive.rs:44:9
    |
-LL |         Ordering::AcqRel | Ordering::SeqCst => repeat(),
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try removing the arm
+LL | /         Ordering::AcqRel | Ordering::SeqCst => repeat(),
+LL | |
+   | |________^ help: try removing the arm
    |
    = help: or try changing either arm body
 note: `_` wildcard arm here
-  --> tests/ui/match_same_arms_non_exhaustive.rs:47:9
+  --> tests/ui/match_same_arms_non_exhaustive.rs:46:9
    |
 LL |         _ => repeat(),
    |         ^^^^^^^^^^^^^
@@ -14,14 +15,15 @@ LL |         _ => repeat(),
    = help: to override `-D warnings` add `#[allow(clippy::match_same_arms)]`
 
 error: this match arm has an identical body to the `_` wildcard arm
-  --> tests/ui/match_same_arms_non_exhaustive.rs:59:13
+  --> tests/ui/match_same_arms_non_exhaustive.rs:58:13
    |
-LL |             Ordering::AcqRel | Ordering::SeqCst => repeat(),
-   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try removing the arm
+LL | /             Ordering::AcqRel | Ordering::SeqCst => repeat(),
+LL | |
+   | |____________^ help: try removing the arm
    |
    = help: or try changing either arm body
 note: `_` wildcard arm here
-  --> tests/ui/match_same_arms_non_exhaustive.rs:61:13
+  --> tests/ui/match_same_arms_non_exhaustive.rs:60:13
    |
 LL |             _ => repeat(),
    |             ^^^^^^^^^^^^^