From 7e57947c67826a7a31272976a5e71949358c6237 Mon Sep 17 00:00:00 2001
From: promptkp <prompt3838@gmail.com>
Date: Thu, 22 Aug 2024 16:28:08 +0700
Subject: [PATCH 1/9] add new lint: stacked_if_match

---
 CHANGELOG.md                         |  1 +
 clippy_lints/src/declared_lints.rs   |  1 +
 clippy_lints/src/lib.rs              |  2 ++
 clippy_lints/src/stacked_if_match.rs | 51 ++++++++++++++++++++++++++++
 tests/ui/stacked_if_match.rs         |  5 +++
 5 files changed, 60 insertions(+)
 create mode 100644 clippy_lints/src/stacked_if_match.rs
 create mode 100644 tests/ui/stacked_if_match.rs

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 0e5d1688e4a7..a00a69851f7d 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5931,6 +5931,7 @@ Released 2018-09-13
 [`skip_while_next`]: https://rust-lang.github.io/rust-clippy/master/index.html#skip_while_next
 [`slow_vector_initialization`]: https://rust-lang.github.io/rust-clippy/master/index.html#slow_vector_initialization
 [`stable_sort_primitive`]: https://rust-lang.github.io/rust-clippy/master/index.html#stable_sort_primitive
+[`stacked_if_match`]: https://rust-lang.github.io/rust-clippy/master/index.html#stacked_if_match
 [`std_instead_of_alloc`]: https://rust-lang.github.io/rust-clippy/master/index.html#std_instead_of_alloc
 [`std_instead_of_core`]: https://rust-lang.github.io/rust-clippy/master/index.html#std_instead_of_core
 [`str_split_at_newline`]: https://rust-lang.github.io/rust-clippy/master/index.html#str_split_at_newline
diff --git a/clippy_lints/src/declared_lints.rs b/clippy_lints/src/declared_lints.rs
index 16c64830e70d..11fbe4224eb2 100644
--- a/clippy_lints/src/declared_lints.rs
+++ b/clippy_lints/src/declared_lints.rs
@@ -662,6 +662,7 @@ pub static LINTS: &[&crate::LintInfo] = &[
     crate::size_of_in_element_count::SIZE_OF_IN_ELEMENT_COUNT_INFO,
     crate::size_of_ref::SIZE_OF_REF_INFO,
     crate::slow_vector_initialization::SLOW_VECTOR_INITIALIZATION_INFO,
+    crate::stacked_if_match::STACKED_IF_MATCH_INFO,
     crate::std_instead_of_core::ALLOC_INSTEAD_OF_CORE_INFO,
     crate::std_instead_of_core::STD_INSTEAD_OF_ALLOC_INFO,
     crate::std_instead_of_core::STD_INSTEAD_OF_CORE_INFO,
diff --git a/clippy_lints/src/lib.rs b/clippy_lints/src/lib.rs
index 3604090b68cc..d1acd339cbfc 100644
--- a/clippy_lints/src/lib.rs
+++ b/clippy_lints/src/lib.rs
@@ -335,6 +335,7 @@ mod single_range_in_vec_init;
 mod size_of_in_element_count;
 mod size_of_ref;
 mod slow_vector_initialization;
+mod stacked_if_match;
 mod std_instead_of_core;
 mod string_patterns;
 mod strings;
@@ -942,5 +943,6 @@ pub fn register_lints(store: &mut rustc_lint::LintStore, conf: &'static Conf) {
     store.register_late_pass(move |_| Box::new(manual_div_ceil::ManualDivCeil::new(conf)));
     store.register_late_pass(|_| Box::new(manual_is_power_of_two::ManualIsPowerOfTwo));
     store.register_late_pass(|_| Box::new(non_zero_suggestions::NonZeroSuggestions));
+    store.register_late_pass(|_| Box::new(stacked_if_match::StackedIfMatch));
     // add lints here, do not remove this comment, it's used in `new_lint`
 }
diff --git a/clippy_lints/src/stacked_if_match.rs b/clippy_lints/src/stacked_if_match.rs
new file mode 100644
index 000000000000..9204f7f02249
--- /dev/null
+++ b/clippy_lints/src/stacked_if_match.rs
@@ -0,0 +1,51 @@
+use rustc_hir::*;
+use rustc_lint::{LateContext, LateLintPass};
+use rustc_session::declare_lint_pass;
+
+declare_clippy_lint! {
+    /// ### What it does
+    /// Checks for stacked `if` and `match`, e.g., `if if`.
+    ///
+    /// ### Why is this bad?
+    /// Stacked `if`'s and `match`'s are hard to read.
+    ///
+    /// ### Example
+    /// ```no_run
+    /// if if a == b {
+    ///     c == d
+    /// } else {
+    ///     e == f
+    /// } {
+    ///     println!("true");
+    /// } else {
+    ///     println!("false");
+    /// }
+    /// ```
+    ///
+    /// Use instead:
+    /// ```no_run
+    /// let cond = if a == b {
+    ///     c == d
+    /// } else {
+    ///     e == f
+    /// };
+    ///
+    /// if cond {
+    ///     println!("true");
+    /// } else {
+    ///     println!("false");
+    /// }
+    /// ```
+    #[clippy::version = "1.82.0"]
+    pub STACKED_IF_MATCH,
+    style,
+    "`if if` and `match match` that can be eliminated"
+}
+
+declare_lint_pass!(StackedIfMatch => [STACKED_IF_MATCH]);
+
+impl<'tcx> LateLintPass<'tcx> for StackedIfMatch {
+   fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
+
+    }
+}
diff --git a/tests/ui/stacked_if_match.rs b/tests/ui/stacked_if_match.rs
new file mode 100644
index 000000000000..62cc920f41b6
--- /dev/null
+++ b/tests/ui/stacked_if_match.rs
@@ -0,0 +1,5 @@
+#![warn(clippy::stacked_if_match)]
+
+fn main() {
+    // test code goes here
+}

From 6eaedc3147bda52193272797b9c38d8d7dc48156 Mon Sep 17 00:00:00 2001
From: promptkp <prompt3838@gmail.com>
Date: Sun, 25 Aug 2024 17:35:57 +0700
Subject: [PATCH 2/9] first finished stacked_if_match

---
 clippy_lints/src/stacked_if_match.rs |  62 +++++++++++--
 tests/ui/stacked_if_match.rs         | 131 ++++++++++++++++++++++++++-
 2 files changed, 182 insertions(+), 11 deletions(-)

diff --git a/clippy_lints/src/stacked_if_match.rs b/clippy_lints/src/stacked_if_match.rs
index 9204f7f02249..1dece0e51c74 100644
--- a/clippy_lints/src/stacked_if_match.rs
+++ b/clippy_lints/src/stacked_if_match.rs
@@ -1,13 +1,19 @@
+use clippy_utils::source::snippet;
+use rustc_middle::lint::in_external_macro;
 use rustc_hir::*;
-use rustc_lint::{LateContext, LateLintPass};
+use rustc_lint::{LateContext, LateLintPass, LintContext};
 use rustc_session::declare_lint_pass;
+use rustc_errors::Applicability;
+use clippy_utils::visitors::{for_each_expr, Descend};
+use clippy_utils::diagnostics::span_lint_and_sugg;
+use std::ops::ControlFlow;
 
 declare_clippy_lint! {
     /// ### What it does
-    /// Checks for stacked `if` and `match`, e.g., `if if`.
+    /// Checks for `if if` and `match match`.
     ///
     /// ### Why is this bad?
-    /// Stacked `if`'s and `match`'s are hard to read.
+    /// `if if` and `match match` are hard to read.
     ///
     /// ### Example
     /// ```no_run
@@ -17,23 +23,19 @@ declare_clippy_lint! {
     ///     e == f
     /// } {
     ///     println!("true");
-    /// } else {
-    ///     println!("false");
     /// }
     /// ```
     ///
     /// Use instead:
     /// ```no_run
-    /// let cond = if a == b {
+    /// let result = if a == b {
     ///     c == d
     /// } else {
     ///     e == f
     /// };
     ///
-    /// if cond {
+    /// if result {
     ///     println!("true");
-    /// } else {
-    ///     println!("false");
     /// }
     /// ```
     #[clippy::version = "1.82.0"]
@@ -46,6 +48,48 @@ declare_lint_pass!(StackedIfMatch => [STACKED_IF_MATCH]);
 
 impl<'tcx> LateLintPass<'tcx> for StackedIfMatch {
    fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
+        if expr.span.from_expansion() || in_external_macro(cx.sess(), expr.span) {
+            return;
+        }
+
+        let Some((cond, keyword)) = (match expr.kind {
+            ExprKind::If(if_expr, _, _) => Some((if_expr, "if")),
+            ExprKind::Match(match_expr, _, MatchSource::Normal) => Some((match_expr, "match")),
+            _ => None,
+        }) else {
+            return;
+        };
+
+        let cond_snippet = snippet(cx, cond.span, "");
+        if !cond_snippet.starts_with("if") && !cond_snippet.starts_with("match") {
+            return;
+        }
+
+        for_each_expr(cx, cond, |sub_expr| {
+            if matches!(sub_expr.kind, ExprKind::DropTemps(..)) {
+                return ControlFlow::Continue(Descend::Yes);
+            }
+
+            if !sub_expr.span.eq_ctxt(expr.span) || sub_expr.span.lo() != cond.span.lo() {
+                return ControlFlow::Continue(Descend::No);
+            }
 
+            if (keyword == "if" && matches!(sub_expr.kind, ExprKind::If(..)))
+                || (keyword == "match" && matches!(sub_expr.kind, ExprKind::Match(.., MatchSource::Normal))) {
+                let inner_snippet = snippet(cx, sub_expr.span, "..");
+                span_lint_and_sugg(
+                    cx,
+                    STACKED_IF_MATCH,
+                    expr.span.with_hi(sub_expr.span.hi()),
+                    format!("avoid using `{keyword} {keyword}`"),
+                    format!("try binding inner `{keyword}` with `let`"),
+                    format!("let result = {inner_snippet}; {keyword} result"),
+                    Applicability::MachineApplicable,
+                );
+                ControlFlow::Break(())
+            } else {
+                ControlFlow::Continue(Descend::Yes)
+            }
+        });
     }
 }
diff --git a/tests/ui/stacked_if_match.rs b/tests/ui/stacked_if_match.rs
index 62cc920f41b6..48a190629864 100644
--- a/tests/ui/stacked_if_match.rs
+++ b/tests/ui/stacked_if_match.rs
@@ -1,5 +1,132 @@
 #![warn(clippy::stacked_if_match)]
+#![allow(unused)]
 
-fn main() {
-    // test code goes here
+
+fn stacked_if() {
+    let x = 0;
+    if if x == 1 {
+        x == 2
+    } else {
+        x == 3
+    } {
+        println!("true");
+    }
+
+    if if x == 1 {
+        2
+    } else {
+        3
+    } == 4 {
+        println!("true");
+    }
+}
+
+fn stacked_match() {
+    let x = 0;
+    match match x {
+        1 => 2,
+        _ => 3,
+    } {
+        1 => {},
+        2 => {},
+        _ => {},
+    }
+
+    match match x {
+        1 => 2,
+        _ => 3,
+    } + 1 {
+        1 => {},
+        2 => {},
+        _ => {},
+    }
+}
+
+fn if_no_lint() {
+    let x = 0;
+
+    if (if x == 1 {
+        x == 2
+    } else {
+        x == 3
+    }) {
+        println!("true");
+    }
+
+    if 1 == if x == 1 {
+        1
+    } else {
+        2
+    } {
+        println!("true");
+    }
+}
+
+fn match_no_lint() {
+    let x = 0;
+    match (match x {
+        1 => 2,
+        _ => 3,
+    }) {
+        1 => {},
+        2 => {},
+        _ => {},
+    }
+
+    match 1 + match x {
+        1 => 2,
+        _ => 3,
+    } {
+        1 => {},
+        2 => {},
+        _ => {},
+    }
 }
+
+macro_rules! if_macro {
+    ($var:ident) => {
+        if $var == 1 {
+            true
+        } else {
+            false
+        }
+    };
+}
+
+macro_rules! match_macro {
+    ($var:ident) => {
+        match $var {
+            1 => 2,
+            _ => 3,
+        }
+    };
+}
+
+macro_rules! if_if_macro {
+    () => {
+        if if true {
+            true
+        } else {
+            false
+        } {
+            println!("true");
+        }
+    };
+}
+
+fn macro_no_lint() {
+    let x = 0;
+    if if_macro!(x) {
+        println!("true");
+    }
+
+    match match_macro!(x) {
+        1 => {},
+        2 => {},
+        _ => {},
+    }
+
+    if_if_macro!();
+}
+
+fn main() {}

From dc5c0482dba68e32c245dd55fab051584e2366c0 Mon Sep 17 00:00:00 2001
From: promptkp <prompt3838@gmail.com>
Date: Sun, 25 Aug 2024 18:32:55 +0700
Subject: [PATCH 3/9] stacked_if_match done

---
 clippy_lints/src/stacked_if_match.rs | 23 ++++++++------
 tests/ui/stacked_if_match.rs         | 46 ++++++++++------------------
 2 files changed, 30 insertions(+), 39 deletions(-)

diff --git a/clippy_lints/src/stacked_if_match.rs b/clippy_lints/src/stacked_if_match.rs
index 1dece0e51c74..ac6f4684dd68 100644
--- a/clippy_lints/src/stacked_if_match.rs
+++ b/clippy_lints/src/stacked_if_match.rs
@@ -1,11 +1,11 @@
+use clippy_utils::diagnostics::span_lint_and_sugg;
 use clippy_utils::source::snippet;
-use rustc_middle::lint::in_external_macro;
+use clippy_utils::visitors::{for_each_expr, Descend};
+use rustc_errors::Applicability;
 use rustc_hir::*;
 use rustc_lint::{LateContext, LateLintPass, LintContext};
+use rustc_middle::lint::in_external_macro;
 use rustc_session::declare_lint_pass;
-use rustc_errors::Applicability;
-use clippy_utils::visitors::{for_each_expr, Descend};
-use clippy_utils::diagnostics::span_lint_and_sugg;
 use std::ops::ControlFlow;
 
 declare_clippy_lint! {
@@ -47,7 +47,7 @@ declare_clippy_lint! {
 declare_lint_pass!(StackedIfMatch => [STACKED_IF_MATCH]);
 
 impl<'tcx> LateLintPass<'tcx> for StackedIfMatch {
-   fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
+    fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
         if expr.span.from_expansion() || in_external_macro(cx.sess(), expr.span) {
             return;
         }
@@ -74,15 +74,20 @@ impl<'tcx> LateLintPass<'tcx> for StackedIfMatch {
                 return ControlFlow::Continue(Descend::No);
             }
 
-            if (keyword == "if" && matches!(sub_expr.kind, ExprKind::If(..)))
-                || (keyword == "match" && matches!(sub_expr.kind, ExprKind::Match(.., MatchSource::Normal))) {
+            let sub_keyword = match sub_expr.kind {
+                ExprKind::If(..) => "if",
+                ExprKind::Match(.., MatchSource::Normal) => "match",
+                _ => "",
+            };
+
+            if keyword == sub_keyword {
                 let inner_snippet = snippet(cx, sub_expr.span, "..");
                 span_lint_and_sugg(
                     cx,
                     STACKED_IF_MATCH,
                     expr.span.with_hi(sub_expr.span.hi()),
-                    format!("avoid using `{keyword} {keyword}`"),
-                    format!("try binding inner `{keyword}` with `let`"),
+                    format!("avoid using `{keyword} {keyword}` by binding inner `{keyword}` with `let`"),
+                    format!("try"),
                     format!("let result = {inner_snippet}; {keyword} result"),
                     Applicability::MachineApplicable,
                 );
diff --git a/tests/ui/stacked_if_match.rs b/tests/ui/stacked_if_match.rs
index 48a190629864..23a023b674f5 100644
--- a/tests/ui/stacked_if_match.rs
+++ b/tests/ui/stacked_if_match.rs
@@ -1,22 +1,23 @@
 #![warn(clippy::stacked_if_match)]
 #![allow(unused)]
 
-
 fn stacked_if() {
     let x = 0;
-    if if x == 1 {
-        x == 2
-    } else {
-        x == 3
-    } {
+    if if x == 1 { x == 2 } else { x == 3 } {
+        println!("true");
+    }
+
+    if if x == 1 { 2 } else { 3 } == 4 {
         println!("true");
     }
 
     if if x == 1 {
-        2
+        let y = 2;
+        y == 2
     } else {
-        3
-    } == 4 {
+        let z = 3;
+        z == 3
+    } {
         println!("true");
     }
 }
@@ -35,7 +36,8 @@ fn stacked_match() {
     match match x {
         1 => 2,
         _ => 3,
-    } + 1 {
+    } + 1
+    {
         1 => {},
         2 => {},
         _ => {},
@@ -45,19 +47,11 @@ fn stacked_match() {
 fn if_no_lint() {
     let x = 0;
 
-    if (if x == 1 {
-        x == 2
-    } else {
-        x == 3
-    }) {
+    if (if x == 1 { x == 2 } else { x == 3 }) {
         println!("true");
     }
 
-    if 1 == if x == 1 {
-        1
-    } else {
-        2
-    } {
+    if 1 == if x == 1 { 1 } else { 2 } {
         println!("true");
     }
 }
@@ -85,11 +79,7 @@ fn match_no_lint() {
 
 macro_rules! if_macro {
     ($var:ident) => {
-        if $var == 1 {
-            true
-        } else {
-            false
-        }
+        if $var == 1 { true } else { false }
     };
 }
 
@@ -104,11 +94,7 @@ macro_rules! match_macro {
 
 macro_rules! if_if_macro {
     () => {
-        if if true {
-            true
-        } else {
-            false
-        } {
+        if if true { true } else { false } {
             println!("true");
         }
     };

From 5a30b984afd3bb07358e6756f7a8a1f889e0d472 Mon Sep 17 00:00:00 2001
From: promptkp <prompt3838@gmail.com>
Date: Sun, 25 Aug 2024 19:13:58 +0700
Subject: [PATCH 4/9] fix fmt in stacked_if_match

---
 clippy_lints/src/stacked_if_match.rs | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/clippy_lints/src/stacked_if_match.rs b/clippy_lints/src/stacked_if_match.rs
index ac6f4684dd68..99caad73e442 100644
--- a/clippy_lints/src/stacked_if_match.rs
+++ b/clippy_lints/src/stacked_if_match.rs
@@ -2,7 +2,7 @@ use clippy_utils::diagnostics::span_lint_and_sugg;
 use clippy_utils::source::snippet;
 use clippy_utils::visitors::{for_each_expr, Descend};
 use rustc_errors::Applicability;
-use rustc_hir::*;
+use rustc_hir::{Expr, ExprKind, MatchSource};
 use rustc_lint::{LateContext, LateLintPass, LintContext};
 use rustc_middle::lint::in_external_macro;
 use rustc_session::declare_lint_pass;
@@ -87,7 +87,7 @@ impl<'tcx> LateLintPass<'tcx> for StackedIfMatch {
                     STACKED_IF_MATCH,
                     expr.span.with_hi(sub_expr.span.hi()),
                     format!("avoid using `{keyword} {keyword}` by binding inner `{keyword}` with `let`"),
-                    format!("try"),
+                    "try",
                     format!("let result = {inner_snippet}; {keyword} result"),
                     Applicability::MachineApplicable,
                 );

From 9f97bb4fbc139a6e47320215a16ac6d45d345723 Mon Sep 17 00:00:00 2001
From: promptkp <prompt3838@gmail.com>
Date: Sun, 25 Aug 2024 19:28:56 +0700
Subject: [PATCH 5/9] allow stacked_if_match in other tests

---
 tests/ui/match_single_binding.fixed           |   3 +-
 tests/ui/match_single_binding.rs              |   3 +-
 tests/ui/match_single_binding.stderr          |  48 +++----
 tests/ui/match_single_binding2.fixed          |   1 +
 tests/ui/match_single_binding2.rs             |   1 +
 tests/ui/match_single_binding2.stderr         |   8 +-
 tests/ui/significant_drop_in_scrutinee.rs     |   7 +-
 tests/ui/significant_drop_in_scrutinee.stderr |  58 ++++-----
 tests/ui/stacked_if_match.fixed               | 118 ++++++++++++++++++
 tests/ui/stacked_if_match.stderr              |  74 +++++++++++
 10 files changed, 261 insertions(+), 60 deletions(-)
 create mode 100644 tests/ui/stacked_if_match.fixed
 create mode 100644 tests/ui/stacked_if_match.stderr

diff --git a/tests/ui/match_single_binding.fixed b/tests/ui/match_single_binding.fixed
index 3a3eee4c958b..a7050f22dca4 100644
--- a/tests/ui/match_single_binding.fixed
+++ b/tests/ui/match_single_binding.fixed
@@ -5,7 +5,8 @@
     clippy::no_effect,
     clippy::toplevel_ref_arg,
     clippy::uninlined_format_args,
-    clippy::useless_vec
+    clippy::useless_vec,
+    clippy::stacked_if_match
 )]
 
 struct Point {
diff --git a/tests/ui/match_single_binding.rs b/tests/ui/match_single_binding.rs
index ff2f842ac39e..317a4b5cfe4a 100644
--- a/tests/ui/match_single_binding.rs
+++ b/tests/ui/match_single_binding.rs
@@ -5,7 +5,8 @@
     clippy::no_effect,
     clippy::toplevel_ref_arg,
     clippy::uninlined_format_args,
-    clippy::useless_vec
+    clippy::useless_vec,
+    clippy::stacked_if_match
 )]
 
 struct Point {
diff --git a/tests/ui/match_single_binding.stderr b/tests/ui/match_single_binding.stderr
index 19ab85180ad2..b5c1f60d4288 100644
--- a/tests/ui/match_single_binding.stderr
+++ b/tests/ui/match_single_binding.stderr
@@ -1,5 +1,5 @@
 error: this match could be written as a `let` statement
-  --> tests/ui/match_single_binding.rs:33:5
+  --> tests/ui/match_single_binding.rs:34:5
    |
 LL | /     match (a, b, c) {
 LL | |         (x, y, z) => {
@@ -19,7 +19,7 @@ LL +     }
    |
 
 error: this match could be written as a `let` statement
-  --> tests/ui/match_single_binding.rs:39:5
+  --> tests/ui/match_single_binding.rs:40:5
    |
 LL | /     match (a, b, c) {
 LL | |         (x, y, z) => println!("{} {} {}", x, y, z),
@@ -33,7 +33,7 @@ LL +     println!("{} {} {}", x, y, z);
    |
 
 error: this match could be replaced by its body itself
-  --> tests/ui/match_single_binding.rs:56:5
+  --> tests/ui/match_single_binding.rs:57:5
    |
 LL | /     match a {
 LL | |         _ => println!("whatever"),
@@ -41,7 +41,7 @@ LL | |     }
    | |_____^ help: consider using the match body instead: `println!("whatever");`
 
 error: this match could be replaced by its body itself
-  --> tests/ui/match_single_binding.rs:60:5
+  --> tests/ui/match_single_binding.rs:61:5
    |
 LL | /     match a {
 LL | |         _ => {
@@ -60,7 +60,7 @@ LL +     }
    |
 
 error: this match could be replaced by its body itself
-  --> tests/ui/match_single_binding.rs:67:5
+  --> tests/ui/match_single_binding.rs:68:5
    |
 LL | /     match a {
 LL | |         _ => {
@@ -82,7 +82,7 @@ LL +     }
    |
 
 error: this match could be written as a `let` statement
-  --> tests/ui/match_single_binding.rs:77:5
+  --> tests/ui/match_single_binding.rs:78:5
    |
 LL | /     match p {
 LL | |         Point { x, y } => println!("Coords: ({}, {})", x, y),
@@ -96,7 +96,7 @@ LL +     println!("Coords: ({}, {})", x, y);
    |
 
 error: this match could be written as a `let` statement
-  --> tests/ui/match_single_binding.rs:81:5
+  --> tests/ui/match_single_binding.rs:82:5
    |
 LL | /     match p {
 LL | |         Point { x: x1, y: y1 } => println!("Coords: ({}, {})", x1, y1),
@@ -110,7 +110,7 @@ LL +     println!("Coords: ({}, {})", x1, y1);
    |
 
 error: this match could be written as a `let` statement
-  --> tests/ui/match_single_binding.rs:86:5
+  --> tests/ui/match_single_binding.rs:87:5
    |
 LL | /     match x {
 LL | |         ref r => println!("Got a reference to {}", r),
@@ -124,7 +124,7 @@ LL +     println!("Got a reference to {}", r);
    |
 
 error: this match could be written as a `let` statement
-  --> tests/ui/match_single_binding.rs:91:5
+  --> tests/ui/match_single_binding.rs:92:5
    |
 LL | /     match x {
 LL | |         ref mut mr => println!("Got a mutable reference to {}", mr),
@@ -138,7 +138,7 @@ LL +     println!("Got a mutable reference to {}", mr);
    |
 
 error: this match could be written as a `let` statement
-  --> tests/ui/match_single_binding.rs:95:5
+  --> tests/ui/match_single_binding.rs:96:5
    |
 LL | /     let product = match coords() {
 LL | |         Point { x, y } => x * y,
@@ -152,7 +152,7 @@ LL +     let product = x * y;
    |
 
 error: this match could be written as a `let` statement
-  --> tests/ui/match_single_binding.rs:103:18
+  --> tests/ui/match_single_binding.rs:104:18
    |
 LL |           .map(|i| match i.unwrap() {
    |  __________________^
@@ -169,7 +169,7 @@ LL ~         })
    |
 
 error: this match could be replaced by its body itself
-  --> tests/ui/match_single_binding.rs:129:5
+  --> tests/ui/match_single_binding.rs:130:5
    |
 LL | /     match x {
 LL | |         // =>
@@ -178,7 +178,7 @@ LL | |     }
    | |_____^ help: consider using the match body instead: `println!("Not an array index start")`
 
 error: this assignment could be simplified
-  --> tests/ui/match_single_binding.rs:138:5
+  --> tests/ui/match_single_binding.rs:139:5
    |
 LL | /     val = match val.split_at(idx) {
 LL | |         (pre, suf) => {
@@ -198,7 +198,7 @@ LL ~     };
    |
 
 error: this match could be replaced by its scrutinee and body
-  --> tests/ui/match_single_binding.rs:151:16
+  --> tests/ui/match_single_binding.rs:152:16
    |
 LL |       let _ = || match side_effects() {
    |  ________________^
@@ -215,7 +215,7 @@ LL ~     };
    |
 
 error: this match could be written as a `let` statement
-  --> tests/ui/match_single_binding.rs:157:5
+  --> tests/ui/match_single_binding.rs:158:5
    |
 LL | /     match r {
 LL | |         x => match x {
@@ -240,7 +240,7 @@ LL ~     };
    |
 
 error: this match could be replaced by its body itself
-  --> tests/ui/match_single_binding.rs:170:5
+  --> tests/ui/match_single_binding.rs:171:5
    |
 LL | /     match 1 {
 LL | |         _ => (),
@@ -248,7 +248,7 @@ LL | |     }
    | |_____^ help: consider using the match body instead: `();`
 
 error: this match could be replaced by its body itself
-  --> tests/ui/match_single_binding.rs:174:13
+  --> tests/ui/match_single_binding.rs:175:13
    |
 LL |       let a = match 1 {
    |  _____________^
@@ -257,7 +257,7 @@ LL | |     };
    | |_____^ help: consider using the match body instead: `()`
 
 error: this match could be replaced by its body itself
-  --> tests/ui/match_single_binding.rs:178:5
+  --> tests/ui/match_single_binding.rs:179:5
    |
 LL | /     match 1 {
 LL | |         _ => side_effects(),
@@ -265,7 +265,7 @@ LL | |     }
    | |_____^ help: consider using the match body instead: `side_effects();`
 
 error: this match could be replaced by its body itself
-  --> tests/ui/match_single_binding.rs:182:13
+  --> tests/ui/match_single_binding.rs:183:13
    |
 LL |       let b = match 1 {
    |  _____________^
@@ -274,7 +274,7 @@ LL | |     };
    | |_____^ help: consider using the match body instead: `side_effects()`
 
 error: this match could be replaced by its body itself
-  --> tests/ui/match_single_binding.rs:186:5
+  --> tests/ui/match_single_binding.rs:187:5
    |
 LL | /     match 1 {
 LL | |         _ => println!("1"),
@@ -282,7 +282,7 @@ LL | |     }
    | |_____^ help: consider using the match body instead: `println!("1");`
 
 error: this match could be replaced by its body itself
-  --> tests/ui/match_single_binding.rs:190:13
+  --> tests/ui/match_single_binding.rs:191:13
    |
 LL |       let c = match 1 {
    |  _____________^
@@ -291,7 +291,7 @@ LL | |     };
    | |_____^ help: consider using the match body instead: `println!("1")`
 
 error: this match could be replaced by its body itself
-  --> tests/ui/match_single_binding.rs:195:9
+  --> tests/ui/match_single_binding.rs:196:9
    |
 LL | /         match 1 {
 LL | |             _ => (),
@@ -299,7 +299,7 @@ LL | |         },
    | |_________^ help: consider using the match body instead: `()`
 
 error: this match could be replaced by its body itself
-  --> tests/ui/match_single_binding.rs:198:9
+  --> tests/ui/match_single_binding.rs:199:9
    |
 LL | /         match 1 {
 LL | |             _ => side_effects(),
@@ -307,7 +307,7 @@ LL | |         },
    | |_________^ help: consider using the match body instead: `side_effects()`
 
 error: this match could be replaced by its body itself
-  --> tests/ui/match_single_binding.rs:201:9
+  --> tests/ui/match_single_binding.rs:202:9
    |
 LL | /         match 1 {
 LL | |             _ => println!("1"),
diff --git a/tests/ui/match_single_binding2.fixed b/tests/ui/match_single_binding2.fixed
index 5673aa78c76a..2b1f943a51e7 100644
--- a/tests/ui/match_single_binding2.fixed
+++ b/tests/ui/match_single_binding2.fixed
@@ -1,6 +1,7 @@
 #![warn(clippy::match_single_binding)]
 #![allow(unused_variables)]
 #![allow(clippy::uninlined_format_args)]
+#![allow(clippy::stacked_if_match)]
 
 fn main() {
     // Lint (additional curly braces needed, see #6572)
diff --git a/tests/ui/match_single_binding2.rs b/tests/ui/match_single_binding2.rs
index 575e7f5816b8..c533d5625636 100644
--- a/tests/ui/match_single_binding2.rs
+++ b/tests/ui/match_single_binding2.rs
@@ -1,6 +1,7 @@
 #![warn(clippy::match_single_binding)]
 #![allow(unused_variables)]
 #![allow(clippy::uninlined_format_args)]
+#![allow(clippy::stacked_if_match)]
 
 fn main() {
     // Lint (additional curly braces needed, see #6572)
diff --git a/tests/ui/match_single_binding2.stderr b/tests/ui/match_single_binding2.stderr
index 38659596af1f..73aa0cf86c5b 100644
--- a/tests/ui/match_single_binding2.stderr
+++ b/tests/ui/match_single_binding2.stderr
@@ -1,5 +1,5 @@
 error: this match could be written as a `let` statement
-  --> tests/ui/match_single_binding2.rs:17:36
+  --> tests/ui/match_single_binding2.rs:18:36
    |
 LL |               Some((iter, _item)) => match iter.size_hint() {
    |  ____________________________________^
@@ -18,7 +18,7 @@ LL ~             },
    |
 
 error: this match could be written as a `let` statement
-  --> tests/ui/match_single_binding2.rs:30:13
+  --> tests/ui/match_single_binding2.rs:31:13
    |
 LL | /             match get_tup() {
 LL | |                 (a, b) => println!("a {:?} and b {:?}", a, b),
@@ -32,7 +32,7 @@ LL +             println!("a {:?} and b {:?}", a, b)
    |
 
 error: this match could be replaced by its scrutinee and body
-  --> tests/ui/match_single_binding2.rs:41:5
+  --> tests/ui/match_single_binding2.rs:42:5
    |
 LL | /     match side_effects() {
 LL | |         _ => println!("Side effects"),
@@ -46,7 +46,7 @@ LL +     println!("Side effects");
    |
 
 error: this match could be replaced by its scrutinee and body
-  --> tests/ui/match_single_binding2.rs:48:5
+  --> tests/ui/match_single_binding2.rs:49:5
    |
 LL | /     match match x {
 LL | |         0 => 1,
diff --git a/tests/ui/significant_drop_in_scrutinee.rs b/tests/ui/significant_drop_in_scrutinee.rs
index 0db6fbfb7be9..2de8e1bd0399 100644
--- a/tests/ui/significant_drop_in_scrutinee.rs
+++ b/tests/ui/significant_drop_in_scrutinee.rs
@@ -2,7 +2,12 @@
 //@no-rustfix
 #![warn(clippy::significant_drop_in_scrutinee)]
 #![allow(dead_code, unused_assignments)]
-#![allow(clippy::match_single_binding, clippy::single_match, clippy::uninlined_format_args)]
+#![allow(
+    clippy::match_single_binding,
+    clippy::single_match,
+    clippy::uninlined_format_args,
+    clippy::stacked_if_match
+)]
 
 use std::num::ParseIntError;
 use std::ops::Deref;
diff --git a/tests/ui/significant_drop_in_scrutinee.stderr b/tests/ui/significant_drop_in_scrutinee.stderr
index c0c93cd10c02..62030cbe70e7 100644
--- a/tests/ui/significant_drop_in_scrutinee.stderr
+++ b/tests/ui/significant_drop_in_scrutinee.stderr
@@ -1,5 +1,5 @@
 error: temporary with significant `Drop` in `match` scrutinee will live until the end of the `match` expression
-  --> tests/ui/significant_drop_in_scrutinee.rs:55:11
+  --> tests/ui/significant_drop_in_scrutinee.rs:60:11
    |
 LL |     match mutex.lock().unwrap().foo() {
    |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -20,7 +20,7 @@ LL ~     match value {
    |
 
 error: temporary with significant `Drop` in `match` scrutinee will live until the end of the `match` expression
-  --> tests/ui/significant_drop_in_scrutinee.rs:143:11
+  --> tests/ui/significant_drop_in_scrutinee.rs:148:11
    |
 LL |     match s.lock_m().get_the_value() {
    |           ^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -42,7 +42,7 @@ LL ~     match value {
    |
 
 error: temporary with significant `Drop` in `match` scrutinee will live until the end of the `match` expression
-  --> tests/ui/significant_drop_in_scrutinee.rs:166:11
+  --> tests/ui/significant_drop_in_scrutinee.rs:171:11
    |
 LL |     match s.lock_m_m().get_the_value() {
    |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -64,7 +64,7 @@ LL ~     match value {
    |
 
 error: temporary with significant `Drop` in `match` scrutinee will live until the end of the `match` expression
-  --> tests/ui/significant_drop_in_scrutinee.rs:216:11
+  --> tests/ui/significant_drop_in_scrutinee.rs:221:11
    |
 LL |     match counter.temp_increment().len() {
    |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -80,7 +80,7 @@ LL ~     match value {
    |
 
 error: temporary with significant `Drop` in `match` scrutinee will live until the end of the `match` expression
-  --> tests/ui/significant_drop_in_scrutinee.rs:241:16
+  --> tests/ui/significant_drop_in_scrutinee.rs:246:16
    |
 LL |         match (mutex1.lock().unwrap().s.len(), true) {
    |                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -99,7 +99,7 @@ LL ~         match (value, true) {
    |
 
 error: temporary with significant `Drop` in `match` scrutinee will live until the end of the `match` expression
-  --> tests/ui/significant_drop_in_scrutinee.rs:252:22
+  --> tests/ui/significant_drop_in_scrutinee.rs:257:22
    |
 LL |         match (true, mutex1.lock().unwrap().s.len(), true) {
    |                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -118,7 +118,7 @@ LL ~         match (true, value, true) {
    |
 
 error: temporary with significant `Drop` in `match` scrutinee will live until the end of the `match` expression
-  --> tests/ui/significant_drop_in_scrutinee.rs:264:16
+  --> tests/ui/significant_drop_in_scrutinee.rs:269:16
    |
 LL |         match (mutex1.lock().unwrap().s.len(), true, mutex2.lock().unwrap().s.len()) {
    |                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -139,7 +139,7 @@ LL ~         match (value, true, mutex2.lock().unwrap().s.len()) {
    |
 
 error: temporary with significant `Drop` in `match` scrutinee will live until the end of the `match` expression
-  --> tests/ui/significant_drop_in_scrutinee.rs:264:54
+  --> tests/ui/significant_drop_in_scrutinee.rs:269:54
    |
 LL |         match (mutex1.lock().unwrap().s.len(), true, mutex2.lock().unwrap().s.len()) {
    |                                                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -160,7 +160,7 @@ LL ~         match (mutex1.lock().unwrap().s.len(), true, value) {
    |
 
 error: temporary with significant `Drop` in `match` scrutinee will live until the end of the `match` expression
-  --> tests/ui/significant_drop_in_scrutinee.rs:319:11
+  --> tests/ui/significant_drop_in_scrutinee.rs:324:11
    |
 LL |     match mutex.lock().unwrap().s.len() > 1 {
    |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -179,7 +179,7 @@ LL ~     match value > 1 {
    |
 
 error: temporary with significant `Drop` in `match` scrutinee will live until the end of the `match` expression
-  --> tests/ui/significant_drop_in_scrutinee.rs:328:15
+  --> tests/ui/significant_drop_in_scrutinee.rs:333:15
    |
 LL |     match 1 < mutex.lock().unwrap().s.len() {
    |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -198,7 +198,7 @@ LL ~     match 1 < value {
    |
 
 error: temporary with significant `Drop` in `match` scrutinee will live until the end of the `match` expression
-  --> tests/ui/significant_drop_in_scrutinee.rs:348:11
+  --> tests/ui/significant_drop_in_scrutinee.rs:353:11
    |
 LL |     match mutex1.lock().unwrap().s.len() < mutex2.lock().unwrap().s.len() {
    |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -219,7 +219,7 @@ LL ~     match value < mutex2.lock().unwrap().s.len() {
    |
 
 error: temporary with significant `Drop` in `match` scrutinee will live until the end of the `match` expression
-  --> tests/ui/significant_drop_in_scrutinee.rs:348:44
+  --> tests/ui/significant_drop_in_scrutinee.rs:353:44
    |
 LL |     match mutex1.lock().unwrap().s.len() < mutex2.lock().unwrap().s.len() {
    |                                            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -240,7 +240,7 @@ LL ~     match mutex1.lock().unwrap().s.len() < value {
    |
 
 error: temporary with significant `Drop` in `match` scrutinee will live until the end of the `match` expression
-  --> tests/ui/significant_drop_in_scrutinee.rs:361:11
+  --> tests/ui/significant_drop_in_scrutinee.rs:366:11
    |
 LL |     match mutex1.lock().unwrap().s.len() >= mutex2.lock().unwrap().s.len() {
    |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -261,7 +261,7 @@ LL ~     match value >= mutex2.lock().unwrap().s.len() {
    |
 
 error: temporary with significant `Drop` in `match` scrutinee will live until the end of the `match` expression
-  --> tests/ui/significant_drop_in_scrutinee.rs:361:45
+  --> tests/ui/significant_drop_in_scrutinee.rs:366:45
    |
 LL |     match mutex1.lock().unwrap().s.len() >= mutex2.lock().unwrap().s.len() {
    |                                             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -282,7 +282,7 @@ LL ~     match mutex1.lock().unwrap().s.len() >= value {
    |
 
 error: temporary with significant `Drop` in `match` scrutinee will live until the end of the `match` expression
-  --> tests/ui/significant_drop_in_scrutinee.rs:398:11
+  --> tests/ui/significant_drop_in_scrutinee.rs:403:11
    |
 LL |     match get_mutex_guard().s.len() > 1 {
    |           ^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -301,7 +301,7 @@ LL ~     match value > 1 {
    |
 
 error: temporary with significant `Drop` in `match` scrutinee will live until the end of the `match` expression
-  --> tests/ui/significant_drop_in_scrutinee.rs:417:11
+  --> tests/ui/significant_drop_in_scrutinee.rs:422:11
    |
 LL |       match match i {
    |  ___________^
@@ -334,7 +334,7 @@ LL ~     match value
    |
 
 error: temporary with significant `Drop` in `match` scrutinee will live until the end of the `match` expression
-  --> tests/ui/significant_drop_in_scrutinee.rs:445:11
+  --> tests/ui/significant_drop_in_scrutinee.rs:450:11
    |
 LL |       match if i > 1 {
    |  ___________^
@@ -368,7 +368,7 @@ LL ~     match value
    |
 
 error: temporary with significant `Drop` in `match` scrutinee will live until the end of the `match` expression
-  --> tests/ui/significant_drop_in_scrutinee.rs:501:11
+  --> tests/ui/significant_drop_in_scrutinee.rs:506:11
    |
 LL |     match s.lock().deref().deref() {
    |           ^^^^^^^^^^^^^^^^^^^^^^^^
@@ -386,7 +386,7 @@ LL ~     match (&value) {
    |
 
 error: temporary with significant `Drop` in `match` scrutinee will live until the end of the `match` expression
-  --> tests/ui/significant_drop_in_scrutinee.rs:551:11
+  --> tests/ui/significant_drop_in_scrutinee.rs:556:11
    |
 LL |     match mutex.lock().unwrap().i = i {
    |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -405,7 +405,7 @@ LL ~     match () {
    |
 
 error: temporary with significant `Drop` in `match` scrutinee will live until the end of the `match` expression
-  --> tests/ui/significant_drop_in_scrutinee.rs:559:15
+  --> tests/ui/significant_drop_in_scrutinee.rs:564:15
    |
 LL |     match i = mutex.lock().unwrap().i {
    |               ^^^^^^^^^^^^^^^^^^^^^^^
@@ -424,7 +424,7 @@ LL ~     match i = value {
    |
 
 error: temporary with significant `Drop` in `match` scrutinee will live until the end of the `match` expression
-  --> tests/ui/significant_drop_in_scrutinee.rs:567:11
+  --> tests/ui/significant_drop_in_scrutinee.rs:572:11
    |
 LL |     match mutex.lock().unwrap().i += 1 {
    |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -443,7 +443,7 @@ LL ~     match () {
    |
 
 error: temporary with significant `Drop` in `match` scrutinee will live until the end of the `match` expression
-  --> tests/ui/significant_drop_in_scrutinee.rs:575:16
+  --> tests/ui/significant_drop_in_scrutinee.rs:580:16
    |
 LL |     match i += mutex.lock().unwrap().i {
    |                ^^^^^^^^^^^^^^^^^^^^^^^
@@ -462,7 +462,7 @@ LL ~     match i += value {
    |
 
 error: temporary with significant `Drop` in `match` scrutinee will live until the end of the `match` expression
-  --> tests/ui/significant_drop_in_scrutinee.rs:640:11
+  --> tests/ui/significant_drop_in_scrutinee.rs:645:11
    |
 LL |     match rwlock.read().unwrap().to_number() {
    |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -478,7 +478,7 @@ LL ~     match value {
    |
 
 error: temporary with significant `Drop` in `match` scrutinee will live until the end of the `match` expression
-  --> tests/ui/significant_drop_in_scrutinee.rs:668:11
+  --> tests/ui/significant_drop_in_scrutinee.rs:673:11
    |
 LL |     match mutex.lock().unwrap().foo() {
    |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -494,7 +494,7 @@ LL ~     match value {
    |
 
 error: temporary with significant `Drop` in `match` scrutinee will live until the end of the `match` expression
-  --> tests/ui/significant_drop_in_scrutinee.rs:731:11
+  --> tests/ui/significant_drop_in_scrutinee.rs:736:11
    |
 LL |     match guard.take().len() {
    |           ^^^^^^^^^^^^^^^^^^
@@ -510,7 +510,7 @@ LL ~     match value {
    |
 
 error: temporary with significant `Drop` in `for` loop condition will live until the end of the `for` expression
-  --> tests/ui/significant_drop_in_scrutinee.rs:757:16
+  --> tests/ui/significant_drop_in_scrutinee.rs:762:16
    |
 LL |     for val in mutex.lock().unwrap().copy_old_lifetime() {
    |                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -526,7 +526,7 @@ LL ~     for val in value {
    |
 
 error: temporary with significant `Drop` in `for` loop condition will live until the end of the `for` expression
-  --> tests/ui/significant_drop_in_scrutinee.rs:797:17
+  --> tests/ui/significant_drop_in_scrutinee.rs:802:17
    |
 LL |     for val in [mutex.lock().unwrap()[0], 2] {
    |                 ^^^^^^^^^^^^^^^^^^^^^^^^
@@ -542,7 +542,7 @@ LL ~     for val in [value, 2] {
    |
 
 error: temporary with significant `Drop` in `if let` scrutinee will live until the end of the `if let` expression
-  --> tests/ui/significant_drop_in_scrutinee.rs:807:24
+  --> tests/ui/significant_drop_in_scrutinee.rs:812:24
    |
 LL |     if let Some(val) = mutex.lock().unwrap().first().copied() {
    |                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -558,7 +558,7 @@ LL ~     if let Some(val) = value {
    |
 
 error: temporary with significant `Drop` in `while let` scrutinee will live until the end of the `while let` expression
-  --> tests/ui/significant_drop_in_scrutinee.rs:823:27
+  --> tests/ui/significant_drop_in_scrutinee.rs:828:27
    |
 LL |     while let Some(val) = mutex.lock().unwrap().pop() {
    |                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^
diff --git a/tests/ui/stacked_if_match.fixed b/tests/ui/stacked_if_match.fixed
new file mode 100644
index 000000000000..293f33c53263
--- /dev/null
+++ b/tests/ui/stacked_if_match.fixed
@@ -0,0 +1,118 @@
+#![warn(clippy::stacked_if_match)]
+#![allow(unused)]
+
+fn stacked_if() {
+    let x = 0;
+    let result = if x == 1 { x == 2 } else { x == 3 }; if result {
+        println!("true");
+    }
+
+    let result = if x == 1 { 2 } else { 3 }; if result == 4 {
+        println!("true");
+    }
+
+    let result = if x == 1 {
+        let y = 2;
+        y == 2
+    } else {
+        let z = 3;
+        z == 3
+    }; if result {
+        println!("true");
+    }
+}
+
+fn stacked_match() {
+    let x = 0;
+    let result = match x {
+        1 => 2,
+        _ => 3,
+    }; match result {
+        1 => {},
+        2 => {},
+        _ => {},
+    }
+
+    let result = match x {
+        1 => 2,
+        _ => 3,
+    }; match result + 1
+    {
+        1 => {},
+        2 => {},
+        _ => {},
+    }
+}
+
+fn if_no_lint() {
+    let x = 0;
+
+    if (if x == 1 { x == 2 } else { x == 3 }) {
+        println!("true");
+    }
+
+    if 1 == if x == 1 { 1 } else { 2 } {
+        println!("true");
+    }
+}
+
+fn match_no_lint() {
+    let x = 0;
+    match (match x {
+        1 => 2,
+        _ => 3,
+    }) {
+        1 => {},
+        2 => {},
+        _ => {},
+    }
+
+    match 1 + match x {
+        1 => 2,
+        _ => 3,
+    } {
+        1 => {},
+        2 => {},
+        _ => {},
+    }
+}
+
+macro_rules! if_macro {
+    ($var:ident) => {
+        if $var == 1 { true } else { false }
+    };
+}
+
+macro_rules! match_macro {
+    ($var:ident) => {
+        match $var {
+            1 => 2,
+            _ => 3,
+        }
+    };
+}
+
+macro_rules! if_if_macro {
+    () => {
+        if if true { true } else { false } {
+            println!("true");
+        }
+    };
+}
+
+fn macro_no_lint() {
+    let x = 0;
+    if if_macro!(x) {
+        println!("true");
+    }
+
+    match match_macro!(x) {
+        1 => {},
+        2 => {},
+        _ => {},
+    }
+
+    if_if_macro!();
+}
+
+fn main() {}
diff --git a/tests/ui/stacked_if_match.stderr b/tests/ui/stacked_if_match.stderr
new file mode 100644
index 000000000000..5dcb40610c6c
--- /dev/null
+++ b/tests/ui/stacked_if_match.stderr
@@ -0,0 +1,74 @@
+error: avoid using `if if` by binding inner `if` with `let`
+  --> tests/ui/stacked_if_match.rs:6:5
+   |
+LL |     if if x == 1 { x == 2 } else { x == 3 } {
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `let result = if x == 1 { x == 2 } else { x == 3 }; if result`
+   |
+   = note: `-D clippy::stacked-if-match` implied by `-D warnings`
+   = help: to override `-D warnings` add `#[allow(clippy::stacked_if_match)]`
+
+error: avoid using `if if` by binding inner `if` with `let`
+  --> tests/ui/stacked_if_match.rs:10:5
+   |
+LL |     if if x == 1 { 2 } else { 3 } == 4 {
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `let result = if x == 1 { 2 } else { 3 }; if result`
+
+error: avoid using `if if` by binding inner `if` with `let`
+  --> tests/ui/stacked_if_match.rs:14:5
+   |
+LL | /     if if x == 1 {
+LL | |         let y = 2;
+LL | |         y == 2
+LL | |     } else {
+LL | |         let z = 3;
+LL | |         z == 3
+LL | |     } {
+   | |_____^
+   |
+help: try
+   |
+LL ~     let result = if x == 1 {
+LL +         let y = 2;
+LL +         y == 2
+LL +     } else {
+LL +         let z = 3;
+LL +         z == 3
+LL ~     }; if result {
+   |
+
+error: avoid using `match match` by binding inner `match` with `let`
+  --> tests/ui/stacked_if_match.rs:27:5
+   |
+LL | /     match match x {
+LL | |         1 => 2,
+LL | |         _ => 3,
+LL | |     } {
+   | |_____^
+   |
+help: try
+   |
+LL ~     let result = match x {
+LL +         1 => 2,
+LL +         _ => 3,
+LL ~     }; match result {
+   |
+
+error: avoid using `match match` by binding inner `match` with `let`
+  --> tests/ui/stacked_if_match.rs:36:5
+   |
+LL | /     match match x {
+LL | |         1 => 2,
+LL | |         _ => 3,
+LL | |     } + 1
+   | |_____^
+   |
+help: try
+   |
+LL ~     let result = match x {
+LL +         1 => 2,
+LL +         _ => 3,
+LL ~     }; match result + 1
+   |
+
+error: aborting due to 5 previous errors
+

From e7c528d2e0c0e8a5089c4a7bd94eeeedcacc34c4 Mon Sep 17 00:00:00 2001
From: promptkp <prompt3838@gmail.com>
Date: Sun, 25 Aug 2024 20:17:37 +0700
Subject: [PATCH 6/9] fix example with hidden

---
 clippy_lints/src/stacked_if_match.rs | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/clippy_lints/src/stacked_if_match.rs b/clippy_lints/src/stacked_if_match.rs
index 99caad73e442..744cb2f76b1e 100644
--- a/clippy_lints/src/stacked_if_match.rs
+++ b/clippy_lints/src/stacked_if_match.rs
@@ -17,6 +17,7 @@ declare_clippy_lint! {
     ///
     /// ### Example
     /// ```no_run
+    /// # let (a, b, c, d, e, f) = (1, 2, 3, 4, 5, 6);
     /// if if a == b {
     ///     c == d
     /// } else {
@@ -28,6 +29,7 @@ declare_clippy_lint! {
     ///
     /// Use instead:
     /// ```no_run
+    /// # let (a, b, c, d, e, f) = (1, 2, 3, 4, 5, 6);
     /// let result = if a == b {
     ///     c == d
     /// } else {

From d873c61cf7903287da2a7e786afd6c11c2bfb113 Mon Sep 17 00:00:00 2001
From: promptkp <prompt3838@gmail.com>
Date: Sun, 1 Sep 2024 19:57:03 +0700
Subject: [PATCH 7/9] add no lint tests for match if and if match

---
 tests/ui/stacked_if_match.rs | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/tests/ui/stacked_if_match.rs b/tests/ui/stacked_if_match.rs
index 23a023b674f5..765aeee4e4d3 100644
--- a/tests/ui/stacked_if_match.rs
+++ b/tests/ui/stacked_if_match.rs
@@ -77,6 +77,31 @@ fn match_no_lint() {
     }
 }
 
+fn if_match_no_lint() {
+    let x = 0;
+    if match x {
+        1 => 2,
+        _ => 3,
+    } == 4 {
+        println!("true");
+    }
+}
+
+fn match_if_no_lint() {
+    let x = 0;
+    match if x == 1 {
+        let y = 2;
+        y + 1
+    } else {
+        let z = 3;
+        z + 1
+    } {
+        1 => {},
+        2 => {},
+        _ => {},
+    }
+}
+
 macro_rules! if_macro {
     ($var:ident) => {
         if $var == 1 { true } else { false }

From cd67825bb32bcb529bb9641731cb8ac6321c15af Mon Sep 17 00:00:00 2001
From: promptkp <prompt3838@gmail.com>
Date: Sun, 1 Sep 2024 19:59:21 +0700
Subject: [PATCH 8/9] fmt

---
 tests/ui/stacked_if_match.rs | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/tests/ui/stacked_if_match.rs b/tests/ui/stacked_if_match.rs
index 765aeee4e4d3..dca4c1bc5058 100644
--- a/tests/ui/stacked_if_match.rs
+++ b/tests/ui/stacked_if_match.rs
@@ -82,7 +82,8 @@ fn if_match_no_lint() {
     if match x {
         1 => 2,
         _ => 3,
-    } == 4 {
+    } == 4
+    {
         println!("true");
     }
 }

From 0f82ab1f7a46ce218c26f2e1922864467875a101 Mon Sep 17 00:00:00 2001
From: promptkp <prompt3838@gmail.com>
Date: Sun, 1 Sep 2024 20:12:38 +0700
Subject: [PATCH 9/9] update stacked_if_match.fixed

---
 tests/ui/stacked_if_match.fixed | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/tests/ui/stacked_if_match.fixed b/tests/ui/stacked_if_match.fixed
index 293f33c53263..69e1bd984f9b 100644
--- a/tests/ui/stacked_if_match.fixed
+++ b/tests/ui/stacked_if_match.fixed
@@ -77,6 +77,32 @@ fn match_no_lint() {
     }
 }
 
+fn if_match_no_lint() {
+    let x = 0;
+    if match x {
+        1 => 2,
+        _ => 3,
+    } == 4
+    {
+        println!("true");
+    }
+}
+
+fn match_if_no_lint() {
+    let x = 0;
+    match if x == 1 {
+        let y = 2;
+        y + 1
+    } else {
+        let z = 3;
+        z + 1
+    } {
+        1 => {},
+        2 => {},
+        _ => {},
+    }
+}
+
 macro_rules! if_macro {
     ($var:ident) => {
         if $var == 1 { true } else { false }