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fix(equatable_if_let): don't lint if pattern or initializer come from expansion #15958

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fix(equatable_if_let): don't lint if pattern or initializer come from expansion #15958

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e6549ec
clean-up
ada4a Oct 26, 2025
1e186cf
fix(equatable_if_let): don't lint if pattern or initializer come from…
ada4a Oct 26, 2025
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69 changes: 37 additions & 32 deletions clippy_lints/src/equatable_if_let.rs
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Original file line number Diff line number Diff line change
@@ -1,4 +1,4 @@
use clippy_utils::diagnostics::span_lint_and_sugg;
use clippy_utils::diagnostics::span_lint_and_then;
use clippy_utils::source::snippet_with_context;
use clippy_utils::ty::implements_trait;
use rustc_errors::Applicability;
Expand Down Expand Up @@ -40,9 +40,9 @@ declare_clippy_lint! {
declare_lint_pass!(PatternEquality => [EQUATABLE_IF_LET]);

/// detects if pattern matches just one thing
fn unary_pattern(pat: &Pat<'_>) -> bool {
fn is_unary_pattern(pat: &Pat<'_>) -> bool {
fn array_rec(pats: &[Pat<'_>]) -> bool {
pats.iter().all(unary_pattern)
pats.iter().all(is_unary_pattern)
}
match &pat.kind {
PatKind::Missing => unreachable!(),
Expand All @@ -53,9 +53,9 @@ fn unary_pattern(pat: &Pat<'_>) -> bool {
| PatKind::Never
| PatKind::Or(_)
| PatKind::Err(_) => false,
PatKind::Struct(_, a, etc) => etc.is_none() && a.iter().all(|x| unary_pattern(x.pat)),
PatKind::Struct(_, a, etc) => etc.is_none() && a.iter().all(|x| is_unary_pattern(x.pat)),
PatKind::Tuple(a, etc) | PatKind::TupleStruct(_, a, etc) => etc.as_opt_usize().is_none() && array_rec(a),
PatKind::Ref(x, _) | PatKind::Box(x) | PatKind::Deref(x) | PatKind::Guard(x, _) => unary_pattern(x),
PatKind::Ref(x, _) | PatKind::Box(x) | PatKind::Deref(x) | PatKind::Guard(x, _) => is_unary_pattern(x),
PatKind::Expr(_) => true,
}
}
Expand Down Expand Up @@ -103,48 +103,53 @@ fn contains_type_mismatch(cx: &LateContext<'_>, pat: &Pat<'_>) -> bool {
impl<'tcx> LateLintPass<'tcx> for PatternEquality {
fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>) {
if let ExprKind::Let(let_expr) = expr.kind
&& unary_pattern(let_expr.pat)
&& !expr.span.in_external_macro(cx.sess().source_map())
&& is_unary_pattern(let_expr.pat)
&& !let_expr.pat.span.from_expansion()
&& !let_expr.init.span.from_expansion()
{
let exp_ty = cx.typeck_results().expr_ty(let_expr.init);
let pat_ty = cx.typeck_results().pat_ty(let_expr.pat);
let mut applicability = Applicability::MachineApplicable;

let mut app = Applicability::MachineApplicable;
let ctxt = expr.span.ctxt();

if is_structural_partial_eq(cx, exp_ty, pat_ty) && !contains_type_mismatch(cx, let_expr.pat) {
let pat_str = match let_expr.pat.kind {
PatKind::Struct(..) => format!(
"({})",
snippet_with_context(cx, let_expr.pat.span, expr.span.ctxt(), "..", &mut applicability).0,
),
_ => snippet_with_context(cx, let_expr.pat.span, expr.span.ctxt(), "..", &mut applicability)
.0
.to_string(),
};
span_lint_and_sugg(
span_lint_and_then(
cx,
EQUATABLE_IF_LET,
expr.span,
"this pattern matching can be expressed using equality",
"try",
format!(
"{} == {pat_str}",
snippet_with_context(cx, let_expr.init.span, expr.span.ctxt(), "..", &mut applicability).0,
),
applicability,
|diag| {
let pat_str = {
let str = snippet_with_context(cx, let_expr.pat.span, ctxt, "..", &mut app).0;
if let PatKind::Struct(..) = let_expr.pat.kind {
format!("({str})").into()
} else {
str
}
};

let sugg = format!(
"{} == {pat_str}",
snippet_with_context(cx, let_expr.init.span, ctxt, "..", &mut app).0,
);
diag.span_suggestion(expr.span, "try", sugg, app);
},
);
} else {
span_lint_and_sugg(
span_lint_and_then(
cx,
EQUATABLE_IF_LET,
expr.span,
"this pattern matching can be expressed using `matches!`",
"try",
format!(
"matches!({}, {})",
snippet_with_context(cx, let_expr.init.span, expr.span.ctxt(), "..", &mut applicability).0,
snippet_with_context(cx, let_expr.pat.span, expr.span.ctxt(), "..", &mut applicability).0,
),
applicability,
|diag| {
let sugg = format!(
"matches!({}, {})",
snippet_with_context(cx, let_expr.init.span, ctxt, "..", &mut app).0,
snippet_with_context(cx, let_expr.pat.span, ctxt, "..", &mut app).0,
);
diag.span_suggestion(expr.span, "try", sugg, app);
},
);
}
}
Expand Down
53 changes: 37 additions & 16 deletions tests/ui/equatable_if_let.fixed
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -1,14 +1,7 @@
//@aux-build:proc_macros.rs

#![allow(
unused_variables,
dead_code,
clippy::derive_partial_eq_without_eq,
clippy::needless_if
)]
#![allow(clippy::derive_partial_eq_without_eq, clippy::needless_if)]
#![warn(clippy::equatable_if_let)]

extern crate proc_macros;
use proc_macros::{external, inline_macros};

use std::cmp::Ordering;
Expand Down Expand Up @@ -48,7 +41,6 @@ impl PartialEq for NotStructuralEq {
}
}

#[inline_macros]
fn main() {
let a = 2;
let b = 3;
Expand Down Expand Up @@ -95,13 +87,6 @@ fn main() {
//~^ equatable_if_let
if matches!(h, NoPartialEqStruct { a: 2, b: false }) {}
//~^ equatable_if_let

if "abc" == inline!("abc") {
//~^ equatable_if_let
println!("OK");
}

external!({ if let 2 = $a {} });
}

mod issue8710 {
Expand Down Expand Up @@ -139,3 +124,39 @@ mod issue8710 {
}
}
}

#[inline_macros]
fn issue14548() {
if let inline!("abc") = "abc" {
println!("OK");
}

let a = 2;
external!({ if let 2 = $a {} });

macro_rules! generate_script {
($($($font:literal)|*),+) => {
pub fn script(font: &str) {
$(
if let $($font)|* = font {}
)*
}
}
}

generate_script! {
"Sans" | "Serif" | "Sans Mono",
"Znamenny Musical Notation"
}

macro_rules! generate_script2 {
($($font:literal)|*) => {{
pub fn script2(font: &str) {
if let $($font)|* = font {}
}
}}
}

generate_script2!("Sans" | "Serif" | "Sans Mono");
generate_script2!("Znamenny Musical Notation");
}
53 changes: 37 additions & 16 deletions tests/ui/equatable_if_let.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -1,14 +1,7 @@
//@aux-build:proc_macros.rs

#![allow(
unused_variables,
dead_code,
clippy::derive_partial_eq_without_eq,
clippy::needless_if
)]
#![allow(clippy::derive_partial_eq_without_eq, clippy::needless_if)]
#![warn(clippy::equatable_if_let)]

extern crate proc_macros;
use proc_macros::{external, inline_macros};

use std::cmp::Ordering;
Expand Down Expand Up @@ -48,7 +41,6 @@ impl PartialEq for NotStructuralEq {
}
}

#[inline_macros]
fn main() {
let a = 2;
let b = 3;
Expand Down Expand Up @@ -95,13 +87,6 @@ fn main() {
//~^ equatable_if_let
if let NoPartialEqStruct { a: 2, b: false } = h {}
//~^ equatable_if_let

if let inline!("abc") = "abc" {
//~^ equatable_if_let
println!("OK");
}

external!({ if let 2 = $a {} });
}

mod issue8710 {
Expand Down Expand Up @@ -139,3 +124,39 @@ mod issue8710 {
}
}
}

#[inline_macros]
fn issue14548() {
if let inline!("abc") = "abc" {
println!("OK");
}

let a = 2;
external!({ if let 2 = $a {} });

macro_rules! generate_script {
($($($font:literal)|*),+) => {
pub fn script(font: &str) {
$(
if let $($font)|* = font {}
)*
}
}
}

generate_script! {
"Sans" | "Serif" | "Sans Mono",
"Znamenny Musical Notation"
}

macro_rules! generate_script2 {
($($font:literal)|*) => {{
pub fn script2(font: &str) {
if let $($font)|* = font {}
}
}}
}

generate_script2!("Sans" | "Serif" | "Sans Mono");
generate_script2!("Znamenny Musical Notation");
}
40 changes: 17 additions & 23 deletions tests/ui/equatable_if_let.stderr
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -1,5 +1,5 @@
error: this pattern matching can be expressed using equality
--> tests/ui/equatable_if_let.rs:64:8
--> tests/ui/equatable_if_let.rs:56:8
|
LL | if let 2 = a {}
| ^^^^^^^^^ help: try: `a == 2`
Expand All @@ -8,100 +8,94 @@ LL | if let 2 = a {}
= help: to override `-D warnings` add `#[allow(clippy::equatable_if_let)]`

error: this pattern matching can be expressed using equality
--> tests/ui/equatable_if_let.rs:66:8
--> tests/ui/equatable_if_let.rs:58:8
|
LL | if let Ordering::Greater = a.cmp(&b) {}
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `a.cmp(&b) == Ordering::Greater`

error: this pattern matching can be expressed using equality
--> tests/ui/equatable_if_let.rs:68:8
--> tests/ui/equatable_if_let.rs:60:8
|
LL | if let Some(2) = c {}
| ^^^^^^^^^^^^^^^ help: try: `c == Some(2)`

error: this pattern matching can be expressed using equality
--> tests/ui/equatable_if_let.rs:70:8
--> tests/ui/equatable_if_let.rs:62:8
|
LL | if let Struct { a: 2, b: false } = d {}
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `d == (Struct { a: 2, b: false })`

error: this pattern matching can be expressed using equality
--> tests/ui/equatable_if_let.rs:72:8
--> tests/ui/equatable_if_let.rs:64:8
|
LL | if let Enum::TupleVariant(32, 64) = e {}
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `e == Enum::TupleVariant(32, 64)`

error: this pattern matching can be expressed using equality
--> tests/ui/equatable_if_let.rs:74:8
--> tests/ui/equatable_if_let.rs:66:8
|
LL | if let Enum::RecordVariant { a: 64, b: 32 } = e {}
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `e == (Enum::RecordVariant { a: 64, b: 32 })`

error: this pattern matching can be expressed using equality
--> tests/ui/equatable_if_let.rs:76:8
--> tests/ui/equatable_if_let.rs:68:8
|
LL | if let Enum::UnitVariant = e {}
| ^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `e == Enum::UnitVariant`

error: this pattern matching can be expressed using equality
--> tests/ui/equatable_if_let.rs:78:8
--> tests/ui/equatable_if_let.rs:70:8
|
LL | if let (Enum::UnitVariant, &Struct { a: 2, b: false }) = (e, &d) {}
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `(e, &d) == (Enum::UnitVariant, &Struct { a: 2, b: false })`

error: this pattern matching can be expressed using `matches!`
--> tests/ui/equatable_if_let.rs:88:8
--> tests/ui/equatable_if_let.rs:80:8
|
LL | if let NotPartialEq::A = f {}
| ^^^^^^^^^^^^^^^^^^^^^^^ help: try: `matches!(f, NotPartialEq::A)`

error: this pattern matching can be expressed using equality
--> tests/ui/equatable_if_let.rs:90:8
--> tests/ui/equatable_if_let.rs:82:8
|
LL | if let NotStructuralEq::A = g {}
| ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `g == NotStructuralEq::A`

error: this pattern matching can be expressed using `matches!`
--> tests/ui/equatable_if_let.rs:92:8
--> tests/ui/equatable_if_let.rs:84:8
|
LL | if let Some(NotPartialEq::A) = Some(f) {}
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `matches!(Some(f), Some(NotPartialEq::A))`

error: this pattern matching can be expressed using equality
--> tests/ui/equatable_if_let.rs:94:8
--> tests/ui/equatable_if_let.rs:86:8
|
LL | if let Some(NotStructuralEq::A) = Some(g) {}
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `Some(g) == Some(NotStructuralEq::A)`

error: this pattern matching can be expressed using `matches!`
--> tests/ui/equatable_if_let.rs:96:8
--> tests/ui/equatable_if_let.rs:88:8
|
LL | if let NoPartialEqStruct { a: 2, b: false } = h {}
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `matches!(h, NoPartialEqStruct { a: 2, b: false })`

error: this pattern matching can be expressed using equality
--> tests/ui/equatable_if_let.rs:99:8
|
LL | if let inline!("abc") = "abc" {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `"abc" == inline!("abc")`

error: this pattern matching can be expressed using `matches!`
--> tests/ui/equatable_if_let.rs:109:12
--> tests/ui/equatable_if_let.rs:94:12
|
LL | if let Some('i') = cs.iter().next() {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `matches!(cs.iter().next(), Some('i'))`

error: this pattern matching can be expressed using `matches!`
--> tests/ui/equatable_if_let.rs:117:12
--> tests/ui/equatable_if_let.rs:102:12
|
LL | if let Some(1) = cs.iter().next() {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `matches!(cs.iter().next(), Some(1))`

error: this pattern matching can be expressed using `matches!`
--> tests/ui/equatable_if_let.rs:135:12
--> tests/ui/equatable_if_let.rs:120:12
|
LL | if let Some(MyEnum::B) = get_enum() {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `matches!(get_enum(), Some(MyEnum::B))`

error: aborting due to 17 previous errors
error: aborting due to 16 previous errors

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