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[redundant_guards]: don't lint on float literals #11305

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merged 2 commits into from
Aug 8, 2023
Merged

[redundant_guards]: don't lint on float literals #11305

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f959ccc
[`redundant_guards`]: don't lint on floats
y21 Aug 8, 2023
b615650
document the new behavior and add test for float in struct
y21 Aug 8, 2023
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10 changes: 8 additions & 2 deletions clippy_lints/src/matches/redundant_guards.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -2,6 +2,7 @@ use clippy_utils::diagnostics::span_lint_and_then;
use clippy_utils::path_to_local;
use clippy_utils::source::snippet_with_applicability;
use clippy_utils::visitors::{for_each_expr, is_local_used};
use rustc_ast::LitKind;
use rustc_errors::Applicability;
use rustc_hir::def::{DefKind, Res};
use rustc_hir::{Arm, BinOpKind, Expr, ExprKind, Guard, MatchSource, Node, Pat, PatKind};
Expand Down Expand Up @@ -160,6 +161,11 @@ fn emit_redundant_guards<'tcx>(
}

/// Checks if the given `Expr` can also be represented as a `Pat`.
///
/// All literals generally also work as patterns, however float literals are special.
/// They are currently (as of 2023/08/08) still allowed in patterns, but that will become
/// an error in the future, and rustc already actively warns against this (see rust#41620),
/// so we don't consider those as usable within patterns for linting purposes.
fn expr_can_be_pat(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
for_each_expr(expr, |expr| {
if match expr.kind {
Expand All @@ -177,8 +183,8 @@ fn expr_can_be_pat(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
ExprKind::AddrOf(..)
| ExprKind::Array(..)
| ExprKind::Tup(..)
| ExprKind::Struct(..)
| ExprKind::Lit(..) => true,
| ExprKind::Struct(..) => true,
ExprKind::Lit(lit) if !matches!(lit.node, LitKind::Float(..)) => true,
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_ => false,
} {
return ControlFlow::Continue(());
Expand Down
13 changes: 13 additions & 0 deletions tests/ui/redundant_guards.fixed
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Expand Up @@ -15,6 +15,19 @@ struct B {

struct C(u32, u32);

#[derive(PartialEq)]
struct FloatWrapper(f32);
fn issue11304() {
match 0.1 {
x if x == 0.0 => todo!(),
_ => todo!(),
}
match FloatWrapper(0.1) {
x if x == FloatWrapper(0.0) => todo!(),
_ => todo!(),
}
}

fn main() {
let c = C(1, 2);
match c {
Expand Down
13 changes: 13 additions & 0 deletions tests/ui/redundant_guards.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -15,6 +15,19 @@ struct B {

struct C(u32, u32);

#[derive(PartialEq)]
struct FloatWrapper(f32);
fn issue11304() {
match 0.1 {
x if x == 0.0 => todo!(),
_ => todo!(),
}
match FloatWrapper(0.1) {
x if x == FloatWrapper(0.0) => todo!(),
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We'd ideally suggest FloatWrapper(f) if f == 0.0 here, but that can be done in the future.

_ => todo!(),
}
}

fn main() {
let c = C(1, 2);
match c {
Expand Down
16 changes: 8 additions & 8 deletions tests/ui/redundant_guards.stderr
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Original file line number Diff line number Diff line change
@@ -1,5 +1,5 @@
error: redundant guard
--> $DIR/redundant_guards.rs:21:20
--> $DIR/redundant_guards.rs:34:20
|
LL | C(x, y) if let 1 = y => ..,
| ^^^^^^^^^
Expand All @@ -12,7 +12,7 @@ LL + C(x, 1) => ..,
|

error: redundant guard
--> $DIR/redundant_guards.rs:27:20
--> $DIR/redundant_guards.rs:40:20
|
LL | Some(x) if matches!(x, Some(1) if true) => ..,
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Expand All @@ -23,7 +23,7 @@ LL | Some(Some(1)) if true => ..,
| ~~~~~~~ ~~~~~~~

error: redundant guard
--> $DIR/redundant_guards.rs:28:20
--> $DIR/redundant_guards.rs:41:20
|
LL | Some(x) if matches!(x, Some(1)) => {
| ^^^^^^^^^^^^^^^^^^^^
Expand All @@ -35,7 +35,7 @@ LL + Some(Some(1)) => {
|

error: redundant guard
--> $DIR/redundant_guards.rs:32:20
--> $DIR/redundant_guards.rs:45:20
|
LL | Some(x) if let Some(1) = x => ..,
| ^^^^^^^^^^^^^^^
Expand All @@ -47,7 +47,7 @@ LL + Some(Some(1)) => ..,
|

error: redundant guard
--> $DIR/redundant_guards.rs:33:20
--> $DIR/redundant_guards.rs:46:20
|
LL | Some(x) if x == Some(2) => ..,
| ^^^^^^^^^^^^
Expand All @@ -59,7 +59,7 @@ LL + Some(Some(2)) => ..,
|

error: redundant guard
--> $DIR/redundant_guards.rs:56:20
--> $DIR/redundant_guards.rs:69:20
|
LL | B { e } if matches!(e, Some(A(2))) => ..,
| ^^^^^^^^^^^^^^^^^^^^^^^
Expand All @@ -71,7 +71,7 @@ LL + B { e: Some(A(2)) } => ..,
|

error: redundant guard
--> $DIR/redundant_guards.rs:93:20
--> $DIR/redundant_guards.rs:106:20
|
LL | E::A(y) if y == "not from an or pattern" => {},
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Expand All @@ -83,7 +83,7 @@ LL + E::A("not from an or pattern") => {},
|

error: redundant guard
--> $DIR/redundant_guards.rs:100:14
--> $DIR/redundant_guards.rs:113:14
|
LL | x if matches!(x, Some(0)) => ..,
| ^^^^^^^^^^^^^^^^^^^^
Expand Down