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Rollup merge of rust-lang#121364 - Urgau:unary_precedence, r=compiler-errors
Implement lint against ambiguous negative literals This PR implements a lint against ambiguous negative literals with a literal and method calls right after it. ## `ambiguous_negative_literals` (deny-by-default) The `ambiguous_negative_literals` lint checks for cases that are confusing between a negative literal and a negation that's not part of the literal. ### Example ```rust,compile_fail -1i32.abs(); // equals -1, while `(-1i32).abs()` equals 1 ``` ### Explanation Method calls take precedence over unary precedence. Setting the precedence explicitly makes the code clearer and avoid potential bugs. <details> <summary>Old proposed lint</summary> ## `ambiguous_unary_precedence` (deny-by-default) The `ambiguous_unary_precedence` lint checks for use the negative unary operator with a literal and method calls. ### Example ```rust -1i32.abs(); // equals -1, while `(-1i32).abs()` equals 1 ``` ### Explanation Unary operations take precedence on binary operations and method calls take precedence over unary precedence. Setting the precedence explicitly makes the code clearer and avoid potential bugs. </details> ----- Note: This is a strip down version of rust-lang#117161, without the binary op precedence. Fixes rust-lang#117155 `@rustbot` labels +I-lang-nominated cc `@scottmcm` r? compiler
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‎clippy_lints/src/precedence.rs

Lines changed: 1 addition & 55 deletions
Original file line numberDiff line numberDiff line change
@@ -1,38 +1,17 @@
11
use clippy_utils::diagnostics::span_lint_and_sugg;
22
use clippy_utils::source::snippet_with_applicability;
3-
use rustc_ast::ast::{BinOpKind, Expr, ExprKind, MethodCall, UnOp};
4-
use rustc_ast::token;
3+
use rustc_ast::ast::{BinOpKind, Expr, ExprKind};
54
use rustc_errors::Applicability;
65
use rustc_lint::{EarlyContext, EarlyLintPass};
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use rustc_session::declare_lint_pass;
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use rustc_span::source_map::Spanned;
98

10-
const ALLOWED_ODD_FUNCTIONS: [&str; 14] = [
11-
"asin",
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"asinh",
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"atan",
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"atanh",
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"cbrt",
16-
"fract",
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"round",
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"signum",
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"sin",
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"sinh",
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"tan",
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"tanh",
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"to_degrees",
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"to_radians",
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];
26-
279
declare_clippy_lint! {
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/// ### What it does
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/// Checks for operations where precedence may be unclear
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/// and suggests to add parentheses. Currently it catches the following:
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/// * mixed usage of arithmetic and bit shifting/combining operators without
3214
/// parentheses
33-
/// * a "negative" numeric literal (which is really a unary `-` followed by a
34-
/// numeric literal)
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/// followed by a method call
3615
///
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/// ### Why is this bad?
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/// Not everyone knows the precedence of those operators by
@@ -41,7 +20,6 @@ declare_clippy_lint! {
4120
///
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/// ### Example
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/// * `1 << 2 + 3` equals 32, while `(1 << 2) + 3` equals 7
44-
/// * `-1i32.abs()` equals -1, while `(-1i32).abs()` equals 1
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#[clippy::version = "pre 1.29.0"]
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pub PRECEDENCE,
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complexity,
@@ -104,38 +82,6 @@ impl EarlyLintPass for Precedence {
10482
(false, false) => (),
10583
}
10684
}
107-
108-
if let ExprKind::Unary(UnOp::Neg, operand) = &expr.kind {
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let mut arg = operand;
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let mut all_odd = true;
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while let ExprKind::MethodCall(box MethodCall { seg, receiver, .. }) = &arg.kind {
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let seg_str = seg.ident.name.as_str();
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all_odd &= ALLOWED_ODD_FUNCTIONS
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.iter()
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.any(|odd_function| **odd_function == *seg_str);
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arg = receiver;
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}
119-
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if !all_odd
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&& let ExprKind::Lit(lit) = &arg.kind
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&& let token::LitKind::Integer | token::LitKind::Float = &lit.kind
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{
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let mut applicability = Applicability::MachineApplicable;
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span_lint_and_sugg(
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cx,
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PRECEDENCE,
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expr.span,
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"unary minus has lower precedence than method call",
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"consider adding parentheses to clarify your intent",
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format!(
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"-({})",
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snippet_with_applicability(cx, operand.span, "..", &mut applicability)
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),
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applicability,
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);
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}
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}
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}
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}
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‎tests/ui/precedence.fixed

Lines changed: 0 additions & 34 deletions
Original file line numberDiff line numberDiff line change
@@ -20,40 +20,6 @@ fn main() {
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1 ^ (1 - 1);
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3 | (2 - 1);
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3 & (5 - 2);
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-(1i32.abs());
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-(1f32.abs());
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// These should not trigger an error
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let _ = (-1i32).abs();
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let _ = (-1f32).abs();
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let _ = -(1i32).abs();
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let _ = -(1f32).abs();
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let _ = -(1i32.abs());
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let _ = -(1f32.abs());
33-
34-
// Odd functions should not trigger an error
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let _ = -1f64.asin();
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let _ = -1f64.asinh();
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let _ = -1f64.atan();
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let _ = -1f64.atanh();
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let _ = -1f64.cbrt();
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let _ = -1f64.fract();
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let _ = -1f64.round();
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let _ = -1f64.signum();
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let _ = -1f64.sin();
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let _ = -1f64.sinh();
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let _ = -1f64.tan();
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let _ = -1f64.tanh();
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let _ = -1f64.to_degrees();
48-
let _ = -1f64.to_radians();
49-
50-
// Chains containing any non-odd function should trigger (issue #5924)
51-
let _ = -(1.0_f64.cos().cos());
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let _ = -(1.0_f64.cos().sin());
53-
let _ = -(1.0_f64.sin().cos());
54-
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// Chains of odd functions shouldn't trigger
56-
let _ = -1f64.sin().sin();
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5824
let b = 3;
5925
trip!(b * 8);

‎tests/ui/precedence.rs

Lines changed: 0 additions & 34 deletions
Original file line numberDiff line numberDiff line change
@@ -20,40 +20,6 @@ fn main() {
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1 ^ 1 - 1;
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3 | 2 - 1;
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3 & 5 - 2;
23-
-1i32.abs();
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-1f32.abs();
25-
26-
// These should not trigger an error
27-
let _ = (-1i32).abs();
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let _ = (-1f32).abs();
29-
let _ = -(1i32).abs();
30-
let _ = -(1f32).abs();
31-
let _ = -(1i32.abs());
32-
let _ = -(1f32.abs());
33-
34-
// Odd functions should not trigger an error
35-
let _ = -1f64.asin();
36-
let _ = -1f64.asinh();
37-
let _ = -1f64.atan();
38-
let _ = -1f64.atanh();
39-
let _ = -1f64.cbrt();
40-
let _ = -1f64.fract();
41-
let _ = -1f64.round();
42-
let _ = -1f64.signum();
43-
let _ = -1f64.sin();
44-
let _ = -1f64.sinh();
45-
let _ = -1f64.tan();
46-
let _ = -1f64.tanh();
47-
let _ = -1f64.to_degrees();
48-
let _ = -1f64.to_radians();
49-
50-
// Chains containing any non-odd function should trigger (issue #5924)
51-
let _ = -1.0_f64.cos().cos();
52-
let _ = -1.0_f64.cos().sin();
53-
let _ = -1.0_f64.sin().cos();
54-
55-
// Chains of odd functions shouldn't trigger
56-
let _ = -1f64.sin().sin();
5723

5824
let b = 3;
5925
trip!(b * 8);

‎tests/ui/precedence.stderr

Lines changed: 1 addition & 31 deletions
Original file line numberDiff line numberDiff line change
@@ -43,35 +43,5 @@ error: operator precedence can trip the unwary
4343
LL | 3 & 5 - 2;
4444
| ^^^^^^^^^ help: consider parenthesizing your expression: `3 & (5 - 2)`
4545

46-
error: unary minus has lower precedence than method call
47-
--> tests/ui/precedence.rs:23:5
48-
|
49-
LL | -1i32.abs();
50-
| ^^^^^^^^^^^ help: consider adding parentheses to clarify your intent: `-(1i32.abs())`
51-
52-
error: unary minus has lower precedence than method call
53-
--> tests/ui/precedence.rs:24:5
54-
|
55-
LL | -1f32.abs();
56-
| ^^^^^^^^^^^ help: consider adding parentheses to clarify your intent: `-(1f32.abs())`
57-
58-
error: unary minus has lower precedence than method call
59-
--> tests/ui/precedence.rs:51:13
60-
|
61-
LL | let _ = -1.0_f64.cos().cos();
62-
| ^^^^^^^^^^^^^^^^^^^^ help: consider adding parentheses to clarify your intent: `-(1.0_f64.cos().cos())`
63-
64-
error: unary minus has lower precedence than method call
65-
--> tests/ui/precedence.rs:52:13
66-
|
67-
LL | let _ = -1.0_f64.cos().sin();
68-
| ^^^^^^^^^^^^^^^^^^^^ help: consider adding parentheses to clarify your intent: `-(1.0_f64.cos().sin())`
69-
70-
error: unary minus has lower precedence than method call
71-
--> tests/ui/precedence.rs:53:13
72-
|
73-
LL | let _ = -1.0_f64.sin().cos();
74-
| ^^^^^^^^^^^^^^^^^^^^ help: consider adding parentheses to clarify your intent: `-(1.0_f64.sin().cos())`
75-
76-
error: aborting due to 12 previous errors
46+
error: aborting due to 7 previous errors
7747

‎tests/ui/unnecessary_cast.fixed

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -206,7 +206,7 @@ mod fixable {
206206

207207
fn issue_9563() {
208208
let _: f64 = (-8.0_f64).exp();
209-
#[allow(clippy::precedence)]
209+
#[allow(ambiguous_negative_literals)]
210210
let _: f64 = -8.0_f64.exp(); // should suggest `-8.0_f64.exp()` here not to change code behavior
211211
}
212212

‎tests/ui/unnecessary_cast.rs

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -206,7 +206,7 @@ mod fixable {
206206

207207
fn issue_9563() {
208208
let _: f64 = (-8.0 as f64).exp();
209-
#[allow(clippy::precedence)]
209+
#[allow(ambiguous_negative_literals)]
210210
let _: f64 = -(8.0 as f64).exp(); // should suggest `-8.0_f64.exp()` here not to change code behavior
211211
}
212212

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