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This commit is contained in:
JarredAllen 2020-03-03 15:52:53 -08:00
parent 0d584f3ff7
commit f8e949fa1c
4 changed files with 179 additions and 81 deletions
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113
clippy_lints/src/floating_point_arithmetic.rs
View File

@ -1,17 +1,17 @@
use crate::consts::{
constant, Constant,
constant, constant_simple, Constant,
Constant::{F32, F64},
};
use crate::utils::{higher, span_lint_and_sugg, sugg, SpanlessEq};
use if_chain::if_chain;
use rustc::ty;
use rustc_errors::Applicability;
use rustc_hir::{BinOpKind, Block, Expr, ExprKind, Lit, UnOp};
use rustc_hir::{BinOpKind, Expr, ExprKind, UnOp};
use rustc_lint::{LateContext, LateLintPass};
use rustc_session::{declare_lint_pass, declare_tool_lint};
use rustc_span::source_map::Spanned;
use rustc_ast::ast::{self, FloatTy, LitFloatType, LitKind};
use rustc_ast::ast;
use std::f32::consts as f32_consts;
use std::f64::consts as f64_consts;
use sugg::{format_numeric_literal, Sugg};
@ -378,8 +378,8 @@ fn check_mul_add(cx: &LateContext<'_, '_>, expr: &Expr<'_>) {
fn is_testing_positive(cx: &LateContext<'_, '_>, expr: &Expr<'_>, test: &Expr<'_>) -> bool {
if let ExprKind::Binary(Spanned { node: op, .. }, left, right) = expr.kind {
match op {
BinOpKind::Gt | BinOpKind::Ge => is_zero(right) && are_exprs_equal(cx, left, test),
BinOpKind::Lt | BinOpKind::Le => is_zero(left) && are_exprs_equal(cx, right, test),
BinOpKind::Gt | BinOpKind::Ge => is_zero(cx, right) && are_exprs_equal(cx, left, test),
BinOpKind::Lt | BinOpKind::Le => is_zero(cx, left) && are_exprs_equal(cx, right, test),
_ => false,
}
} else {
@ -387,11 +387,12 @@ fn is_testing_positive(cx: &LateContext<'_, '_>, expr: &Expr<'_>, test: &Expr<'_
}
}
/// See [`is_testing_positive`]
fn is_testing_negative(cx: &LateContext<'_, '_>, expr: &Expr<'_>, test: &Expr<'_>) -> bool {
if let ExprKind::Binary(Spanned { node: op, .. }, left, right) = expr.kind {
match op {
BinOpKind::Gt | BinOpKind::Ge => is_zero(left) && are_exprs_equal(cx, right, test),
BinOpKind::Lt | BinOpKind::Le => is_zero(right) && are_exprs_equal(cx, left, test),
BinOpKind::Gt | BinOpKind::Ge => is_zero(cx, left) && are_exprs_equal(cx, right, test),
BinOpKind::Lt | BinOpKind::Le => is_zero(cx, right) && are_exprs_equal(cx, left, test),
_ => false,
}
} else {
@ -404,85 +405,69 @@ fn are_exprs_equal(cx: &LateContext<'_, '_>, expr1: &Expr<'_>, expr2: &Expr<'_>)
}
/// Returns true iff expr is some zero literal
fn is_zero(expr: &Expr<'_>) -> bool {
if let ExprKind::Lit(Lit { node: lit, .. }) = &expr.kind {
match lit {
LitKind::Int(0, _) => true,
LitKind::Float(symb, LitFloatType::Unsuffixed)
| LitKind::Float(symb, LitFloatType::Suffixed(FloatTy::F64)) => {
symb.as_str().parse::<f64>().unwrap() == 0.0
},
LitKind::Float(symb, LitFloatType::Suffixed(FloatTy::F32)) => symb.as_str().parse::<f32>().unwrap() == 0.0,
_ => false,
}
} else {
false
fn is_zero(cx: &LateContext<'_, '_>, expr: &Expr<'_>) -> bool {
match constant_simple(cx, cx.tables, expr) {
Some(Constant::Int(i)) => i == 0,
Some(Constant::F32(f)) => f == 0.0,
Some(Constant::F64(f)) => f == 0.0,
_ => false,
}
}
/// If the expressions are not opposites, return None
/// Otherwise, return true if expr2 = -expr1, false if expr1 = -expr2 and return the positive
/// expression
fn are_opposites<'a>(
/// If the two expressions are negations of each other, then it returns
/// a tuple, in which the first element is true iff expr1 is the
/// positive expressions, and the second element is the positive
/// one of the two expressions
/// If the two expressions are not negations of each other, then it
/// returns None.
fn are_negated<'a>(
cx: &LateContext<'_, '_>,
expr1: &'a Expr<'a>,
expr2: &'a Expr<'a>,
) -> Option<(bool, &'a Expr<'a>)> {
if let ExprKind::Block(
Block {
stmts: [],
expr: Some(expr1_inner),
..
},
_,
) = &expr1.kind
{
if let ExprKind::Block(
Block {
stmts: [],
expr: Some(expr2_inner),
..
},
_,
) = &expr2.kind
{
if let ExprKind::Unary(UnOp::UnNeg, expr1_neg) = &expr1_inner.kind {
if are_exprs_equal(cx, expr1_neg, expr2_inner) {
return Some((false, expr2_inner));
}
}
if let ExprKind::Unary(UnOp::UnNeg, expr2_neg) = &expr2_inner.kind {
if are_exprs_equal(cx, expr1_inner, expr2_neg) {
return Some((true, expr1_inner));
}
}
if let ExprKind::Unary(UnOp::UnNeg, expr1_negated) = &expr1.kind {
if are_exprs_equal(cx, expr1_negated, expr2) {
return Some((false, expr2));
}
}
if let ExprKind::Unary(UnOp::UnNeg, expr2_negated) = &expr2.kind {
if are_exprs_equal(cx, expr1, expr2_negated) {
return Some((true, expr1));
}
}
None
}
fn check_custom_abs(cx: &LateContext<'_, '_>, expr: &Expr<'_>) {
if let Some((cond, body, Some(else_body))) = higher::if_block(&expr) {
if let Some((expr1_pos, body)) = are_opposites(cx, body, else_body) {
let pos_abs_sugg = (
"This looks like you've implemented your own absolute value function",
if_chain! {
if let Some((cond, body, Some(else_body))) = higher::if_block(&expr);
if let ExprKind::Block(block, _) = body.kind;
if block.stmts.is_empty();
if let Some(if_body_expr) = block.expr;
if let ExprKind::Block(else_block, _) = else_body.kind;
if else_block.stmts.is_empty();
if let Some(else_body_expr) = else_block.expr;
if let Some((if_expr_positive, body)) = are_negated(cx, if_body_expr, else_body_expr);
then {
let positive_abs_sugg = (
"manual implementation of `abs` method",
format!("{}.abs()", Sugg::hir(cx, body, "..")),
);
let neg_abs_sugg = (
"This looks like you've implemented your own negative absolute value function",
let negative_abs_sugg = (
"manual implementation of negation of `abs` method",
format!("-{}.abs()", Sugg::hir(cx, body, "..")),
);
let sugg = if is_testing_positive(cx, cond, body) {
if expr1_pos {
pos_abs_sugg
if if_expr_positive {
positive_abs_sugg
} else {
neg_abs_sugg
negative_abs_sugg
}
} else if is_testing_negative(cx, cond, body) {
if expr1_pos {
neg_abs_sugg
if if_expr_positive {
negative_abs_sugg
} else {
pos_abs_sugg
positive_abs_sugg
}
} else {
return;

98
tests/ui/floating_point_abs.fixed Normal file
View File

@ -0,0 +1,98 @@
// run-rustfix
#![warn(clippy::suboptimal_flops)]
struct A {
a: f64,
b: f64,
}
fn fake_abs1(num: f64) -> f64 {
num.abs()
}
fn fake_abs2(num: f64) -> f64 {
num.abs()
}
fn fake_abs3(a: A) -> f64 {
a.a.abs()
}
fn fake_abs4(num: f64) -> f64 {
num.abs()
}
fn fake_abs5(a: A) -> f64 {
a.a.abs()
}
fn fake_nabs1(num: f64) -> f64 {
-num.abs()
}
fn fake_nabs2(num: f64) -> f64 {
-num.abs()
}
fn fake_nabs3(a: A) -> A {
A {
a: -a.a.abs(),
b: a.b,
}
}
fn not_fake_abs1(num: f64) -> f64 {
if num > 0.0 {
num
} else {
-num - 1f64
}
}
fn not_fake_abs2(num: f64) -> f64 {
if num > 0.0 {
num + 1.0
} else {
-(num + 1.0)
}
}
fn not_fake_abs3(num1: f64, num2: f64) -> f64 {
if num1 > 0.0 {
num2
} else {
-num2
}
}
fn not_fake_abs4(a: A) -> f64 {
if a.a > 0.0 {
a.b
} else {
-a.b
}
}
fn not_fake_abs5(a: A) -> f64 {
if a.a > 0.0 {
a.a
} else {
-a.b
}
}
fn main() {
fake_abs1(5.0);
fake_abs2(5.0);
fake_abs3(A { a: 5.0, b: 5.0 } );
fake_abs4(5.0);
fake_abs5(A { a: 5.0, b: 5.0 } );
fake_nabs1(5.0);
fake_nabs2(5.0);
fake_nabs3(A { a: 5.0, b: 5.0 } );
not_fake_abs1(5.0);
not_fake_abs2(5.0);
not_fake_abs3(5.0, 5.0);
not_fake_abs4(A { a: 5.0, b: 5.0 } );
not_fake_abs5(A { a: 5.0, b: 5.0 } );
}

17
tests/ui/floating_point_abs.rs
View File

@ -1,3 +1,4 @@
// run-rustfix
#![warn(clippy::suboptimal_flops)]
struct A {
@ -108,4 +109,18 @@ fn not_fake_abs5(a: A) -> f64 {
}
}
fn main() {}
fn main() {
fake_abs1(5.0);
fake_abs2(5.0);
fake_abs3(A { a: 5.0, b: 5.0 } );
fake_abs4(5.0);
fake_abs5(A { a: 5.0, b: 5.0 } );
fake_nabs1(5.0);
fake_nabs2(5.0);
fake_nabs3(A { a: 5.0, b: 5.0 } );
not_fake_abs1(5.0);
not_fake_abs2(5.0);
not_fake_abs3(5.0, 5.0);
not_fake_abs4(A { a: 5.0, b: 5.0 } );
not_fake_abs5(A { a: 5.0, b: 5.0 } );
}

32
tests/ui/floating_point_abs.stderr
View File

@ -1,5 +1,5 @@
error: This looks like you've implemented your own absolute value function
--> $DIR/floating_point_abs.rs:9:5
error: manual implementation of `abs` method
--> $DIR/floating_point_abs.rs:10:5
|
LL | / if num >= 0.0 {
LL | | num
@ -10,8 +10,8 @@ LL | | }
|
= note: `-D clippy::suboptimal-flops` implied by `-D warnings`
error: This looks like you've implemented your own absolute value function
--> $DIR/floating_point_abs.rs:17:5
error: manual implementation of `abs` method
--> $DIR/floating_point_abs.rs:18:5
|
LL | / if 0.0 < num {
LL | | num
@ -20,8 +20,8 @@ LL | | -num
LL | | }
| |_____^ help: try: `num.abs()`
error: This looks like you've implemented your own absolute value function
--> $DIR/floating_point_abs.rs:25:5
error: manual implementation of `abs` method
--> $DIR/floating_point_abs.rs:26:5
|
LL | / if a.a > 0.0 {
LL | | a.a
@ -30,8 +30,8 @@ LL | | -a.a
LL | | }
| |_____^ help: try: `a.a.abs()`
error: This looks like you've implemented your own absolute value function
--> $DIR/floating_point_abs.rs:33:5
error: manual implementation of `abs` method
--> $DIR/floating_point_abs.rs:34:5
|
LL | / if 0.0 >= num {
LL | | -num
@ -40,8 +40,8 @@ LL | | num
LL | | }
| |_____^ help: try: `num.abs()`
error: This looks like you've implemented your own absolute value function
--> $DIR/floating_point_abs.rs:41:5
error: manual implementation of `abs` method
--> $DIR/floating_point_abs.rs:42:5
|
LL | / if a.a < 0.0 {
LL | | -a.a
@ -50,8 +50,8 @@ LL | | a.a
LL | | }
| |_____^ help: try: `a.a.abs()`
error: This looks like you've implemented your own negative absolute value function
--> $DIR/floating_point_abs.rs:49:5
error: manual implementation of negation of `abs` method
--> $DIR/floating_point_abs.rs:50:5
|
LL | / if num < 0.0 {
LL | | num
@ -60,8 +60,8 @@ LL | | -num
LL | | }
| |_____^ help: try: `-num.abs()`
error: This looks like you've implemented your own negative absolute value function
--> $DIR/floating_point_abs.rs:57:5
error: manual implementation of negation of `abs` method
--> $DIR/floating_point_abs.rs:58:5
|
LL | / if 0.0 >= num {
LL | | num
@ -70,8 +70,8 @@ LL | | -num
LL | | }
| |_____^ help: try: `-num.abs()`
error: This looks like you've implemented your own negative absolute value function
--> $DIR/floating_point_abs.rs:66:12
error: manual implementation of negation of `abs` method
--> $DIR/floating_point_abs.rs:67:12
|
LL | a: if a.a >= 0.0 { -a.a } else { a.a },
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `-a.a.abs()`