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This commit is contained in:
Geoffrey Copin 2020-10-22 23:53:50 +02:00
parent bb0ce32423
commit e8f12d2f02
4 changed files with 52 additions and 31 deletions
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53
clippy_lints/src/types.rs
View file

@ -3,7 +3,6 @@
use std::borrow::Cow;
use std::cmp::Ordering;
use std::collections::BTreeMap;
use std::fmt::Display;
use if_chain::if_chain;
use rustc_ast::{FloatTy, IntTy, LitFloatType, LitIntType, LitKind, UintTy};
@ -12,7 +11,7 @@ use rustc_hir as hir;
use rustc_hir::intravisit::{walk_body, walk_expr, walk_ty, FnKind, NestedVisitorMap, Visitor};
use rustc_hir::{
BinOpKind, Block, Body, Expr, ExprKind, FnDecl, FnRetTy, FnSig, GenericArg, GenericParamKind, HirId, ImplItem,
ImplItemKind, Item, ItemKind, Lifetime, Local, MatchSource, MutTy, Mutability, Node, QPath, Stmt, StmtKind,
ImplItemKind, Item, ItemKind, Lifetime, Lit, Local, MatchSource, MutTy, Mutability, Node, QPath, Stmt, StmtKind,
TraitFn, TraitItem, TraitItemKind, TyKind, UnOp,
};
use rustc_lint::{LateContext, LateLintPass, LintContext};
@ -1225,7 +1224,8 @@ declare_clippy_lint! {
}
declare_clippy_lint! {
/// **What it does:** Checks for casts to the same type.
/// **What it does:** Checks for casts to the same type, casts of int literals to integer types
/// and casts of float literals to float types.
///
/// **Why is this bad?** It's just unnecessary.
///
@ -1234,6 +1234,7 @@ declare_clippy_lint! {
/// **Example:**
/// ```rust
/// let _ = 2i32 as i32;
/// let _ = 0.5 as f32;
/// ```
pub UNNECESSARY_CAST,
complexity,
@ -1599,7 +1600,9 @@ impl<'tcx> LateLintPass<'tcx> for Casts {
if let ExprKind::Cast(ref ex, _) = expr.kind {
let (cast_from, cast_to) = (cx.typeck_results().expr_ty(ex), cx.typeck_results().expr_ty(expr));
lint_fn_to_numeric_cast(cx, expr, ex, cast_from, cast_to);
if let ExprKind::Lit(ref lit) = ex.kind {
if let Some(lit) = get_numeric_literal(ex) {
let literal_str = snippet_opt(cx, lit.span).unwrap_or_default();
if_chain! {
if let LitKind::Int(n, _) = lit.node;
if let Some(src) = snippet_opt(cx, lit.span);
@ -1609,25 +1612,19 @@ impl<'tcx> LateLintPass<'tcx> for Casts {
let to_nbits = fp_ty_mantissa_nbits(cast_to);
if from_nbits != 0 && to_nbits != 0 && from_nbits <= to_nbits && num_lit.is_decimal();
then {
show_unnecessary_cast(cx, expr, n , cast_from, cast_to);
show_unnecessary_cast(cx, expr, num_lit.integer, cast_from, cast_to);
return;
}
}
match lit.node {
LitKind::Int(num, LitIntType::Unsuffixed) if cast_to.is_integral() => {
show_unnecessary_cast(cx, expr, num, cast_from, cast_to);
return;
LitKind::Int(_, LitIntType::Unsuffixed) if cast_to.is_integral() => {
show_unnecessary_cast(cx, expr, &literal_str, cast_from, cast_to);
},
LitKind::Float(num, LitFloatType::Unsuffixed) if cast_to.is_floating_point() => {
show_unnecessary_cast(cx, expr, num, cast_from, cast_to);
return;
LitKind::Float(_, LitFloatType::Unsuffixed) if cast_to.is_floating_point() => {
show_unnecessary_cast(cx, expr, &literal_str, cast_from, cast_to);
},
_ => (),
};
match lit.node {
LitKind::Int(_, LitIntType::Unsuffixed) | LitKind::Float(_, LitFloatType::Unsuffixed) => {},
LitKind::Int(_, LitIntType::Unsuffixed) | LitKind::Float(_, LitFloatType::Unsuffixed) => (),
_ => {
if cast_from.kind() == cast_to.kind() && !in_external_macro(cx.sess(), expr.span) {
span_lint(
@ -1652,13 +1649,21 @@ impl<'tcx> LateLintPass<'tcx> for Casts {
}
}
fn show_unnecessary_cast<Num: Display>(
cx: &LateContext<'_>,
expr: &Expr<'_>,
num: Num,
cast_from: Ty<'_>,
cast_to: Ty<'_>,
) {
fn get_numeric_literal<'e>(expr: &'e Expr<'e>) -> Option<&'e Lit> {
match expr.kind {
ExprKind::Lit(ref lit) => Some(lit),
ExprKind::Unary(UnOp::UnNeg, e) => {
if let ExprKind::Lit(ref lit) = e.kind {
Some(lit)
} else {
None
}
},
_ => None,
}
}
fn show_unnecessary_cast(cx: &LateContext<'_>, expr: &Expr<'_>, literal_str: &str, cast_from: Ty<'_>, cast_to: Ty<'_>) {
let literal_kind_name = if cast_from.is_integral() { "integer" } else { "float" };
span_lint_and_sugg(
cx,
@ -1666,7 +1671,7 @@ fn show_unnecessary_cast<Num: Display>(
expr.span,
&format!("casting {} literal to `{}` is unnecessary", literal_kind_name, cast_to),
"try",
format!("{}_{}", num, cast_to),
format!("{}_{}", literal_str, cast_to),
Applicability::MachineApplicable,
);
}

6
tests/ui/unnecessary_cast_fixable.fixed
View file

@ -20,8 +20,10 @@ fn main() {
0b11 as f64;
1_u32;
16_i32;
2_usize;
0x10_i32;
0b10_usize;
0o73_u16;
1_000_000_000_u32;
1.0_f64;
0.5_f32;

2
tests/ui/unnecessary_cast_fixable.rs
View file

@ -22,6 +22,8 @@ fn main() {
1 as u32;
0x10 as i32;
0b10 as usize;
0o73 as u16;
1_000_000_000 as u32;
1.0 as f64;
0.5 as f32;

22
tests/ui/unnecessary_cast_fixable.stderr
View file

@ -28,25 +28,37 @@ error: casting integer literal to `i32` is unnecessary
--> $DIR/unnecessary_cast_fixable.rs:23:5
|
LL | 0x10 as i32;
| ^^^^^^^^^^^ help: try: `16_i32`
| ^^^^^^^^^^^ help: try: `0x10_i32`
error: casting integer literal to `usize` is unnecessary
--> $DIR/unnecessary_cast_fixable.rs:24:5
|
LL | 0b10 as usize;
| ^^^^^^^^^^^^^ help: try: `2_usize`
| ^^^^^^^^^^^^^ help: try: `0b10_usize`
error: casting integer literal to `u16` is unnecessary
--> $DIR/unnecessary_cast_fixable.rs:25:5
|
LL | 0o73 as u16;
| ^^^^^^^^^^^ help: try: `0o73_u16`
error: casting integer literal to `u32` is unnecessary
--> $DIR/unnecessary_cast_fixable.rs:26:5
|
LL | 1_000_000_000 as u32;
| ^^^^^^^^^^^^^^^^^^^^ help: try: `1_000_000_000_u32`
error: casting float literal to `f64` is unnecessary
--> $DIR/unnecessary_cast_fixable.rs:26:5
--> $DIR/unnecessary_cast_fixable.rs:28:5
|
LL | 1.0 as f64;
| ^^^^^^^^^^ help: try: `1.0_f64`
error: casting float literal to `f32` is unnecessary
--> $DIR/unnecessary_cast_fixable.rs:27:5
--> $DIR/unnecessary_cast_fixable.rs:29:5
|
LL | 0.5 as f32;
| ^^^^^^^^^^ help: try: `0.5_f32`
error: aborting due to 8 previous errors
error: aborting due to 10 previous errors