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Move cast_sign_loss to its own module

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This commit is contained in:
Yoshitomo Nakanishi 2021-03-09 12:37:46 +09:00
parent 0534bf4698
commit 0975031117
2 changed files with 78 additions and 66 deletions
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70
clippy_lints/src/casts/cast_sign_loss.rs Normal file
View File

@ -0,0 +1,70 @@
use rustc_hir::{Expr, ExprKind};
use rustc_lint::LateContext;
use rustc_middle::ty::{self, Ty};
use if_chain::if_chain;
use crate::consts::{constant, Constant};
use crate::utils::{method_chain_args, sext, span_lint};
use super::CAST_SIGN_LOSS;
pub(super) fn check(cx: &LateContext<'_>, expr: &Expr<'_>, cast_op: &Expr<'_>, cast_from: Ty<'_>, cast_to: Ty<'_>) {
if should_lint(cx, cast_op, cast_from, cast_to) {
span_lint(
cx,
CAST_SIGN_LOSS,
expr.span,
&format!(
"casting `{}` to `{}` may lose the sign of the value",
cast_from, cast_to
),
);
}
}
fn should_lint(cx: &LateContext<'_>, cast_op: &Expr<'_>, cast_from: Ty<'_>, cast_to: Ty<'_>) -> bool {
match (cast_from.is_integral(), cast_to.is_integral()) {
(true, true) => {
if !cast_from.is_signed() || cast_to.is_signed() {
return false;
}
// Don't lint for positive constants.
let const_val = constant(cx, &cx.typeck_results(), cast_op);
if_chain! {
if let Some((Constant::Int(n), _)) = const_val;
if let ty::Int(ity) = *cast_from.kind();
if sext(cx.tcx, n, ity) >= 0;
then {
return false;
}
}
// Don't lint for the result of methods that always return non-negative values.
if let ExprKind::MethodCall(ref path, _, _, _) = cast_op.kind {
let mut method_name = path.ident.name.as_str();
let allowed_methods = ["abs", "checked_abs", "rem_euclid", "checked_rem_euclid"];
if_chain! {
if method_name == "unwrap";
if let Some(arglist) = method_chain_args(cast_op, &["unwrap"]);
if let ExprKind::MethodCall(ref inner_path, _, _, _) = &arglist[0][0].kind;
then {
method_name = inner_path.ident.name.as_str();
}
}
if allowed_methods.iter().any(|&name| method_name == name) {
return false;
}
}
true
},
(false, true) => !cast_to.is_signed(),
(_, _) => false,
}
}

74
clippy_lints/src/casts/mod.rs
View File

@ -1,6 +1,7 @@
mod cast_lossless;
mod cast_possible_truncation;
mod cast_precision_loss;
mod cast_sign_loss;
mod utils;
use std::borrow::Cow;
@ -17,11 +18,10 @@
use rustc_span::symbol::sym;
use rustc_target::abi::LayoutOf;
use crate::consts::{constant, Constant};
use crate::utils::sugg::Sugg;
use crate::utils::{
is_hir_ty_cfg_dependant, is_isize_or_usize, meets_msrv, method_chain_args, numeric_literal::NumericLiteral, sext,
snippet_opt, snippet_with_applicability, span_lint, span_lint_and_sugg, span_lint_and_then,
is_hir_ty_cfg_dependant, is_isize_or_usize, meets_msrv, numeric_literal::NumericLiteral, snippet_opt,
snippet_with_applicability, span_lint, span_lint_and_sugg, span_lint_and_then,
};
use utils::int_ty_to_nbits;
@ -261,52 +261,6 @@ enum ArchSuffix {
None,
}
fn check_loss_of_sign(cx: &LateContext<'_>, expr: &Expr<'_>, op: &Expr<'_>, cast_from: Ty<'_>, cast_to: Ty<'_>) {
if !cast_from.is_signed() || cast_to.is_signed() {
return;
}
// don't lint for positive constants
let const_val = constant(cx, &cx.typeck_results(), op);
if_chain! {
if let Some((Constant::Int(n), _)) = const_val;
if let ty::Int(ity) = *cast_from.kind();
if sext(cx.tcx, n, ity) >= 0;
then {
return
}
}
// don't lint for the result of methods that always return non-negative values
if let ExprKind::MethodCall(ref path, _, _, _) = op.kind {
let mut method_name = path.ident.name.as_str();
let allowed_methods = ["abs", "checked_abs", "rem_euclid", "checked_rem_euclid"];
if_chain! {
if method_name == "unwrap";
if let Some(arglist) = method_chain_args(op, &["unwrap"]);
if let ExprKind::MethodCall(ref inner_path, _, _, _) = &arglist[0][0].kind;
then {
method_name = inner_path.ident.name.as_str();
}
}
if allowed_methods.iter().any(|&name| method_name == name) {
return;
}
}
span_lint(
cx,
CAST_SIGN_LOSS,
expr.span,
&format!(
"casting `{}` to `{}` may lose the sign of the value",
cast_from, cast_to
),
);
}
fn check_truncation_and_wrapping(cx: &LateContext<'_>, expr: &Expr<'_>, cast_from: Ty<'_>, cast_to: Ty<'_>) {
let arch_64_suffix = " on targets with 64-bit wide pointers";
let arch_32_suffix = " on targets with 32-bit wide pointers";
@ -490,29 +444,17 @@ fn show_unnecessary_cast(cx: &LateContext<'_>, expr: &Expr<'_>, literal_str: &st
fn lint_numeric_casts<'tcx>(
cx: &LateContext<'tcx>,
expr: &Expr<'tcx>,
cast_expr: &Expr<'_>,
cast_op: &Expr<'_>,
cast_from: Ty<'tcx>,
cast_to: Ty<'tcx>,
) {
cast_precision_loss::check(cx, expr, cast_from, cast_to);
cast_lossless::check(cx, expr, cast_expr, cast_from, cast_to);
cast_possible_truncation::check(cx, expr, cast_from, cast_to);
cast_precision_loss::check(cx, expr, cast_from, cast_to);
cast_lossless::check(cx, expr, cast_op, cast_from, cast_to);
cast_sign_loss::check(cx, expr, cast_op, cast_from, cast_to);
match (cast_from.is_integral(), cast_to.is_integral()) {
(false, true) => {
if !cast_to.is_signed() {
span_lint(
cx,
CAST_SIGN_LOSS,
expr.span,
&format!(
"casting `{}` to `{}` may lose the sign of the value",
cast_from, cast_to
),
);
}
},
(true, true) => {
check_loss_of_sign(cx, expr, cast_expr, cast_from, cast_to);
check_truncation_and_wrapping(cx, expr, cast_from, cast_to);
},
(_, _) => {},