mirror of
https://github.com/rust-lang/rust-clippy
synced 2024-12-19 01:24:05 +00:00
109 lines
3.6 KiB
Rust
109 lines
3.6 KiB
Rust
use clippy_utils::diagnostics::span_lint_and_sugg;
|
|
use clippy_utils::source::snippet_opt;
|
|
use clippy_utils::{match_def_path, meets_msrv, msrvs, paths};
|
|
use rustc_ast::ast::LitKind;
|
|
use rustc_errors::Applicability;
|
|
use rustc_hir::{BinOpKind, Expr, ExprKind, GenericArg, QPath};
|
|
use rustc_lint::{LateContext, LateLintPass};
|
|
use rustc_middle::ty::{self, Ty};
|
|
use rustc_semver::RustcVersion;
|
|
use rustc_session::{declare_tool_lint, impl_lint_pass};
|
|
|
|
declare_clippy_lint! {
|
|
/// ### What it does
|
|
/// Checks for uses of `std::mem::size_of::<T>() * 8` when
|
|
/// `T::BITS` is available.
|
|
///
|
|
/// ### Why is this bad?
|
|
/// Can be written as the shorter `T::BITS`.
|
|
///
|
|
/// ### Example
|
|
/// ```rust
|
|
/// std::mem::size_of::<usize>() * 8;
|
|
/// ```
|
|
/// Use instead:
|
|
/// ```rust
|
|
/// usize::BITS;
|
|
/// ```
|
|
#[clippy::version = "1.60.0"]
|
|
pub MANUAL_BITS,
|
|
style,
|
|
"manual implementation of `size_of::<T>() * 8` can be simplified with `T::BITS`"
|
|
}
|
|
|
|
#[derive(Clone)]
|
|
pub struct ManualBits {
|
|
msrv: Option<RustcVersion>,
|
|
}
|
|
|
|
impl ManualBits {
|
|
#[must_use]
|
|
pub fn new(msrv: Option<RustcVersion>) -> Self {
|
|
Self { msrv }
|
|
}
|
|
}
|
|
|
|
impl_lint_pass!(ManualBits => [MANUAL_BITS]);
|
|
|
|
impl<'tcx> LateLintPass<'tcx> for ManualBits {
|
|
fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
|
|
if !meets_msrv(self.msrv.as_ref(), &msrvs::MANUAL_BITS) {
|
|
return;
|
|
}
|
|
|
|
if_chain! {
|
|
if let ExprKind::Binary(bin_op, left_expr, right_expr) = expr.kind;
|
|
if let BinOpKind::Mul = &bin_op.node;
|
|
if let Some((real_ty, resolved_ty, other_expr)) = get_one_size_of_ty(cx, left_expr, right_expr);
|
|
if matches!(resolved_ty.kind(), ty::Int(_) | ty::Uint(_));
|
|
if let ExprKind::Lit(lit) = &other_expr.kind;
|
|
if let LitKind::Int(8, _) = lit.node;
|
|
|
|
then {
|
|
span_lint_and_sugg(
|
|
cx,
|
|
MANUAL_BITS,
|
|
expr.span,
|
|
"usage of `mem::size_of::<T>()` to obtain the size of `T` in bits",
|
|
"consider using",
|
|
format!("{}::BITS", snippet_opt(cx, real_ty.span).unwrap()),
|
|
Applicability::MachineApplicable,
|
|
);
|
|
}
|
|
}
|
|
}
|
|
|
|
extract_msrv_attr!(LateContext);
|
|
}
|
|
|
|
fn get_one_size_of_ty<'tcx>(
|
|
cx: &LateContext<'tcx>,
|
|
expr1: &'tcx Expr<'_>,
|
|
expr2: &'tcx Expr<'_>,
|
|
) -> Option<(&'tcx rustc_hir::Ty<'tcx>, Ty<'tcx>, &'tcx Expr<'tcx>)> {
|
|
match (get_size_of_ty(cx, expr1), get_size_of_ty(cx, expr2)) {
|
|
(Some((real_ty, resolved_ty)), None) => Some((real_ty, resolved_ty, expr2)),
|
|
(None, Some((real_ty, resolved_ty))) => Some((real_ty, resolved_ty, expr1)),
|
|
_ => None,
|
|
}
|
|
}
|
|
|
|
fn get_size_of_ty<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) -> Option<(&'tcx rustc_hir::Ty<'tcx>, Ty<'tcx>)> {
|
|
if_chain! {
|
|
if let ExprKind::Call(count_func, _func_args) = expr.kind;
|
|
if let ExprKind::Path(ref count_func_qpath) = count_func.kind;
|
|
|
|
if let QPath::Resolved(_, count_func_path) = count_func_qpath;
|
|
if let Some(segment_zero) = count_func_path.segments.get(0);
|
|
if let Some(args) = segment_zero.args;
|
|
if let Some(GenericArg::Type(real_ty)) = args.args.get(0);
|
|
|
|
if let Some(def_id) = cx.qpath_res(count_func_qpath, count_func.hir_id).opt_def_id();
|
|
if match_def_path(cx, def_id, &paths::MEM_SIZE_OF);
|
|
then {
|
|
cx.typeck_results().node_substs(count_func.hir_id).types().next().map(|resolved_ty| (real_ty, resolved_ty))
|
|
} else {
|
|
None
|
|
}
|
|
}
|
|
}
|