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|
use super::USELESS_TRANSMUTE;
use clippy_utils::diagnostics::{span_lint, span_lint_and_then};
use clippy_utils::sugg;
use rustc_errors::Applicability;
use rustc_hir::Expr;
use rustc_lint::LateContext;
use rustc_middle::ty::{self, Ty, TypeVisitableExt};
/// Checks for `useless_transmute` lint.
/// Returns `true` if it's triggered, otherwise returns `false`.
pub(super) fn check<'tcx>(
cx: &LateContext<'tcx>,
e: &'tcx Expr<'_>,
from_ty: Ty<'tcx>,
to_ty: Ty<'tcx>,
arg: &'tcx Expr<'_>,
) -> bool {
match (&from_ty.kind(), &to_ty.kind()) {
_ if from_ty == to_ty && !from_ty.has_erased_regions() => {
span_lint(
cx,
USELESS_TRANSMUTE,
e.span,
&format!("transmute from a type (`{from_ty}`) to itself"),
);
true
},
(ty::Ref(_, rty, rty_mutbl), ty::RawPtr(ptr_ty)) => {
// No way to give the correct suggestion here. Avoid linting for now.
if !rty.has_erased_regions() {
span_lint_and_then(
cx,
USELESS_TRANSMUTE,
e.span,
"transmute from a reference to a pointer",
|diag| {
if let Some(arg) = sugg::Sugg::hir_opt(cx, arg) {
let rty_and_mut = ty::TypeAndMut {
ty: *rty,
mutbl: *rty_mutbl,
};
let sugg = if *ptr_ty == rty_and_mut {
arg.as_ty(to_ty)
} else {
arg.as_ty(cx.tcx.mk_ptr(rty_and_mut)).as_ty(to_ty)
};
diag.span_suggestion(e.span, "try", sugg, Applicability::Unspecified);
}
},
);
}
true
},
(ty::Int(_) | ty::Uint(_), ty::RawPtr(_)) => {
span_lint_and_then(
cx,
USELESS_TRANSMUTE,
e.span,
"transmute from an integer to a pointer",
|diag| {
if let Some(arg) = sugg::Sugg::hir_opt(cx, arg) {
diag.span_suggestion(e.span, "try", arg.as_ty(to_ty.to_string()), Applicability::Unspecified);
}
},
);
true
},
_ => false,
}
}
|
