102 lines
3.7 KiB
Rust
102 lines
3.7 KiB
Rust
use clippy_config::msrvs::{self, Msrv};
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use clippy_utils::diagnostics::span_lint_and_sugg;
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use clippy_utils::source::snippet_with_applicability;
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use clippy_utils::sugg::Sugg;
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use rustc_errors::Applicability;
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use rustc_hir::{Expr, ExprKind, Mutability, QPath, TyKind};
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use rustc_hir_pretty::qpath_to_string;
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use rustc_lint::LateContext;
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use rustc_middle::ty;
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use rustc_span::sym;
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use super::PTR_AS_PTR;
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enum OmitFollowedCastReason<'a> {
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None,
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Null(&'a QPath<'a>),
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NullMut(&'a QPath<'a>),
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}
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impl OmitFollowedCastReason<'_> {
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fn corresponding_item(&self) -> Option<&QPath<'_>> {
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match self {
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OmitFollowedCastReason::None => None,
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OmitFollowedCastReason::Null(x) | OmitFollowedCastReason::NullMut(x) => Some(*x),
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}
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}
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}
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pub(super) fn check(cx: &LateContext<'_>, expr: &Expr<'_>, msrv: &Msrv) {
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if !msrv.meets(msrvs::POINTER_CAST) {
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return;
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}
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if let ExprKind::Cast(cast_expr, cast_to_hir_ty) = expr.kind
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&& let (cast_from, cast_to) = (cx.typeck_results().expr_ty(cast_expr), cx.typeck_results().expr_ty(expr))
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&& let ty::RawPtr(_, from_mutbl) = cast_from.kind()
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&& let ty::RawPtr(to_pointee_ty, to_mutbl) = cast_to.kind()
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&& matches!((from_mutbl, to_mutbl),
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(Mutability::Not, Mutability::Not) | (Mutability::Mut, Mutability::Mut))
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// The `U` in `pointer::cast` have to be `Sized`
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// as explained here: https://github.com/rust-lang/rust/issues/60602.
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&& to_pointee_ty.is_sized(cx.tcx, cx.param_env)
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{
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let mut app = Applicability::MachineApplicable;
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let turbofish = match &cast_to_hir_ty.kind {
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TyKind::Infer => String::new(),
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TyKind::Ptr(mut_ty) => {
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if matches!(mut_ty.ty.kind, TyKind::Infer) {
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String::new()
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} else {
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format!(
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"::<{}>",
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snippet_with_applicability(cx, mut_ty.ty.span, "/* type */", &mut app)
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)
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}
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},
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_ => return,
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};
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// following `cast` does not compile because it fails to infer what type is expected
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// as type argument to `std::ptr::ptr_null` or `std::ptr::ptr_null_mut`, so
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// we omit following `cast`:
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let omit_cast = if let ExprKind::Call(func, []) = cast_expr.kind
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&& let ExprKind::Path(ref qpath @ QPath::Resolved(None, path)) = func.kind
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&& let Some(method_defid) = path.res.opt_def_id()
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{
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if cx.tcx.is_diagnostic_item(sym::ptr_null, method_defid) {
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OmitFollowedCastReason::Null(qpath)
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} else if cx.tcx.is_diagnostic_item(sym::ptr_null_mut, method_defid) {
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OmitFollowedCastReason::NullMut(qpath)
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} else {
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OmitFollowedCastReason::None
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}
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} else {
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OmitFollowedCastReason::None
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};
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let (help, final_suggestion) = if let Some(method) = omit_cast.corresponding_item() {
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// don't force absolute path
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let method = qpath_to_string(&cx.tcx, method);
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("try call directly", format!("{method}{turbofish}()"))
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} else {
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let cast_expr_sugg = Sugg::hir_with_applicability(cx, cast_expr, "_", &mut app);
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(
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"try `pointer::cast`, a safer alternative",
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format!("{}.cast{turbofish}()", cast_expr_sugg.maybe_par()),
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)
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};
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span_lint_and_sugg(
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cx,
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PTR_AS_PTR,
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expr.span,
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"`as` casting between raw pointers without changing its mutability",
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help,
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final_suggestion,
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app,
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);
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}
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}
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