mirror of
https://github.com/rust-lang/rust-clippy
synced 2024-12-30 15:03:36 +00:00
104 lines
4.2 KiB
Rust
104 lines
4.2 KiB
Rust
use crate::utils::{is_normalizable, last_path_segment, snippet};
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use if_chain::if_chain;
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use rustc_hir::{Expr, GenericArg, QPath, TyKind};
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use rustc_lint::LateContext;
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use rustc_middle::ty::{self, cast::CastKind, Ty};
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use rustc_span::DUMMY_SP;
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use rustc_typeck::check::{cast::CastCheck, FnCtxt, Inherited};
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/// Gets the snippet of `Bar` in `…::transmute<Foo, &Bar>`. If that snippet is
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/// not available , use
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/// the type's `ToString` implementation. In weird cases it could lead to types
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/// with invalid `'_`
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/// lifetime, but it should be rare.
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pub(super) fn get_type_snippet(cx: &LateContext<'_>, path: &QPath<'_>, to_ref_ty: Ty<'_>) -> String {
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let seg = last_path_segment(path);
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if_chain! {
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if let Some(ref params) = seg.args;
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if !params.parenthesized;
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if let Some(to_ty) = params.args.iter().filter_map(|arg| match arg {
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GenericArg::Type(ty) => Some(ty),
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_ => None,
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}).nth(1);
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if let TyKind::Rptr(_, ref to_ty) = to_ty.kind;
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then {
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return snippet(cx, to_ty.ty.span, &to_ref_ty.to_string()).to_string();
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}
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}
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to_ref_ty.to_string()
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}
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// check if the component types of the transmuted collection and the result have different ABI,
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// size or alignment
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pub(super) fn is_layout_incompatible<'tcx>(cx: &LateContext<'tcx>, from: Ty<'tcx>, to: Ty<'tcx>) -> bool {
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let empty_param_env = ty::ParamEnv::empty();
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// check if `from` and `to` are normalizable to avoid ICE (#4968)
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if !(is_normalizable(cx, empty_param_env, from) && is_normalizable(cx, empty_param_env, to)) {
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return false;
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}
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let from_ty_layout = cx.tcx.layout_of(empty_param_env.and(from));
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let to_ty_layout = cx.tcx.layout_of(empty_param_env.and(to));
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if let (Ok(from_layout), Ok(to_layout)) = (from_ty_layout, to_ty_layout) {
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from_layout.size != to_layout.size || from_layout.align != to_layout.align || from_layout.abi != to_layout.abi
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} else {
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// no idea about layout, so don't lint
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false
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}
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}
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/// Check if the type conversion can be expressed as a pointer cast, instead of
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/// a transmute. In certain cases, including some invalid casts from array
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/// references to pointers, this may cause additional errors to be emitted and/or
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/// ICE error messages. This function will panic if that occurs.
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pub(super) fn can_be_expressed_as_pointer_cast<'tcx>(
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cx: &LateContext<'tcx>,
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e: &'tcx Expr<'_>,
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from_ty: Ty<'tcx>,
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to_ty: Ty<'tcx>,
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) -> bool {
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use CastKind::{AddrPtrCast, ArrayPtrCast, FnPtrAddrCast, FnPtrPtrCast, PtrAddrCast, PtrPtrCast};
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matches!(
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check_cast(cx, e, from_ty, to_ty),
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Some(PtrPtrCast | PtrAddrCast | AddrPtrCast | ArrayPtrCast | FnPtrPtrCast | FnPtrAddrCast)
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)
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}
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/// If a cast from `from_ty` to `to_ty` is valid, returns an Ok containing the kind of
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/// the cast. In certain cases, including some invalid casts from array references
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/// to pointers, this may cause additional errors to be emitted and/or ICE error
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/// messages. This function will panic if that occurs.
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fn check_cast<'tcx>(cx: &LateContext<'tcx>, e: &'tcx Expr<'_>, from_ty: Ty<'tcx>, to_ty: Ty<'tcx>) -> Option<CastKind> {
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let hir_id = e.hir_id;
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let local_def_id = hir_id.owner;
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Inherited::build(cx.tcx, local_def_id).enter(|inherited| {
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let fn_ctxt = FnCtxt::new(&inherited, cx.param_env, hir_id);
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// If we already have errors, we can't be sure we can pointer cast.
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assert!(
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!fn_ctxt.errors_reported_since_creation(),
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"Newly created FnCtxt contained errors"
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);
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if let Ok(check) = CastCheck::new(
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&fn_ctxt, e, from_ty, to_ty,
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// We won't show any error to the user, so we don't care what the span is here.
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DUMMY_SP, DUMMY_SP,
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) {
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let res = check.do_check(&fn_ctxt);
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// do_check's documentation says that it might return Ok and create
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// errors in the fcx instead of returing Err in some cases. Those cases
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// should be filtered out before getting here.
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assert!(
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!fn_ctxt.errors_reported_since_creation(),
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"`fn_ctxt` contained errors after cast check!"
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);
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res.ok()
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} else {
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None
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}
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})
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}
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