Allow various type erasure patterns in transmute_undefined_repr
This commit is contained in:
Jason Newcomb
parent
01732b6019
commit
447a24588a
@ -1,11 +1,11 @@
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use clippy_utils::diagnostics::span_lint;
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use clippy_utils::is_hir_ty_cfg_dependant;
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use clippy_utils::ty::is_c_void;
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use if_chain::if_chain;
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use rustc_hir::{Expr, ExprKind, GenericArg};
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use rustc_lint::LateContext;
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use rustc_middle::ty::layout::LayoutOf;
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use rustc_middle::ty::{self, Ty};
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use rustc_span::symbol::sym;
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use super::CAST_PTR_ALIGNMENT;
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@ -62,19 +62,3 @@ fn lint_cast_ptr_alignment<'tcx>(cx: &LateContext<'tcx>, expr: &Expr<'_>, cast_f
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}
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}
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}
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/// Check if the given type is either `core::ffi::c_void` or
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/// one of the platform specific `libc::<platform>::c_void` of libc.
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fn is_c_void(cx: &LateContext<'_>, ty: Ty<'_>) -> bool {
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if let ty::Adt(adt, _) = ty.kind() {
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let names = cx.get_def_path(adt.did);
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if names.is_empty() {
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return false;
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}
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if names[0] == sym::libc || names[0] == sym::core && *names.last().unwrap() == sym!(c_void) {
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return true;
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}
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}
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false
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}
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@ -1,5 +1,6 @@
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use super::TRANSMUTE_UNDEFINED_REPR;
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use clippy_utils::diagnostics::span_lint_and_then;
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use clippy_utils::ty::is_c_void;
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use rustc_hir::Expr;
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use rustc_lint::LateContext;
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use rustc_middle::ty::subst::{GenericArg, Subst};
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@ -100,7 +101,8 @@ pub(super) fn check<'tcx>(
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from_ty: from_sub_ty,
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to_ty: to_sub_ty,
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} => match (reduce_ty(cx, from_sub_ty), reduce_ty(cx, to_sub_ty)) {
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(ReducedTy::IntArray, _) | (_, ReducedTy::IntArray) => return false,
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(ReducedTy::IntArray | ReducedTy::TypeErasure, _)
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| (_, ReducedTy::IntArray | ReducedTy::TypeErasure) => return false,
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(ReducedTy::UnorderedFields(from_ty), ReducedTy::UnorderedFields(to_ty)) if from_ty != to_ty => {
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span_lint_and_then(
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cx,
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@ -228,8 +230,10 @@ fn reduce_refs<'tcx>(
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}
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enum ReducedTy<'tcx> {
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/// The type is a struct containing either zero sized fields, or multiple sized fields with a
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/// defined order.
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/// The type can be used for type erasure.
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TypeErasure,
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/// The type is a struct containing either zero non-zero sized fields, or multiple non-zero
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/// sized fields with a defined order.
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OrderedFields(Ty<'tcx>),
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/// The type is a struct containing multiple non-zero sized fields with no defined order.
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UnorderedFields(Ty<'tcx>),
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@ -252,6 +256,7 @@ fn reduce_ty<'tcx>(cx: &LateContext<'tcx>, mut ty: Ty<'tcx>) -> ReducedTy<'tcx>
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ty = sub_ty;
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continue;
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},
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ty::Tuple(args) if args.is_empty() => ReducedTy::TypeErasure,
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ty::Tuple(args) => {
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let mut iter = args.iter().map(GenericArg::expect_ty);
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let Some(sized_ty) = iter.find(|ty| !is_zero_sized_ty(cx, ty)) else {
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@ -270,7 +275,7 @@ fn reduce_ty<'tcx>(cx: &LateContext<'tcx>, mut ty: Ty<'tcx>) -> ReducedTy<'tcx>
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.iter()
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.map(|f| cx.tcx.type_of(f.did).subst(cx.tcx, substs));
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let Some(sized_ty) = iter.find(|ty| !is_zero_sized_ty(cx, ty)) else {
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return ReducedTy::OrderedFields(ty);
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return ReducedTy::TypeErasure;
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};
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if iter.all(|ty| is_zero_sized_ty(cx, ty)) {
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ty = sized_ty;
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@ -282,6 +287,10 @@ fn reduce_ty<'tcx>(cx: &LateContext<'tcx>, mut ty: Ty<'tcx>) -> ReducedTy<'tcx>
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ReducedTy::UnorderedFields(ty)
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}
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},
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ty::Adt(def, _) if def.is_enum() && (def.variants.is_empty() || is_c_void(cx, ty)) => {
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ReducedTy::TypeErasure
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},
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ty::Foreign(_) => ReducedTy::TypeErasure,
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ty::Ref(_, ty, _) => ReducedTy::Ref(ty),
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ty::RawPtr(ty) => ReducedTy::Ref(ty.ty),
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_ => ReducedTy::Other(ty),
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@ -1,6 +1,7 @@
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#![feature(box_patterns)]
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#![feature(control_flow_enum)]
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#![feature(let_else)]
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#![feature(let_chains)]
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#![feature(once_cell)]
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#![feature(rustc_private)]
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#![recursion_limit = "512"]
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@ -572,3 +572,17 @@ pub fn get_discriminant_value(tcx: TyCtxt<'_>, adt: &'_ AdtDef, i: VariantIdx) -
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},
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}
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}
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/// Check if the given type is either `core::ffi::c_void`, `std::os::raw::c_void`, or one of the
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/// platform specific `libc::<platform>::c_void` types in libc.
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pub fn is_c_void(cx: &LateContext<'_>, ty: Ty<'_>) -> bool {
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if let ty::Adt(adt, _) = ty.kind()
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&& let &[krate, .., name] = &*cx.get_def_path(adt.did)
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&& let sym::libc | sym::core | sym::std = krate
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&& name.as_str() == "c_void"
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{
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true
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} else {
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false
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}
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}
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@ -1,6 +1,9 @@
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#![warn(clippy::transmute_undefined_repr)]
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#![allow(clippy::unit_arg)]
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use core::ffi::c_void;
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use core::mem::transmute;
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fn value<T>() -> T {
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unimplemented!()
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}
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@ -14,49 +17,60 @@ fn value<T>() -> T {
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fn main() {
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unsafe {
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let _: () = core::mem::transmute(value::<Empty>());
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let _: Empty = core::mem::transmute(value::<()>());
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let _: () = transmute(value::<Empty>());
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let _: Empty = transmute(value::<()>());
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let _: Ty<u32> = core::mem::transmute(value::<u32>());
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let _: Ty<u32> = core::mem::transmute(value::<u32>());
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let _: Ty<u32> = transmute(value::<u32>());
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let _: Ty<u32> = transmute(value::<u32>());
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let _: Ty2C<u32, i32> = core::mem::transmute(value::<Ty2<u32, i32>>()); // Lint, Ty2 is unordered
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let _: Ty2<u32, i32> = core::mem::transmute(value::<Ty2C<u32, i32>>()); // Lint, Ty2 is unordered
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let _: Ty2C<u32, i32> = transmute(value::<Ty2<u32, i32>>()); // Lint, Ty2 is unordered
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let _: Ty2<u32, i32> = transmute(value::<Ty2C<u32, i32>>()); // Lint, Ty2 is unordered
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let _: Ty2<u32, i32> = core::mem::transmute(value::<Ty<Ty2<u32, i32>>>()); // Ok, Ty2 types are the same
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let _: Ty<Ty2<u32, i32>> = core::mem::transmute(value::<Ty2<u32, i32>>()); // Ok, Ty2 types are the same
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let _: Ty2<u32, i32> = transmute(value::<Ty<Ty2<u32, i32>>>()); // Ok, Ty2 types are the same
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let _: Ty<Ty2<u32, i32>> = transmute(value::<Ty2<u32, i32>>()); // Ok, Ty2 types are the same
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let _: Ty2<u32, f32> = core::mem::transmute(value::<Ty<Ty2<u32, i32>>>()); // Lint, different Ty2 instances
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let _: Ty<Ty2<u32, i32>> = core::mem::transmute(value::<Ty2<u32, f32>>()); // Lint, different Ty2 instances
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let _: Ty2<u32, f32> = transmute(value::<Ty<Ty2<u32, i32>>>()); // Lint, different Ty2 instances
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let _: Ty<Ty2<u32, i32>> = transmute(value::<Ty2<u32, f32>>()); // Lint, different Ty2 instances
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let _: Ty<&()> = core::mem::transmute(value::<&()>());
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let _: &() = core::mem::transmute(value::<Ty<&()>>());
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let _: Ty<&()> = transmute(value::<&()>());
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let _: &() = transmute(value::<Ty<&()>>());
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let _: &Ty2<u32, f32> = core::mem::transmute(value::<Ty<&Ty2<u32, i32>>>()); // Lint, different Ty2 instances
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let _: Ty<&Ty2<u32, i32>> = core::mem::transmute(value::<&Ty2<u32, f32>>()); // Lint, different Ty2 instances
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let _: &Ty2<u32, f32> = transmute(value::<Ty<&Ty2<u32, i32>>>()); // Lint, different Ty2 instances
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let _: Ty<&Ty2<u32, i32>> = transmute(value::<&Ty2<u32, f32>>()); // Lint, different Ty2 instances
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let _: Ty<usize> = core::mem::transmute(value::<&Ty2<u32, i32>>()); // Ok, pointer to usize conversion
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let _: &Ty2<u32, i32> = core::mem::transmute(value::<Ty<usize>>()); // Ok, pointer to usize conversion
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let _: Ty<usize> = transmute(value::<&Ty2<u32, i32>>()); // Ok, pointer to usize conversion
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let _: &Ty2<u32, i32> = transmute(value::<Ty<usize>>()); // Ok, pointer to usize conversion
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let _: Ty<[u8; 8]> = core::mem::transmute(value::<Ty2<u32, i32>>()); // Ok, transmute to byte array
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let _: Ty2<u32, i32> = core::mem::transmute(value::<Ty<[u8; 8]>>()); // Ok, transmute from byte array
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let _: Ty<[u8; 8]> = transmute(value::<Ty2<u32, i32>>()); // Ok, transmute to byte array
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let _: Ty2<u32, i32> = transmute(value::<Ty<[u8; 8]>>()); // Ok, transmute from byte array
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// issue #8417
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let _: Ty2C<Ty2<u32, i32>, ()> = core::mem::transmute(value::<Ty2<u32, i32>>()); // Ok, Ty2 types are the same
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let _: Ty2<u32, i32> = core::mem::transmute(value::<Ty2C<Ty2<u32, i32>, ()>>()); // Ok, Ty2 types are the same
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let _: Ty2C<Ty2<u32, i32>, ()> = transmute(value::<Ty2<u32, i32>>()); // Ok, Ty2 types are the same
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let _: Ty2<u32, i32> = transmute(value::<Ty2C<Ty2<u32, i32>, ()>>()); // Ok, Ty2 types are the same
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// Ty2 types are the same
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let _: &'static mut Ty2<u32, u32> = core::mem::transmute(value::<Box<Ty2<u32, u32>>>()); // Ok
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// Ty2 types are the same
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let _: Box<Ty2<u32, u32>> = core::mem::transmute(value::<&'static mut Ty2<u32, u32>>()); // Ok
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let _: *mut Ty2<u32, u32> = core::mem::transmute(value::<Box<Ty2<u32, u32>>>()); // Ok, Ty2 types are the same
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let _: Box<Ty2<u32, u32>> = core::mem::transmute(value::<*mut Ty2<u32, u32>>()); // Ok, Ty2 types are the same
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let _: &'static mut Ty2<u32, u32> = transmute(value::<Box<Ty2<u32, u32>>>()); // Ok, Ty2 types are the same
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let _: Box<Ty2<u32, u32>> = transmute(value::<&'static mut Ty2<u32, u32>>()); // Ok, Ty2 types are the same
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let _: *mut Ty2<u32, u32> = transmute(value::<Box<Ty2<u32, u32>>>()); // Ok, Ty2 types are the same
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let _: Box<Ty2<u32, u32>> = transmute(value::<*mut Ty2<u32, u32>>()); // Ok, Ty2 types are the same
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// Different Ty2 instances
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let _: &'static mut Ty2<u32, f32> = core::mem::transmute(value::<Box<Ty2<u32, u32>>>()); // Lint
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// Different Ty2 instances
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let _: Box<Ty2<u32, u32>> = core::mem::transmute(value::<&'static mut Ty2<u32, f32>>()); // Lint
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let _: &'static mut Ty2<u32, f32> = transmute(value::<Box<Ty2<u32, u32>>>()); // Lint, different Ty2 instances
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let _: Box<Ty2<u32, u32>> = transmute(value::<&'static mut Ty2<u32, f32>>()); // Lint, different Ty2 instances
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let _: *const () = transmute(value::<Ty<&Ty2<u32, f32>>>()); // Ok, type erasure
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let _: Ty<&Ty2<u32, f32>> = transmute(value::<*const ()>()); // Ok, reverse type erasure
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let _: *const c_void = transmute(value::<Ty<&Ty2<u32, f32>>>()); // Ok, type erasure
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let _: Ty<&Ty2<u32, f32>> = transmute(value::<*const c_void>()); // Ok, reverse type erasure
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enum Erase {}
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let _: *const Erase = transmute(value::<Ty<&Ty2<u32, f32>>>()); // Ok, type erasure
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let _: Ty<&Ty2<u32, f32>> = transmute(value::<*const Erase>()); // Ok, reverse type erasure
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struct Erase2(
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[u8; 0],
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core::marker::PhantomData<(*mut u8, core::marker::PhantomPinned)>,
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);
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let _: *const Erase2 = transmute(value::<Ty<&Ty2<u32, f32>>>()); // Ok, type erasure
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let _: Ty<&Ty2<u32, f32>> = transmute(value::<*const Erase2>()); // Ok, reverse type erasure
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}
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}
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@ -1,62 +1,62 @@
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error: transmute from `Ty2<u32, i32>` which has an undefined layout
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--> $DIR/transmute_undefined_repr.rs:23:33
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--> $DIR/transmute_undefined_repr.rs:26:33
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LL | let _: Ty2C<u32, i32> = core::mem::transmute(value::<Ty2<u32, i32>>()); // Lint, Ty2 is unordered
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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LL | let _: Ty2C<u32, i32> = transmute(value::<Ty2<u32, i32>>()); // Lint, Ty2 is unordered
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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= note: `-D clippy::transmute-undefined-repr` implied by `-D warnings`
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error: transmute into `Ty2<u32, i32>` which has an undefined layout
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--> $DIR/transmute_undefined_repr.rs:24:32
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--> $DIR/transmute_undefined_repr.rs:27:32
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LL | let _: Ty2<u32, i32> = core::mem::transmute(value::<Ty2C<u32, i32>>()); // Lint, Ty2 is unordered
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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LL | let _: Ty2<u32, i32> = transmute(value::<Ty2C<u32, i32>>()); // Lint, Ty2 is unordered
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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error: transmute from `Ty<Ty2<u32, i32>>` to `Ty2<u32, f32>`, both of which have an undefined layout
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--> $DIR/transmute_undefined_repr.rs:29:32
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--> $DIR/transmute_undefined_repr.rs:32:32
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LL | let _: Ty2<u32, f32> = core::mem::transmute(value::<Ty<Ty2<u32, i32>>>()); // Lint, different Ty2 instances
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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LL | let _: Ty2<u32, f32> = transmute(value::<Ty<Ty2<u32, i32>>>()); // Lint, different Ty2 instances
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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= note: two instances of the same generic type (`Ty2`) may have different layouts
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error: transmute from `Ty2<u32, f32>` to `Ty<Ty2<u32, i32>>`, both of which have an undefined layout
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--> $DIR/transmute_undefined_repr.rs:30:36
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--> $DIR/transmute_undefined_repr.rs:33:36
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LL | let _: Ty<Ty2<u32, i32>> = core::mem::transmute(value::<Ty2<u32, f32>>()); // Lint, different Ty2 instances
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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LL | let _: Ty<Ty2<u32, i32>> = transmute(value::<Ty2<u32, f32>>()); // Lint, different Ty2 instances
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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|
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= note: two instances of the same generic type (`Ty2`) may have different layouts
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error: transmute from `Ty<&Ty2<u32, i32>>` to `&Ty2<u32, f32>`, both of which have an undefined layout
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--> $DIR/transmute_undefined_repr.rs:35:33
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--> $DIR/transmute_undefined_repr.rs:38:33
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LL | let _: &Ty2<u32, f32> = core::mem::transmute(value::<Ty<&Ty2<u32, i32>>>()); // Lint, different Ty2 instances
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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LL | let _: &Ty2<u32, f32> = transmute(value::<Ty<&Ty2<u32, i32>>>()); // Lint, different Ty2 instances
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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|
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= note: two instances of the same generic type (`Ty2`) may have different layouts
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error: transmute from `&Ty2<u32, f32>` to `Ty<&Ty2<u32, i32>>`, both of which have an undefined layout
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--> $DIR/transmute_undefined_repr.rs:36:37
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--> $DIR/transmute_undefined_repr.rs:39:37
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LL | let _: Ty<&Ty2<u32, i32>> = core::mem::transmute(value::<&Ty2<u32, f32>>()); // Lint, different Ty2 instances
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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LL | let _: Ty<&Ty2<u32, i32>> = transmute(value::<&Ty2<u32, f32>>()); // Lint, different Ty2 instances
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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|
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= note: two instances of the same generic type (`Ty2`) may have different layouts
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error: transmute from `std::boxed::Box<Ty2<u32, u32>>` to `&mut Ty2<u32, f32>`, both of which have an undefined layout
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--> $DIR/transmute_undefined_repr.rs:56:45
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LL | let _: &'static mut Ty2<u32, f32> = core::mem::transmute(value::<Box<Ty2<u32, u32>>>()); // Lint
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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LL | let _: &'static mut Ty2<u32, f32> = transmute(value::<Box<Ty2<u32, u32>>>()); // Lint, different Ty2 instances
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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|
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= note: two instances of the same generic type (`Ty2`) may have different layouts
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error: transmute from `&mut Ty2<u32, f32>` to `std::boxed::Box<Ty2<u32, u32>>`, both of which have an undefined layout
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--> $DIR/transmute_undefined_repr.rs:58:37
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--> $DIR/transmute_undefined_repr.rs:57:37
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LL | let _: Box<Ty2<u32, u32>> = core::mem::transmute(value::<&'static mut Ty2<u32, f32>>()); // Lint
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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LL | let _: Box<Ty2<u32, u32>> = transmute(value::<&'static mut Ty2<u32, f32>>()); // Lint, different Ty2 instances
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
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|
|
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= note: two instances of the same generic type (`Ty2`) may have different layouts
|
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|
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|
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Reference in New Issue
Block a user