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Diffstat (limited to '')
-rw-r--r-- | src/tools/clippy/clippy_lints/src/transmute/transmute_ptr_to_ref.rs | 84 |
1 files changed, 84 insertions, 0 deletions
diff --git a/src/tools/clippy/clippy_lints/src/transmute/transmute_ptr_to_ref.rs b/src/tools/clippy/clippy_lints/src/transmute/transmute_ptr_to_ref.rs new file mode 100644 index 000000000..5eb03275b --- /dev/null +++ b/src/tools/clippy/clippy_lints/src/transmute/transmute_ptr_to_ref.rs @@ -0,0 +1,84 @@ +use super::TRANSMUTE_PTR_TO_REF; +use clippy_utils::diagnostics::span_lint_and_then; +use clippy_utils::source::snippet_with_applicability; +use clippy_utils::{meets_msrv, msrvs, sugg}; +use rustc_errors::Applicability; +use rustc_hir::{self as hir, Expr, GenericArg, Mutability, Path, TyKind}; +use rustc_lint::LateContext; +use rustc_middle::ty::{self, Ty, TypeVisitable}; +use rustc_semver::RustcVersion; + +/// Checks for `transmute_ptr_to_ref` 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<'_>, + path: &'tcx Path<'_>, + msrv: Option<RustcVersion>, +) -> bool { + match (&from_ty.kind(), &to_ty.kind()) { + (ty::RawPtr(from_ptr_ty), ty::Ref(_, to_ref_ty, mutbl)) => { + span_lint_and_then( + cx, + TRANSMUTE_PTR_TO_REF, + e.span, + &format!( + "transmute from a pointer type (`{}`) to a reference type (`{}`)", + from_ty, to_ty + ), + |diag| { + let arg = sugg::Sugg::hir(cx, arg, ".."); + let (deref, cast) = if *mutbl == Mutability::Mut { + ("&mut *", "*mut") + } else { + ("&*", "*const") + }; + let mut app = Applicability::MachineApplicable; + + let sugg = if let Some(ty) = get_explicit_type(path) { + let ty_snip = snippet_with_applicability(cx, ty.span, "..", &mut app); + if meets_msrv(msrv, msrvs::POINTER_CAST) { + format!("{}{}.cast::<{}>()", deref, arg.maybe_par(), ty_snip) + } else if from_ptr_ty.has_erased_regions() { + sugg::make_unop(deref, arg.as_ty(format!("{} () as {} {}", cast, cast, ty_snip))) + .to_string() + } else { + sugg::make_unop(deref, arg.as_ty(format!("{} {}", cast, ty_snip))).to_string() + } + } else if from_ptr_ty.ty == *to_ref_ty { + if from_ptr_ty.has_erased_regions() { + if meets_msrv(msrv, msrvs::POINTER_CAST) { + format!("{}{}.cast::<{}>()", deref, arg.maybe_par(), to_ref_ty) + } else { + sugg::make_unop(deref, arg.as_ty(format!("{} () as {} {}", cast, cast, to_ref_ty))) + .to_string() + } + } else { + sugg::make_unop(deref, arg).to_string() + } + } else { + sugg::make_unop(deref, arg.as_ty(format!("{} {}", cast, to_ref_ty))).to_string() + }; + + diag.span_suggestion(e.span, "try", sugg, app); + }, + ); + true + }, + _ => false, + } +} + +/// Gets the type `Bar` in `…::transmute<Foo, &Bar>`. +fn get_explicit_type<'tcx>(path: &'tcx Path<'tcx>) -> Option<&'tcx hir::Ty<'tcx>> { + if let GenericArg::Type(ty) = path.segments.last()?.args?.args.get(1)? + && let TyKind::Rptr(_, ty) = &ty.kind + { + Some(ty.ty) + } else { + None + } +} |