60 lines
2.1 KiB
Rust
60 lines
2.1 KiB
Rust
use super::utils::check_cast;
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use super::TRANSMUTES_EXPRESSIBLE_AS_PTR_CASTS;
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use clippy_utils::diagnostics::span_lint_and_sugg;
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use clippy_utils::sugg::Sugg;
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use rustc_ast::ExprPrecedence;
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use rustc_errors::Applicability;
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use rustc_hir::{Expr, Node};
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use rustc_lint::LateContext;
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use rustc_middle::ty::{cast::CastKind, Ty};
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/// Checks for `transmutes_expressible_as_ptr_casts` lint.
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/// Returns `true` if it's triggered, otherwise returns `false`.
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pub(super) fn check<'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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from_ty_adjusted: bool,
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to_ty: Ty<'tcx>,
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arg: &'tcx Expr<'_>,
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) -> bool {
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use CastKind::{AddrPtrCast, ArrayPtrCast, FnPtrAddrCast, FnPtrPtrCast, PtrAddrCast, PtrPtrCast};
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let mut app = Applicability::MachineApplicable;
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let mut sugg = match check_cast(cx, e, from_ty, to_ty) {
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Some(PtrPtrCast | AddrPtrCast | ArrayPtrCast | FnPtrPtrCast | FnPtrAddrCast) => {
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Sugg::hir_with_context(cx, arg, e.span.ctxt(), "..", &mut app)
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.as_ty(to_ty.to_string())
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.to_string()
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},
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Some(PtrAddrCast) if !from_ty_adjusted => Sugg::hir_with_context(cx, arg, e.span.ctxt(), "..", &mut app)
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.as_ty(to_ty.to_string())
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.to_string(),
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// The only adjustments here would be ref-to-ptr and unsize coercions. The result of an unsize coercions can't
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// be transmuted to a usize. For ref-to-ptr coercions, borrows need to be cast to a pointer before being cast to
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// a usize.
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Some(PtrAddrCast) => format!(
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"{} as {to_ty}",
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Sugg::hir_with_context(cx, arg, e.span.ctxt(), "..", &mut app).as_ty(from_ty)
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),
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_ => return false,
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};
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if let Node::Expr(parent) = cx.tcx.hir().get_parent(e.hir_id)
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&& parent.precedence().order() > ExprPrecedence::Cast.order()
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{
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sugg = format!("({sugg})");
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}
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span_lint_and_sugg(
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cx,
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TRANSMUTES_EXPRESSIBLE_AS_PTR_CASTS,
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e.span,
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&format!("transmute from `{from_ty}` to `{to_ty}` which could be expressed as a pointer cast instead"),
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"try",
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sugg,
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app,
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);
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true
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}
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