clippy_lints/src/transmute/transmute_ptr_to_ref.rs

   1 use super::utils::get_type_snippet;
   2 use super::TRANSMUTE_PTR_TO_REF;
   3 use clippy_utils::diagnostics::span_lint_and_then;
   4 use clippy_utils::sugg;
   5 use rustc_errors::Applicability;
   6 use rustc_hir::{Expr, Mutability, QPath};
   7 use rustc_lint::LateContext;
   8 use rustc_middle::ty::{self, Ty};
   9
  10 /// Checks for `transmute_ptr_to_ref` lint.
  11 /// Returns `true` if it's triggered, otherwise returns `false`.
  12 pub(super) fn check<'tcx>(
  13     cx: &LateContext<'tcx>,
  14     e: &'tcx Expr<'_>,
  15     from_ty: Ty<'tcx>,
  16     to_ty: Ty<'tcx>,
  17     args: &'tcx [Expr<'_>],
  18     qpath: &'tcx QPath<'_>,
  19 ) -> bool {
  20     match (&from_ty.kind(), &to_ty.kind()) {
  21         (ty::RawPtr(from_ptr_ty), ty::Ref(_, to_ref_ty, mutbl)) => {
  22             span_lint_and_then(
  23                 cx,
  24                 TRANSMUTE_PTR_TO_REF,
  25                 e.span,
  26                 &format!(
  27                     "transmute from a pointer type (`{}`) to a reference type (`{}`)",
  28                     from_ty, to_ty
  29                 ),
  30                 |diag| {
  31                     let arg = sugg::Sugg::hir(cx, &args[0], "..");
  32                     let (deref, cast) = if *mutbl == Mutability::Mut {
  33                         ("&mut *", "*mut")
  34                     } else {
  35                         ("&*", "*const")
  36                     };
  37
  38                     let arg = if from_ptr_ty.ty == *to_ref_ty {
  39                         arg
  40                     } else {
  41                         arg.as_ty(&format!("{} {}", cast, get_type_snippet(cx, qpath, to_ref_ty)))
  42                     };
  43
  44                     diag.span_suggestion(
  45                         e.span,
  46                         "try",
  47                         sugg::make_unop(deref, arg).to_string(),
  48                         Applicability::Unspecified,
  49                     );
  50                 },
  51             );
  52             true
  53         },
  54         _ => false,
  55     }
  56 }