Merge tag 'debian/1.52.1+dfsg1-1_exp2' into proxmox/buster

[rustc.git] / src / tools / clippy / clippy_lints / src / transmute / transmute_ptr_to_ref.rs

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 (file)
index 0000000..f5dbbbe
--- /dev/null
+++ b/src/tools/clippy/clippy_lints/src/transmute/transmute_ptr_to_ref.rs
@@ -0,0 +1,55 @@
+use super::utils::get_type_snippet;
+use super::TRANSMUTE_PTR_TO_REF;
+use crate::utils::{span_lint_and_then, sugg};
+use rustc_errors::Applicability;
+use rustc_hir::{Expr, Mutability, QPath};
+use rustc_lint::LateContext;
+use rustc_middle::ty::{self, Ty};
+
+/// 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>,
+    args: &'tcx [Expr<'_>],
+    qpath: &'tcx QPath<'_>,
+) -> 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, &args[0], "..");
+                    let (deref, cast) = if *mutbl == Mutability::Mut {
+                        ("&mut *", "*mut")
+                    } else {
+                        ("&*", "*const")
+                    };
+
+                    let arg = if from_ptr_ty.ty == *to_ref_ty {
+                        arg
+                    } else {
+                        arg.as_ty(&format!("{} {}", cast, get_type_snippet(cx, qpath, to_ref_ty)))
+                    };
+
+                    diag.span_suggestion(
+                        e.span,
+                        "try",
+                        sugg::make_unop(deref, arg).to_string(),
+                        Applicability::Unspecified,
+                    );
+                },
+            );
+            true
+        },
+        _ => false,
+    }
+}