1 files changed, 37 insertions, 21 deletions
diff --git a/src/tools/clippy/clippy_lints/src/transmute/transmutes_expressible_as_ptr_casts.rs b/src/tools/clippy/clippy_lints/src/transmute/transmutes_expressible_as_ptr_casts.rs
index b79d4e915..8530b4324 100644
--- a/src/tools/clippy/clippy_lints/src/transmute/transmutes_expressible_as_ptr_casts.rs
+++ b/src/tools/clippy/clippy_lints/src/transmute/transmutes_expressible_as_ptr_casts.rs
@@ -1,11 +1,11 @@
-use super::utils::can_be_expressed_as_pointer_cast;
+use super::utils::check_cast;
 use super::TRANSMUTES_EXPRESSIBLE_AS_PTR_CASTS;
-use clippy_utils::diagnostics::span_lint_and_then;
-use clippy_utils::sugg;
+use clippy_utils::diagnostics::span_lint_and_sugg;
+use clippy_utils::sugg::Sugg;
 use rustc_errors::Applicability;
 use rustc_hir::Expr;
 use rustc_lint::LateContext;
-use rustc_middle::ty::Ty;
+use rustc_middle::ty::{cast::CastKind, Ty};
 
 /// Checks for `transmutes_expressible_as_ptr_casts` lint.
 /// Returns `true` if it's triggered, otherwise returns `false`.
@@ -13,24 +13,40 @@ pub(super) fn check<'tcx>(
     cx: &LateContext<'tcx>,
     e: &'tcx Expr<'_>,
     from_ty: Ty<'tcx>,
+    from_ty_adjusted: bool,
     to_ty: Ty<'tcx>,
     arg: &'tcx Expr<'_>,
 ) -> bool {
-    if can_be_expressed_as_pointer_cast(cx, e, from_ty, to_ty) {
-        span_lint_and_then(
-            cx,
-            TRANSMUTES_EXPRESSIBLE_AS_PTR_CASTS,
-            e.span,
-            &format!("transmute from `{from_ty}` to `{to_ty}` which could be expressed as a pointer cast instead"),
-            |diag| {
-                if let Some(arg) = sugg::Sugg::hir_opt(cx, arg) {
-                    let sugg = arg.as_ty(to_ty.to_string()).to_string();
-                    diag.span_suggestion(e.span, "try", sugg, Applicability::MachineApplicable);
-                }
-            },
-        );
-        true
-    } else {
-        false
-    }
+    use CastKind::{AddrPtrCast, ArrayPtrCast, FnPtrAddrCast, FnPtrPtrCast, PtrAddrCast, PtrPtrCast};
+    let mut app = Applicability::MachineApplicable;
+    let sugg = match check_cast(cx, e, from_ty, to_ty) {
+        Some(PtrPtrCast | AddrPtrCast | ArrayPtrCast | FnPtrPtrCast | FnPtrAddrCast) => {
+            Sugg::hir_with_context(cx, arg, e.span.ctxt(), "..", &mut app)
+                .as_ty(to_ty.to_string())
+                .to_string()
+        },
+        Some(PtrAddrCast) if !from_ty_adjusted => Sugg::hir_with_context(cx, arg, e.span.ctxt(), "..", &mut app)
+            .as_ty(to_ty.to_string())
+            .to_string(),
+
+        // The only adjustments here would be ref-to-ptr and unsize coercions. The result of an unsize coercions can't
+        // be transmuted to a usize. For ref-to-ptr coercions, borrows need to be cast to a pointer before being cast to
+        // a usize.
+        Some(PtrAddrCast) => format!(
+            "{} as {to_ty}",
+            Sugg::hir_with_context(cx, arg, e.span.ctxt(), "..", &mut app).as_ty(from_ty)
+        ),
+        _ => return false,
+    };
+
+    span_lint_and_sugg(
+        cx,
+        TRANSMUTES_EXPRESSIBLE_AS_PTR_CASTS,
+        e.span,
+        &format!("transmute from `{from_ty}` to `{to_ty}` which could be expressed as a pointer cast instead"),
+        "try",
+        sugg,
+        app,
+    );
+    true
 }