From 25c221ec92bdf7be29335f4ea830edb9509a8ce9 Mon Sep 17 00:00:00 2001
From: Yusuke Tanaka <yusuktan@maguro.dev>
Date: Thu, 11 Feb 2021 01:27:44 +0900
Subject: [PATCH] Move transmutes_expressible_as_ptr_casts to its own module

---
 clippy_lints/src/transmute/mod.rs             | 25 ++----------
 .../transmutes_expressible_as_ptr_casts.rs    | 38 +++++++++++++++++++
 2 files changed, 42 insertions(+), 21 deletions(-)
 create mode 100644 clippy_lints/src/transmute/transmutes_expressible_as_ptr_casts.rs

diff --git a/clippy_lints/src/transmute/mod.rs b/clippy_lints/src/transmute/mod.rs
index 8cb4f6500574..3b010f39c8ab 100644
--- a/clippy_lints/src/transmute/mod.rs
+++ b/clippy_lints/src/transmute/mod.rs
@@ -6,6 +6,7 @@ mod transmute_int_to_float;
 mod transmute_ptr_to_ptr;
 mod transmute_ptr_to_ref;
 mod transmute_ref_to_ref;
+mod transmutes_expressible_as_ptr_casts;
 mod unsound_collection_transmute;
 mod useless_transmute;
 mod utils;
@@ -389,27 +390,9 @@ impl<'tcx> LateLintPass<'tcx> for Transmute {
                 if triggered {
                     return;
                 }
-
-                match (&from_ty.kind(), &to_ty.kind()) {
-                    (_, _) 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 `{}` to `{}` which could be expressed as a pointer cast instead",
-                            from_ty,
-                            to_ty
-                        ),
-                        |diag| {
-                            if let Some(arg) = sugg::Sugg::hir_opt(cx, &args[0]) {
-                                let sugg = arg.as_ty(&to_ty.to_string()).to_string();
-                                diag.span_suggestion(e.span, "try", sugg, Applicability::MachineApplicable);
-                            }
-                        }
-                    ),
-                    _ => {
-                        return;
-                    },
+                let triggered = transmutes_expressible_as_ptr_casts::check(cx, e, from_ty, to_ty, args);
+                if triggered {
+                    return;
                 }
             }
         }
diff --git a/clippy_lints/src/transmute/transmutes_expressible_as_ptr_casts.rs b/clippy_lints/src/transmute/transmutes_expressible_as_ptr_casts.rs
new file mode 100644
index 000000000000..dea896622f11
--- /dev/null
+++ b/clippy_lints/src/transmute/transmutes_expressible_as_ptr_casts.rs
@@ -0,0 +1,38 @@
+use super::utils::can_be_expressed_as_pointer_cast;
+use super::TRANSMUTES_EXPRESSIBLE_AS_PTR_CASTS;
+use crate::utils::{span_lint_and_then, sugg};
+use rustc_errors::Applicability;
+use rustc_hir::Expr;
+use rustc_lint::LateContext;
+use rustc_middle::ty::Ty;
+
+/// Checks for `transmutes_expressible_as_ptr_casts` 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<'_>],
+) -> 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 `{}` to `{}` which could be expressed as a pointer cast instead",
+                from_ty, to_ty
+            ),
+            |diag| {
+                if let Some(arg) = sugg::Sugg::hir_opt(cx, &args[0]) {
+                    let sugg = arg.as_ty(&to_ty.to_string()).to_string();
+                    diag.span_suggestion(e.span, "try", sugg, Applicability::MachineApplicable);
+                }
+            },
+        );
+        true
+    } else {
+        false
+    }
+}