From 6442d45d3a55cee14ccee14c004ea344072d54cd Mon Sep 17 00:00:00 2001
From: Yusuke Tanaka <yusuktan@maguro.dev>
Date: Thu, 11 Feb 2021 00:10:19 +0900
Subject: [PATCH] Move transmute_ptr_to_ref to its own module

---
 clippy_lints/src/transmute/mod.rs             | 36 ++----------
 .../src/transmute/transmute_ptr_to_ref.rs     | 56 +++++++++++++++++++
 2 files changed, 61 insertions(+), 31 deletions(-)
 create mode 100644 clippy_lints/src/transmute/transmute_ptr_to_ref.rs

diff --git a/clippy_lints/src/transmute/mod.rs b/clippy_lints/src/transmute/mod.rs
index 7e05771c8..f00cb9b93 100644
--- a/clippy_lints/src/transmute/mod.rs
+++ b/clippy_lints/src/transmute/mod.rs
@@ -1,4 +1,5 @@
 mod crosspointer_transmute;
+mod transmute_ptr_to_ref;
 mod useless_transmute;
 mod utils;
 mod wrong_transmute;
@@ -360,39 +361,12 @@ impl<'tcx> LateLintPass<'tcx> for Transmute {
                 if triggered {
                     return;
                 }
+                let triggered = transmute_ptr_to_ref::check(cx, e, from_ty, to_ty, args, qpath);
+                if triggered {
+                    return;
+                }
 
                 match (&from_ty.kind(), &to_ty.kind()) {
-                    (ty::RawPtr(from_pty), 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_pty.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,
-                            );
-                        },
-                    ),
                     (ty::Int(ty::IntTy::I32) | ty::Uint(ty::UintTy::U32), &ty::Char) => {
                         span_lint_and_then(
                             cx,
diff --git a/clippy_lints/src/transmute/transmute_ptr_to_ref.rs b/clippy_lints/src/transmute/transmute_ptr_to_ref.rs
new file mode 100644
index 000000000..7be47da35
--- /dev/null
+++ b/clippy_lints/src/transmute/transmute_ptr_to_ref.rs
@@ -0,0 +1,56 @@
+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;
+use rustc_middle::ty::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_pty), 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_pty.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,
+    }
+}