Move transmute_int_to_char to its own module

Author: magurotuna

clippy_lints/src/transmute/mod.rs

@@ -1,4 +1,5 @@
 mod crosspointer_transmute;
+mod transmute_int_to_char;
 mod transmute_ptr_to_ref;
 mod useless_transmute;
 mod utils;
@@ -365,30 +366,12 @@ impl<'tcx> LateLintPass<'tcx> for Transmute {
                 if triggered {
                     return;
                 }
+                let triggered = transmute_int_to_char::check(cx, e, from_ty, to_ty, args);
+                if triggered {
+                    return;
+                }
 
                 match (&from_ty.kind(), &to_ty.kind()) {
-                    (ty::Int(ty::IntTy::I32) | ty::Uint(ty::UintTy::U32), &ty::Char) => {
-                        span_lint_and_then(
-                            cx,
-                            TRANSMUTE_INT_TO_CHAR,
-                            e.span,
-                            &format!("transmute from a `{}` to a `char`", from_ty),
-                            |diag| {
-                                let arg = sugg::Sugg::hir(cx, &args[0], "..");
-                                let arg = if let ty::Int(_) = from_ty.kind() {
-                                    arg.as_ty(ast::UintTy::U32.name_str())
-                                } else {
-                                    arg
-                                };
-                                diag.span_suggestion(
-                                    e.span,
-                                    "consider using",
-                                    format!("std::char::from_u32({}).unwrap()", arg.to_string()),
-                                    Applicability::Unspecified,
-                                );
-                            },
-                        )
-                    },
                     (ty::Ref(_, ty_from, from_mutbl), ty::Ref(_, ty_to, to_mutbl)) => {
                         if_chain! {
                             if let (&ty::Slice(slice_ty), &ty::Str) = (&ty_from.kind(), &ty_to.kind());

clippy_lints/src/transmute/transmute_int_to_char.rs

@@ -0,0 +1,47 @@
+use super::TRANSMUTE_INT_TO_CHAR;
+use crate::utils::{span_lint_and_then, sugg};
+use rustc_ast as ast;
+use rustc_errors::Applicability;
+use rustc_hir::Expr;
+use rustc_lint::LateContext;
+use rustc_middle::ty;
+use rustc_middle::ty::Ty;
+
+/// Checks for `transmute_int_to_char` 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 {
+    match (&from_ty.kind(), &to_ty.kind()) {
+        (ty::Int(ty::IntTy::I32) | ty::Uint(ty::UintTy::U32), &ty::Char) => {
+            {
+                span_lint_and_then(
+                    cx,
+                    TRANSMUTE_INT_TO_CHAR,
+                    e.span,
+                    &format!("transmute from a `{}` to a `char`", from_ty),
+                    |diag| {
+                        let arg = sugg::Sugg::hir(cx, &args[0], "..");
+                        let arg = if let ty::Int(_) = from_ty.kind() {
+                            arg.as_ty(ast::UintTy::U32.name_str())
+                        } else {
+                            arg
+                        };
+                        diag.span_suggestion(
+                            e.span,
+                            "consider using",
+                            format!("std::char::from_u32({}).unwrap()", arg.to_string()),
+                            Applicability::Unspecified,
+                        );
+                    },
+                )
+            };
+            true
+        },
+        _ => false,
+    }
+}