cast_ptr_alignment: move the regular check into the if

this allows reusing `cast_from` and `cast_to`

one possible problem is that the `if` has an additional
`is_hir_ty_cfg_dependant` check which the let-chain of the  original
`check` didn't have.. but maybe this is actually more correct

Author: ada4a

clippy_lints/src/casts/cast_ptr_alignment.rs

@@ -8,17 +8,8 @@ use rustc_middle::ty::{self, Ty};
 
 use super::CAST_PTR_ALIGNMENT;
 
-pub(super) fn check(cx: &LateContext<'_>, expr: &Expr<'_>) {
-    if let ExprKind::Cast(cast_expr, cast_to) = expr.kind {
-        if is_hir_ty_cfg_dependant(cx, cast_to) {
-            return;
-        }
-        let (cast_from, cast_to) = (
-            cx.typeck_results().expr_ty(cast_expr),
-            cx.typeck_results().expr_ty(expr),
-        );
-        lint_cast_ptr_alignment(cx, expr, cast_from, cast_to);
-    }
+pub(super) fn check<'tcx>(cx: &LateContext<'tcx>, expr: &Expr<'_>, cast_from: Ty<'tcx>, cast_to: Ty<'tcx>) {
+    lint_cast_ptr_alignment(cx, expr, cast_from, cast_to);
 }
 
 pub(super) fn check_cast_method(cx: &LateContext<'_>, expr: &Expr<'_>) {

clippy_lints/src/casts/mod.rs

@@ -873,6 +873,7 @@ impl<'tcx> LateLintPass<'tcx> for Casts {
             }
             char_lit_as_u8::check(cx, expr, cast_from_expr, cast_to);
             cast_slice_from_raw_parts::check(cx, expr, cast_from_expr, cast_to, self.msrv);
+            cast_ptr_alignment::check(cx, expr, cast_from, cast_to);
             ptr_cast_constness::check(cx, expr, cast_from_expr, cast_from, cast_to, self.msrv);
             as_ptr_cast_mut::check(cx, expr, cast_from_expr, cast_to);
             fn_to_numeric_cast_any::check(cx, expr, cast_from_expr, cast_from, cast_to);
@@ -914,7 +915,6 @@ impl<'tcx> LateLintPass<'tcx> for Casts {
         if self.msrv.meets(cx, msrvs::PTR_SLICE_RAW_PARTS) {
             cast_slice_from_raw_parts::check_implicit_cast(cx, expr);
         }
-        cast_ptr_alignment::check(cx, expr);
         cast_ptr_alignment::check_cast_method(cx, expr);
         ptr_as_ptr::check(cx, expr, self.msrv);
         cast_slice_different_sizes::check(cx, expr, self.msrv);