Refactor arc_with_non_send_sync

* Check HIR beffore type checking
* Only lint when `Arc::new` is called

Author: Jarcho

clippy_lints/src/arc_with_non_send_sync.rs

@@ -1,7 +1,7 @@
 use clippy_utils::diagnostics::span_lint_and_then;
+use clippy_utils::is_from_proc_macro;
 use clippy_utils::ty::{implements_trait, is_type_diagnostic_item};
-use clippy_utils::{is_from_proc_macro, last_path_segment};
-use rustc_hir::{Expr, ExprKind};
+use rustc_hir::{Expr, ExprKind, QPath};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_middle::ty;
 use rustc_middle::ty::print::with_forced_trimmed_paths;
@@ -42,12 +42,11 @@ declare_lint_pass!(ArcWithNonSendSync => [ARC_WITH_NON_SEND_SYNC]);
 
 impl<'tcx> LateLintPass<'tcx> for ArcWithNonSendSync {
     fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>) {
-        if !expr.span.from_expansion()
-            && let ty = cx.typeck_results().expr_ty(expr)
-            && is_type_diagnostic_item(cx, ty, sym::Arc)
-            && let ExprKind::Call(func, [arg]) = expr.kind
-            && let ExprKind::Path(func_path) = func.kind
-            && last_path_segment(&func_path).ident.name == sym::new
+        if let ExprKind::Call(func, [arg]) = expr.kind
+            && let ExprKind::Path(QPath::TypeRelative(func_ty, func_name)) = func.kind
+            && func_name.ident.name == sym::new
+            && !expr.span.from_expansion()
+            && is_type_diagnostic_item(cx, cx.typeck_results().node_type(func_ty.hir_id), sym::Arc)
             && let arg_ty = cx.typeck_results().expr_ty(arg)
             // make sure that the type is not and does not contain any type parameters
             && arg_ty.walk().all(|arg| {