non_octal_unix_permissions: get_diagnostic_name once

Author: ada4a

clippy_lints/src/non_octal_unix_permissions.rs

@@ -43,13 +43,11 @@ impl<'tcx> LateLintPass<'tcx> for NonOctalUnixPermissions {
         match &expr.kind {
             ExprKind::MethodCall(path, func, [param], _) => {
                 if let Some(adt) = cx.typeck_results().expr_ty(func).peel_refs().ty_adt_def()
-                    && ((path.ident.name == sym::mode
-                        && matches!(
-                            cx.tcx.get_diagnostic_name(adt.did()),
-                            Some(sym::FsOpenOptions | sym::DirBuilder)
-                        ))
-                        || (path.ident.name == sym::set_mode
-                            && cx.tcx.is_diagnostic_item(sym::FsPermissions, adt.did())))
+                    && matches!(
+                        (path.ident.name, cx.tcx.get_diagnostic_name(adt.did())),
+                        (sym::mode, Some(sym::FsOpenOptions | sym::DirBuilder))
+                            | (sym::set_mode, Some(sym::FsPermissions))
+                    )
                     && let ExprKind::Lit(_) = param.kind
                     && param.span.eq_ctxt(expr.span)
                     && param