[libcxx-commits] [libcxx] [libc++][test] Make narrowing in `nasty_char_traits::to_char_type` more explicit (PR #138375)

[A. Jiang via libcxx-commits]

https://github.com/frederick-vs-ja created https://github.com/llvm/llvm-project/pull/138375

Previously, the cast was allowed due to [P0960R3](https://wg21.link/p0960r3), which made narrowing implicitly done in the parenthesized aggregate initialization. It seems that MSVC doesn't like such an implicit manner and emits warning C4242.

This patch makes the narrowing more explicit. Follows up #135338.

>From a8fc7cefbfe642d6f1c13fe75970ab0d8c51b27c Mon Sep 17 00:00:00 2001
From: "A. Jiang" <de34 at live.cn>
Date: Sat, 3 May 2025 11:06:51 +0800
Subject: [PATCH] [libc++][test] Explicit cast in
 `nasty_char_traits::to_char_type`

---
 libcxx/test/support/nasty_string.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libcxx/test/support/nasty_string.h b/libcxx/test/support/nasty_string.h
index c2968f52e3a00..6b17bbc3f2232 100644
--- a/libcxx/test/support/nasty_string.h
+++ b/libcxx/test/support/nasty_string.h
@@ -70,7 +70,7 @@ struct nasty_char_traits {
 
   static constexpr int_type not_eof(int_type c) noexcept { return eq_int_type(c, eof()) ? ~eof() : c; }
 
-  static constexpr char_type to_char_type(int_type c) noexcept { return char_type(c); }
+  static constexpr char_type to_char_type(int_type c) noexcept { return {static_cast<char>(c)}; }
 
   static constexpr int_type to_int_type(char_type c) noexcept { return int_type(c.c); }