From c575d567574bc7bc04244c8b81d341bb373a4801 Mon Sep 17 00:00:00 2001
From: denchat <19730041+denchat@users.noreply.github.com>
Date: Thu, 9 May 2019 01:49:53 +0700
Subject: [PATCH] Fix conditional `char8_t` from `format.h` and fix
 `-Wunused-result` of [[no_discard]] begin() when in c++17

---
 test/format-test.cc | 17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)

diff --git a/test/format-test.cc b/test/format-test.cc
index 3321a552..99fa2f01 100644
--- a/test/format-test.cc
+++ b/test/format-test.cc
@@ -2491,10 +2491,19 @@ TEST(FormatTest, FmtStringInTemplate) {
 
 #endif  // FMT_USE_CONSTEXPR
 
+// C++20 feature test, since r346892 Clang considers char8_t a fundamental
+// type in this mode. If this is the case __cpp_char8_t will be defined.
+#ifndef __cpp_char8_t
+// A UTF-8 code unit type.
+#define CHAR8_T fmt::char8_t
+#else
+#define CHAR8_T char8_t
+#endif
+
 TEST(FormatTest, ConstructU8StringViewFromCString) {
   fmt::u8string_view s("ab");
   EXPECT_EQ(s.size(), 2u);
-  const fmt::char8_t* data = s.data();
+  const CHAR8_T* data = s.data();
   EXPECT_EQ(data[0], 'a');
   EXPECT_EQ(data[1], 'b');
 }
@@ -2502,7 +2511,7 @@ TEST(FormatTest, ConstructU8StringViewFromCString) {
 TEST(FormatTest, ConstructU8StringViewFromDataAndSize) {
   fmt::u8string_view s("foobar", 3);
   EXPECT_EQ(s.size(), 3u);
-  const fmt::char8_t* data = s.data();
+  const CHAR8_T* data = s.data();
   EXPECT_EQ(data[0], 'f');
   EXPECT_EQ(data[1], 'o');
   EXPECT_EQ(data[2], 'o');
@@ -2513,7 +2522,7 @@ TEST(FormatTest, U8StringViewLiteral) {
   using namespace fmt::literals;
   fmt::u8string_view s = "ab"_u;
   EXPECT_EQ(s.size(), 2u);
-  const fmt::char8_t* data = s.data();
+  const CHAR8_T* data = s.data();
   EXPECT_EQ(data[0], 'a');
   EXPECT_EQ(data[1], 'b');
   EXPECT_EQ(format("{:*^5}"_u, "🤡"_u), "**🤡**"_u);
@@ -2536,6 +2545,6 @@ TEST(FormatTest, CharTraitsIsNotAmbiguous) {
   char_traits<char>::char_type c;
 #if __cplusplus >= 201103L
   std::string s;
-  begin(s);
+  auto lval = begin(s);
 #endif
 }