Make char8_t a strongly-typed enum

include/fmt/format-inl.h

@@ -206,7 +206,7 @@ FMT_FUNC size_t internal::count_code_points(u8string_view s) {
   const char8_t *data = s.data();
   int num_code_points = 0;
   for (size_t i = 0, size = s.size(); i != size; ++i) {
-    if ((data[i].value & 0xc0) != 0x80)
+    if ((data[i] & 0xc0) != 0x80)
       ++num_code_points;
   }
   return num_code_points;

include/fmt/format.h

@@ -437,12 +437,7 @@ void basic_buffer<T>::append(const U *begin, const U *end) {
 }  // namespace internal
 
 // A UTF-8 code unit type.
-struct char8_t {
-  char value;
-  FMT_CONSTEXPR FMT_EXPLICIT operator bool() const FMT_NOEXCEPT {
-    return value != 0;
-  }
-};
+enum char8_t: unsigned char {};
 
 // A UTF-8 string view.
 class u8string_view : public basic_string_view<char8_t> {

test/format-test.cc

@@ -2407,17 +2407,17 @@ TEST(FormatTest, ConstructU8StringViewFromCString) {
   fmt::u8string_view s("ab");
   EXPECT_EQ(s.size(), 2u);
   const fmt::char8_t *data = s.data();
-  EXPECT_EQ(data[0].value, 'a');
-  EXPECT_EQ(data[1].value, 'b');
+  EXPECT_EQ(data[0], 'a');
+  EXPECT_EQ(data[1], 'b');
 }
 
 TEST(FormatTest, ConstructU8StringViewFromDataAndSize) {
   fmt::u8string_view s("foobar", 3);
   EXPECT_EQ(s.size(), 3u);
   const fmt::char8_t *data = s.data();
-  EXPECT_EQ(data[0].value, 'f');
-  EXPECT_EQ(data[1].value, 'o');
-  EXPECT_EQ(data[2].value, 'o');
+  EXPECT_EQ(data[0], 'f');
+  EXPECT_EQ(data[1], 'o');
+  EXPECT_EQ(data[2], 'o');
 }
 
 #if FMT_USE_USER_DEFINED_LITERALS
@@ -2426,7 +2426,7 @@ TEST(FormatTest, U8StringViewLiteral) {
   fmt::u8string_view s = "ab"_u;
   EXPECT_EQ(s.size(), 2u);
   const fmt::char8_t *data = s.data();
-  EXPECT_EQ(data[0].value, 'a');
-  EXPECT_EQ(data[1].value, 'b');
+  EXPECT_EQ(data[0], 'a');
+  EXPECT_EQ(data[1], 'b');
 }
 #endif