Make precision computation consistent with width

include/fmt/format.h

@@ -680,8 +680,8 @@ FMT_CONSTEXPR inline size_t compute_width(string_view s) {
 }
 
 inline auto compute_width(basic_string_view<char8_type> s) -> size_t {
-  return compute_width(basic_string_view<char>(
-      reinterpret_cast<const char*>(s.data()), s.size()));
+  return compute_width(
+      string_view(reinterpret_cast<const char*>(s.data()), s.size()));
 }
 
 template <typename Char>
@@ -691,9 +691,8 @@ inline auto code_point_index(basic_string_view<Char> s, size_t n) -> size_t {
 }
 
 // Calculates the index of the nth code point in a UTF-8 string.
-inline auto code_point_index(basic_string_view<char8_type> s, size_t n)
-    -> size_t {
-  const char8_type* data = s.data();
+inline auto code_point_index(string_view s, size_t n) -> size_t {
+  const char* data = s.data();
   size_t num_code_points = 0;
   for (size_t i = 0, size = s.size(); i != size; ++i) {
     if ((data[i] & 0xc0) != 0x80 && ++num_code_points > n) return i;
@@ -701,6 +700,12 @@ inline auto code_point_index(basic_string_view<char8_type> s, size_t n)
   return s.size();
 }
 
+inline auto code_point_index(basic_string_view<char8_type> s, size_t n)
+    -> size_t {
+  return code_point_index(
+      string_view(reinterpret_cast<const char*>(s.data()), s.size()), n);
+}
+
 #ifndef FMT_USE_FLOAT128
 #  ifdef __SIZEOF_FLOAT128__
 #    define FMT_USE_FLOAT128 1

test/format-test.cc

@@ -1035,6 +1035,7 @@ TEST(format_test, precision) {
       format_error, "number is too big");
 
   EXPECT_EQ("st", fmt::format("{0:.2}", "str"));
+  EXPECT_EQ("вожык", fmt::format("{0:.5}", "вожыкі"));
 }
 
 TEST(format_test, runtime_precision) {