Merge branch 'googletest-version' of github.com:microsoft/LightGBM in…

…to googletest-version

include/LightGBM/utils/common.h

@@ -1201,8 +1201,8 @@ inline static std::vector<T> StringToArray(const std::string& str, char delimite
 * /Users/jlamb/repos/LightGBM/include/LightGBM/utils/common.h:1203:35: error: 'format' is not a constant expression
 */
 template <typename T>
-inline static void format_to_buf(char* buffer, const size_t buf_len, const char* format, const T value) {
-    const auto result = fmt::format_to_n(buffer, buf_len, format, value);
+inline static void format_to_buf(char* buffer, const size_t buf_len, fmt::format_string<T> format, const T value) {
+    auto result = fmt::format_to_n(buffer, buf_len, format, value);
     if (result.size >= buf_len) {
       Log::Fatal("Numerical conversion failed. Buffer is too small.");
     }
@@ -1212,29 +1212,29 @@ inline static void format_to_buf(char* buffer, const size_t buf_len, const char*
 template<typename T, bool is_float, bool high_precision>
 struct __TToStringHelper {
   void operator()(T value, char* buffer, size_t buf_len) const {
-    format_to_buf(buffer, buf_len, "{}", value);
+    format_to_buf(buffer, buf_len, fmt::format_string<T>("{}"), value);
   }
 };
 
 template<typename T>
 struct __TToStringHelper<T, true, false> {
   void operator()(T value, char* buffer, size_t buf_len) const {
-    format_to_buf(buffer, buf_len, "{:g}", value);
+    format_to_buf(buffer, buf_len, fmt::format_string<T>("{:g}"), value);
   }
 };
 
 template<typename T>
 struct __TToStringHelper<T, true, true> {
   void operator()(T value, char* buffer, size_t buf_len) const {
-    format_to_buf(buffer, buf_len, "{:.17g}", value);
+    format_to_buf(buffer, buf_len, fmt::format_string<T>("{:.17g}"), value);
   }
 };
 
 /*!
 * Converts an array to a string with with values separated by the space character.
 * This method replaces Common's ``ArrayToString`` and ``ArrayToStringFast`` functionality
 * and is locale-independent.
-* 
+*
 * \note If ``high_precision_output`` is set to true,
 *       floating point values are output with more digits of precision.
 */