libfmt 12.1 - Suppress warning, MSVC-specific

discarding return value of function with [[nodiscard]] attribute
for std::isalpha

This comes from libfmt templated code

Author: vaintroub

cmake/libfmt.cmake

@@ -15,8 +15,8 @@ MACRO(BUNDLE_LIBFMT)
   ExternalProject_Add(
     libfmt
     PREFIX   "${dir}"
-    URL "https://github.com/fmtlib/fmt/releases/download/12.0.0/fmt-12.0.0.zip"
-    URL_MD5 9bd04e6e8c5b1733e4eefb473604219d
+    URL "https://github.com/fmtlib/fmt/releases/download/12.1.0/fmt-12.1.0.zip"
+    URL_MD5 028c6979cad96a4260154f091885171a
     INSTALL_COMMAND ""
     CONFIGURE_COMMAND ""
     BUILD_COMMAND ""

sql/item_strfunc.cc

@@ -1622,7 +1622,18 @@ String *Item_func_sformat::val_str(String *res)
   /* Create the string output  */
   try
   {
+#ifdef _MSC_VER
+/*
+  C4834 : "discarding return value of function with [[nodiscard]] attribute"
+  in fmt 12.1 template code, for isalpha()
+*/
+#pragma warning(push)
+#pragma warning(disable : 4834)
+#endif
     auto text = fmt::vformat(fmt_locale, fmt_arg->c_ptr_safe(), arg_store);
+#ifdef _MSC_VER
+#pragma warning(pop)
+#endif
     res->length(0);
     res->set_charset(collation.collation);
     res->append(text.c_str(), text.size(), fmt_arg->charset());