$ rpmbuild -v -bb mkvtoolnix.spec 2>&1 | tee mkvtoolnix.build.out

. . . WARNING: unable to read lib/avilib-0.6.10/avilib.c: invalid byte sequence in US-ASCII WARNING: unable to read lib/avilib-0.6.10/avimisc.c: invalid byte sequence in US-ASCII WARNING: unable to read src/common/checksums/adler32.cpp: invalid byte sequence in US-ASCII WARNING: unable to read src/common/checksums/base.cpp: invalid byte sequence in US-ASCII WARNING: unable to read src/common/checksums/crc.cpp: invalid byte sequence in US-ASCII WARNING: unable to read src/common/checksums/md5.cpp: invalid byte sequence in US-ASCII WARNING: unable to read src/common/spu.cpp: invalid byte sequence in US-ASCII . . . At end of build, it belched

g++ -Wall -Wno-comment -Wfatal-errors -Wlogical-op -D_FILE_OFFSET_BITS=64 -DMTX_LOCALE_DIR="/usr/share/locale" -DMTX_PKG_DATA_DIR="/usr/share/mkvtoolnix" -DMTX_DOC_DIR="/usr/share/doc/mkvtoolnix" -fstack-protector -fPIC -std=gnu++11 -Wnon-virtual-dtor -Woverloaded-virtual -Wextra -Wno-missing-field-initializers -Wno-maybe-uninitialized -I/usr/include/qt5/QtWidgets -I/usr/include/qt5 -I/usr/include/qt5/QtGui -I/usr/include/qt5 -I/usr/include/qt5/QtNetwork -I/usr/include/qt5 -I/usr/include/qt5/QtCore -I/usr/include/qt5 -I/usr/include -O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong --param=ssp-buffer-size=4 -grecord-gcc-switches -m64 -mtune=generic -include src/common/common_pch.h -I. -Ilib -Ilib/avilib-0.6.10 -Isrc -c -MMD -MF ./rake.d/dependency.d/tmp/src_common_json_o.d -o src/common/json.o -x c++ src/common/json.cpp In file included from src/common/json.cpp:19:0: src/common/json.h:23:76: error: 'nlohmann::json<std::map, std::vector, std::basic_string<char, std::char_traits<char>, std::allocator<char> >, bool, long int, double, std::allocator>::parser_callback_t' has not been declared nlohmann::json parse(nlohmann::json::string_t const &data, nlohmann::json::parser_callback_t callback = nullptr); ^ compilation terminated due to -Wfatal-errors.