On Linux, using the master branch (3e306ee1d5c79eda64eb991fb2696bf530f0b30d) or the 0.21 one (926f76cb205ce9ef085f4945cdb439746b140414), after building depends against libc++
:
0$ make -j 9 -C depends CC=clang CXX='clang++ -stdlib=libc++'
configuring with
0$ ./autogen.sh && CONFIG_SITE=$PWD/depends/x86_64-pc-linux-gnu/share/config.site ./configure -q CC=clang CXX='clang++ -stdlib=libc++'
fails to pick up the Qt package.
This issue prevents TSAN from being enabled for GUI builds (see #19162).