Bug#1000398: fixed upstream

Dear Nick Lewychy-San, > Would it be possible to pick up that change? I cherrypicked this commit to a header of this version , then I test to compile with LLVM CLANG(-13) with C++-20, seems to succeed compilation, not happen FTBFS. This change seems to be correct. Regards, Ohta On Sat, 27 Nov

Bug#1000398: libstdc++-11-dev: Failed to compile with clang++ C++20 mode due to chenges of std::valarray.

Package: libstdc++-11-dev Version: 11.2.0-12 Severity: important Dear Maintainer, When compiling any C++20 source code using std::valarray with clang++, failed to compile with below message: --- /usr/bin/../lib/gcc/x86_64-linux-gnu/11/../../../../include/c++/11/valarray:foo:var error: exception