semarie@quade:~$ uname -a
OpenBSD quade.local 6.9 GENERIC.MP#3 amd64
semarie@quade:~$ c++ -E -Wp,-v -xc++ /dev/null
clang -cc1 version 11.1.0 based upon LLVM 11.1.0 default target amd64-unknown-openbsd6.9
#include "..." search starts here:
#include <...> search starts here:
 /usr/include/c++/v1
 /usr/lib/clang/11.1.0/include
 /usr/include
End of search list.
# 1 "/dev/null"
# 1 "<built-in>" 1
# 1 "<built-in>" 3
# 382 "<built-in>" 3
# 1 "<command line>" 1
# 1 "<built-in>" 2
# 1 "/dev/null" 2