From: #18308 (comment)
The following monstrosity is quite useful when invoked inside depends, and reviewers can use it to compare the behaviour of this change against master.
0make print-{{,{host,{,{i686,x86_64,riscv64}_}linux}_}{CC,CXX},boost_{cc,cxx}}
It would also be helpful to make sure that setting HOST, CC, and CXX does the right thing. The 3 hosts I found offered good coverage were: {x86_64,i686,riscv64}-linux-gnu. As we special-case the x86_64 and i686 hosts in depends/hosts/linux.mk, and riscv64 is a sanity check for a non-special-cased host.