On Thu, 10 Aug 2017, Ximin Luo wrote: > Normally, system-wide CFLAGS etc are a static expression of policy. What I > mean > by that is, writing logic to determine CFLAGS for particular package, would > "look like" the actual wording of that policy. So for example, "all packages > should have debug" => "CFLAGS+=-g", "packages that match property X should > have > flag Y" => "if X then CFLAGS += Y". OTOH if your policy is "packages should be > reproducible" and we have to add these prefix-remapping flags to CFLAGS, > you're > adding a dependency from the value of CFLAGS itself, onto the build-time > filesystem. So CFLAGS is no longer a static expression of policy, it depends > on > information not part of the policy. > > So, prefix-map is really different from other CFLAGS, it adds extra dependency > relationships that other flags don't add.
I think the difference is essentially that these options belong in CC not CFLAGS (CFLAGS is for non-semantic options, CC should include any options that are required in every compilation). (FWIW, I support having the environment variable, but think there should be some command-line option exactly equivalent to it.) -- Joseph S. Myers jos...@codesourcery.com
