lib.systems: allow specifying libc = null

It makes sense to allow platform definitions to opt out of having libc
at all.  One use case would be targetting some obscure new Linux
target that doesn't have a libc implementation yet, and another is
UEFI, which is basically libc-less Windows.

Not having libc is not commonly specified in (GNU) triples (even
Linux's build system will just target either -gnu or -musl depending
on the platform), so instead, we use a separate attribute for it.

1 files changed, 1 insertions, 0 deletions

diff --git a/lib/systems/default.nix b/lib/systems/default.nix
index b2cb8848f08b..19ba594d535d 100644
--- a/lib/systems/default.nix
+++ b/lib/systems/default.nix
@@ -50,6 +50,7 @@ rec {
         else if final.isFreeBSD             then "fblibc"
         else if final.isNetBSD              then "nblibc"
         else if final.isAvr                 then "avrlibc"
+        else if final.isGhcjs               then null
         else if final.isNone                then "newlib"
         # TODO(@Ericson2314) think more about other operating systems
         else                                     "native/impure";