pkgs/top-level/stage.nix: add pkgsLLVMLibc

lib/systems/default.nix

@@ -102,6 +102,7 @@ let
         else if final.isMusl                  then "musl"
         else if final.isUClibc                then "uclibc"
         else if final.isAndroid               then "bionic"
+        else if final.isLLVMLibc              then "llvm"
         else if final.isLinux  /* default */  then "glibc"
         else if final.isFreeBSD               then "fblibc"
         else if final.isOpenBSD               then "oblibc"

lib/systems/inspect.nix

@@ -113,6 +113,7 @@ rec {
     isGnu          = with abis; map (a: { abi = a; }) [ gnuabi64 gnuabin32 gnu gnueabi gnueabihf gnuabielfv1 gnuabielfv2 ];
     isMusl         = with abis; map (a: { abi = a; }) [ musl musleabi musleabihf muslabin32 muslabi64 ];
     isUClibc       = with abis; map (a: { abi = a; }) [ uclibc uclibceabi uclibceabihf ];
+    isLLVMLibc     = [ { abi = abis.llvm; } ];
 
     isEfi = [
       { cpu = { family = "arm"; version = "6"; }; }

lib/systems/parse.nix

@@ -416,6 +416,9 @@ rec {
     uclibceabihf = { float = "hard"; };
     uclibc       = {};
 
+    # LLVM libc
+    llvm         = {};
+
     unknown = {};
   };
 

pkgs/top-level/stage.nix

@@ -98,6 +98,10 @@ let
           or lib.systems.parse.abis.musl;
       });
 
+  makeLLVMParsedPlatform = parsed:
+    (parsed // {
+      abi = lib.systems.parse.abis.llvm;
+    });
 
   stdenvAdapters = self: super:
     let
@@ -207,6 +211,18 @@ let
       };
     };
 
+    pkgsLLVMLibc = nixpkgsFun {
+      overlays = [ (self': super': {
+        pkgsLLVMLibc = super';
+      })] ++ overlays;
+      ${if stdenv.hostPlatform == stdenv.buildPlatform
+        then "localSystem" else "crossSystem"} = {
+        config = lib.systems.parse.tripleFromSystem (makeLLVMParsedPlatform stdenv.hostPlatform.parsed);
+        useLLVM = true;
+        linker = "lld";
+      };
+    };
+
     pkgsArocc = nixpkgsFun {
       overlays = [
         (self': super': {