Merge remote-tracking branch 'upstream/staging-next' into down-integrate-staging

pkgs/build-support/cc-wrapper/default.nix

@@ -312,10 +312,11 @@ stdenv.mkDerivation {
     # vs libstdc++, etc.) since Darwin isn't `useLLVM` on all counts. (See
     # https://clang.llvm.org/docs/Toolchain.html for all the axes one might
     # break `useLLVM` into.)
-    + optionalString (isClang && gccForLibs != null
+    + optionalString (isClang
                       && targetPlatform.isLinux
                       && !(stdenv.targetPlatform.useAndroidPrebuilt or false)
-                      && !(stdenv.targetPlatform.useLLVM or false)) ''
+                      && !(stdenv.targetPlatform.useLLVM or false)
+                      && gccForLibs != null) ''
       echo "--gcc-toolchain=${gccForLibs}" >> $out/nix-support/cc-cflags
     ''
 

pkgs/build-support/docker/default.nix

@@ -418,7 +418,11 @@ rec {
         # details on what's going on here; basically this command
         # means that the runAsRootScript will be executed in a nearly
         # completely isolated environment.
-        unshare -imnpuf --mount-proc chroot mnt ${runAsRootScript}
+        #
+        # Ideally we would use --mount-proc=mnt/proc or similar, but this
+        # doesn't work. The workaround is to setup proc after unshare.
+        # See: https://github.com/karelzak/util-linux/issues/648
+        unshare -imnpuf --mount-proc sh -c 'mount --rbind /proc mnt/proc && chroot mnt ${runAsRootScript}'
 
         # Unmount directories and remove them.
         umount -R mnt/dev mnt/sys mnt${storeDir}