* Add a Nix expression search path feature. Paths between angle

  brackets, e.g.

    import <nixpkgs/pkgs/lib>

  are resolved by looking them up relative to the elements listed in
  the search path.  This allows us to get rid of hacks like

    import "${builtins.getEnv "NIXPKGS_ALL"}/pkgs/lib"

  The search path can be specified through the ‘-I’ command-line flag
  and through the colon-separated ‘NIX_PATH’ environment variable,
  e.g.,

    $ nix-build -I /etc/nixos ...

  If a file is not found in the search path, an error message is
  lazily thrown.

1 files changed, 3 insertions, 0 deletions

diff --git a/src/libexpr/common-opts.hh b/src/libexpr/common-opts.hh
index 80298ce55d..6b7247fc3d 100644
--- a/src/libexpr/common-opts.hh
+++ b/src/libexpr/common-opts.hh
@@ -11,6 +11,9 @@ bool parseOptionArg(const string & arg, Strings::iterator & i,
     const Strings::iterator & argsEnd, EvalState & state,
     Bindings & autoArgs);
     
+bool parseSearchPathArg(const string & arg, Strings::iterator & i,
+    const Strings::iterator & argsEnd, EvalState & state);
+
 }