runCommand: set meta.position from the arguments

Currently all packages defined by a call to runCommand have their
meta.position pointing to trivial-builders.nix.

This change makes uses of runCommand that supply at least one attribute
in the second argument point to the right file.

1 files changed, 4 insertions, 0 deletions

diff --git a/pkgs/build-support/trivial-builders/default.nix b/pkgs/build-support/trivial-builders/default.nix
index d3cb22a1f5351..2af36008c7a51 100644
--- a/pkgs/build-support/trivial-builders/default.nix
+++ b/pkgs/build-support/trivial-builders/default.nix
@@ -87,6 +87,10 @@ rec {
       inherit buildCommand name;
       passAsFile = [ "buildCommand" ]
         ++ (derivationArgs.passAsFile or []);
+      pos = let args = builtins.attrNames derivationArgs; in
+        if builtins.length args > 0
+        then builtins.unsafeGetAttrPos (builtins.head args) derivationArgs
+        else null;
     }
     // (lib.optionalAttrs runLocal {
           preferLocalBuild = true;