types.attrTag: Remove substSubmodules

I haven't managed to trigger the error, and it turns out that this
method is optional.
Specifically, getSubmodules is unimplemented (and unimplementable),
the tests pass, and we seem to have good location info.

1 files changed, 0 insertions, 9 deletions

diff --git a/lib/types.nix b/lib/types.nix
index 2e44dd5472ee..694e800f5092 100644
--- a/lib/types.nix
+++ b/lib/types.nix
@@ -662,15 +662,6 @@ rec {
                 };
             })
             tags;
-        substSubModules = m:
-          attrTag
-            (mapAttrs
-              (n: opt:
-                opt // {
-                  type = (opt.type or types.unspecified).substSubModules m;
-                }
-              )
-              tags);
         check = v: isAttrs v && length (attrNames v) == 1 && tags?${head (attrNames v)};
         merge = loc: defs:
           let