lib: correctly render docs for nested identifiers

Applies https://github.com/nix-community/nixdoc/pull/27 and fixes up the
location information rendering, allowing lib functions to be nested in
further scopes

Needed for later commits

doc/doc-support/lib-function-locations.nix

@@ -2,19 +2,21 @@
 let
   revision = pkgs.lib.trivial.revisionWithDefault (nixpkgs.revision or "master");
 
-  libDefPos = set:
-    builtins.map
-      (name: {
-        name = name;
+  libDefPos = prefix: set:
+    builtins.concatMap
+      (name: [{
+        name = builtins.concatStringsSep "." (prefix ++ [name]);
         location = builtins.unsafeGetAttrPos name set;
-      })
-      (builtins.attrNames set);
+      }] ++ nixpkgsLib.optionals
+        (builtins.length prefix == 0 && builtins.isAttrs set.${name})
+        (libDefPos (prefix ++ [name]) set.${name})
+      ) (builtins.attrNames set);
 
   libset = toplib:
     builtins.map
       (subsetname: {
         subsetname = subsetname;
-        functions = libDefPos toplib.${subsetname};
+        functions = libDefPos [] toplib.${subsetname};
       })
       (builtins.map (x: x.name) libsets);
 

pkgs/tools/nix/nixdoc/default.nix

@@ -1,4 +1,4 @@
-{ lib, stdenv, fetchFromGitHub, rustPlatform, darwin }:
+{ lib, stdenv, fetchFromGitHub, fetchpatch, rustPlatform, darwin }:
 
 rustPlatform.buildRustPackage rec {
   pname = "nixdoc";
@@ -11,6 +11,14 @@ rustPlatform.buildRustPackage rec {
     sha256 = "14d4dq06jdqazxvv7fq5872zy0capxyb0fdkp8qg06gxl1iw201s";
   };
 
+  patches = [
+    # Support nested identifiers https://github.com/nix-community/nixdoc/pull/27
+    (fetchpatch {
+      url = "https://github.com/nix-community/nixdoc/pull/27/commits/ea542735bf675fe2ccd37edaffb9138d1a8c1b7e.patch";
+      sha256 = "1fmz44jv2r9qsnjxvkkjfb0safy69l4x4vx1g5gisrp8nwdn94rj";
+    })
+  ];
+
   buildInputs =  lib.optionals stdenv.isDarwin [ darwin.Security ];
 
   cargoSha256 = "1nv6g8rmjjbwqmjkrpqncypqvx5c7xp2zlx5h6rw2j9d1wlys0v5";