From 9523df7eb600e7fc2a88bc5227d9dfe12055a9bd Mon Sep 17 00:00:00 2001
From: Silvan Mosberger <contact@infinisil.com>
Date: Wed, 2 Sep 2020 00:17:26 +0200
Subject: [PATCH] nixos/assertions: Use module-builtin assertion implementation

---
 lib/modules.nix                               | 12 +++++------
 nixos/modules/misc/assertions.nix             | 21 ++++++++++++++++++-
 nixos/modules/system/activation/top-level.nix | 10 +--------
 3 files changed, 27 insertions(+), 16 deletions(-)

diff --git a/lib/modules.nix b/lib/modules.nix
index 0d761c632d02..31200ae0b035 100644
--- a/lib/modules.nix
+++ b/lib/modules.nix
@@ -254,11 +254,11 @@ rec {
       */
       injectAssertions = assertions: config: let
         # Partition into assertions that are triggered on this level and ones that aren't
-        parted = partition (a: length a.triggerPath == 0) assertions;
+        parted = lib.partition (a: length a.triggerPath == 0) assertions;
 
         # From the ones that are triggered, filter out ones that aren't enabled
         # and group into warnings/errors
-        byType = groupBy (a: a.type) (filter (a: a.enable) parted.right);
+        byType = lib.groupBy (a: a.type) (filter (a: a.enable) parted.right);
 
         # Triggers semantically are just lib.id, but they print warning cause errors in addition
         warningTrigger = value: lib.foldr (w: warn w.show) value (byType.warning or []);
@@ -266,16 +266,16 @@ rec {
           if byType.error or [] == [] then value else
           throw ''
             Failed assertions:
-            ${concatMapStringsSep "\n" (a: "- ${a.show}") byType.error}
+            ${lib.concatMapStringsSep "\n" (a: "- ${a.show}") byType.error}
           '';
         # Trigger for both warnings and errors
         trigger = value: warningTrigger (errorTrigger value);
 
         # From the non-triggered assertions, split off the first element of triggerPath
         # to get a mapping from nested attributes to a list of assertions for that attribute
-        nested = zipAttrs (map (a: {
+        nested = lib.zipAttrs (map (a: {
           ${head a.triggerPath} = a // {
-            triggerPath = tail a.triggerPath;
+            triggerPath = lib.tail a.triggerPath;
           };
         }) parted.wrong);
 
@@ -296,7 +296,7 @@ rec {
       # has a `show` attribute for how to show it if triggered
       assertions = mapAttrsToList (name: value:
         let id =
-          if hasPrefix "_" name then ""
+          if lib.hasPrefix "_" name then ""
           else "[${showOption prefix}${optionalString (prefix != []) "/"}${name}] ";
         in value // {
           show = "${id}${value.message}";
diff --git a/nixos/modules/misc/assertions.nix b/nixos/modules/misc/assertions.nix
index 550b3ac97f6a..e931611247f2 100644
--- a/nixos/modules/misc/assertions.nix
+++ b/nixos/modules/misc/assertions.nix
@@ -1,4 +1,4 @@
-{ lib, ... }:
+{ lib, config, ... }:
 
 with lib;
 
@@ -29,6 +29,25 @@ with lib;
       '';
     };
 
+    _module.assertions = mkOption {
+      type = types.attrsOf (types.submodule {
+        triggerPath = mkDefault [ "system" "build" "toplevel" ];
+      });
+    };
+
   };
+
+  config._module.assertions = lib.listToAttrs (lib.imap1 (n: value:
+    let
+      name = "_${toString n}";
+      isWarning = lib.isString value;
+      result = {
+        enable = if isWarning then true else ! value.assertion;
+        type = if isWarning then "warning" else "error";
+        message = if isWarning then value else value.message;
+      };
+    in nameValuePair name result
+  ) (config.assertions ++ config.warnings));
+
   # impl of assertions is in <nixpkgs/nixos/modules/system/activation/top-level.nix>
 }
diff --git a/nixos/modules/system/activation/top-level.nix b/nixos/modules/system/activation/top-level.nix
index 03d7e7493230..17b62ad9569b 100644
--- a/nixos/modules/system/activation/top-level.nix
+++ b/nixos/modules/system/activation/top-level.nix
@@ -117,18 +117,10 @@ let
     perl = "${pkgs.perl}/bin/perl " + (concatMapStringsSep " " (lib: "-I${lib}/${pkgs.perl.libPrefix}") (with pkgs.perlPackages; [ FileSlurp NetDBus XMLParser XMLTwig ]));
   };
 
-  # Handle assertions and warnings
-
-  failedAssertions = map (x: x.message) (filter (x: !x.assertion) config.assertions);
-
-  baseSystemAssertWarn = if failedAssertions != []
-    then throw "\nFailed assertions:\n${concatStringsSep "\n" (map (x: "- ${x}") failedAssertions)}"
-    else showWarnings config.warnings baseSystem;
-
   # Replace runtime dependencies
   system = fold ({ oldDependency, newDependency }: drv:
       pkgs.replaceDependency { inherit oldDependency newDependency drv; }
-    ) baseSystemAssertWarn config.system.replaceRuntimeDependencies;
+    ) baseSystem config.system.replaceRuntimeDependencies;
 
 in