Revert "Module-builtin assertions, disabling assertions and submodule assertions"

1 files changed, 22 insertions, 142 deletions

diff --git a/lib/modules.nix b/lib/modules.nix
index 5548c5f7049..3f2bfd478b0 100644
--- a/lib/modules.nix
+++ b/lib/modules.nix
@@ -46,7 +46,6 @@ let
     showFiles
     showOption
     unknownModule
-    literalExample
     ;
 in
 
@@ -73,20 +72,14 @@ rec {
                   check ? true
                 }:
     let
-      # An internal module that's always added, defining special options which
-      # change the behavior of the module evaluation itself. This is under a
-      # `_`-prefixed namespace in order to prevent name clashes with
-      # user-defined options
+      # This internal module declare internal options under the `_module'
+      # attribute.  These options are fragile, as they are used by the
+      # module system to change the interpretation of modules.
       internalModule = rec {
-        # FIXME: Using ./modules.nix directly breaks the doc for some reason
-        _file = "lib/modules.nix";
+        _file = ./modules.nix;
 
         key = _file;
 
-        # Most of these options are set to be internal only for prefix != [],
-        # aka it's a submodule evaluation. This way their docs are displayed
-        # only once as a top-level NixOS option, but will be hidden for all
-        # submodules, even though they are available there too
         options = {
           _module.args = mkOption {
             # Because things like `mkIf` are entirely useless for
@@ -96,7 +89,7 @@ rec {
             # a `_module.args.pkgs = import (fetchTarball { ... }) {}` won't
             # start a download when `pkgs` wasn't evaluated.
             type = types.lazyAttrsOf types.unspecified;
-            internal = prefix != [];
+            internal = true;
             description = "Arguments passed to each module.";
           };
 
@@ -104,19 +97,13 @@ rec {
             type = types.bool;
             internal = true;
             default = check;
-            description = ''
-              Whether to check whether all option definitions have matching
-              declarations.
-
-              Note that this has nothing to do with the similarly named
-              <option>_module.checks</option> option
-            '';
+            description = "Whether to check whether all option definitions have matching declarations.";
           };
 
           _module.freeformType = mkOption {
             # Disallow merging for now, but could be implemented nicely with a `types.optionType`
             type = types.nullOr (types.uniq types.attrs);
-            internal = prefix != [];
+            internal = true;
             default = null;
             description = ''
               If set, merge all definitions that don't have an associated option
@@ -129,75 +116,6 @@ rec {
               turned off.
             '';
           };
-
-          _module.checks = mkOption {
-            description = ''
-              Evaluation checks to trigger during module evaluation. The
-              attribute name will be displayed when it is triggered, allowing
-              users to disable/change these checks if necessary. See
-              the section on Warnings and Assertions in the manual for more
-              information.
-            '';
-            example = literalExample ''
-              {
-                gpgSshAgent = {
-                  enable = config.programs.gnupg.agent.enableSSHSupport && config.programs.ssh.startAgent;
-                  message = "You can't use ssh-agent and GnuPG agent with SSH support enabled at the same time!";
-                };
-
-                grafanaPassword = {
-                  enable = config.services.grafana.database.password != "";
-                  message = "Grafana passwords will be stored as plaintext in the Nix store!";
-                  type = "warning";
-                };
-              }
-            '';
-            default = {};
-            internal = prefix != [];
-            type = types.attrsOf (types.submodule {
-              options.enable = mkOption {
-                description = ''
-                  Whether to enable this check. Set this to false to not trigger
-                  any errors or warning messages. This is useful for ignoring a
-                  check in case it doesn't make sense in certain scenarios.
-                '';
-                default = true;
-                type = types.bool;
-              };
-
-              options.check = mkOption {
-                description = ''
-                  The condition that must succeed in order for this check to be
-                  successful and not trigger a warning or error.
-                '';
-                readOnly = true;
-                type = types.bool;
-              };
-
-              options.type = mkOption {
-                description = ''
-                  The type of the check. The default
-                  <literal>"error"</literal> type will cause evaluation to fail,
-                  while the <literal>"warning"</literal> type will only show a
-                  warning.
-                '';
-                type = types.enum [ "error" "warning" ];
-                default = "error";
-                example = "warning";
-              };
-
-              options.message = mkOption {
-                description = ''
-                  The message to display if this check triggers.
-                  To display option names in the message, add
-                  <literal>options</literal> to the module function arguments
-                  and use <literal>''${options.path.to.option}</literal>.
-                '';
-                type = types.str;
-                example = "Enabling both \${options.services.foo.enable} and \${options.services.bar.enable} is not possible.";
-              };
-            });
-          };
         };
 
         config = {
@@ -236,35 +154,6 @@ rec {
           # paths, meaning recursiveUpdate will never override any value
           else recursiveUpdate freeformConfig declaredConfig;
 
-      # Triggers all checks defined by _module.checks before returning its argument
-      triggerChecks = let
-
-        handleCheck = errors: name:
-          let
-            value = config._module.checks.${name};
-            show =
-              # Assertions with a _ prefix aren't meant to be configurable
-              if lib.hasPrefix "_" name then value.message
-              else "[${showOption prefix}${optionalString (prefix != []) "/"}${name}] ${value.message}";
-          in
-            if value.enable -> value.check then errors
-            else if value.type == "warning" then lib.warn show errors
-            else if value.type == "error" then errors ++ [ show ]
-            else abort "Unknown check type ${value.type}";
-
-        errors = lib.foldl' handleCheck [] (lib.attrNames config._module.checks);
-
-        errorMessage = ''
-          Failed checks:
-          ${lib.concatMapStringsSep "\n" (a: "- ${a}") errors}
-        '';
-
-        trigger = if errors == [] then null else throw errorMessage;
-
-      in builtins.seq trigger;
-
-      finalConfig = triggerChecks (removeAttrs config [ "_module" ]);
-
       checkUnmatched =
         if config._module.check && config._module.freeformType == null && merged.unmatchedDefns != [] then
           let
@@ -284,7 +173,7 @@ rec {
 
       result = builtins.seq checkUnmatched {
         inherit options;
-        config = finalConfig;
+        config = removeAttrs config [ "_module" ];
         inherit (config) _module;
       };
     in result;
@@ -625,8 +514,6 @@ rec {
         definitions = map (def: def.value) res.defsFinal;
         files = map (def: def.file) res.defsFinal;
         inherit (res) isDefined;
-        # This allows options to be correctly displayed using `${options.path.to.it}`
-        __toString = _: showOption loc;
       };
 
   # Merge definitions of a value of a given type.
@@ -886,15 +773,14 @@ rec {
         visible = false;
         apply = x: throw "The option `${showOption optionName}' can no longer be used since it's been removed. ${replacementInstructions}";
       });
-      config._module.checks =
-        let opt = getAttrFromPath optionName options; in {
-        ${"removed-" + showOption optionName} = lib.mkIf opt.isDefined {
+      config.assertions =
+        let opt = getAttrFromPath optionName options; in [{
+          assertion = !opt.isDefined;
           message = ''
             The option definition `${showOption optionName}' in ${showFiles opt.files} no longer has any effect; please remove it.
             ${replacementInstructions}
           '';
-        };
-      };
+        }];
     };
 
   /* Return a module that causes a warning to be shown if the
@@ -955,18 +841,14 @@ rec {
       })) from);
 
       config = {
-        _module.checks =
-          let warningMessages = map (f:
-            let val = getAttrFromPath f config;
-                opt = getAttrFromPath f options;
-            in {
-              ${"merged" + showOption f} = lib.mkIf (val != "_mkMergedOptionModule") {
-                type = "warning";
-                message = "The option `${showOption f}' defined in ${showFiles opt.files} has been changed to `${showOption to}' that has a different type. Please read `${showOption to}' documentation and update your configuration accordingly.";
-              };
-            }
-            ) from;
-          in mkMerge warningMessages;
+        warnings = filter (x: x != "") (map (f:
+          let val = getAttrFromPath f config;
+              opt = getAttrFromPath f options;
+          in
+          optionalString
+            (val != "_mkMergedOptionModule")
+            "The option `${showOption f}' defined in ${showFiles opt.files} has been changed to `${showOption to}' that has a different type. Please read `${showOption to}' documentation and update your configuration accordingly."
+        ) from);
       } // setAttrByPath to (mkMerge
              (optional
                (any (f: (getAttrFromPath f config) != "_mkMergedOptionModule") from)
@@ -1025,10 +907,8 @@ rec {
       });
       config = mkMerge [
         {
-          _module.checks.${"renamed-" + showOption from} = mkIf (warn && fromOpt.isDefined) {
-            type = "warning";
-            message = "The option `${showOption from}' defined in ${showFiles fromOpt.files} has been renamed to `${showOption to}'.";
-          };
+          warnings = optional (warn && fromOpt.isDefined)
+            "The option `${showOption from}' defined in ${showFiles fromOpt.files} has been renamed to `${showOption to}'.";
         }
         (if withPriority
           then mkAliasAndWrapDefsWithPriority (setAttrByPath to) fromOpt