From 69b558415905ef2468ae556f2318ee853d797bbb Mon Sep 17 00:00:00 2001
From: AkechiShiro <14914796+AkechiShiro@users.noreply.github.com>
Date: Thu, 29 Aug 2024 22:49:17 +0200
Subject: [PATCH] RFC 127: Add implementation tests

* Also fix merge conflicts
* Make sure that performance PR is conserved
* Use RunCommand instead of alias RunCommandNoCC
* Add enum types to meta-types.nix and use them for problemTypes
* Nixfmt (excepted check-meta.nix)
* "import" elem
* Remove dead code
---
 pkgs/stdenv/generic/check-meta.nix            | 86 ++++++++-----------
 pkgs/stdenv/generic/meta-types.nix            | 84 ++++++++++++------
 pkgs/stdenv/generic/problems.nix              | 53 +++++++-----
 .../default.nix                               | 23 +++++
 .../expected-stderr                           | 38 ++++++++
 .../deprecated-and-removal-error/default.nix  | 22 +++++
 .../expected-stderr                           | 35 ++++++++
 .../cases/deprecated-error/default.nix        | 20 +++++
 .../cases/deprecated-error/expected-stderr    | 32 +++++++
 .../cases/deprecated-ignore/default.nix       | 18 ++++
 .../cases/deprecated-ignore/expected-stderr   |  1 +
 .../cases/deprecated-warn/default.nix         | 18 ++++
 .../cases/deprecated-warn/expected-stderr     |  2 +
 .../cases/invalid-kind-error/default.nix      | 15 ++++
 .../cases/invalid-kind-error/expected-stderr  |  7 ++
 .../default.nix                               | 23 +++++
 .../expected-stderr                           |  2 +
 .../default.nix                               | 19 ++++
 .../expected-stderr                           |  2 +
 .../cases/maintainerless-error/default.nix    | 17 ++++
 .../maintainerless-error/expected-stderr      | 32 +++++++
 .../cases/maintainerless-ignore/default.nix   | 17 ++++
 .../maintainerless-ignore/expected-stderr     |  1 +
 .../cases/maintainerless-warn/default.nix     | 17 ++++
 .../cases/maintainerless-warn/expected-stderr |  2 +
 .../problems/cases/no-problems/default.nix    | 15 ++++
 .../cases/no-problems/expected-stderr         |  1 +
 .../problems/cases/removal-error/default.nix  | 15 ++++
 .../cases/removal-error/expected-stderr       | 32 +++++++
 .../problems/cases/removal-ignore/default.nix | 17 ++++
 .../cases/removal-ignore/expected-stderr      |  1 +
 .../cases/removal-twice-error/default.nix     | 21 +++++
 .../cases/removal-twice-error/expected-stderr |  6 ++
 .../problems/cases/removal-warn/default.nix   | 18 ++++
 .../cases/removal-warn/expected-stderr        |  2 +
 pkgs/test/problems/default.nix                | 10 +--
 36 files changed, 616 insertions(+), 108 deletions(-)
 create mode 100644 pkgs/test/problems/cases/deprecated-and-removal-and-maintainerless-error/default.nix
 create mode 100644 pkgs/test/problems/cases/deprecated-and-removal-and-maintainerless-error/expected-stderr
 create mode 100644 pkgs/test/problems/cases/deprecated-and-removal-error/default.nix
 create mode 100644 pkgs/test/problems/cases/deprecated-and-removal-error/expected-stderr
 create mode 100644 pkgs/test/problems/cases/deprecated-error/default.nix
 create mode 100644 pkgs/test/problems/cases/deprecated-error/expected-stderr
 create mode 100644 pkgs/test/problems/cases/deprecated-ignore/default.nix
 create mode 100644 pkgs/test/problems/cases/deprecated-ignore/expected-stderr
 create mode 100644 pkgs/test/problems/cases/deprecated-warn/default.nix
 create mode 100644 pkgs/test/problems/cases/deprecated-warn/expected-stderr
 create mode 100644 pkgs/test/problems/cases/invalid-kind-error/default.nix
 create mode 100644 pkgs/test/problems/cases/invalid-kind-error/expected-stderr
 create mode 100644 pkgs/test/problems/cases/maintainerless-and-removal-and-deprecated-warn/default.nix
 create mode 100644 pkgs/test/problems/cases/maintainerless-and-removal-and-deprecated-warn/expected-stderr
 create mode 100644 pkgs/test/problems/cases/maintainerless-and-removal-warn/default.nix
 create mode 100644 pkgs/test/problems/cases/maintainerless-and-removal-warn/expected-stderr
 create mode 100644 pkgs/test/problems/cases/maintainerless-error/default.nix
 create mode 100644 pkgs/test/problems/cases/maintainerless-error/expected-stderr
 create mode 100644 pkgs/test/problems/cases/maintainerless-ignore/default.nix
 create mode 100644 pkgs/test/problems/cases/maintainerless-ignore/expected-stderr
 create mode 100644 pkgs/test/problems/cases/maintainerless-warn/default.nix
 create mode 100644 pkgs/test/problems/cases/maintainerless-warn/expected-stderr
 create mode 100644 pkgs/test/problems/cases/no-problems/default.nix
 create mode 100644 pkgs/test/problems/cases/no-problems/expected-stderr
 create mode 100644 pkgs/test/problems/cases/removal-error/default.nix
 create mode 100644 pkgs/test/problems/cases/removal-error/expected-stderr
 create mode 100644 pkgs/test/problems/cases/removal-ignore/default.nix
 create mode 100644 pkgs/test/problems/cases/removal-ignore/expected-stderr
 create mode 100644 pkgs/test/problems/cases/removal-twice-error/default.nix
 create mode 100644 pkgs/test/problems/cases/removal-twice-error/expected-stderr
 create mode 100644 pkgs/test/problems/cases/removal-warn/default.nix
 create mode 100644 pkgs/test/problems/cases/removal-warn/expected-stderr

diff --git a/pkgs/stdenv/generic/check-meta.nix b/pkgs/stdenv/generic/check-meta.nix
index 12012043a0d79..537380724d382 100644
--- a/pkgs/stdenv/generic/check-meta.nix
+++ b/pkgs/stdenv/generic/check-meta.nix
@@ -353,19 +353,9 @@ let
     in
     builtins.trace msg true;
 
-   # Deep type-checking. Note that calling `type.check` is not enough: see `lib.mkOptionType`'s documentation.
-  # We don't include this in lib for now because this function is flawed: it accepts things like `mkIf true 42`.
-  typeCheck = type: value: let
-    merged = lib.mergeDefinitions [ ] type [
-      { file = lib.unknownModule; inherit value; }
-    ];
-    eval = builtins.tryEval (builtins.deepSeq merged.mergedValue null);
-  in eval.success;
-
-
   metaTypes = let
     types = import ./meta-types.nix { inherit lib; };
-    inherit (types) str union int attrs attrsOf any listOf bool;
+    inherit (types) str union int attrs attrsOf any listOf bool enum;
     platforms = listOf (union [ str (attrsOf any) ]);  # see lib.meta.platformMatch
   in {
     # These keys are documented
@@ -404,8 +394,11 @@ let
     insecure = bool;
     # This is checked in more detail further down
     problems = attrsOf (attrsOf any);
-    # TODO: refactor once something like Profpatsch's types-simple will land
-    # This is currently dead code due to https://github.com/NixOS/nix/issues/2532
+    problemTypes = {
+      kind = enum problemKindsManual;
+      message = str;
+      urls = listOf str;
+    };
     tests = {
       name = "test";
       verify = x: x == {} || ( # Accept {} for tests that are unsupported
@@ -437,15 +430,8 @@ let
     badPlatforms = platforms;
   };
 
-  # Type of a meta.problems.* value
-  problemTypes = with lib.types; {
-    # Only allow some problem kinds to be used here in `meta`
-    kind = enum problemKindsManual;
-    message = str;
-    urls = listOf str;
-  };
-
-  checkMetaAttr = let
+  # Check that a value matches a specific type. Returns an error message, or null if the check passed
+    checkMetaAttr = let
     # Map attrs directly to the verify function for performance
     metaTypes' = mapAttrs (_: t: t.verify) metaTypes;
   in k: v:
@@ -458,15 +444,7 @@ let
         }" ]
     else
       [ "key 'meta.${k}' is unrecognized; expected one of: \n  [${concatMapStringsSep ", " (x: "'${x}'") (attrNames metaTypes)}]" ];
-
-  checkMeta =
-    meta:
-    # Basic attribute checks
-    lib.optionals config.checkMeta (
-      lib.remove null (
-        lib.mapAttrsToList (checkMetaAttr "meta" metaTypes) meta
-      )
-    )
+  checkMeta = meta: optionals config.checkMeta (concatMap (attr: checkMetaAttr attr meta.${attr}) (attrNames meta)
 
     # Extended checks for problems, as they do not fit the module system
     ++ lib.optionals (meta ? problems) (
@@ -476,7 +454,7 @@ let
         (lib.mapAttrs (name: problem: { kind = name; } // problem))
         (lib.mapAttrsToList (
           name: problem:
-          lib.mapAttrsToList (checkMetaAttr "meta.problems.${name}" problemTypes) problem
+          lib.mapAttrsToList (checkMetaAttr "meta.problems.${name}" meta.problemTypes) problem
         ))
         (lib.concatLists)
         (lib.remove null)
@@ -511,11 +489,11 @@ let
         (lib.mapAttrsToList (
           kind: names:
           "keys [ ${
-            concatMapStringsSep " " (name: "'meta.problems.${name}'") names
+            lib.concatMapStringsSep " " (name: "'meta.problems.${name}'") names
           } ] all have the same problem kind, which is not allowed for kind '${kind}'"
         ))
       ]
-    );
+    ));
 
   checkOutputsToInstall = attrs: let
       expectedOutputs = attrs.meta.outputsToInstall or [];
@@ -533,21 +511,24 @@ let
   # reason is one of "unfree", "blocklisted", "broken", "insecure", ...
   # !!! reason strings are hardcoded into OfBorg, make sure to keep them in sync
   # Along with a boolean flag for each reason
-  checkValidity =
-    let
-      validYes = {
-        valid = "yes";
-        handled = true;
-      };
-    in
-    attrs:
+    checkValidity = attrs:
     # Check meta attribute types first, to make sure it is always called even when there are other issues
     # Note that this is not a full type check and functions below still need to by careful about their inputs!
-    let
-      res = checkMeta (attrs.meta or {});
-    in
-    if res != [] then
-      { valid = "no"; reason = "unknown-meta"; errormsg = "has an invalid meta attrset:${concatMapStrings (x: "\n  - " + x) res}\n"; }
+    let res = checkMeta (attrs.meta or {}); in if res != [] then
+      { valid = "no"; reason = "unknown-meta"; errormsg = "has an invalid meta attrset:${lib.concatMapStrings (x: "\n  - " + x) res}\n";
+        unfree = false; nonSource = false; broken = false; unsupported = false; insecure = false;
+      }
+    else {
+      unfree = hasUnfreeLicense attrs;
+      nonSource = hasNonSourceProvenance attrs;
+      broken = isMarkedBroken attrs;
+      unsupported = hasUnsupportedPlatform attrs;
+      insecure = isMarkedInsecure attrs;
+    } // (
+    # Check meta attribute types first, to make sure it is always called even when there are other issues
+    # Note that this is not a full type check and functions below still need to by careful about their inputs!
+    let res = checkMeta (attrs.meta or {}); in if res != [] then
+      { valid = "no"; reason = "unknown-meta"; errormsg = "has malformed metadata:${lib.concatMapStrings (x: "\n\t - " + x) res}"; }
     # --- Put checks that cannot be ignored here ---
     else if checkOutputsToInstall attrs then
       { valid = "no"; reason = "broken-outputs"; errormsg = "has invalid meta.outputsToInstall"; }
@@ -559,10 +540,12 @@ let
       { valid = "no"; reason = "blocklisted"; errormsg = "has a blocklisted license (‘${showLicense attrs.meta.license}’)"; }
     else if hasDeniedNonSourceProvenance attrs then
       { valid = "no"; reason = "non-source"; errormsg = "contains elements not built from source (‘${showSourceType attrs.meta.sourceProvenance}’)"; }
+
+    # --- Put checks that can be ignored here ---
     else if !allowBroken && attrs.meta.broken or false then
       { valid = "no"; reason = "broken"; errormsg = "is marked as broken"; }
     else if !allowUnsupportedSystem && hasUnsupportedPlatform attrs then
-      let toPretty' = toPretty {
+      let toPretty = lib.generators.toPretty {
             allowPrettyValues = true;
             indent = "  ";
           };
@@ -570,8 +553,8 @@ let
            errormsg = ''
              is not available on the requested hostPlatform:
                hostPlatform.config = "${hostPlatform.config}"
-               package.meta.platforms = ${toPretty' (attrs.meta.platforms or [])}
-               package.meta.badPlatforms = ${toPretty' (attrs.meta.badPlatforms or [])}
+               package.meta.platforms = ${toPretty (attrs.meta.platforms or [])}
+               package.meta.badPlatforms = ${toPretty (attrs.meta.badPlatforms or [])}
             '';
          }
     else if !(hasAllowedInsecure attrs) then
@@ -602,8 +585,7 @@ let
         ;
       }
     # -----
-    else validYes;
-
+    else { valid = "yes"; });
 
   # The meta attribute is passed in the resulting attribute set,
   # but it's not part of the actual derivation, i.e., it's not
diff --git a/pkgs/stdenv/generic/meta-types.nix b/pkgs/stdenv/generic/meta-types.nix
index ddbd1daca696e..d944f5dd2b32d 100644
--- a/pkgs/stdenv/generic/meta-types.nix
+++ b/pkgs/stdenv/generic/meta-types.nix
@@ -5,7 +5,20 @@
 # TODO: add a method to the module system types
 #       see https://github.com/NixOS/nixpkgs/pull/273935#issuecomment-1854173100
 let
-  inherit (builtins) isString isInt isAttrs isList all any attrValues isFunction isBool concatStringsSep isFloat;
+  inherit (builtins)
+    isString
+    isInt
+    isAttrs
+    isList
+    all
+    any
+    attrValues
+    isFunction
+    isBool
+    concatStringsSep
+    isFloat
+    elem
+    ;
   isTypeDef = t: isAttrs t && t ? name && isString t.name && t ? verify && isFunction t.verify;
 
 in
@@ -14,7 +27,7 @@ lib.fix (self: {
     name = "string";
     verify = isString;
   };
-  str = self.string;  # Type alias
+  str = self.string; # Type alias
 
   any = {
     name = "any";
@@ -46,31 +59,48 @@ lib.fix (self: {
     verify = isList;
   };
 
-  attrsOf = t: assert isTypeDef t; let
-    inherit (t) verify;
-  in {
-    name = "attrsOf<${t.name}>";
-    verify =
-      # attrsOf<any> can be optimised to just isAttrs
-      if t == self.any then isAttrs
-      else attrs: isAttrs attrs && all verify (attrValues attrs);
-  };
+  attrsOf =
+    t:
+    assert isTypeDef t;
+    let
+      inherit (t) verify;
+    in
+    {
+      name = "attrsOf<${t.name}>";
+      verify =
+        # attrsOf<any> can be optimised to just isAttrs
+        if t == self.any then isAttrs else attrs: isAttrs attrs && all verify (attrValues attrs);
+    };
 
-  listOf = t: assert isTypeDef t; let
-    inherit (t) verify;
-  in {
-    name = "listOf<${t.name}>";
-    verify =
-      # listOf<any> can be optimised to just isList
-      if t == self.any then isList
-      else v: isList v && all verify v;
-  };
+  listOf =
+    t:
+    assert isTypeDef t;
+    let
+      inherit (t) verify;
+    in
+    {
+      name = "listOf<${t.name}>";
+      verify =
+        # listOf<any> can be optimised to just isList
+        if t == self.any then isList else v: isList v && all verify v;
+    };
 
-  union = types: assert all isTypeDef types; let
-    # Store a list of functions so we don't have to pay the cost of attrset lookups at runtime.
-    funcs = map (t: t.verify) types;
-  in {
-    name = "union<${concatStringsSep "," (map (t: t.name) types)}>";
-    verify = v: any (func: func v) funcs;
-  };
+  union =
+    types:
+    assert all isTypeDef types;
+    let
+      # Store a list of functions so we don't have to pay the cost of attrset lookups at runtime.
+      funcs = map (t: t.verify) types;
+    in
+    {
+      name = "union<${concatStringsSep "," (map (t: t.name) types)}>";
+      verify = v: any (func: func v) funcs;
+    };
+  enum =
+    values:
+    assert isList values && all isString values;
+    {
+      name = "enum<${concatStringsSep "," values}>";
+      verify = v: isString v && elem v values;
+    };
 })
diff --git a/pkgs/stdenv/generic/problems.nix b/pkgs/stdenv/generic/problems.nix
index fd2e67e12047c..ff5f32d92a931 100644
--- a/pkgs/stdenv/generic/problems.nix
+++ b/pkgs/stdenv/generic/problems.nix
@@ -4,7 +4,11 @@
 
 rec {
   # Problem handler levels
-  problemHandlers = [ "error" "warn" "ignore" ];
+  problemHandlers = [
+    "error"
+    "warn"
+    "ignore"
+  ];
 
   # Take the maximum (highest severity) problem handler
   maxProblemHandler =
@@ -14,8 +18,7 @@ rec {
     else if a == "warn" || b == "warn" then
       "warn"
     else
-      "ignore"
-  ;
+      "ignore";
 
   # Currently known list of known problem kinds. Keep up to date with pkgs/top-level/config.nix
   problemKinds = [
@@ -40,7 +43,10 @@ rec {
   ];
   # Same thing but a set with null values (comes in handy at times)
   problemKindsUnique' = lib.pipe problemKindsUnique [
-    (map (name: { inherit name; value = null; }))
+    (map (name: {
+      inherit name;
+      value = null;
+    }))
     lib.listToAttrs
   ];
 
@@ -61,7 +67,7 @@ rec {
 
       # Take the problems plus add automatically generated ones
       problems =
-        (pkg.meta.problems or {})
+        (pkg.meta.problems or { })
         // lib.optionalAttrs (hasNoMaintainers pkg) {
           maintainerless = {
             message = "This package has no declared maintainer, i.e. an empty `meta.maintainers` attribute";
@@ -69,34 +75,37 @@ rec {
         };
 
       # Inject default values, since metaTypes can't do it for us currently
-      addDefaults = name: problem: { inherit name; kind = name; } // problem;
+      addDefaults =
+        name: problem:
+        {
+          inherit name;
+          kind = name;
+        }
+        // problem;
 
       # Determine the handler level from config for this problem
-      addHandler = problem:
+      addHandler =
+        problem:
         let
           handler =
             # Try to find an explicit handler
-            (handlers.${pkgName} or {}).${problem.name}
-            # Fall back, iterating through the matchers
-            or (
-              lib.pipe matchers [
+            (handlers.${pkgName} or { }).${problem.name}
+              # Fall back, iterating through the matchers
+              or (lib.pipe matchers [
                 # Find matches
-                (lib.filter
-                  (matcher:
-                    (if matcher.name != null then problem.name == matcher.name else true)
-                    && (if matcher.kind != null then problem.kind == matcher.kind else true)
-                    && (if matcher.package != null then pkgName == matcher.package else true)
-                  )
-                )
+                (lib.filter (
+                  matcher:
+                  (if matcher.name != null then problem.name == matcher.name else true)
+                  && (if matcher.kind != null then problem.kind == matcher.kind else true)
+                  && (if matcher.package != null then pkgName == matcher.package else true)
+                ))
                 # Extract handler level
                 (builtins.map (lib.getAttr "handler"))
                 # Take the strongest matched handler level
                 (lib.foldl' maxProblemHandler "ignore")
-              ]
-            );
+              ]);
         in
         problem // { inherit handler; };
     in
-    builtins.map addHandler
-      (lib.mapAttrsToList addDefaults problems);
+    builtins.map addHandler (lib.mapAttrsToList addDefaults problems);
 }
diff --git a/pkgs/test/problems/cases/deprecated-and-removal-and-maintainerless-error/default.nix b/pkgs/test/problems/cases/deprecated-and-removal-and-maintainerless-error/default.nix
new file mode 100644
index 0000000000000..562c7594c5d17
--- /dev/null
+++ b/pkgs/test/problems/cases/deprecated-and-removal-and-maintainerless-error/default.nix
@@ -0,0 +1,23 @@
+{ nixpkgs }:
+let
+  pkgs = import nixpkgs {
+    system = "x86_64-linux";
+    overlays = [ ];
+    config = {
+      problems.handlers = {
+        "a"."deprecated" = "error";
+        "a"."removal" = "error";
+        "a"."maintainerless" = "error";
+      };
+    };
+  };
+in
+pkgs.stdenvNoCC.mkDerivation {
+  pname = "a";
+  version = "0";
+  meta.problems = {
+    deprecated.message = "Package is deprecated and replaced by b";
+    removal.message = "Package will be removed.";
+  };
+  meta.maintainers = [ ];
+}
diff --git a/pkgs/test/problems/cases/deprecated-and-removal-and-maintainerless-error/expected-stderr b/pkgs/test/problems/cases/deprecated-and-removal-and-maintainerless-error/expected-stderr
new file mode 100644
index 0000000000000..7b72e3fc5052d
--- /dev/null
+++ b/pkgs/test/problems/cases/deprecated-and-removal-and-maintainerless-error/expected-stderr
@@ -0,0 +1,38 @@
+error: Package ‘a-0’ in /nix/store/eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee-default.nix:17 has some problem that must be acknowledged, refusing to evaluate.
+
+
+
+Package problems:
+
+- deprecated: Package is deprecated and replaced by b
+- maintainerless: This package has no declared maintainer, i.e. an empty `meta.maintainers` attribute
+- removal: Package will be removed.
+
+You can use it anyway by ignoring its problems, using one of the
+following methods:
+
+a) For `nixos-rebuild` you can add "warn" or "ignore" entries to
+  `nixpkgs.config.problems.handlers` inside configuration.nix,
+  like this:
+
+    {
+      nixpkgs.config.problems.handlers = {
+        "a"."deprecated" = "warn";
+        "a"."maintainerless" = "warn";
+        "a"."removal" = "warn";
+      };
+    }
+
+b) For `nix-env`, `nix-build`, `nix-shell` or any other Nix command you can add
+  "warn" or "ignore" to `problems.handlers` in
+  ~/.config/nixpkgs/config.nix, like this:
+
+    {
+      problems.handlers = {
+        "a"."deprecated" = "warn";
+        "a"."maintainerless" = "warn";
+        "a"."removal" = "warn";
+      };
+    }
+
+(use '--show-trace' to show detailed location information)
diff --git a/pkgs/test/problems/cases/deprecated-and-removal-error/default.nix b/pkgs/test/problems/cases/deprecated-and-removal-error/default.nix
new file mode 100644
index 0000000000000..20a18cc17c78e
--- /dev/null
+++ b/pkgs/test/problems/cases/deprecated-and-removal-error/default.nix
@@ -0,0 +1,22 @@
+{ nixpkgs }:
+let
+  pkgs = import nixpkgs {
+    system = "x86_64-linux";
+    overlays = [ ];
+    config = {
+      problems.handlers = {
+        "a"."deprecated" = "error";
+        "a"."removal" = "error";
+      };
+    };
+  };
+in
+pkgs.stdenvNoCC.mkDerivation {
+  pname = "a";
+  version = "0";
+  meta.problems = {
+    deprecated.message = "Package is deprecated and replaced by b";
+    removal.message = "Package will be removed";
+  };
+  meta.maintainers = [ "hello" ];
+}
diff --git a/pkgs/test/problems/cases/deprecated-and-removal-error/expected-stderr b/pkgs/test/problems/cases/deprecated-and-removal-error/expected-stderr
new file mode 100644
index 0000000000000..f5a0f1cce688d
--- /dev/null
+++ b/pkgs/test/problems/cases/deprecated-and-removal-error/expected-stderr
@@ -0,0 +1,35 @@
+error: Package ‘a-0’ in /nix/store/eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee-default.nix:16 has some problem that must be acknowledged, refusing to evaluate.
+
+
+
+Package problems:
+
+- deprecated: Package is deprecated and replaced by b
+- removal: Package will be removed
+
+You can use it anyway by ignoring its problems, using one of the
+following methods:
+
+a) For `nixos-rebuild` you can add "warn" or "ignore" entries to
+  `nixpkgs.config.problems.handlers` inside configuration.nix,
+  like this:
+
+    {
+      nixpkgs.config.problems.handlers = {
+        "a"."deprecated" = "warn";
+        "a"."removal" = "warn";
+      };
+    }
+
+b) For `nix-env`, `nix-build`, `nix-shell` or any other Nix command you can add
+  "warn" or "ignore" to `problems.handlers` in
+  ~/.config/nixpkgs/config.nix, like this:
+
+    {
+      problems.handlers = {
+        "a"."deprecated" = "warn";
+        "a"."removal" = "warn";
+      };
+    }
+
+(use '--show-trace' to show detailed location information)
diff --git a/pkgs/test/problems/cases/deprecated-error/default.nix b/pkgs/test/problems/cases/deprecated-error/default.nix
new file mode 100644
index 0000000000000..405d394bd893f
--- /dev/null
+++ b/pkgs/test/problems/cases/deprecated-error/default.nix
@@ -0,0 +1,20 @@
+{ nixpkgs }:
+let
+  pkgs = import nixpkgs {
+    system = "x86_64-linux";
+    overlays = [ ];
+    config = {
+      problems.handlers = {
+        "a"."deprecated" = "error";
+      };
+    };
+  };
+in
+pkgs.stdenvNoCC.mkDerivation {
+  pname = "a";
+  version = "0";
+  meta.problems.deprecated = {
+    message = "Package is deprecated and replaced by b";
+  };
+  meta.maintainers = [ "hello" ];
+}
diff --git a/pkgs/test/problems/cases/deprecated-error/expected-stderr b/pkgs/test/problems/cases/deprecated-error/expected-stderr
new file mode 100644
index 0000000000000..13fdb8d1706ba
--- /dev/null
+++ b/pkgs/test/problems/cases/deprecated-error/expected-stderr
@@ -0,0 +1,32 @@
+error: Package ‘a-0’ in /nix/store/eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee-default.nix:15 has some problem that must be acknowledged, refusing to evaluate.
+
+
+
+Package problems:
+
+- deprecated: Package is deprecated and replaced by b
+
+You can use it anyway by ignoring its problems, using one of the
+following methods:
+
+a) For `nixos-rebuild` you can add "warn" or "ignore" entries to
+  `nixpkgs.config.problems.handlers` inside configuration.nix,
+  like this:
+
+    {
+      nixpkgs.config.problems.handlers = {
+        "a"."deprecated" = "warn";
+      };
+    }
+
+b) For `nix-env`, `nix-build`, `nix-shell` or any other Nix command you can add
+  "warn" or "ignore" to `problems.handlers` in
+  ~/.config/nixpkgs/config.nix, like this:
+
+    {
+      problems.handlers = {
+        "a"."deprecated" = "warn";
+      };
+    }
+
+(use '--show-trace' to show detailed location information)
diff --git a/pkgs/test/problems/cases/deprecated-ignore/default.nix b/pkgs/test/problems/cases/deprecated-ignore/default.nix
new file mode 100644
index 0000000000000..0ce36d2948423
--- /dev/null
+++ b/pkgs/test/problems/cases/deprecated-ignore/default.nix
@@ -0,0 +1,18 @@
+{ nixpkgs }:
+let
+  pkgs = import nixpkgs {
+    system = "x86_64-linux";
+    overlays = [ ];
+    config = {
+      problems.handlers = {
+        "a"."deprecated" = "ignore";
+      };
+    };
+  };
+in
+pkgs.stdenvNoCC.mkDerivation {
+  pname = "a";
+  version = "0";
+  meta.problems.deprecated.message = "Package is deprecated and is replaced by b.";
+  meta.maintainers = [ "hello" ];
+}
diff --git a/pkgs/test/problems/cases/deprecated-ignore/expected-stderr b/pkgs/test/problems/cases/deprecated-ignore/expected-stderr
new file mode 100644
index 0000000000000..c255c1d5a32bd
--- /dev/null
+++ b/pkgs/test/problems/cases/deprecated-ignore/expected-stderr
@@ -0,0 +1 @@
+warning: you did not specify '--add-root'; the result might be removed by the garbage collector
diff --git a/pkgs/test/problems/cases/deprecated-warn/default.nix b/pkgs/test/problems/cases/deprecated-warn/default.nix
new file mode 100644
index 0000000000000..bcafc3e96f6a7
--- /dev/null
+++ b/pkgs/test/problems/cases/deprecated-warn/default.nix
@@ -0,0 +1,18 @@
+{ nixpkgs }:
+let
+  pkgs = import nixpkgs {
+    system = "x86_64-linux";
+    overlays = [ ];
+    config = {
+      problems.handlers = {
+        "a"."deprecated" = "warn";
+      };
+    };
+  };
+in
+pkgs.stdenvNoCC.mkDerivation {
+  pname = "a";
+  version = "0";
+  meta.problems.deprecated.message = "Package a is deprecated and superseeded by b.";
+  meta.maintainers = [ "hello" ];
+}
diff --git a/pkgs/test/problems/cases/deprecated-warn/expected-stderr b/pkgs/test/problems/cases/deprecated-warn/expected-stderr
new file mode 100644
index 0000000000000..a55882a849c09
--- /dev/null
+++ b/pkgs/test/problems/cases/deprecated-warn/expected-stderr
@@ -0,0 +1,2 @@
+trace: Package a-0 in /nix/store/eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee-default.nix:15 has the following problems: [ "deprecated" ], continuing anyway.
+warning: you did not specify '--add-root'; the result might be removed by the garbage collector
diff --git a/pkgs/test/problems/cases/invalid-kind-error/default.nix b/pkgs/test/problems/cases/invalid-kind-error/default.nix
new file mode 100644
index 0000000000000..a97437752acc1
--- /dev/null
+++ b/pkgs/test/problems/cases/invalid-kind-error/default.nix
@@ -0,0 +1,15 @@
+{ nixpkgs }:
+let
+  pkgs = import nixpkgs {
+    system = "x86_64-linux";
+    overlays = [ ];
+    config = { };
+  };
+in
+pkgs.stdenvNoCC.mkDerivation {
+  pname = "a";
+  version = "0";
+  meta.problems = {
+    invalid.message = "No maintainers";
+  };
+}
diff --git a/pkgs/test/problems/cases/invalid-kind-error/expected-stderr b/pkgs/test/problems/cases/invalid-kind-error/expected-stderr
new file mode 100644
index 0000000000000..d27676672b6ac
--- /dev/null
+++ b/pkgs/test/problems/cases/invalid-kind-error/expected-stderr
@@ -0,0 +1,7 @@
+error: Package ‘a-0’ in /nix/store/eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee-default.nix:11 has an invalid meta attrset:
+  - key 'meta.problems.invalid.kind' has invalid value; expected one of "removal", "deprecated", got
+    "invalid"
+, refusing to evaluate.
+
+
+(use '--show-trace' to show detailed location information)
diff --git a/pkgs/test/problems/cases/maintainerless-and-removal-and-deprecated-warn/default.nix b/pkgs/test/problems/cases/maintainerless-and-removal-and-deprecated-warn/default.nix
new file mode 100644
index 0000000000000..9261c2e45fae9
--- /dev/null
+++ b/pkgs/test/problems/cases/maintainerless-and-removal-and-deprecated-warn/default.nix
@@ -0,0 +1,23 @@
+{ nixpkgs }:
+let
+  pkgs = import nixpkgs {
+    system = "x86_64-linux";
+    overlays = [ ];
+    config = {
+      problems.handlers = {
+        "a"."maintainerless" = "warn";
+        "a"."deprecated" = "warn";
+        "a"."removal" = "warn";
+      };
+    };
+  };
+in
+pkgs.stdenvNoCC.mkDerivation {
+  pname = "a";
+  version = "0";
+  meta.maintainers = [ ];
+  meta.problems = {
+    removal.message = "Package to be removed.";
+    deprecated.message = "Package will be deprecated";
+  };
+}
diff --git a/pkgs/test/problems/cases/maintainerless-and-removal-and-deprecated-warn/expected-stderr b/pkgs/test/problems/cases/maintainerless-and-removal-and-deprecated-warn/expected-stderr
new file mode 100644
index 0000000000000..656f92bc94fca
--- /dev/null
+++ b/pkgs/test/problems/cases/maintainerless-and-removal-and-deprecated-warn/expected-stderr
@@ -0,0 +1,2 @@
+trace: Package a-0 in /nix/store/eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee-default.nix:17 has the following problems: [ "deprecated" "maintainerless" "removal" ], continuing anyway.
+warning: you did not specify '--add-root'; the result might be removed by the garbage collector
diff --git a/pkgs/test/problems/cases/maintainerless-and-removal-warn/default.nix b/pkgs/test/problems/cases/maintainerless-and-removal-warn/default.nix
new file mode 100644
index 0000000000000..82266eafa95c6
--- /dev/null
+++ b/pkgs/test/problems/cases/maintainerless-and-removal-warn/default.nix
@@ -0,0 +1,19 @@
+{ nixpkgs }:
+let
+  pkgs = import nixpkgs {
+    system = "x86_64-linux";
+    overlays = [ ];
+    config = {
+      problems.handlers = {
+        "a"."maintainerless" = "warn";
+        "a"."removal" = "warn";
+      };
+    };
+  };
+in
+pkgs.stdenvNoCC.mkDerivation {
+  pname = "a";
+  version = "0";
+  meta.maintainers = [ ];
+  meta.problems.removal.message = "Package will be removed.";
+}
diff --git a/pkgs/test/problems/cases/maintainerless-and-removal-warn/expected-stderr b/pkgs/test/problems/cases/maintainerless-and-removal-warn/expected-stderr
new file mode 100644
index 0000000000000..1f8e51654aff6
--- /dev/null
+++ b/pkgs/test/problems/cases/maintainerless-and-removal-warn/expected-stderr
@@ -0,0 +1,2 @@
+trace: Package a-0 in /nix/store/eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee-default.nix:16 has the following problems: [ "maintainerless" "removal" ], continuing anyway.
+warning: you did not specify '--add-root'; the result might be removed by the garbage collector
diff --git a/pkgs/test/problems/cases/maintainerless-error/default.nix b/pkgs/test/problems/cases/maintainerless-error/default.nix
new file mode 100644
index 0000000000000..150e623a4bdff
--- /dev/null
+++ b/pkgs/test/problems/cases/maintainerless-error/default.nix
@@ -0,0 +1,17 @@
+{ nixpkgs }:
+let
+  pkgs = import nixpkgs {
+    system = "x86_64-linux";
+    overlays = [ ];
+    config = {
+      problems.handlers = {
+        "a"."maintainerless" = "error";
+      };
+    };
+  };
+in
+pkgs.stdenvNoCC.mkDerivation {
+  pname = "a";
+  version = "0";
+  meta.maintainers = [ ];
+}
diff --git a/pkgs/test/problems/cases/maintainerless-error/expected-stderr b/pkgs/test/problems/cases/maintainerless-error/expected-stderr
new file mode 100644
index 0000000000000..176fd604057ba
--- /dev/null
+++ b/pkgs/test/problems/cases/maintainerless-error/expected-stderr
@@ -0,0 +1,32 @@
+error: Package ‘a-0’ in /nix/store/eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee-default.nix:15 has some problem that must be acknowledged, refusing to evaluate.
+
+
+
+Package problems:
+
+- maintainerless: This package has no declared maintainer, i.e. an empty `meta.maintainers` attribute
+
+You can use it anyway by ignoring its problems, using one of the
+following methods:
+
+a) For `nixos-rebuild` you can add "warn" or "ignore" entries to
+  `nixpkgs.config.problems.handlers` inside configuration.nix,
+  like this:
+
+    {
+      nixpkgs.config.problems.handlers = {
+        "a"."maintainerless" = "warn";
+      };
+    }
+
+b) For `nix-env`, `nix-build`, `nix-shell` or any other Nix command you can add
+  "warn" or "ignore" to `problems.handlers` in
+  ~/.config/nixpkgs/config.nix, like this:
+
+    {
+      problems.handlers = {
+        "a"."maintainerless" = "warn";
+      };
+    }
+
+(use '--show-trace' to show detailed location information)
diff --git a/pkgs/test/problems/cases/maintainerless-ignore/default.nix b/pkgs/test/problems/cases/maintainerless-ignore/default.nix
new file mode 100644
index 0000000000000..8531510073d40
--- /dev/null
+++ b/pkgs/test/problems/cases/maintainerless-ignore/default.nix
@@ -0,0 +1,17 @@
+{ nixpkgs }:
+let
+  pkgs = import nixpkgs {
+    system = "x86_64-linux";
+    overlays = [ ];
+    config = {
+      problems.handlers = {
+        "a"."maintainerless" = "ignore";
+      };
+    };
+  };
+in
+pkgs.stdenvNoCC.mkDerivation {
+  pname = "a";
+  version = "0";
+  meta.maintainers = [ ];
+}
diff --git a/pkgs/test/problems/cases/maintainerless-ignore/expected-stderr b/pkgs/test/problems/cases/maintainerless-ignore/expected-stderr
new file mode 100644
index 0000000000000..c255c1d5a32bd
--- /dev/null
+++ b/pkgs/test/problems/cases/maintainerless-ignore/expected-stderr
@@ -0,0 +1 @@
+warning: you did not specify '--add-root'; the result might be removed by the garbage collector
diff --git a/pkgs/test/problems/cases/maintainerless-warn/default.nix b/pkgs/test/problems/cases/maintainerless-warn/default.nix
new file mode 100644
index 0000000000000..75708dcd42ad5
--- /dev/null
+++ b/pkgs/test/problems/cases/maintainerless-warn/default.nix
@@ -0,0 +1,17 @@
+{ nixpkgs }:
+let
+  pkgs = import nixpkgs {
+    system = "x86_64-linux";
+    overlays = [ ];
+    config = {
+      problems.handlers = {
+        "a"."maintainerless" = "warn";
+      };
+    };
+  };
+in
+pkgs.stdenvNoCC.mkDerivation {
+  pname = "a";
+  version = "0";
+  meta.maintainers = [ ];
+}
diff --git a/pkgs/test/problems/cases/maintainerless-warn/expected-stderr b/pkgs/test/problems/cases/maintainerless-warn/expected-stderr
new file mode 100644
index 0000000000000..45fd822f0feb5
--- /dev/null
+++ b/pkgs/test/problems/cases/maintainerless-warn/expected-stderr
@@ -0,0 +1,2 @@
+trace: Package a-0 in /nix/store/eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee-default.nix:15 has the following problems: [ "maintainerless" ], continuing anyway.
+warning: you did not specify '--add-root'; the result might be removed by the garbage collector
diff --git a/pkgs/test/problems/cases/no-problems/default.nix b/pkgs/test/problems/cases/no-problems/default.nix
new file mode 100644
index 0000000000000..f7b14483233d9
--- /dev/null
+++ b/pkgs/test/problems/cases/no-problems/default.nix
@@ -0,0 +1,15 @@
+{ nixpkgs }:
+let
+  pkgs = import nixpkgs {
+    system = "x86_64-linux";
+    overlays = [ ];
+    config = {
+      problems.handlers = { };
+    };
+  };
+in
+pkgs.stdenvNoCC.mkDerivation {
+  pname = "a";
+  version = "0";
+  meta.maintainers = [ "hello" ];
+}
diff --git a/pkgs/test/problems/cases/no-problems/expected-stderr b/pkgs/test/problems/cases/no-problems/expected-stderr
new file mode 100644
index 0000000000000..c255c1d5a32bd
--- /dev/null
+++ b/pkgs/test/problems/cases/no-problems/expected-stderr
@@ -0,0 +1 @@
+warning: you did not specify '--add-root'; the result might be removed by the garbage collector
diff --git a/pkgs/test/problems/cases/removal-error/default.nix b/pkgs/test/problems/cases/removal-error/default.nix
new file mode 100644
index 0000000000000..43b62a3fcf51b
--- /dev/null
+++ b/pkgs/test/problems/cases/removal-error/default.nix
@@ -0,0 +1,15 @@
+{ nixpkgs }:
+let
+  pkgs = import nixpkgs {
+    system = "x86_64-linux";
+    overlays = [ ];
+    config = { };
+  };
+in
+pkgs.stdenvNoCC.mkDerivation {
+  pname = "a";
+  version = "0";
+  meta.problems = {
+    removal.message = "This package has been abandoned upstream and will be removed";
+  };
+}
diff --git a/pkgs/test/problems/cases/removal-error/expected-stderr b/pkgs/test/problems/cases/removal-error/expected-stderr
new file mode 100644
index 0000000000000..915218a9ad024
--- /dev/null
+++ b/pkgs/test/problems/cases/removal-error/expected-stderr
@@ -0,0 +1,32 @@
+error: Package ‘a-0’ in /nix/store/eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee-default.nix:11 has some problem that must be acknowledged, refusing to evaluate.
+
+
+
+Package problems:
+
+- removal: This package has been abandoned upstream and will be removed
+
+You can use it anyway by ignoring its problems, using one of the
+following methods:
+
+a) For `nixos-rebuild` you can add "warn" or "ignore" entries to
+  `nixpkgs.config.problems.handlers` inside configuration.nix,
+  like this:
+
+    {
+      nixpkgs.config.problems.handlers = {
+        "a"."removal" = "warn";
+      };
+    }
+
+b) For `nix-env`, `nix-build`, `nix-shell` or any other Nix command you can add
+  "warn" or "ignore" to `problems.handlers` in
+  ~/.config/nixpkgs/config.nix, like this:
+
+    {
+      problems.handlers = {
+        "a"."removal" = "warn";
+      };
+    }
+
+(use '--show-trace' to show detailed location information)
diff --git a/pkgs/test/problems/cases/removal-ignore/default.nix b/pkgs/test/problems/cases/removal-ignore/default.nix
new file mode 100644
index 0000000000000..0cccb8873b276
--- /dev/null
+++ b/pkgs/test/problems/cases/removal-ignore/default.nix
@@ -0,0 +1,17 @@
+{ nixpkgs }:
+let
+  pkgs = import nixpkgs {
+    system = "x86_64-linux";
+    overlays = [ ];
+    config = {
+      problems.handlers = {
+        "a"."removal" = "ignore";
+      };
+    };
+  };
+in
+pkgs.stdenvNoCC.mkDerivation {
+  pname = "a";
+  version = "0";
+  meta.problems.removal.message = "To be removed";
+}
diff --git a/pkgs/test/problems/cases/removal-ignore/expected-stderr b/pkgs/test/problems/cases/removal-ignore/expected-stderr
new file mode 100644
index 0000000000000..c255c1d5a32bd
--- /dev/null
+++ b/pkgs/test/problems/cases/removal-ignore/expected-stderr
@@ -0,0 +1 @@
+warning: you did not specify '--add-root'; the result might be removed by the garbage collector
diff --git a/pkgs/test/problems/cases/removal-twice-error/default.nix b/pkgs/test/problems/cases/removal-twice-error/default.nix
new file mode 100644
index 0000000000000..c2dec5f6d7cf7
--- /dev/null
+++ b/pkgs/test/problems/cases/removal-twice-error/default.nix
@@ -0,0 +1,21 @@
+{ nixpkgs }:
+let
+  pkgs = import nixpkgs {
+    system = "x86_64-linux";
+    overlays = [ ];
+    config = { };
+  };
+in
+pkgs.stdenvNoCC.mkDerivation {
+  pname = "a";
+  version = "0";
+  meta.problems = {
+    removal = {
+      message = "This package has been abandoned upstream and will be removed";
+    };
+    removal2 = {
+      kind = "removal";
+      message = "This package has been abandoned upstream and will be removed2";
+    };
+  };
+}
diff --git a/pkgs/test/problems/cases/removal-twice-error/expected-stderr b/pkgs/test/problems/cases/removal-twice-error/expected-stderr
new file mode 100644
index 0000000000000..63b7c9eecfad1
--- /dev/null
+++ b/pkgs/test/problems/cases/removal-twice-error/expected-stderr
@@ -0,0 +1,6 @@
+error: Package ‘a-0’ in /nix/store/eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee-default.nix:11 has an invalid meta attrset:
+  - keys [ 'meta.problems.removal' 'meta.problems.removal2' ] all have the same problem kind, which is not allowed for kind 'removal'
+, refusing to evaluate.
+
+
+(use '--show-trace' to show detailed location information)
diff --git a/pkgs/test/problems/cases/removal-warn/default.nix b/pkgs/test/problems/cases/removal-warn/default.nix
new file mode 100644
index 0000000000000..0044c2fc39e09
--- /dev/null
+++ b/pkgs/test/problems/cases/removal-warn/default.nix
@@ -0,0 +1,18 @@
+{ nixpkgs }:
+let
+  pkgs = import nixpkgs {
+    system = "x86_64-linux";
+    overlays = [ ];
+    config = {
+      problems.handlers = {
+        "a"."removal" = "warn";
+      };
+    };
+  };
+in
+pkgs.stdenvNoCC.mkDerivation {
+  pname = "a";
+  version = "0";
+  meta.maintainers = [ "hello" ];
+  meta.problems.removal.message = "Package to be removed.";
+}
diff --git a/pkgs/test/problems/cases/removal-warn/expected-stderr b/pkgs/test/problems/cases/removal-warn/expected-stderr
new file mode 100644
index 0000000000000..93f814163896c
--- /dev/null
+++ b/pkgs/test/problems/cases/removal-warn/expected-stderr
@@ -0,0 +1,2 @@
+trace: Package a-0 in /nix/store/eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee-default.nix:15 has the following problems: [ "removal" ], continuing anyway.
+warning: you did not specify '--add-root'; the result might be removed by the garbage collector
diff --git a/pkgs/test/problems/default.nix b/pkgs/test/problems/default.nix
index 26fe640673d56..3366c3688eda8 100644
--- a/pkgs/test/problems/default.nix
+++ b/pkgs/test/problems/default.nix
@@ -1,7 +1,7 @@
 {
   lib,
   nixVersions,
-  runCommandNoCC,
+  runCommand,
   removeReferencesTo,
   path,
 }:
@@ -12,11 +12,7 @@ lib.mapAttrs (
   name: _:
   let
     nixFile = "${./cases + "/${name}/default.nix"}";
-    result = runCommandNoCC "test-problems-${name}" {
-      nativeBuildInputs = [
-        removeReferencesTo
-      ];
-    } ''
+    result = runCommand "test-problems-${name}" { nativeBuildInputs = [ removeReferencesTo ]; } ''
       export NIX_STATE_DIR=$(mktemp -d)
       mkdir $out
 
@@ -41,7 +37,7 @@ lib.mapAttrs (
       echo "Command exited with code $(<$out/code)"
       remove-references-to -t ${nixFile} $out/*
     '';
-    checker = runCommandNoCC "test-problems-check-${name}" { } ''
+    checker = runCommand "test-problems-check-${name}" { } ''
       if ! diff ${result}/stderr ${./cases + "/${name}/expected-stderr"}; then
         echo "Output of $(< ${result}/command) does not match what was expected (${result}/stderr)"
         exit 1