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-rw-r--r--lib/asserts.nix29
-rw-r--r--lib/customisation.nix105
-rw-r--r--lib/fileset/README.md3
-rw-r--r--lib/fileset/default.nix150
-rw-r--r--lib/fileset/internal.nix169
-rwxr-xr-xlib/fileset/tests.sh226
-rw-r--r--lib/fixed-points.nix2
-rw-r--r--lib/licenses.nix15
-rw-r--r--lib/meta.nix9
-rw-r--r--lib/strings.nix14
-rw-r--r--lib/systems/examples.nix1
-rw-r--r--lib/systems/inspect.nix26
-rw-r--r--lib/systems/parse.nix11
-rwxr-xr-xlib/tests/filesystem.sh10
-rw-r--r--lib/tests/misc.nix33
15 files changed, 702 insertions, 101 deletions
diff --git a/lib/asserts.nix b/lib/asserts.nix
index 98e0b490acf2..8d0a621f4c1c 100644
--- a/lib/asserts.nix
+++ b/lib/asserts.nix
@@ -50,4 +50,33 @@ rec {
       lib.generators.toPretty {} xs}, but is: ${
         lib.generators.toPretty {} val}";
 
+  /* Specialized `assertMsg` for checking if every one of `vals` is one of the elements
+     of the list `xs`. Useful for checking lists of supported attributes.
+
+     Example:
+       let sslLibraries = [ "libressl" "bearssl" ];
+       in assertEachOneOf "sslLibraries" sslLibraries [ "openssl" "bearssl" ]
+       stderr> error: each element in sslLibraries must be one of [
+       stderr>   "openssl"
+       stderr>   "bearssl"
+       stderr> ], but is: [
+       stderr>   "libressl"
+       stderr>   "bearssl"
+       stderr> ]
+
+     Type:
+       assertEachOneOf :: String -> List ComparableVal -> List ComparableVal -> Bool
+  */
+  assertEachOneOf =
+    # The name of the variable the user entered `val` into, for inclusion in the error message
+    name:
+    # The list of values of what the user provided, to be compared against the values in `xs`
+    vals:
+    # The list of valid values
+    xs:
+    assertMsg
+    (lib.all (val: lib.elem val xs) vals)
+    "each element in ${name} must be one of ${
+      lib.generators.toPretty {} xs}, but is: ${
+        lib.generators.toPretty {} vals}";
 }
diff --git a/lib/customisation.nix b/lib/customisation.nix
index 5ef4f29e6f6a..c7d40339d05f 100644
--- a/lib/customisation.nix
+++ b/lib/customisation.nix
@@ -13,16 +13,7 @@ rec {
      scenarios (e.g. in ~/.config/nixpkgs/config.nix).  For instance,
      if you want to "patch" the derivation returned by a package
      function in Nixpkgs to build another version than what the
-     function itself provides, you can do something like this:
-
-       mySed = overrideDerivation pkgs.gnused (oldAttrs: {
-         name = "sed-4.2.2-pre";
-         src = fetchurl {
-           url = ftp://alpha.gnu.org/gnu/sed/sed-4.2.2-pre.tar.bz2;
-           hash = "sha256-MxBJRcM2rYzQYwJ5XKxhXTQByvSg5jZc5cSHEZoB2IY=";
-         };
-         patches = [];
-       });
+     function itself provides.
 
      For another application, see build-support/vm, where this
      function is used to build arbitrary derivations inside a QEMU
@@ -35,6 +26,19 @@ rec {
 
      You should in general prefer `drv.overrideAttrs` over this function;
      see the nixpkgs manual for more information on overriding.
+
+     Example:
+       mySed = overrideDerivation pkgs.gnused (oldAttrs: {
+         name = "sed-4.2.2-pre";
+         src = fetchurl {
+           url = ftp://alpha.gnu.org/gnu/sed/sed-4.2.2-pre.tar.bz2;
+           hash = "sha256-MxBJRcM2rYzQYwJ5XKxhXTQByvSg5jZc5cSHEZoB2IY=";
+         };
+         patches = [];
+       });
+
+     Type:
+       overrideDerivation :: Derivation -> ( Derivation -> AttrSet ) -> Derivation
   */
   overrideDerivation = drv: f:
     let
@@ -55,6 +59,10 @@ rec {
      injects `override` attribute which can be used to override arguments of
      the function.
 
+     Please refer to  documentation on [`<pkg>.overrideDerivation`](#sec-pkg-overrideDerivation) to learn about `overrideDerivation` and caveats
+     related to its use.
+
+     Example:
        nix-repl> x = {a, b}: { result = a + b; }
 
        nix-repl> y = lib.makeOverridable x { a = 1; b = 2; }
@@ -65,9 +73,8 @@ rec {
        nix-repl> y.override { a = 10; }
        { override = «lambda»; overrideDerivation = «lambda»; result = 12; }
 
-     Please refer to "Nixpkgs Contributors Guide" section
-     "<pkg>.overrideDerivation" to learn about `overrideDerivation` and caveats
-     related to its use.
+     Type:
+       makeOverridable :: (AttrSet -> a) -> AttrSet -> a
   */
   makeOverridable = f: lib.setFunctionArgs
     (origArgs: let
@@ -105,20 +112,29 @@ rec {
     `autoArgs`.  This function is intended to be partially
     parameterised, e.g.,
 
+      ```nix
       callPackage = callPackageWith pkgs;
       pkgs = {
         libfoo = callPackage ./foo.nix { };
         libbar = callPackage ./bar.nix { };
       };
+      ```
 
     If the `libbar` function expects an argument named `libfoo`, it is
     automatically passed as an argument.  Overrides or missing
     arguments can be supplied in `args`, e.g.
 
+      ```nix
       libbar = callPackage ./bar.nix {
         libfoo = null;
         enableX11 = true;
       };
+      ```
+
+    <!-- TODO: Apply "Example:" tag to the examples above -->
+
+    Type:
+      callPackageWith :: AttrSet -> ((AttrSet -> a) | Path) -> AttrSet -> a
   */
   callPackageWith = autoArgs: fn: args:
     let
@@ -129,7 +145,7 @@ rec {
       # This includes automatic ones and ones passed explicitly
       allArgs = builtins.intersectAttrs fargs autoArgs // args;
 
-      # A list of argument names that the function requires, but
+      # a list of argument names that the function requires, but
       # wouldn't be passed to it
       missingArgs = lib.attrNames
         # Filter out arguments that have a default value
@@ -176,7 +192,11 @@ rec {
 
   /* Like callPackage, but for a function that returns an attribute
      set of derivations. The override function is added to the
-     individual attributes. */
+     individual attributes.
+
+     Type:
+       callPackagesWith :: AttrSet -> ((AttrSet -> AttrSet) | Path) -> AttrSet -> AttrSet
+  */
   callPackagesWith = autoArgs: fn: args:
     let
       f = if lib.isFunction fn then fn else import fn;
@@ -193,7 +213,11 @@ rec {
 
 
   /* Add attributes to each output of a derivation without changing
-     the derivation itself and check a given condition when evaluating. */
+     the derivation itself and check a given condition when evaluating.
+
+     Type:
+       extendDerivation :: Bool -> Any -> Derivation -> Derivation
+  */
   extendDerivation = condition: passthru: drv:
     let
       outputs = drv.outputs or [ "out" ];
@@ -227,7 +251,11 @@ rec {
   /* Strip a derivation of all non-essential attributes, returning
      only those needed by hydra-eval-jobs. Also strictly evaluate the
      result to ensure that there are no thunks kept alive to prevent
-     garbage collection. */
+     garbage collection.
+
+     Type:
+       hydraJob :: (Derivation | Null) -> (Derivation | Null)
+  */
   hydraJob = drv:
     let
       outputs = drv.outputs or ["out"];
@@ -265,7 +293,11 @@ rec {
      called with the overridden packages. The package sets may be
      hierarchical: the packages in the set are called with the scope
      provided by `newScope` and the set provides a `newScope` attribute
-     which can form the parent scope for later package sets. */
+     which can form the parent scope for later package sets.
+
+     Type:
+       makeScope :: (AttrSet -> ((AttrSet -> a) | Path) -> AttrSet -> a) -> (AttrSet -> AttrSet) -> AttrSet
+  */
   makeScope = newScope: f:
     let self = f self // {
           newScope = scope: newScope (self // scope);
@@ -287,13 +319,48 @@ rec {
     { inherit otherSplices keep extra f; };
 
   /* Like makeScope, but aims to support cross compilation. It's still ugly, but
-     hopefully it helps a little bit. */
+     hopefully it helps a little bit.
+
+     Type:
+       makeScopeWithSplicing' ::
+         { splicePackages :: Splice -> AttrSet
+         , newScope :: AttrSet -> ((AttrSet -> a) | Path) -> AttrSet -> a
+         }
+         -> { otherSplices :: Splice, keep :: AttrSet -> AttrSet, extra :: AttrSet -> AttrSet }
+         -> AttrSet
+
+       Splice ::
+         { pkgsBuildBuild :: AttrSet
+         , pkgsBuildHost :: AttrSet
+         , pkgsBuildTarget :: AttrSet
+         , pkgsHostHost :: AttrSet
+         , pkgsHostTarget :: AttrSet
+         , pkgsTargetTarget :: AttrSet
+         }
+  */
   makeScopeWithSplicing' =
     { splicePackages
     , newScope
     }:
     { otherSplices
+    # Attrs from `self` which won't be spliced.
+    # Avoid using keep, it's only used for a python hook workaround, added in PR #104201.
+    # ex: `keep = (self: { inherit (self) aAttr; })`
     , keep ? (_self: {})
+    # Additional attrs to add to the sets `callPackage`.
+    # When the package is from a subset (but not a subset within a package IS #211340)
+    # within `spliced0` it will be spliced.
+    # When using an package outside the set but it's available from `pkgs`, use the package from `pkgs.__splicedPackages`.
+    # If the package is not available within the set or in `pkgs`, such as a package in a let binding, it will not be spliced
+    # ex:
+    # ```
+    # nix-repl> darwin.apple_sdk.frameworks.CoreFoundation
+    #   «derivation ...CoreFoundation-11.0.0.drv»
+    # nix-repl> darwin.CoreFoundation
+    #   error: attribute 'CoreFoundation' missing
+    # nix-repl> darwin.callPackage ({ CoreFoundation }: CoreFoundation) { }
+    #   «derivation ...CoreFoundation-11.0.0.drv»
+    # ```
     , extra ? (_spliced0: {})
     , f
     }:
diff --git a/lib/fileset/README.md b/lib/fileset/README.md
index d7398438826e..8518d88a7d64 100644
--- a/lib/fileset/README.md
+++ b/lib/fileset/README.md
@@ -225,6 +225,9 @@ Arguments:
   This use case makes little sense for files that are already in the store.
   This should be a separate abstraction as e.g. `pkgs.drvLayout` instead, which could have a similar interface but be specific to derivations.
   Additional capabilities could be supported that can't be done at evaluation time, such as renaming files, creating new directories, setting executable bits, etc.
+- (+) An API for filtering/transforming Nix store paths could be much more powerful,
+  because it's not limited to just what is possible at evaluation time with `builtins.path`.
+  Operations such as moving and adding files would be supported.
 
 ### Single files
 
diff --git a/lib/fileset/default.nix b/lib/fileset/default.nix
index 640d0b49d3ea..372d445269f5 100644
--- a/lib/fileset/default.nix
+++ b/lib/fileset/default.nix
@@ -8,8 +8,10 @@ let
     _toSourceFilter
     _fromSourceFilter
     _unionMany
+    _fileFilter
     _printFileset
     _intersection
+    _difference
     ;
 
   inherit (builtins)
@@ -43,6 +45,7 @@ let
     ;
 
   inherit (lib.trivial)
+    isFunction
     pipe
     ;
 
@@ -121,11 +124,10 @@ in {
       Paths in [strings](https://nixos.org/manual/nix/stable/language/values.html#type-string), including Nix store paths, cannot be passed as `root`.
       `root` has to be a directory.
 
-<!-- Ignore the indentation here, this is a nixdoc rendering bug that needs to be fixed: https://github.com/nix-community/nixdoc/issues/75 -->
-:::{.note}
-Changing `root` only affects the directory structure of the resulting store path, it does not change which files are added to the store.
-The only way to change which files get added to the store is by changing the `fileset` attribute.
-:::
+      :::{.note}
+      Changing `root` only affects the directory structure of the resulting store path, it does not change which files are added to the store.
+      The only way to change which files get added to the store is by changing the `fileset` attribute.
+      :::
     */
     root,
     /*
@@ -134,10 +136,9 @@ The only way to change which files get added to the store is by changing the `fi
       This argument can also be a path,
       which gets [implicitly coerced to a file set](#sec-fileset-path-coercion).
 
-<!-- Ignore the indentation here, this is a nixdoc rendering bug that needs to be fixed: https://github.com/nix-community/nixdoc/issues/75 -->
-:::{.note}
-If a directory does not recursively contain any file, it is omitted from the store path contents.
-:::
+      :::{.note}
+      If a directory does not recursively contain any file, it is omitted from the store path contents.
+      :::
 
     */
     fileset,
@@ -160,7 +161,7 @@ If a directory does not recursively contain any file, it is omitted from the sto
               Note that this only works for sources created from paths.''
       else if isStringLike root then
         throw ''
-          lib.fileset.toSource: `root` ("${toString root}") is a string-like value, but it should be a path instead.
+          lib.fileset.toSource: `root` (${toString root}) is a string-like value, but it should be a path instead.
               Paths in strings are not supported by `lib.fileset`, use `lib.sources` or derivations instead.''
       else
         throw ''
@@ -169,13 +170,13 @@ If a directory does not recursively contain any file, it is omitted from the sto
     # See also ../path/README.md
     else if ! fileset._internalIsEmptyWithoutBase && rootFilesystemRoot != filesetFilesystemRoot then
       throw ''
-        lib.fileset.toSource: Filesystem roots are not the same for `fileset` and `root` ("${toString root}"):
-            `root`: root "${toString rootFilesystemRoot}"
-            `fileset`: root "${toString filesetFilesystemRoot}"
-            Different roots are not supported.''
+        lib.fileset.toSource: Filesystem roots are not the same for `fileset` and `root` (${toString root}):
+            `root`: Filesystem root is "${toString rootFilesystemRoot}"
+            `fileset`: Filesystem root is "${toString filesetFilesystemRoot}"
+            Different filesystem roots are not supported.''
     else if ! pathExists root then
       throw ''
-        lib.fileset.toSource: `root` (${toString root}) does not exist.''
+        lib.fileset.toSource: `root` (${toString root}) is a path that does not exist.''
     else if pathType root != "directory" then
       throw ''
         lib.fileset.toSource: `root` (${toString root}) is a file, but it should be a directory instead. Potential solutions:
@@ -296,11 +297,11 @@ If a directory does not recursively contain any file, it is omitted from the sto
     _unionMany
       (_coerceMany "lib.fileset.union" [
         {
-          context = "first argument";
+          context = "First argument";
           value = fileset1;
         }
         {
-          context = "second argument";
+          context = "Second argument";
           value = fileset2;
         }
       ]);
@@ -342,12 +343,13 @@ If a directory does not recursively contain any file, it is omitted from the sto
     # which get [implicitly coerced to file sets](#sec-fileset-path-coercion).
     filesets:
     if ! isList filesets then
-      throw "lib.fileset.unions: Expected argument to be a list, but got a ${typeOf filesets}."
+      throw ''
+        lib.fileset.unions: Argument is of type ${typeOf filesets}, but it should be a list instead.''
     else
       pipe filesets [
         # Annotate the elements with context, used by _coerceMany for better errors
         (imap0 (i: el: {
-          context = "element ${toString i}";
+          context = "Element ${toString i}";
           value = el;
         }))
         (_coerceMany "lib.fileset.unions")
@@ -355,6 +357,56 @@ If a directory does not recursively contain any file, it is omitted from the sto
       ];
 
   /*
+    Filter a file set to only contain files matching some predicate.
+
+    Type:
+      fileFilter ::
+        ({
+          name :: String,
+          type :: String,
+          ...
+        } -> Bool)
+        -> FileSet
+        -> FileSet
+
+    Example:
+      # Include all regular `default.nix` files in the current directory
+      fileFilter (file: file.name == "default.nix") ./.
+
+      # Include all non-Nix files from the current directory
+      fileFilter (file: ! hasSuffix ".nix" file.name) ./.
+
+      # Include all files that start with a "." in the current directory
+      fileFilter (file: hasPrefix "." file.name) ./.
+
+      # Include all regular files (not symlinks or others) in the current directory
+      fileFilter (file: file.type == "regular")
+  */
+  fileFilter =
+    /*
+      The predicate function to call on all files contained in given file set.
+      A file is included in the resulting file set if this function returns true for it.
+
+      This function is called with an attribute set containing these attributes:
+
+      - `name` (String): The name of the file
+
+      - `type` (String, one of `"regular"`, `"symlink"` or `"unknown"`): The type of the file.
+        This matches result of calling [`builtins.readFileType`](https://nixos.org/manual/nix/stable/language/builtins.html#builtins-readFileType) on the file's path.
+
+      Other attributes may be added in the future.
+    */
+    predicate:
+    # The file set to filter based on the predicate function
+    fileset:
+    if ! isFunction predicate then
+      throw ''
+        lib.fileset.fileFilter: First argument is of type ${typeOf predicate}, but it should be a function.''
+    else
+      _fileFilter predicate
+        (_coerce "lib.fileset.fileFilter: Second argument" fileset);
+
+  /*
     The file set containing all files that are in both of two given file sets.
     See also [Intersection (set theory)](https://en.wikipedia.org/wiki/Intersection_(set_theory)).
 
@@ -380,11 +432,11 @@ If a directory does not recursively contain any file, it is omitted from the sto
     let
       filesets = _coerceMany "lib.fileset.intersection" [
         {
-          context = "first argument";
+          context = "First argument";
           value = fileset1;
         }
         {
-          context = "second argument";
+          context = "Second argument";
           value = fileset2;
         }
       ];
@@ -394,6 +446,58 @@ If a directory does not recursively contain any file, it is omitted from the sto
       (elemAt filesets 1);
 
   /*
+    The file set containing all files from the first file set that are not in the second file set.
+    See also [Difference (set theory)](https://en.wikipedia.org/wiki/Complement_(set_theory)#Relative_complement).
+
+    The given file sets are evaluated as lazily as possible,
+    with the first argument being evaluated first if needed.
+
+    Type:
+      union :: FileSet -> FileSet -> FileSet
+
+    Example:
+      # Create a file set containing all files from the current directory,
+      # except ones under ./tests
+      difference ./. ./tests
+
+      let
+        # A set of Nix-related files
+        nixFiles = unions [ ./default.nix ./nix ./tests/default.nix ];
+      in
+      # Create a file set containing all files under ./tests, except ones in `nixFiles`,
+      # meaning only without ./tests/default.nix
+      difference ./tests nixFiles
+  */
+  difference =
+    # The positive file set.
+    # The result can only contain files that are also in this file set.
+    #
+    # This argument can also be a path,
+    # which gets [implicitly coerced to a file set](#sec-fileset-path-coercion).
+    positive:
+    # The negative file set.
+    # The result will never contain files that are also in this file set.
+    #
+    # This argument can also be a path,
+    # which gets [implicitly coerced to a file set](#sec-fileset-path-coercion).
+    negative:
+    let
+      filesets = _coerceMany "lib.fileset.difference" [
+        {
+          context = "First argument (positive set)";
+          value = positive;
+        }
+        {
+          context = "Second argument (negative set)";
+          value = negative;
+        }
+      ];
+    in
+    _difference
+      (elemAt filesets 0)
+      (elemAt filesets 1);
+
+  /*
     Incrementally evaluate and trace a file set in a pretty way.
     This function is only intended for debugging purposes.
     The exact tracing format is unspecified and may change.
@@ -428,7 +532,7 @@ If a directory does not recursively contain any file, it is omitted from the sto
     let
       # "fileset" would be a better name, but that would clash with the argument name,
       # and we cannot change that because of https://github.com/nix-community/nixdoc/issues/76
-      actualFileset = _coerce "lib.fileset.trace: argument" fileset;
+      actualFileset = _coerce "lib.fileset.trace: Argument" fileset;
     in
     seq
       (_printFileset actualFileset)
@@ -475,7 +579,7 @@ If a directory does not recursively contain any file, it is omitted from the sto
     let
       # "fileset" would be a better name, but that would clash with the argument name,
       # and we cannot change that because of https://github.com/nix-community/nixdoc/issues/76
-      actualFileset = _coerce "lib.fileset.traceVal: argument" fileset;
+      actualFileset = _coerce "lib.fileset.traceVal: Argument" fileset;
     in
     seq
       (_printFileset actualFileset)
diff --git a/lib/fileset/internal.nix b/lib/fileset/internal.nix
index 45115d5a8a3d..717253f45715 100644
--- a/lib/fileset/internal.nix
+++ b/lib/fileset/internal.nix
@@ -7,7 +7,6 @@ let
     isString
     pathExists
     readDir
-    seq
     split
     trace
     typeOf
@@ -17,7 +16,6 @@ let
     attrNames
     attrValues
     mapAttrs
-    setAttrByPath
     zipAttrsWith
     ;
 
@@ -28,7 +26,6 @@ let
   inherit (lib.lists)
     all
     commonPrefix
-    drop
     elemAt
     filter
     findFirst
@@ -184,7 +181,7 @@ rec {
           ${context} is of type ${typeOf value}, but it should be a file set or a path instead.''
     else if ! pathExists value then
       throw ''
-        ${context} (${toString value}) does not exist.''
+        ${context} (${toString value}) is a path that does not exist.''
     else
       _singleton value;
 
@@ -213,9 +210,9 @@ rec {
     if firstWithBase != null && differentIndex != null then
       throw ''
         ${functionContext}: Filesystem roots are not the same:
-            ${(head list).context}: root "${toString firstBaseRoot}"
-            ${(elemAt list differentIndex).context}: root "${toString (elemAt filesets differentIndex)._internalBaseRoot}"
-            Different roots are not supported.''
+            ${(head list).context}: Filesystem root is "${toString firstBaseRoot}"
+            ${(elemAt list differentIndex).context}: Filesystem root is "${toString (elemAt filesets differentIndex)._internalBaseRoot}"
+            Different filesystem roots are not supported.''
     else
       filesets;
 
@@ -429,7 +426,7 @@ rec {
       # Filter suited when there's some files
       # This can't be used for when there's no files, because the base directory is always included
       nonEmpty =
-        path: _:
+        path: type:
         let
           # Add a slash to the path string, turning "/foo" to "/foo/",
           # making sure to not have any false prefix matches below.
@@ -438,25 +435,37 @@ rec {
           # meaning this function can never receive "/" as an argument
           pathSlash = path + "/";
         in
-        # Same as `hasPrefix pathSlash baseString`, but more efficient.
-        # With base /foo/bar we need to include /foo:
-        # hasPrefix "/foo/" "/foo/bar/"
-        if substring 0 (stringLength pathSlash) baseString == pathSlash then
-          true
-        # Same as `! hasPrefix baseString pathSlash`, but more efficient.
-        # With base /foo/bar we need to exclude /baz
-        # ! hasPrefix "/baz/" "/foo/bar/"
-        else if substring 0 baseLength pathSlash != baseString then
-          false
-        else
-          # Same as `removePrefix baseString path`, but more efficient.
-          # From the above code we know that hasPrefix baseString pathSlash holds, so this is safe.
-          # We don't use pathSlash here because we only needed the trailing slash for the prefix matching.
-          # With base /foo and path /foo/bar/baz this gives
-          # inTree (split "/" (removePrefix "/foo/" "/foo/bar/baz"))
-          # == inTree (split "/" "bar/baz")
-          # == inTree [ "bar" "baz" ]
-          inTree (split "/" (substring baseLength (-1) path));
+        (
+          # Same as `hasPrefix pathSlash baseString`, but more efficient.
+          # With base /foo/bar we need to include /foo:
+          # hasPrefix "/foo/" "/foo/bar/"
+          if substring 0 (stringLength pathSlash) baseString == pathSlash then
+            true
+          # Same as `! hasPrefix baseString pathSlash`, but more efficient.
+          # With base /foo/bar we need to exclude /baz
+          # ! hasPrefix "/baz/" "/foo/bar/"
+          else if substring 0 baseLength pathSlash != baseString then
+            false
+          else
+            # Same as `removePrefix baseString path`, but more efficient.
+            # From the above code we know that hasPrefix baseString pathSlash holds, so this is safe.
+            # We don't use pathSlash here because we only needed the trailing slash for the prefix matching.
+            # With base /foo and path /foo/bar/baz this gives
+            # inTree (split "/" (removePrefix "/foo/" "/foo/bar/baz"))
+            # == inTree (split "/" "bar/baz")
+            # == inTree [ "bar" "baz" ]
+            inTree (split "/" (substring baseLength (-1) path))
+        )
+        # This is a way have an additional check in case the above is true without any significant performance cost
+        && (
+          # This relies on the fact that Nix only distinguishes path types "directory", "regular", "symlink" and "unknown",
+          # so everything except "unknown" is allowed, seems reasonable to rely on that
+          type != "unknown"
+          || throw ''
+            lib.fileset.toSource: `fileset` contains a file that cannot be added to the store: ${path}
+                This file is neither a regular file nor a symlink, the only file types supported by the Nix store.
+                Therefore the file set cannot be added to the Nix store as is. Make sure to not include that file to avoid this error.''
+        );
     in
     # Special case because the code below assumes that the _internalBase is always included in the result
     # which shouldn't be done when we have no files at all in the base
@@ -696,4 +705,110 @@ rec {
     else
       # In all other cases it's the rhs
       rhs;
+
+  # Compute the set difference between two file sets.
+  # The filesets must already be coerced and validated to be in the same filesystem root.
+  # Type: Fileset -> Fileset -> Fileset
+  _difference = positive: negative:
+    let
+      # The common base components prefix, e.g.
+      # (/foo/bar, /foo/bar/baz) -> /foo/bar
+      # (/foo/bar, /foo/baz) -> /foo
+      commonBaseComponentsLength =
+        # TODO: Have a `lib.lists.commonPrefixLength` function such that we don't need the list allocation from commonPrefix here
+        length (
+          commonPrefix
+            positive._internalBaseComponents
+            negative._internalBaseComponents
+        );
+
+      # We need filesetTree's with the same base to be able to compute the difference between them
+      # This here is the filesetTree from the negative file set, but for a base path that matches the positive file set.
+      # Examples:
+      # For `difference /foo /foo/bar`, `negativeTreeWithPositiveBase = { bar = "directory"; }`
+      #   because under the base path of `/foo`, only `bar` from the negative file set is included
+      # For `difference /foo/bar /foo`, `negativeTreeWithPositiveBase = "directory"`
+      #   because under the base path of `/foo/bar`, everything from the negative file set is included
+      # For `difference /foo /bar`, `negativeTreeWithPositiveBase = null`
+      #   because under the base path of `/foo`, nothing from the negative file set is included
+      negativeTreeWithPositiveBase =
+        if commonBaseComponentsLength == length positive._internalBaseComponents then
+          # The common prefix is the same as the positive base path, so the second path is equal or longer.
+          # We need to _shorten_ the negative filesetTree to the same base path as the positive one
+          # E.g. for `difference /foo /foo/bar` the common prefix is /foo, equal to the positive file set's base
+          # So we need to shorten the base of the tree for the negative argument from /foo/bar to just /foo
+          _shortenTreeBase positive._internalBaseComponents negative
+        else if commonBaseComponentsLength == length negative._internalBaseComponents then
+          # The common prefix is the same as the negative base path, so the first path is longer.
+          # We need to lengthen the negative filesetTree to the same base path as the positive one.
+          # E.g. for `difference /foo/bar /foo` the common prefix is /foo, equal to the negative file set's base
+          # So we need to lengthen the base of the tree for the negative argument from /foo to /foo/bar
+          _lengthenTreeBase positive._internalBaseComponents negative
+        else
+          # The common prefix is neither the first nor the second path.
+          # This means there's no overlap between the two file sets,
+          # and nothing from the negative argument should get removed from the positive one
+          # E.g for `difference /foo /bar`, we remove nothing to get the same as `/foo`
+          null;
+
+      resultingTree =
+        _differenceTree
+        positive._internalBase
+        positive._internalTree
+        negativeTreeWithPositiveBase;
+    in
+    # If the first file set is empty, we can never have any files in the result
+    if positive._internalIsEmptyWithoutBase then
+      _emptyWithoutBase
+    # If the second file set is empty, nothing gets removed, so the result is just the first file set
+    else if negative._internalIsEmptyWithoutBase then
+      positive
+    else
+      # We use the positive file set base for the result,
+      # because only files from the positive side may be included,
+      # which is what base path is for
+      _create positive._internalBase resultingTree;
+
+  # Computes the set difference of two filesetTree's
+  # Type: Path -> filesetTree -> filesetTree
+  _differenceTree = path: lhs: rhs:
+    # If the lhs doesn't have any files, or the right hand side includes all files
+    if lhs == null || isString rhs then
+      # The result will always be empty
+      null
+    # If the right hand side has no files
+    else if rhs == null then
+      # The result is always the left hand side, because nothing gets removed
+      lhs
+    else
+      # Otherwise we always have two attribute sets to recurse into
+      mapAttrs (name: lhsValue:
+        _differenceTree (path + "/${name}") lhsValue (rhs.${name} or null)
+      ) (_directoryEntries path lhs);
+
+  _fileFilter = predicate: fileset:
+    let
+      recurse = path: tree:
+        mapAttrs (name: subtree:
+          if isAttrs subtree || subtree == "directory" then
+            recurse (path + "/${name}") subtree
+          else if
+            predicate {
+              inherit name;
+              type = subtree;
+              # To ensure forwards compatibility with more arguments being added in the future,
+              # adding an attribute which can't be deconstructed :)
+              "lib.fileset.fileFilter: The predicate function passed as the first argument must be able to handle extra attributes for future compatibility. If you're using `{ name, file }:`, use `{ name, file, ... }:` instead." = null;
+            }
+          then
+            subtree
+          else
+            null
+        ) (_directoryEntries path tree);
+    in
+    if fileset._internalIsEmptyWithoutBase then
+      _emptyWithoutBase
+    else
+      _create fileset._internalBase
+        (recurse fileset._internalBase fileset._internalTree);
 }
diff --git a/lib/fileset/tests.sh b/lib/fileset/tests.sh
index 617794524824..796a03b52f0e 100755
--- a/lib/fileset/tests.sh
+++ b/lib/fileset/tests.sh
@@ -336,7 +336,7 @@ checkFileset() {
 #### Error messages #####
 
 # Absolute paths in strings cannot be passed as `root`
-expectFailure 'toSource { root = "/nix/store/foobar"; fileset = ./.; }' 'lib.fileset.toSource: `root` \("/nix/store/foobar"\) is a string-like value, but it should be a path instead.
+expectFailure 'toSource { root = "/nix/store/foobar"; fileset = ./.; }' 'lib.fileset.toSource: `root` \(/nix/store/foobar\) is a string-like value, but it should be a path instead.
 \s*Paths in strings are not supported by `lib.fileset`, use `lib.sources` or derivations instead.'
 
 expectFailure 'toSource { root = cleanSourceWith { src = ./.; }; fileset = ./.; }' 'lib.fileset.toSource: `root` is a `lib.sources`-based value, but it should be a path instead.
@@ -350,21 +350,21 @@ expectFailure 'toSource { root = 10; fileset = ./.; }' 'lib.fileset.toSource: `r
 mkdir -p {foo,bar}/mock-root
 expectFailure 'with ((import <nixpkgs/lib>).extend (import <nixpkgs/lib/fileset/mock-splitRoot.nix>)).fileset;
   toSource { root = ./foo/mock-root; fileset = ./bar/mock-root; }
-' 'lib.fileset.toSource: Filesystem roots are not the same for `fileset` and `root` \("'"$work"'/foo/mock-root"\):
-\s*`root`: root "'"$work"'/foo/mock-root"
-\s*`fileset`: root "'"$work"'/bar/mock-root"
-\s*Different roots are not supported.'
-rm -rf *
+' 'lib.fileset.toSource: Filesystem roots are not the same for `fileset` and `root` \('"$work"'/foo/mock-root\):
+\s*`root`: Filesystem root is "'"$work"'/foo/mock-root"
+\s*`fileset`: Filesystem root is "'"$work"'/bar/mock-root"
+\s*Different filesystem roots are not supported.'
+rm -rf -- *
 
 # `root` needs to exist
-expectFailure 'toSource { root = ./a; fileset = ./.; }' 'lib.fileset.toSource: `root` \('"$work"'/a\) does not exist.'
+expectFailure 'toSource { root = ./a; fileset = ./.; }' 'lib.fileset.toSource: `root` \('"$work"'/a\) is a path that does not exist.'
 
 # `root` needs to be a file
 touch a
 expectFailure 'toSource { root = ./a; fileset = ./a; }' 'lib.fileset.toSource: `root` \('"$work"'/a\) is a file, but it should be a directory instead. Potential solutions:
 \s*- If you want to import the file into the store _without_ a containing directory, use string interpolation or `builtins.path` instead of this function.
 \s*- If you want to import the file into the store _with_ a containing directory, set `root` to the containing directory, such as '"$work"', and set `fileset` to the file path.'
-rm -rf *
+rm -rf -- *
 
 # The fileset argument should be evaluated, even if the directory is empty
 expectFailure 'toSource { root = ./.; fileset = abort "This should be evaluated"; }' 'evaluation aborted with the following error message: '\''This should be evaluated'\'
@@ -374,7 +374,14 @@ mkdir a
 expectFailure 'toSource { root = ./a; fileset = ./.; }' 'lib.fileset.toSource: `fileset` could contain files in '"$work"', which is not under the `root` \('"$work"'/a\). Potential solutions:
 \s*- Set `root` to '"$work"' or any directory higher up. This changes the layout of the resulting store path.
 \s*- Set `fileset` to a file set that cannot contain files outside the `root` \('"$work"'/a\). This could change the files included in the result.'
-rm -rf *
+rm -rf -- *
+
+# non-regular and non-symlink files cannot be added to the Nix store
+mkfifo a
+expectFailure 'toSource { root = ./.; fileset = ./a; }' 'lib.fileset.toSource: `fileset` contains a file that cannot be added to the store: '"$work"'/a
+\s*This file is neither a regular file nor a symlink, the only file types supported by the Nix store.
+\s*Therefore the file set cannot be added to the Nix store as is. Make sure to not include that file to avoid this error.'
+rm -rf -- *
 
 # Path coercion only works for paths
 expectFailure 'toSource { root = ./.; fileset = 10; }' 'lib.fileset.toSource: `fileset` is of type int, but it should be a file set or a path instead.'
@@ -385,7 +392,7 @@ expectFailure 'toSource { root = ./.; fileset = cleanSourceWith { src = ./.; };
 \s*Note that this only works for sources created from paths.'
 
 # Path coercion errors for non-existent paths
-expectFailure 'toSource { root = ./.; fileset = ./a; }' 'lib.fileset.toSource: `fileset` \('"$work"'/a\) does not exist.'
+expectFailure 'toSource { root = ./.; fileset = ./a; }' 'lib.fileset.toSource: `fileset` \('"$work"'/a\) is a path that does not exist.'
 
 # File sets cannot be evaluated directly
 expectFailure 'union ./. ./.' 'lib.fileset: Directly evaluating a file set is not supported.
@@ -508,26 +515,26 @@ mkdir -p {foo,bar}/mock-root
 expectFailure 'with ((import <nixpkgs/lib>).extend (import <nixpkgs/lib/fileset/mock-splitRoot.nix>)).fileset;
   toSource { root = ./.; fileset = union ./foo/mock-root ./bar/mock-root; }
 ' 'lib.fileset.union: Filesystem roots are not the same:
-\s*first argument: root "'"$work"'/foo/mock-root"
-\s*second argument: root "'"$work"'/bar/mock-root"
-\s*Different roots are not supported.'
+\s*First argument: Filesystem root is "'"$work"'/foo/mock-root"
+\s*Second argument: Filesystem root is "'"$work"'/bar/mock-root"
+\s*Different filesystem roots are not supported.'
 
 expectFailure 'with ((import <nixpkgs/lib>).extend (import <nixpkgs/lib/fileset/mock-splitRoot.nix>)).fileset;
   toSource { root = ./.; fileset = unions [ ./foo/mock-root ./bar/mock-root ]; }
 ' 'lib.fileset.unions: Filesystem roots are not the same:
-\s*element 0: root "'"$work"'/foo/mock-root"
-\s*element 1: root "'"$work"'/bar/mock-root"
-\s*Different roots are not supported.'
-rm -rf *
+\s*Element 0: Filesystem root is "'"$work"'/foo/mock-root"
+\s*Element 1: Filesystem root is "'"$work"'/bar/mock-root"
+\s*Different filesystem roots are not supported.'
+rm -rf -- *
 
 # Coercion errors show the correct context
-expectFailure 'toSource { root = ./.; fileset = union ./a ./.; }' 'lib.fileset.union: first argument \('"$work"'/a\) does not exist.'
-expectFailure 'toSource { root = ./.; fileset = union ./. ./b; }' 'lib.fileset.union: second argument \('"$work"'/b\) does not exist.'
-expectFailure 'toSource { root = ./.; fileset = unions [ ./a ./. ]; }' 'lib.fileset.unions: element 0 \('"$work"'/a\) does not exist.'
-expectFailure 'toSource { root = ./.; fileset = unions [ ./. ./b ]; }' 'lib.fileset.unions: element 1 \('"$work"'/b\) does not exist.'
+expectFailure 'toSource { root = ./.; fileset = union ./a ./.; }' 'lib.fileset.union: First argument \('"$work"'/a\) is a path that does not exist.'
+expectFailure 'toSource { root = ./.; fileset = union ./. ./b; }' 'lib.fileset.union: Second argument \('"$work"'/b\) is a path that does not exist.'
+expectFailure 'toSource { root = ./.; fileset = unions [ ./a ./. ]; }' 'lib.fileset.unions: Element 0 \('"$work"'/a\) is a path that does not exist.'
+expectFailure 'toSource { root = ./.; fileset = unions [ ./. ./b ]; }' 'lib.fileset.unions: Element 1 \('"$work"'/b\) is a path that does not exist.'
 
 # unions needs a list
-expectFailure 'toSource { root = ./.; fileset = unions null; }' 'lib.fileset.unions: Expected argument to be a list, but got a null.'
+expectFailure 'toSource { root = ./.; fileset = unions null; }' 'lib.fileset.unions: Argument is of type null, but it should be a list instead.'
 
 # The tree of later arguments should not be evaluated if a former argument already includes all files
 tree=()
@@ -621,14 +628,14 @@ mkdir -p {foo,bar}/mock-root
 expectFailure 'with ((import <nixpkgs/lib>).extend (import <nixpkgs/lib/fileset/mock-splitRoot.nix>)).fileset;
   toSource { root = ./.; fileset = intersection ./foo/mock-root ./bar/mock-root; }
 ' 'lib.fileset.intersection: Filesystem roots are not the same:
-\s*first argument: root "'"$work"'/foo/mock-root"
-\s*second argument: root "'"$work"'/bar/mock-root"
-\s*Different roots are not supported.'
+\s*First argument: Filesystem root is "'"$work"'/foo/mock-root"
+\s*Second argument: Filesystem root is "'"$work"'/bar/mock-root"
+\s*Different filesystem roots are not supported.'
 rm -rf -- *
 
 # Coercion errors show the correct context
-expectFailure 'toSource { root = ./.; fileset = intersection ./a ./.; }' 'lib.fileset.intersection: first argument \('"$work"'/a\) does not exist.'
-expectFailure 'toSource { root = ./.; fileset = intersection ./. ./b; }' 'lib.fileset.intersection: second argument \('"$work"'/b\) does not exist.'
+expectFailure 'toSource { root = ./.; fileset = intersection ./a ./.; }' 'lib.fileset.intersection: First argument \('"$work"'/a\) is a path that does not exist.'
+expectFailure 'toSource { root = ./.; fileset = intersection ./. ./b; }' 'lib.fileset.intersection: Second argument \('"$work"'/b\) is a path that does not exist.'
 
 # The tree of later arguments should not be evaluated if a former argument already excludes all files
 tree=(
@@ -702,6 +709,171 @@ tree=(
 )
 checkFileset 'intersection (unions [ ./a/b ./c/d ./c/e ]) (unions [ ./a ./c/d/f ./c/e ])'
 
+## Difference
+
+# Subtracting something from itself results in nothing
+tree=(
+    [a]=0
+)
+checkFileset 'difference ./. ./.'
+
+# The tree of the second argument should not be evaluated if not needed
+checkFileset 'difference _emptyWithoutBase (_create ./. (abort "This should not be used!"))'
+checkFileset 'difference (_create ./. null) (_create ./. (abort "This should not be used!"))'
+
+# Subtracting nothing gives the same thing back
+tree=(
+    [a]=1
+)
+checkFileset 'difference ./. _emptyWithoutBase'
+checkFileset 'difference ./. (_create ./. null)'
+
+# Subtracting doesn't influence the base path
+mkdir a b
+touch {a,b}/x
+expectEqual 'toSource { root = ./a; fileset = difference ./a ./b; }' 'toSource { root = ./a; fileset = ./a; }'
+rm -rf -- *
+
+# Also not the other way around
+mkdir a
+expectFailure 'toSource { root = ./a; fileset = difference ./. ./a; }' 'lib.fileset.toSource: `fileset` could contain files in '"$work"', which is not under the `root` \('"$work"'/a\). Potential solutions:
+\s*- Set `root` to '"$work"' or any directory higher up. This changes the layout of the resulting store path.
+\s*- Set `fileset` to a file set that cannot contain files outside the `root` \('"$work"'/a\). This could change the files included in the result.'
+rm -rf -- *
+
+# Difference actually works
+# We test all combinations of ./., ./a, ./a/x and ./b
+tree=(
+    [a/x]=0
+    [a/y]=0
+    [b]=0
+    [c]=0
+)
+checkFileset 'difference ./. ./.'
+checkFileset 'difference ./a ./.'
+checkFileset 'difference ./a/x ./.'
+checkFileset 'difference ./b ./.'
+checkFileset 'difference ./a ./a'
+checkFileset 'difference ./a/x ./a'
+checkFileset 'difference ./a/x ./a/x'
+checkFileset 'difference ./b ./b'
+tree=(
+    [a/x]=0
+    [a/y]=0
+    [b]=1
+    [c]=1
+)
+checkFileset 'difference ./. ./a'
+tree=(
+    [a/x]=1
+    [a/y]=1
+    [b]=0
+    [c]=0
+)
+checkFileset 'difference ./a ./b'
+tree=(
+    [a/x]=1
+    [a/y]=0
+    [b]=0
+    [c]=0
+)
+checkFileset 'difference ./a/x ./b'
+tree=(
+    [a/x]=0
+    [a/y]=1
+    [b]=0
+    [c]=0
+)
+checkFileset 'difference ./a ./a/x'
+tree=(
+    [a/x]=0
+    [a/y]=0
+    [b]=1
+    [c]=0
+)
+checkFileset 'difference ./b ./a'
+checkFileset 'difference ./b ./a/x'
+tree=(
+    [a/x]=0
+    [a/y]=1
+    [b]=1
+    [c]=1
+)
+checkFileset 'difference ./. ./a/x'
+tree=(
+    [a/x]=1
+    [a/y]=1
+    [b]=0
+    [c]=1
+)
+checkFileset 'difference ./. ./b'
+
+## File filter
+
+# The predicate is not called when there's no files
+tree=()
+checkFileset 'fileFilter (file: abort "this is not needed") ./.'
+checkFileset 'fileFilter (file: abort "this is not needed") _emptyWithoutBase'
+
+# The predicate must be able to handle extra attributes
+touch a
+expectFailure 'toSource { root = ./.; fileset = fileFilter ({ name, type }: true) ./.; }' 'called with unexpected argument '\''"lib.fileset.fileFilter: The predicate function passed as the first argument must be able to handle extra attributes for future compatibility. If you'\''re using `\{ name, file \}:`, use `\{ name, file, ... \}:` instead."'\'
+rm -rf -- *
+
+# .name is the name, and it works correctly, even recursively
+tree=(
+    [a]=1
+    [b]=0
+    [c/a]=1
+    [c/b]=0
+    [d/c/a]=1
+    [d/c/b]=0
+)
+checkFileset 'fileFilter (file: file.name == "a") ./.'
+tree=(
+    [a]=0
+    [b]=1
+    [c/a]=0
+    [c/b]=1
+    [d/c/a]=0
+    [d/c/b]=1
+)
+checkFileset 'fileFilter (file: file.name != "a") ./.'
+
+# `.type` is the file type
+mkdir d
+touch d/a
+ln -s d/b d/b
+mkfifo d/c
+expectEqual \
+    'toSource { root = ./.; fileset = fileFilter (file: file.type == "regular") ./.; }' \
+    'toSource { root = ./.; fileset = ./d/a; }'
+expectEqual \
+    'toSource { root = ./.; fileset = fileFilter (file: file.type == "symlink") ./.; }' \
+    'toSource { root = ./.; fileset = ./d/b; }'
+expectEqual \
+    'toSource { root = ./.; fileset = fileFilter (file: file.type == "unknown") ./.; }' \
+    'toSource { root = ./.; fileset = ./d/c; }'
+expectEqual \
+    'toSource { root = ./.; fileset = fileFilter (file: file.type != "regular") ./.; }' \
+    'toSource { root = ./.; fileset = union ./d/b ./d/c; }'
+expectEqual \
+    'toSource { root = ./.; fileset = fileFilter (file: file.type != "symlink") ./.; }' \
+    'toSource { root = ./.; fileset = union ./d/a ./d/c; }'
+expectEqual \
+    'toSource { root = ./.; fileset = fileFilter (file: file.type != "unknown") ./.; }' \
+    'toSource { root = ./.; fileset = union ./d/a ./d/b; }'
+rm -rf -- *
+
+# It's lazy
+tree=(
+    [b]=1
+    [c/a]=1
+)
+# Note that union evaluates the first argument first if necessary, that's why we can use ./c/a here
+checkFileset 'union ./c/a (fileFilter (file: assert file.name != "a"; true) ./.)'
+# but here we need to use ./c
+checkFileset 'union (fileFilter (file: assert file.name != "a"; true) ./.) ./c'
 
 ## Tracing
 
diff --git a/lib/fixed-points.nix b/lib/fixed-points.nix
index 3444e95e15ad..3b5fdc9e8ea1 100644
--- a/lib/fixed-points.nix
+++ b/lib/fixed-points.nix
@@ -45,7 +45,7 @@ rec {
     }
     ```
 
-    This is where `fix` comes in, it contains the syntactic that's not in `f` anymore.
+    This is where `fix` comes in, it contains the syntactic recursion that's not in `f` anymore.
 
     ```nix
     nix-repl> fix = f:
diff --git a/lib/licenses.nix b/lib/licenses.nix
index d9555ca66cb9..a90bab0b15dd 100644
--- a/lib/licenses.nix
+++ b/lib/licenses.nix
@@ -877,6 +877,21 @@ in mkLicense lset) ({
     fullName = "Non-Profit Open Software License 3.0";
   };
 
+  nvidiaCuda = {
+    shortName = "CUDA EULA";
+    fullName = "CUDA Toolkit End User License Agreement (EULA)";
+    url = "https://docs.nvidia.com/cuda/eula/index.html#cuda-toolkit-supplement-license-agreement";
+    free = false;
+  };
+
+  nvidiaCudaRedist = {
+    shortName = "CUDA EULA";
+    fullName = "CUDA Toolkit End User License Agreement (EULA)";
+    url = "https://docs.nvidia.com/cuda/eula/index.html#cuda-toolkit-supplement-license-agreement";
+    free = false;
+    redistributable = true;
+  };
+
   obsidian = {
     fullName = "Obsidian End User Agreement";
     url = "https://obsidian.md/eula";
diff --git a/lib/meta.nix b/lib/meta.nix
index 44730a71551e..2e817c42327d 100644
--- a/lib/meta.nix
+++ b/lib/meta.nix
@@ -162,5 +162,12 @@ rec {
        getExe' pkgs.imagemagick "convert"
        => "/nix/store/5rs48jamq7k6sal98ymj9l4k2bnwq515-imagemagick-7.1.1-15/bin/convert"
   */
-  getExe' = x: y: "${lib.getBin x}/bin/${y}";
+  getExe' = x: y:
+    assert lib.assertMsg (lib.isDerivation x)
+      "lib.meta.getExe': The first argument is of type ${builtins.typeOf x}, but it should be a derivation instead.";
+    assert lib.assertMsg (lib.isString y)
+     "lib.meta.getExe': The second argument is of type ${builtins.typeOf y}, but it should be a string instead.";
+    assert lib.assertMsg (builtins.length (lib.splitString "/" y) == 1)
+     "lib.meta.getExe': The second argument \"${y}\" is a nested path with a \"/\" character, but it should just be the name of the executable instead.";
+    "${lib.getBin x}/bin/${y}";
 }
diff --git a/lib/strings.nix b/lib/strings.nix
index 628669d86bbd..695aaaacd348 100644
--- a/lib/strings.nix
+++ b/lib/strings.nix
@@ -144,6 +144,20 @@ rec {
   */
   concatLines = concatMapStrings (s: s + "\n");
 
+  /*
+    Replicate a string n times,
+    and concatenate the parts into a new string.
+
+    Type: replicate :: int -> string -> string
+
+    Example:
+      replicate 3 "v"
+      => "vvv"
+      replicate 5 "hello"
+      => "hellohellohellohellohello"
+  */
+  replicate = n: s: concatStrings (lib.lists.replicate n s);
+
   /* Construct a Unix-style, colon-separated search path consisting of
      the given `subDir` appended to each of the given paths.
 
diff --git a/lib/systems/examples.nix b/lib/systems/examples.nix
index 0e704b7d7de0..75578b974945 100644
--- a/lib/systems/examples.nix
+++ b/lib/systems/examples.nix
@@ -115,6 +115,7 @@ rec {
   };
 
   gnu64 = { config = "x86_64-unknown-linux-gnu"; };
+  gnu64_simplekernel = gnu64 // platforms.pc_simplekernel; # see test/cross/default.nix
   gnu32  = { config = "i686-unknown-linux-gnu"; };
 
   musl64 = { config = "x86_64-unknown-linux-musl"; };
diff --git a/lib/systems/inspect.nix b/lib/systems/inspect.nix
index 022e459c3945..073df78797c7 100644
--- a/lib/systems/inspect.nix
+++ b/lib/systems/inspect.nix
@@ -100,6 +100,32 @@ rec {
     ];
   };
 
+  # given two patterns, return a pattern which is their logical AND.
+  # Since a pattern is a list-of-disjuncts, this needs to
+  patternLogicalAnd = pat1_: pat2_:
+    let
+      # patterns can be either a list or a (bare) singleton; turn
+      # them into singletons for uniform handling
+      pat1 = lib.toList pat1_;
+      pat2 = lib.toList pat2_;
+    in
+      lib.concatMap (attr1:
+        map (attr2:
+          lib.recursiveUpdateUntil
+            (path: subattr1: subattr2:
+              if (builtins.intersectAttrs subattr1 subattr2) == {} || subattr1 == subattr2
+              then true
+              else throw ''
+                pattern conflict at path ${toString path}:
+                  ${builtins.toJSON subattr1}
+                  ${builtins.toJSON subattr2}
+                '')
+            attr1
+            attr2
+            )
+          pat2)
+        pat1;
+
   matchAnyAttrs = patterns:
     if builtins.isList patterns then attrs: any (pattern: matchAttrs pattern attrs) patterns
     else matchAttrs patterns;
diff --git a/lib/systems/parse.nix b/lib/systems/parse.nix
index 34bfd94b3ce5..b69ad669e187 100644
--- a/lib/systems/parse.nix
+++ b/lib/systems/parse.nix
@@ -29,6 +29,15 @@ let
       assert type.check value;
       setType type.name ({ inherit name; } // value));
 
+  # gnu-config will ignore the portion of a triple matching the
+  # regex `e?abi.*$` when determining the validity of a triple.  In
+  # other words, `i386-linuxabichickenlips` is a valid triple.
+  removeAbiSuffix = x:
+    let match = builtins.match "(.*)e?abi.*" x;
+    in if match==null
+       then x
+       else lib.elemAt match 0;
+
 in
 
 rec {
@@ -466,7 +475,7 @@ rec {
         else                     vendors.unknown;
       kernel = if hasPrefix "darwin" args.kernel      then getKernel "darwin"
                else if hasPrefix "netbsd" args.kernel then getKernel "netbsd"
-               else                                   getKernel args.kernel;
+               else                                   getKernel (removeAbiSuffix args.kernel);
       abi =
         /**/ if args ? abi       then getAbi args.abi
         else if isLinux parsed || isWindows parsed then
diff --git a/lib/tests/filesystem.sh b/lib/tests/filesystem.sh
index cfd333d0001b..7e7e03bc667d 100755
--- a/lib/tests/filesystem.sh
+++ b/lib/tests/filesystem.sh
@@ -64,8 +64,14 @@ expectSuccess "pathType $PWD/directory" '"directory"'
 expectSuccess "pathType $PWD/regular" '"regular"'
 expectSuccess "pathType $PWD/symlink" '"symlink"'
 expectSuccess "pathType $PWD/fifo" '"unknown"'
-# Different errors depending on whether the builtins.readFilePath primop is available or not
-expectFailure "pathType $PWD/non-existent" "error: (evaluation aborted with the following error message: 'lib.filesystem.pathType: Path $PWD/non-existent does not exist.'|getting status of '$PWD/non-existent': No such file or directory)"
+
+# Only check error message when a Nixpkgs-specified error is thrown,
+# which is only the case when `readFileType` is not available
+# and the fallback implementation needs to be used.
+if [[ "$(nix-instantiate --eval --expr 'builtins ? readFileType')" == false ]]; then
+    expectFailure "pathType $PWD/non-existent" \
+        "error: evaluation aborted with the following error message: 'lib.filesystem.pathType: Path $PWD/non-existent does not exist.'"
+fi
 
 expectSuccess "pathIsDirectory /." "true"
 expectSuccess "pathIsDirectory $PWD/directory" "true"
diff --git a/lib/tests/misc.nix b/lib/tests/misc.nix
index 2e7fda2b1f8b..0d30e93aafb9 100644
--- a/lib/tests/misc.nix
+++ b/lib/tests/misc.nix
@@ -191,6 +191,11 @@ runTests {
     expected = "a\nb\nc\n";
   };
 
+  testReplicateString = {
+    expr = strings.replicate 5 "hello";
+    expected = "hellohellohellohellohello";
+  };
+
   testSplitStringsSimple = {
     expr = strings.splitString "." "a.b.c.d";
     expected = [ "a" "b" "c" "d" ];
@@ -1906,4 +1911,32 @@ runTests {
     expr = (with types; either int (listOf (either bool str))).description;
     expected = "signed integer or list of (boolean or string)";
   };
+
+# Meta
+  testGetExe'Output = {
+    expr = getExe' {
+      type = "derivation";
+      out = "somelonghash";
+      bin = "somelonghash";
+    } "executable";
+    expected = "somelonghash/bin/executable";
+  };
+
+  testGetExeOutput = {
+    expr = getExe {
+      type = "derivation";
+      out = "somelonghash";
+      bin = "somelonghash";
+      meta.mainProgram = "mainProgram";
+    };
+    expected = "somelonghash/bin/mainProgram";
+  };
+
+  testGetExe'FailureFirstArg = testingThrow (
+    getExe' "not a derivation" "executable"
+  );
+
+  testGetExe'FailureSecondArg = testingThrow (
+    getExe' { type = "derivation"; } "dir/executable"
+  );
 }
generated by cgit-pink 1.4.1 (git 2.36.1) at 2024-07-14 04:41:37 +0000