Merge pull request #295378 from hercules-ci/makeDerivationArgument

make-derivation.nix: Factor out `makeDerivationArgument`

pkgs/build-support/lib/cmake.nix

···
+{ stdenv, lib }:
+
+let
+  inherit (lib) findFirst isString optional optionals;
+
+  makeCMakeFlags = { cmakeFlags ? [], ... }:
+    cmakeFlags
+    ++ optionals (stdenv.hostPlatform != stdenv.buildPlatform) ([
+      "-DCMAKE_SYSTEM_NAME=${findFirst isString "Generic" (optional (!stdenv.hostPlatform.isRedox) stdenv.hostPlatform.uname.system)}"
+    ] ++ optionals (stdenv.hostPlatform.uname.processor != null) [
+      "-DCMAKE_SYSTEM_PROCESSOR=${stdenv.hostPlatform.uname.processor}"
+    ] ++ optionals (stdenv.hostPlatform.uname.release != null) [
+      "-DCMAKE_SYSTEM_VERSION=${stdenv.hostPlatform.uname.release}"
+    ] ++ optionals (stdenv.hostPlatform.isDarwin) [
+      "-DCMAKE_OSX_ARCHITECTURES=${stdenv.hostPlatform.darwinArch}"
+    ] ++ optionals (stdenv.buildPlatform.uname.system != null) [
+      "-DCMAKE_HOST_SYSTEM_NAME=${stdenv.buildPlatform.uname.system}"
+    ] ++ optionals (stdenv.buildPlatform.uname.processor != null) [
+      "-DCMAKE_HOST_SYSTEM_PROCESSOR=${stdenv.buildPlatform.uname.processor}"
+    ] ++ optionals (stdenv.buildPlatform.uname.release != null) [
+      "-DCMAKE_HOST_SYSTEM_VERSION=${stdenv.buildPlatform.uname.release}"
+    ] ++ optionals (stdenv.buildPlatform.canExecute stdenv.hostPlatform) [
+      "-DCMAKE_CROSSCOMPILING_EMULATOR=env"
+    ] ++ optionals stdenv.hostPlatform.isStatic [
+      "-DCMAKE_LINK_SEARCH_START_STATIC=ON"
+    ]);
+in
+{
+  inherit makeCMakeFlags;
+}

pkgs/build-support/lib/meson.nix

···
+{ stdenv, lib }:
+
+let
+  inherit (lib) boolToString optionals;
+
+  # See https://mesonbuild.com/Reference-tables.html#cpu-families
+  cpuFamily = platform: with platform;
+    /**/ if isAarch32 then "arm"
+    else if isx86_32  then "x86"
+    else platform.uname.processor;
+
+  makeMesonFlags = { mesonFlags ? [], ... }:
+    let
+      crossFile = builtins.toFile "cross-file.conf" ''
+        [properties]
+        bindgen_clang_arguments = ['-target', '${stdenv.targetPlatform.config}']
+        needs_exe_wrapper = ${boolToString (!stdenv.buildPlatform.canExecute stdenv.hostPlatform)}
+
+        [host_machine]
+        system = '${stdenv.targetPlatform.parsed.kernel.name}'
+        cpu_family = '${cpuFamily stdenv.targetPlatform}'
+        cpu = '${stdenv.targetPlatform.parsed.cpu.name}'
+        endian = ${if stdenv.targetPlatform.isLittleEndian then "'little'" else "'big'"}
+
+        [binaries]
+        llvm-config = 'llvm-config-native'
+        rust = ['rustc', '--target', '${stdenv.targetPlatform.rust.rustcTargetSpec}']
+      '';
+      crossFlags = optionals (stdenv.hostPlatform != stdenv.buildPlatform) [ "--cross-file=${crossFile}" ];
+    in crossFlags ++ mesonFlags;
+
+in
+{
+  inherit makeMesonFlags;
+}

pkgs/stdenv/adapters.nix

···
 
 let
   # N.B. Keep in sync with default arg for stdenv/generic.
-  defaultMkDerivationFromStdenv = import ./generic/make-derivation.nix { inherit lib config; };
+  defaultMkDerivationFromStdenv = stdenv: (import ./generic/make-derivation.nix { inherit lib config; } stdenv).mkDerivation;
 
   # Low level function to help with overriding `mkDerivationFromStdenv`. One
   # gives it the old stdenv arguments and a "continuation" function, and

pkgs/stdenv/generic/default.nix

···
 
 , # The implementation of `mkDerivation`, parameterized with the final stdenv so we can tie the knot.
   # This is convient to have as a parameter so the stdenv "adapters" work better
-  mkDerivationFromStdenv ? import ./make-derivation.nix { inherit lib config; }
+  mkDerivationFromStdenv ? stdenv: (import ./make-derivation.nix { inherit lib config; } stdenv).mkDerivation
 }:
 
 let

pkgs/stdenv/generic/make-derivation.nix

···
     assertMsg
     attrNames
     boolToString
-    chooseDevOutputs
     concatLists
     concatMap
     concatMapStrings
···
     extendDerivation
     filter
     findFirst
-    flip
+    getDev
     head
     imap1
     isAttrs
···
     subtractLists
     unique
   ;
+
+  inherit (import ../../build-support/lib/cmake.nix { inherit lib stdenv; }) makeCMakeFlags;
+  inherit (import ../../build-support/lib/meson.nix { inherit lib stdenv; }) makeMesonFlags;
+
+  mkDerivation =
+    fnOrAttrs:
+      if builtins.isFunction fnOrAttrs
+      then makeDerivationExtensible fnOrAttrs
+      else makeDerivationExtensibleConst fnOrAttrs;
 
   checkMeta = import ./check-meta.nix {
     inherit lib config;
···
           makeDerivationExtensible (self: attrs // (if builtins.isFunction f0 || f0?__functor then f self attrs else f0)))
       attrs;
 
-  mkDerivationSimple = overrideAttrs:
+  knownHardeningFlags = [
+    "bindnow"
+    "format"
+    "fortify"
+    "fortify3"
+    "pic"
+    "pie"
+    "relro"
+    "stackprotector"
+    "strictoverflow"
+    "trivialautovarinit"
+    "zerocallusedregs"
+  ];
+
+  removedOrReplacedAttrNames = [
+    "checkInputs" "installCheckInputs"
+    "nativeCheckInputs" "nativeInstallCheckInputs"
+    "__contentAddressed"
+    "__darwinAllowLocalNetworking"
+    "__impureHostDeps" "__propagatedImpureHostDeps"
+    "sandboxProfile" "propagatedSandboxProfile"
+  ];
+
+  # Turn a derivation into its outPath without a string context attached.
+  # See the comment at the usage site.
+  unsafeDerivationToUntrackedOutpath = drv:
+    if isDerivation drv
+    then builtins.unsafeDiscardStringContext drv.outPath
+    else drv;
+
+  makeDerivationArgument =
 
 
-# `mkDerivation` wraps the builtin `derivation` function to
-# produce derivations that use this stdenv and its shell.
+# `makeDerivationArgument` is responsible for the `mkDerivation` arguments that
+# affect the actual derivation, excluding a few behaviors that are not
+# essential, and specific to `mkDerivation`: `env`, `cmakeFlags`, `mesonFlags`.
 #
 # See also:
 #
···
 
 # Configure Phase
 , configureFlags ? []
-, cmakeFlags ? []
-, mesonFlags ? []
 , # Target is not included by default because most programs don't care.
   # Including it then would cause needless mass rebuilds.
   #
···
 
 , enableParallelBuilding ? config.enableParallelBuildingByDefault
 
-, meta ? {}
-, passthru ? {}
-, pos ? # position used in error messages and for meta.position
-    (if attrs.meta.description or null != null
-      then builtins.unsafeGetAttrPos "description" attrs.meta
-      else if attrs.version or null != null
-      then builtins.unsafeGetAttrPos "version" attrs
-      else builtins.unsafeGetAttrPos "name" attrs)
 , separateDebugInfo ? false
 , outputs ? [ "out" ]
 , __darwinAllowLocalNetworking ? false
···
 # but for anything complex, be prepared to debug if enabling.
 , __structuredAttrs ? config.structuredAttrsByDefault or false
 
-, env ? { }
-
 , ... } @ attrs:
 
 # Policy on acceptable hash types in nixpkgs
···
   separateDebugInfo' = separateDebugInfo && stdenv.hostPlatform.isLinux;
   outputs' = outputs ++ optional separateDebugInfo' "debug";
 
-  # Turn a derivation into its outPath without a string context attached.
-  # See the comment at the usage site.
-  unsafeDerivationToUntrackedOutpath = drv:
-    if isDerivation drv
-    then builtins.unsafeDiscardStringContext drv.outPath
-    else drv;
-
   noNonNativeDeps = builtins.length (depsBuildTarget ++ depsBuildTargetPropagated
                                   ++ depsHostHost ++ depsHostHostPropagated
                                   ++ buildInputs ++ propagatedBuildInputs
···
     # disabling fortify implies fortify3 should also be disabled
     then unique (hardeningDisable ++ [ "fortify3" ])
     else hardeningDisable;
-  knownHardeningFlags = [
-    "bindnow"
-    "format"
-    "fortify"
-    "fortify3"
-    "pic"
-    "pie"
-    "relro"
-    "stackprotector"
-    "strictoverflow"
-    "trivialautovarinit"
-    "zerocallusedregs"
-  ];
   defaultHardeningFlags =
     (if stdenv.hasCC then stdenv.cc else {}).defaultHardeningFlags or
       # fallback safe-ish set of flags
···
   erroneousHardeningFlags = subtractLists knownHardeningFlags (hardeningEnable ++ remove "all" hardeningDisable);
 
   checkDependencyList = checkDependencyList' [];
-  checkDependencyList' = positions: name: deps: flip imap1 deps (index: dep:
-    if isDerivation dep || dep == null || builtins.isString dep || builtins.isPath dep then dep
-    else if isList dep then checkDependencyList' ([index] ++ positions) name dep
-    else throw "Dependency is not of a valid type: ${concatMapStrings (ix: "element ${toString ix} of ") ([index] ++ positions)}${name} for ${attrs.name or attrs.pname}");
+  checkDependencyList' = positions: name: deps:
+    imap1
+      (index: dep:
+        if isDerivation dep || dep == null || builtins.isString dep || builtins.isPath dep then dep
+        else if isList dep then checkDependencyList' ([index] ++ positions) name dep
+        else throw "Dependency is not of a valid type: ${concatMapStrings (ix: "element ${toString ix} of ") ([index] ++ positions)}${name} for ${attrs.name or attrs.pname}")
+      deps;
 in if builtins.length erroneousHardeningFlags != 0
 then abort ("mkDerivation was called with unsupported hardening flags: " + lib.generators.toPretty {} {
   inherit erroneousHardeningFlags hardeningDisable hardeningEnable knownHardeningFlags;
···
 
   outputs = outputs';
 
-  references = nativeBuildInputs ++ buildInputs
-            ++ propagatedNativeBuildInputs ++ propagatedBuildInputs;
-
-  dependencies = map (map chooseDevOutputs) [
+  dependencies = [
     [
-      (map (drv: drv.__spliced.buildBuild or drv) (checkDependencyList "depsBuildBuild" depsBuildBuild))
-      (map (drv: drv.__spliced.buildHost or drv) (checkDependencyList "nativeBuildInputs" nativeBuildInputs'))
-      (map (drv: drv.__spliced.buildTarget or drv) (checkDependencyList "depsBuildTarget" depsBuildTarget))
+      (map (drv: getDev drv.__spliced.buildBuild or drv) (checkDependencyList "depsBuildBuild" depsBuildBuild))
+      (map (drv: getDev drv.__spliced.buildHost or drv) (checkDependencyList "nativeBuildInputs" nativeBuildInputs'))
+      (map (drv: getDev drv.__spliced.buildTarget or drv) (checkDependencyList "depsBuildTarget" depsBuildTarget))
     ]
     [
-      (map (drv: drv.__spliced.hostHost or drv) (checkDependencyList "depsHostHost" depsHostHost))
-      (map (drv: drv.__spliced.hostTarget or drv) (checkDependencyList "buildInputs" buildInputs'))
+      (map (drv: getDev drv.__spliced.hostHost or drv) (checkDependencyList "depsHostHost" depsHostHost))
+      (map (drv: getDev drv.__spliced.hostTarget or drv) (checkDependencyList "buildInputs" buildInputs'))
     ]
     [
-      (map (drv: drv.__spliced.targetTarget or drv) (checkDependencyList "depsTargetTarget" depsTargetTarget))
+      (map (drv: getDev drv.__spliced.targetTarget or drv) (checkDependencyList "depsTargetTarget" depsTargetTarget))
     ]
   ];
-  propagatedDependencies = map (map chooseDevOutputs) [
+  propagatedDependencies = [
     [
-      (map (drv: drv.__spliced.buildBuild or drv) (checkDependencyList "depsBuildBuildPropagated" depsBuildBuildPropagated))
-      (map (drv: drv.__spliced.buildHost or drv) (checkDependencyList "propagatedNativeBuildInputs" propagatedNativeBuildInputs))
-      (map (drv: drv.__spliced.buildTarget or drv) (checkDependencyList "depsBuildTargetPropagated" depsBuildTargetPropagated))
+      (map (drv: getDev drv.__spliced.buildBuild or drv) (checkDependencyList "depsBuildBuildPropagated" depsBuildBuildPropagated))
+      (map (drv: getDev drv.__spliced.buildHost or drv) (checkDependencyList "propagatedNativeBuildInputs" propagatedNativeBuildInputs))
+      (map (drv: getDev drv.__spliced.buildTarget or drv) (checkDependencyList "depsBuildTargetPropagated" depsBuildTargetPropagated))
     ]
     [
-      (map (drv: drv.__spliced.hostHost or drv) (checkDependencyList "depsHostHostPropagated" depsHostHostPropagated))
-      (map (drv: drv.__spliced.hostTarget or drv) (checkDependencyList "propagatedBuildInputs" propagatedBuildInputs))
+      (map (drv: getDev drv.__spliced.hostHost or drv) (checkDependencyList "depsHostHostPropagated" depsHostHostPropagated))
+      (map (drv: getDev drv.__spliced.hostTarget or drv) (checkDependencyList "propagatedBuildInputs" propagatedBuildInputs))
     ]
     [
-      (map (drv: drv.__spliced.targetTarget or drv) (checkDependencyList "depsTargetTargetPropagated" depsTargetTargetPropagated))
+      (map (drv: getDev drv.__spliced.targetTarget or drv) (checkDependencyList "depsTargetTargetPropagated" depsTargetTargetPropagated))
     ]
   ];
 
-  computedSandboxProfile =
-    concatMap (input: input.__propagatedSandboxProfile or [])
-      (stdenv.extraNativeBuildInputs
-       ++ stdenv.extraBuildInputs
-       ++ concatLists dependencies);
-
-  computedPropagatedSandboxProfile =
-    concatMap (input: input.__propagatedSandboxProfile or [])
-      (concatLists propagatedDependencies);
-
-  computedImpureHostDeps =
-    unique (concatMap (input: input.__propagatedImpureHostDeps or [])
-      (stdenv.extraNativeBuildInputs
-       ++ stdenv.extraBuildInputs
-       ++ concatLists dependencies));
-
-  computedPropagatedImpureHostDeps =
-    unique (concatMap (input: input.__propagatedImpureHostDeps or [])
-      (concatLists propagatedDependencies));
-
-  envIsExportable = isAttrs env && !isDerivation env;
-
   derivationArg =
-    (removeAttrs attrs
-      (["meta" "passthru" "pos"
-       "checkInputs" "installCheckInputs"
-       "nativeCheckInputs" "nativeInstallCheckInputs"
-       "__contentAddressed"
-       "__darwinAllowLocalNetworking"
-       "__impureHostDeps" "__propagatedImpureHostDeps"
-       "sandboxProfile" "propagatedSandboxProfile"]
-       ++ optional (__structuredAttrs || envIsExportable) "env"))
+    removeAttrs attrs removedOrReplacedAttrNames
     // (optionalAttrs (attrs ? name || (attrs ? pname && attrs ? version)) {
       name =
         let
···
             assert assertMsg (attrs ? version && attrs.version != null) "The ‘version’ attribute cannot be null.";
             "${attrs.pname}${staticMarker}${hostSuffix}-${attrs.version}"
         );
-    }) // optionalAttrs __structuredAttrs { env = checkedEnv; } // {
+    }) // {
       builder = attrs.realBuilder or stdenv.shell;
       args = attrs.args or ["-e" (attrs.builder or ./default-builder.sh)];
       inherit stdenv;
···
         ++ optional (elem "host"   configurePlatforms) "--host=${stdenv.hostPlatform.config}"
         ++ optional (elem "target" configurePlatforms) "--target=${stdenv.targetPlatform.config}";
 
-      cmakeFlags =
-        cmakeFlags
-        ++ optionals (stdenv.hostPlatform != stdenv.buildPlatform) ([
-          "-DCMAKE_SYSTEM_NAME=${findFirst isString "Generic" (optional (!stdenv.hostPlatform.isRedox) stdenv.hostPlatform.uname.system)}"
-        ] ++ optionals (stdenv.hostPlatform.uname.processor != null) [
-          "-DCMAKE_SYSTEM_PROCESSOR=${stdenv.hostPlatform.uname.processor}"
-        ] ++ optionals (stdenv.hostPlatform.uname.release != null) [
-          "-DCMAKE_SYSTEM_VERSION=${stdenv.hostPlatform.uname.release}"
-        ] ++ optionals (stdenv.hostPlatform.isDarwin) [
-          "-DCMAKE_OSX_ARCHITECTURES=${stdenv.hostPlatform.darwinArch}"
-        ] ++ optionals (stdenv.buildPlatform.uname.system != null) [
-          "-DCMAKE_HOST_SYSTEM_NAME=${stdenv.buildPlatform.uname.system}"
-        ] ++ optionals (stdenv.buildPlatform.uname.processor != null) [
-          "-DCMAKE_HOST_SYSTEM_PROCESSOR=${stdenv.buildPlatform.uname.processor}"
-        ] ++ optionals (stdenv.buildPlatform.uname.release != null) [
-          "-DCMAKE_HOST_SYSTEM_VERSION=${stdenv.buildPlatform.uname.release}"
-        ] ++ optionals (stdenv.buildPlatform.canExecute stdenv.hostPlatform) [
-          "-DCMAKE_CROSSCOMPILING_EMULATOR=env"
-        ] ++ lib.optionals stdenv.hostPlatform.isStatic [
-          "-DCMAKE_LINK_SEARCH_START_STATIC=ON"
-        ]);
-
-      mesonFlags =
-        let
-          # See https://mesonbuild.com/Reference-tables.html#cpu-families
-          cpuFamily = platform: with platform;
-            /**/ if isAarch32 then "arm"
-            else if isx86_32  then "x86"
-            else platform.uname.processor;
-
-          crossFile = builtins.toFile "cross-file.conf" ''
-            [properties]
-            bindgen_clang_arguments = ['-target', '${stdenv.targetPlatform.config}']
-            needs_exe_wrapper = ${boolToString (!stdenv.buildPlatform.canExecute stdenv.hostPlatform)}
-
-            [host_machine]
-            system = '${stdenv.targetPlatform.parsed.kernel.name}'
-            cpu_family = '${cpuFamily stdenv.targetPlatform}'
-            cpu = '${stdenv.targetPlatform.parsed.cpu.name}'
-            endian = ${if stdenv.targetPlatform.isLittleEndian then "'little'" else "'big'"}
-
-            [binaries]
-            llvm-config = 'llvm-config-native'
-            rust = ['rustc', '--target', '${stdenv.targetPlatform.rust.rustcTargetSpec}']
-          '';
-          crossFlags = optionals (stdenv.hostPlatform != stdenv.buildPlatform) [ "--cross-file=${crossFile}" ];
-        in crossFlags ++ mesonFlags;
-
       inherit patches;
 
       inherit doCheck doInstallCheck;
···
       NIX_HARDENING_ENABLE = enabledHardeningOptions;
     } // optionalAttrs (stdenv.hostPlatform.isx86_64 && stdenv.hostPlatform ? gcc.arch) {
       requiredSystemFeatures = attrs.requiredSystemFeatures or [] ++ [ "gccarch-${stdenv.hostPlatform.gcc.arch}" ];
-    } // optionalAttrs (stdenv.buildPlatform.isDarwin) {
+    } // optionalAttrs (stdenv.buildPlatform.isDarwin) (
+      let
+        computedSandboxProfile =
+          concatMap (input: input.__propagatedSandboxProfile or [])
+            (stdenv.extraNativeBuildInputs
+            ++ stdenv.extraBuildInputs
+            ++ concatLists dependencies);
+
+        computedPropagatedSandboxProfile =
+          concatMap (input: input.__propagatedSandboxProfile or [])
+            (concatLists propagatedDependencies);
+
+        computedImpureHostDeps =
+          unique (concatMap (input: input.__propagatedImpureHostDeps or [])
+            (stdenv.extraNativeBuildInputs
+            ++ stdenv.extraBuildInputs
+            ++ concatLists dependencies));
+
+        computedPropagatedImpureHostDeps =
+          unique (concatMap (input: input.__propagatedImpureHostDeps or [])
+            (concatLists propagatedDependencies));
+    in {
       inherit __darwinAllowLocalNetworking;
       # TODO: remove `unique` once nix has a list canonicalization primitive
       __sandboxProfile =
···
         "/bin/sh"
       ];
       __propagatedImpureHostDeps = computedPropagatedImpureHostDeps ++ __propagatedImpureHostDeps;
-    } //
+    }) //
     # If we use derivations directly here, they end up as build-time dependencies.
     # This is especially problematic in the case of disallowed*, since the disallowed
     # derivations will be built by nix as build-time dependencies, while those
···
         mapNullable unsafeDerivationToUntrackedOutpath attrs.allowedRequisites;
     };
 
-  meta = checkMeta.commonMeta { inherit validity attrs pos references; };
+in
+  derivationArg;
+
+mkDerivationSimple = overrideAttrs:
+
+# `mkDerivation` wraps the builtin `derivation` function to
+# produce derivations that use this stdenv and its shell.
+#
+# Internally, it delegates most of its behavior to `makeDerivationArgument`,
+# except for the `env`, `cmakeFlags`, and `mesonFlags` attributes, as well
+# as the attributes `meta` and `passthru` that affect [package attributes],
+# and not the derivation itself.
+#
+# See also:
+#
+# * https://nixos.org/nixpkgs/manual/#sec-using-stdenv
+#   Details on how to use this mkDerivation function
+#
+# * https://nixos.org/manual/nix/stable/expressions/derivations.html#derivations
+#   Explanation about derivations in general
+#
+# * [package attributes]: https://nixos.org/manual/nix/stable/glossary#package-attribute-set
+{
+
+# Configure Phase
+  cmakeFlags ? []
+, mesonFlags ? []
+
+, meta ? {}
+, passthru ? {}
+, pos ? # position used in error messages and for meta.position
+    (if attrs.meta.description or null != null
+      then builtins.unsafeGetAttrPos "description" attrs.meta
+      else if attrs.version or null != null
+      then builtins.unsafeGetAttrPos "version" attrs
+      else builtins.unsafeGetAttrPos "name" attrs)
+
+# Experimental.  For simple packages mostly just works,
+# but for anything complex, be prepared to debug if enabling.
+, __structuredAttrs ? config.structuredAttrsByDefault or false
+
+, env ? { }
+
+, ... } @ attrs:
+
+# Policy on acceptable hash types in nixpkgs
+assert attrs ? outputHash -> (
+  let algo =
+    attrs.outputHashAlgo or (head (splitString "-" attrs.outputHash));
+  in
+  if algo == "md5" then
+    throw "Rejected insecure ${algo} hash '${attrs.outputHash}'"
+  else
+    true
+);
+
+let
+  envIsExportable = isAttrs env && !isDerivation env;
+
+  derivationArg = makeDerivationArgument
+    (removeAttrs
+      attrs
+        (["meta" "passthru" "pos"]
+        ++ optional (__structuredAttrs || envIsExportable) "env"
+        )
+    // optionalAttrs __structuredAttrs { env = checkedEnv; }
+    // {
+      cmakeFlags = makeCMakeFlags attrs;
+      mesonFlags = makeMesonFlags attrs;
+    });
+
+  meta = checkMeta.commonMeta {
+    inherit validity attrs pos;
+    references = attrs.nativeBuildInputs ++ attrs.buildInputs
+              ++ attrs.propagatedNativeBuildInputs ++ attrs.propagatedBuildInputs;
+  };
   validity = checkMeta.assertValidity { inherit meta attrs; };
 
   checkedEnv =
···
   (derivation (derivationArg // optionalAttrs envIsExportable checkedEnv));
 
 in
-  fnOrAttrs:
-    if builtins.isFunction fnOrAttrs
-    then makeDerivationExtensible fnOrAttrs
-    else makeDerivationExtensibleConst fnOrAttrs
+{
+  inherit mkDerivation;
+}