nix-everything: Remove libs, add dev and devdoc package outputs

The new package output attributes are somewhat experimental, and
provided for compatibility most of all.

We'll see how well this goes before the changes proposed in
#6507

packaging/everything.nix

@@ -5,20 +5,17 @@
 
   nix-util,
   nix-util-c,
-  nix-util-test-support,
   nix-util-tests,
 
   nix-store,
   nix-store-c,
-  nix-store-test-support,
   nix-store-tests,
 
   nix-fetchers,
   nix-fetchers-tests,
 
   nix-expr,
   nix-expr-c,
-  nix-expr-test-support,
   nix-expr-tests,
 
   nix-flake,
@@ -38,45 +35,84 @@
   nix-external-api-docs,
 
   nix-perl-bindings,
+
+  testers,
+  runCommand,
 }:
 
+let
+  dev = stdenv.mkDerivation (finalAttrs: {
+    name = "nix-${nix-cli.version}-dev";
+    pname = "nix";
+    version = nix-cli.version;
+    dontUnpack = true;
+    dontBuild = true;
+    libs = map lib.getDev [
+      nix-cmd
+      nix-expr
+      nix-expr-c
+      nix-fetchers
+      nix-flake
+      nix-main
+      nix-main-c
+      nix-store
+      nix-store-c
+      nix-util
+      nix-util-c
+      nix-perl-bindings
+    ];
+    installPhase = ''
+      mkdir -p $out/nix-support
+      echo $libs >> $out/nix-support/propagated-build-inputs
+    '';
+    passthru = {
+      tests = {
+        pkg-config =
+          testers.hasPkgConfigModules {
+            package = finalAttrs.finalPackage;
+          };
+      };
+
+      # If we were to fully emulate output selection here, we'd confuse the Nix CLIs,
+      # because they rely on `drvPath`.
+      dev = finalAttrs.finalPackage.out;
+
+      libs = throw "`nix.dev.libs` is not meant to be used; use `nix.libs` instead.";
+    };
+    meta = {
+      pkgConfigModules = [
+        "nix-cmd"
+        "nix-expr"
+        "nix-expr-c"
+        "nix-fetchers"
+        "nix-flake"
+        "nix-main"
+        "nix-main-c"
+        "nix-store"
+        "nix-store-c"
+        "nix-util"
+        "nix-util-c"
+      ];
+    };
+  });
+  devdoc = buildEnv {
+    name = "nix-${nix-cli.version}-devdoc";
+    paths = [
+      nix-internal-api-docs
+      nix-external-api-docs
+    ];
+  };
+
+in
 (buildEnv {
   name = "nix-${nix-cli.version}";
   paths = [
-    nix-util
-    nix-util-c
-    nix-util-test-support
-    nix-util-tests
-
-    nix-store
-    nix-store-c
-    nix-store-test-support
-    nix-store-tests
-
-    nix-fetchers
-    nix-fetchers-tests
-
-    nix-expr
-    nix-expr-c
-    nix-expr-test-support
-    nix-expr-tests
-
-    nix-flake
-    nix-flake-tests
-
-    nix-main
-    nix-main-c
-
-    nix-cmd
+    # unfortunately, `buildEnv` doesn't support multiple outputs
 
     nix-cli
 
+    # TODO: separate doc output attribute?
     nix-manual
-    nix-internal-api-docs
-    nix-external-api-docs
-
-  ] ++ lib.optionals (stdenv.buildPlatform.canExecute stdenv.hostPlatform) [
-    nix-perl-bindings
   ];
 
   meta.mainProgram = "nix";
@@ -85,12 +121,25 @@
   doInstallCheck = true;
 
   checkInputs = [
-    # Actually run the unit tests too
+    # Make sure the unit tests have passed
     nix-util-tests.tests.run
     nix-store-tests.tests.run
     nix-expr-tests.tests.run
+    nix-fetchers-tests.tests.run
     nix-flake-tests.tests.run
-  ];
+
+    # dev bundle is ok
+    # (checkInputs must be empty paths??)
+    (runCommand "check-pkg-config" { checked = dev.tests.pkg-config; } "mkdir $out")
+  ] ++
+    (if stdenv.buildPlatform.canExecute stdenv.hostPlatform
+    then [
+      # TODO: add perl.tests
+      nix-perl-bindings
+    ]
+    else [
+      nix-perl-bindings
+    ]);
   installCheckInputs = [
     nix-functional-tests
   ];
@@ -128,5 +177,25 @@
         nix-main-c
       ;
     };
+
+    tests = prevAttrs.passthru.tests or {} // {
+      # TODO: create a proper fixpoint and:
+      # pkg-config =
+      #   testers.hasPkgConfigModules {
+      #     package = finalPackage;
+      #   };
+    };
+
+    /**
+      A derivation referencing the `dev` outputs of the Nix libraries.
+     */
+    inherit dev;
+    inherit devdoc;
+    outputs = [ "out" "dev" "devdoc" ];
+    all = lib.attrValues (lib.genAttrs finalAttrs.passthru.outputs (outName: finalAttrs.finalPackage.${outName}));
+  };
+  meta = prevAttrs.meta // {
+    description = "The Nix package manager";
+    pkgConfigModules = dev.meta.pkgConfigModules;
   };
 })