Merge remote-tracking branch 'upstream/master' into upstream-merge

33 files changed, 442 insertions, 297 deletions

diff --git a/src/nix/app.cc b/src/nix/app.cc
index e104cc9c1..803d028f0 100644
--- a/src/nix/app.cc
+++ b/src/nix/app.cc
@@ -4,6 +4,7 @@
 #include "eval-cache.hh"
 #include "names.hh"
 #include "command.hh"
+#include "derivations.hh"
 
 namespace nix {
 
@@ -70,7 +71,7 @@ UnresolvedApp Installable::toApp(EvalState & state)
 
         std::vector<StorePathWithOutputs> context2;
         for (auto & [path, name] : context)
-            context2.push_back({state.store->parseStorePath(path), {name}});
+            context2.push_back({path, {name}});
 
         return UnresolvedApp{App {
             .context = std::move(context2),
@@ -114,7 +115,7 @@ App UnresolvedApp::resolve(ref<Store> evalStore, ref<Store> store)
         installableContext.push_back(
             std::make_shared<InstallableDerivedPath>(store, ctxElt.toDerivedPath()));
 
-    auto builtContext = build(evalStore, store, Realise::Outputs, installableContext);
+    auto builtContext = Installable::build(evalStore, store, Realise::Outputs, installableContext);
     res.program = resolveString(*store, unresolved.program, builtContext);
     if (!store->isInStore(res.program))
         throw Error("app program '%s' is not in the Nix store", res.program);
diff --git a/src/nix/build.cc b/src/nix/build.cc
index 6e31757a2..840c7ca38 100644
--- a/src/nix/build.cc
+++ b/src/nix/build.cc
@@ -52,15 +52,26 @@ struct CmdBuild : InstallablesCommand, MixDryRun, MixJSON, MixProfile
 
     void run(ref<Store> store) override
     {
-        auto buildables = build(
+        if (dryRun) {
+            std::vector<DerivedPath> pathsToBuild;
+
+            for (auto & i : installables) {
+                auto b = i->toDerivedPaths();
+                pathsToBuild.insert(pathsToBuild.end(), b.begin(), b.end());
+            }
+            printMissing(store, pathsToBuild, lvlError);
+            if (json)
+                logger->cout("%s", derivedPathsToJSON(pathsToBuild, store).dump());
+            return;
+        }
+
+        auto buildables = Installable::build(
             getEvalStore(), store,
-            dryRun ? Realise::Derivation : Realise::Outputs,
+            Realise::Outputs,
             installables, buildMode);
 
         if (json) logger->cout("%s", derivedPathsWithHintsToJSON(buildables, store).dump());
 
-        if (dryRun) return;
-
         if (outLink != "")
             if (auto store2 = store.dynamic_pointer_cast<LocalFSStore>())
                 for (const auto & [_i, buildable] : enumerate(buildables)) {
diff --git a/src/nix/bundle.cc b/src/nix/bundle.cc
index 113ceca33..81fb8464a 100644
--- a/src/nix/bundle.cc
+++ b/src/nix/bundle.cc
@@ -9,7 +9,7 @@ using namespace nix;
 
 struct CmdBundle : InstallableCommand
 {
-    std::string bundler = "github:matthewbauer/nix-bundle";
+    std::string bundler = "github:NixOS/bundlers";
     std::optional<Path> outLink;
 
     CmdBundle()
@@ -49,9 +49,11 @@ struct CmdBundle : InstallableCommand
 
     Category category() override { return catSecondary; }
 
+    // FIXME: cut&paste from CmdRun.
     Strings getDefaultFlakeAttrPaths() override
     {
         Strings res{
+            "apps." + settings.thisSystem.get() + ".default",
             "defaultApp." + settings.thisSystem.get()
         };
         for (auto & s : SourceExprCommand::getDefaultFlakeAttrPaths())
@@ -61,10 +63,7 @@ struct CmdBundle : InstallableCommand
 
     Strings getDefaultFlakeAttrPathPrefixes() override
     {
-        Strings res{
-            "apps." + settings.thisSystem.get() + "."
-
-        };
+        Strings res{"apps." + settings.thisSystem.get() + "."};
         for (auto & s : SourceExprCommand::getDefaultFlakeAttrPathPrefixes())
             res.push_back(s);
         return res;
@@ -74,21 +73,18 @@ struct CmdBundle : InstallableCommand
     {
         auto evalState = getEvalState();
 
-        auto [progFlakeRef, progName] = parseFlakeRefWithFragment(installable->what(), absPath("."));
-        const flake::LockFlags lockFlagsProg{ .writeLockFile = false };
-        auto programInstallable = InstallableFlake(this,
-            evalState, std::move(progFlakeRef),
-            Strings{progName == "" ? "defaultApp" : progName},
-            Strings(this->getDefaultFlakeAttrPathPrefixes()),
-            lockFlagsProg);
-        auto val = programInstallable.toValue(*evalState).first;
+        auto val = installable->toValue(*evalState).first;
 
         auto [bundlerFlakeRef, bundlerName] = parseFlakeRefWithFragment(bundler, absPath("."));
         const flake::LockFlags lockFlags{ .writeLockFile = false };
-        auto bundler = InstallableFlake(this,
-            evalState, std::move(bundlerFlakeRef),
-            Strings{bundlerName == "" ? "defaultBundler." + settings.thisSystem.get() : settings.thisSystem.get() + "." + bundlerName, bundlerName},
-            Strings({"","bundlers."}), lockFlags);
+        InstallableFlake bundler{this,
+            evalState, std::move(bundlerFlakeRef), bundlerName,
+            {"bundlers." + settings.thisSystem.get() + ".default",
+             "defaultBundler." + settings.thisSystem.get()
+            },
+            {"bundlers." + settings.thisSystem.get() + "."},
+            lockFlags
+        };
 
         auto vRes = evalState->allocValue();
         evalState->callFunction(*bundler.toValue(*evalState).first, *val, *vRes, noPos);
@@ -101,13 +97,13 @@ struct CmdBundle : InstallableCommand
             throw Error("the bundler '%s' does not produce a derivation", bundler.what());
 
         PathSet context2;
-        StorePath drvPath = store->parseStorePath(evalState->coerceToPath(*attr1->pos, *attr1->value, context2));
+        auto drvPath = evalState->coerceToStorePath(*attr1->pos, *attr1->value, context2);
 
         auto attr2 = vRes->attrs->get(evalState->sOutPath);
         if (!attr2)
             throw Error("the bundler '%s' does not produce a derivation", bundler.what());
 
-        StorePath outPath = store->parseStorePath(evalState->coerceToPath(*attr2->pos, *attr2->value, context2));
+        auto outPath = evalState->coerceToStorePath(*attr2->pos, *attr2->value, context2);
 
         store->buildPaths({ DerivedPath::Built { drvPath } });
 
diff --git a/src/nix/bundle.md b/src/nix/bundle.md
index a5186a996..2bb70711f 100644
--- a/src/nix/bundle.md
+++ b/src/nix/bundle.md
@@ -42,24 +42,26 @@ homepage](https://github.com/NixOS/bundlers) for more details.
 If no flake output attribute is given, `nix bundle` tries the following
 flake output attributes:
 
-* `defaultBundler.<system>`
+* `bundlers.<system>.default`
 
 If an attribute *name* is given, `nix run` tries the following flake
 output attributes:
 
-* `bundler.<system>.<name>`
+* `bundlers.<system>.<name>`
 
 # Bundlers
 
 A bundler is specified by a flake output attribute named
-`bundlers.<system>.<name>` or `defaultBundler.<system>`. It looks like this:
+`bundlers.<system>.<name>`. It looks like this:
 
 ```nix
-bundlers.x86_64-linux.identity = drv: drv;
+bundlers.x86_64-linux = rec {
+  identity = drv: drv;
 
-bundlers.x86_64-linux.blender_2_79 = drv: self.packages.x86_64-linux.blender_2_79;
+  blender_2_79 = drv: self.packages.x86_64-linux.blender_2_79;
 
-defaultBundler.x86_64-linux = drv: drv;
+  default = identity;
+};
 ```
 
 A bundler must be a function that accepts an arbitrary value (typically a
diff --git a/src/nix/daemon.cc b/src/nix/daemon.cc
index 6a40a0bd3..940923d3b 100644
--- a/src/nix/daemon.cc
+++ b/src/nix/daemon.cc
@@ -76,7 +76,7 @@ static void setSigChldAction(bool autoReap)
 }
 
 
-bool matchUser(const string & user, const string & group, const Strings & users)
+bool matchUser(const std::string & user, const std::string & group, const Strings & users)
 {
     if (find(users.begin(), users.end(), "*") != users.end())
         return true;
@@ -85,12 +85,12 @@ bool matchUser(const string & user, const string & group, const Strings & users)
         return true;
 
     for (auto & i : users)
-        if (string(i, 0, 1) == "@") {
-            if (group == string(i, 1)) return true;
+        if (i.substr(0, 1) == "@") {
+            if (group == i.substr(1)) return true;
             struct group * gr = getgrnam(i.c_str() + 1);
             if (!gr) continue;
             for (char * * mem = gr->gr_mem; *mem; mem++)
-                if (user == string(*mem)) return true;
+                if (user == std::string(*mem)) return true;
         }
 
     return false;
@@ -198,10 +198,10 @@ static void daemonLoop()
             PeerInfo peer = getPeerInfo(remote.get());
 
             struct passwd * pw = peer.uidKnown ? getpwuid(peer.uid) : 0;
-            string user = pw ? pw->pw_name : std::to_string(peer.uid);
+            std::string user = pw ? pw->pw_name : std::to_string(peer.uid);
 
             struct group * gr = peer.gidKnown ? getgrgid(peer.gid) : 0;
-            string group = gr ? gr->gr_name : std::to_string(peer.gid);
+            std::string group = gr ? gr->gr_name : std::to_string(peer.gid);
 
             Strings trustedUsers = settings.trustedUsers;
             Strings allowedUsers = settings.allowedUsers;
@@ -212,7 +212,7 @@ static void daemonLoop()
             if ((!trusted && !matchUser(user, group, allowedUsers)) || group == settings.buildUsersGroup)
                 throw Error("user '%1%' is not allowed to connect to the Nix daemon", user);
 
-            printInfo(format((string) "accepted connection from pid %1%, user %2%" + (trusted ? " (trusted)" : ""))
+            printInfo(format((std::string) "accepted connection from pid %1%, user %2%" + (trusted ? " (trusted)" : ""))
                 % (peer.pidKnown ? std::to_string(peer.pid) : "<unknown>")
                 % (peer.uidKnown ? user : "<unknown>"));
 
@@ -234,7 +234,7 @@ static void daemonLoop()
 
                 //  For debugging, stuff the pid into argv[1].
                 if (peer.pidKnown && savedArgv[1]) {
-                    string processName = std::to_string(peer.pid);
+                    auto processName = std::to_string(peer.pid);
                     strncpy(savedArgv[1], processName.c_str(), strlen(savedArgv[1]));
                 }
 
diff --git a/src/nix/develop.cc b/src/nix/develop.cc
index 42e13436a..7fc74d34e 100644
--- a/src/nix/develop.cc
+++ b/src/nix/develop.cc
@@ -196,21 +196,22 @@ static StorePath getDerivationEnvironment(ref<Store> store, ref<Store> evalStore
     drv.inputSrcs.insert(std::move(getEnvShPath));
     if (settings.isExperimentalFeatureEnabled(Xp::CaDerivations)) {
         for (auto & output : drv.outputs) {
-            output.second = {
-                .output = DerivationOutputDeferred{},
-            };
+            output.second = DerivationOutput::Deferred {},
             drv.env[output.first] = hashPlaceholder(output.first);
         }
     } else {
         for (auto & output : drv.outputs) {
-            output.second = { .output = DerivationOutputInputAddressed { .path = StorePath::dummy } };
+            output.second = DerivationOutput::Deferred { };
             drv.env[output.first] = "";
         }
-        Hash h = std::get<0>(hashDerivationModulo(*evalStore, drv, true));
+        auto hashesModulo = hashDerivationModulo(*evalStore, drv, true);
 
         for (auto & output : drv.outputs) {
+            Hash h = hashesModulo.hashes.at(output.first);
             auto outPath = store->makeOutputPath(output.first, h, drv.name);
-            output.second = { .output = DerivationOutputInputAddressed { .path = outPath } };
+            output.second = DerivationOutput::InputAddressed {
+                .path = outPath,
+            };
             drv.env[output.first] = store->printStorePath(outPath);
         }
     }
@@ -307,7 +308,7 @@ struct Common : InstallableCommand, MixProfile
         for (auto & [installable_, dir_] : redirects) {
             auto dir = absPath(dir_);
             auto installable = parseInstallable(store, installable_);
-            auto builtPaths = toStorePaths(
+            auto builtPaths = Installable::toStorePaths(
                 getEvalStore(), store, Realise::Nothing, OperateOn::Output, {installable});
             for (auto & path: builtPaths) {
                 auto from = store->printStorePath(path);
@@ -325,8 +326,15 @@ struct Common : InstallableCommand, MixProfile
 
     Strings getDefaultFlakeAttrPaths() override
     {
-        return {"devShell." + settings.thisSystem.get(), "defaultPackage." + settings.thisSystem.get()};
+        Strings paths{
+            "devShells." + settings.thisSystem.get() + ".default",
+            "devShell." + settings.thisSystem.get(),
+        };
+        for (auto & p : SourceExprCommand::getDefaultFlakeAttrPaths())
+            paths.push_back(p);
+        return paths;
     }
+
     Strings getDefaultFlakeAttrPathPrefixes() override
     {
         auto res = SourceExprCommand::getDefaultFlakeAttrPathPrefixes();
@@ -340,7 +348,7 @@ struct Common : InstallableCommand, MixProfile
         if (path && hasSuffix(path->to_string(), "-env"))
             return *path;
         else {
-            auto drvs = toDerivations(store, {installable});
+            auto drvs = Installable::toDerivations(store, {installable});
 
             if (drvs.size() != 1)
                 throw Error("'%s' needs to evaluate to a single derivation, but it evaluated to %d derivations",
@@ -498,12 +506,14 @@ struct CmdDevelop : Common, MixEnvironment
                 this,
                 state,
                 installable->nixpkgsFlakeRef(),
-                Strings{"bashInteractive"},
+                "bashInteractive",
+                Strings{},
                 Strings{"legacyPackages." + settings.thisSystem.get() + "."},
                 nixpkgsLockFlags);
 
             shell = store->printStorePath(
-                toStorePath(getEvalStore(), store, Realise::Outputs, OperateOn::Output, bashInstallable)) + "/bin/bash";
+                Installable::toStorePath(getEvalStore(), store, Realise::Outputs, OperateOn::Output, bashInstallable))
+                + "/bin/bash";
         } catch (Error &) {
             ignoreException();
         }
diff --git a/src/nix/develop.md b/src/nix/develop.md
index 3e7e339d5..8bcff66c9 100644
--- a/src/nix/develop.md
+++ b/src/nix/develop.md
@@ -88,9 +88,9 @@ the flake's `nixConfig` attribute.
 If no flake output attribute is given, `nix develop` tries the following
 flake output attributes:
 
-* `devShell.<system>`
+* `devShells.<system>.default`
 
-* `defaultPackage.<system>`
+* `packages.<system>.default`
 
 If a flake output *name* is given, `nix develop` tries the following flake
 output attributes:
diff --git a/src/nix/diff-closures.cc b/src/nix/diff-closures.cc
index 734c41e0e..0621d662c 100644
--- a/src/nix/diff-closures.cc
+++ b/src/nix/diff-closures.cc
@@ -131,9 +131,9 @@ struct CmdDiffClosures : SourceExprCommand
     void run(ref<Store> store) override
     {
         auto before = parseInstallable(store, _before);
-        auto beforePath = toStorePath(getEvalStore(), store, Realise::Outputs, operateOn, before);
+        auto beforePath = Installable::toStorePath(getEvalStore(), store, Realise::Outputs, operateOn, before);
         auto after = parseInstallable(store, _after);
-        auto afterPath = toStorePath(getEvalStore(), store, Realise::Outputs, operateOn, after);
+        auto afterPath = Installable::toStorePath(getEvalStore(), store, Realise::Outputs, operateOn, after);
         printClosureDiff(store, beforePath, afterPath, "");
     }
 };
diff --git a/src/nix/doctor.cc b/src/nix/doctor.cc
index 4f3003448..ea87e3d87 100644
--- a/src/nix/doctor.cc
+++ b/src/nix/doctor.cc
@@ -24,12 +24,12 @@ std::string formatProtocol(unsigned int proto)
 }
 
 bool checkPass(const std::string & msg) {
-    logger->log(ANSI_GREEN "[PASS] " ANSI_NORMAL + msg);
+    notice(ANSI_GREEN "[PASS] " ANSI_NORMAL + msg);
     return true;
 }
 
 bool checkFail(const std::string & msg) {
-    logger->log(ANSI_RED "[FAIL] " ANSI_NORMAL + msg);
+    notice(ANSI_RED "[FAIL] " ANSI_NORMAL + msg);
     return false;
 }
 
diff --git a/src/nix/edit.md b/src/nix/edit.md
index 80563d06b..89bd09abf 100644
--- a/src/nix/edit.md
+++ b/src/nix/edit.md
@@ -24,8 +24,8 @@ this attribute to the location of the definition of the
 `meta.description`, `version` or `name` derivation attributes.
 
 The editor to invoke is specified by the `EDITOR` environment
-variable. It defaults to `cat`. If the editor is `emacs`, `nano` or
-`vim`, it is passed the line number of the derivation using the
-argument `+<lineno>`.
+variable. It defaults to `cat`. If the editor is `emacs`, `nano`,
+`vim` or `kak`, it is passed the line number of the derivation using
+the argument `+<lineno>`.
 
 )""
diff --git a/src/nix/flake-init.md b/src/nix/flake-init.md
index 890038016..fc1f4f805 100644
--- a/src/nix/flake-init.md
+++ b/src/nix/flake-init.md
@@ -24,19 +24,23 @@ R""(
 
 This command creates a flake in the current directory by copying the
 files of a template. It will not overwrite existing files. The default
-template is `templates#defaultTemplate`, but this can be overridden
+template is `templates#templates.default`, but this can be overridden
 using `-t`.
 
 # Template definitions
 
-A flake can declare templates through its `templates` and
-`defaultTemplate` output attributes. A template has two attributes:
+A flake can declare templates through its `templates` output
+attribute. A template has two attributes:
 
 * `description`: A one-line description of the template, in CommonMark
   syntax.
 
 * `path`: The path of the directory to be copied.
 
+* `welcomeText`: A block of markdown text to display when a user initializes a
+  new flake based on this template.
+
+
 Here is an example:
 
 ```
@@ -45,9 +49,19 @@ outputs = { self }: {
   templates.rust = {
     path = ./rust;
     description = "A simple Rust/Cargo project";
+    welcomeText = ''
+      # Simple Rust/Cargo Template
+      ## Intended usage
+      The intended usage of this flake is...
+
+      ## More info
+      - [Rust language](https://www.rust-lang.org/)
+      - [Rust on the NixOS Wiki](https://nixos.wiki/wiki/Rust)
+      - ...
+    '';
   };
 
-  templates.defaultTemplate = self.templates.rust;
+  templates.default = self.templates.rust;
 }
 ```
 
diff --git a/src/nix/flake-show.md b/src/nix/flake-show.md
index e484cf47e..f3b74285d 100644
--- a/src/nix/flake-show.md
+++ b/src/nix/flake-show.md
@@ -13,10 +13,13 @@ R""(
   │   │   └───build: derivation 'patchelf-0.12.20201207.f34751b'
   │   └───x86_64-linux
   │       └───build: derivation 'patchelf-0.12.20201207.f34751b'
-  ├───defaultPackage
-  │   ├───aarch64-linux: package 'patchelf-0.12.20201207.f34751b'
-  │   ├───i686-linux: package 'patchelf-0.12.20201207.f34751b'
-  │   └───x86_64-linux: package 'patchelf-0.12.20201207.f34751b'
+  ├───packages
+  │   ├───aarch64-linux
+  │   │   └───default: package 'patchelf-0.12.20201207.f34751b'
+  │   ├───i686-linux
+  │   │   └───default: package 'patchelf-0.12.20201207.f34751b'
+  │   └───x86_64-linux
+  │       └───default: package 'patchelf-0.12.20201207.f34751b'
   ├───hydraJobs
   │   ├───build
   │   │   ├───aarch64-linux: derivation 'patchelf-0.12.20201207.f34751b'
diff --git a/src/nix/flake.cc b/src/nix/flake.cc
index 4bc79820c..a876bb3af 100644
--- a/src/nix/flake.cc
+++ b/src/nix/flake.cc
@@ -13,6 +13,7 @@
 #include "registry.hh"
 #include "json.hh"
 #include "eval-cache.hh"
+#include "markdown.hh"
 
 #include <nlohmann/json.hpp>
 #include <queue>
@@ -326,7 +327,7 @@ struct CmdFlakeCheck : FlakeCommand
                 if (!drvInfo)
                     throw Error("flake attribute '%s' is not a derivation", attrPath);
                 // FIXME: check meta attributes
-                return std::make_optional(store->parseStorePath(drvInfo->queryDrvPath()));
+                return drvInfo->queryDrvPath();
             } catch (Error & e) {
                 e.addTrace(pos, hintfmt("while checking the derivation '%s'", attrPath));
                 reportError(e);
@@ -462,7 +463,7 @@ struct CmdFlakeCheck : FlakeCommand
 
                 for (auto & attr : *v.attrs) {
                     std::string name(attr.name);
-                    if (name != "path" && name != "description")
+                    if (name != "path" && name != "description" && name != "welcomeText")
                         throw Error("template '%s' has unsupported attribute '%s'", attrPath, name);
                 }
             } catch (Error & e) {
@@ -500,6 +501,18 @@ struct CmdFlakeCheck : FlakeCommand
 
                         state->forceValue(vOutput, pos);
 
+                        std::string_view replacement =
+                            name == "defaultPackage" ? "packages.<system>.default" :
+                            name == "defaultApps" ? "apps.<system>.default" :
+                            name == "defaultTemplate" ? "templates.default" :
+                            name == "defaultBundler" ? "bundlers.<system>.default" :
+                            name == "overlay" ? "overlays.default" :
+                            name == "devShell" ? "devShells.<system>.default" :
+                            name == "nixosModule" ? "nixosModules.default" :
+                            "";
+                        if (replacement != "")
+                            warn("flake output attribute '%s' is deprecated; use '%s' instead", name, replacement);
+
                         if (name == "checks") {
                             state->forceAttrs(vOutput, pos);
                             for (auto & attr : *vOutput.attrs) {
@@ -649,12 +662,14 @@ struct CmdFlakeCheck : FlakeCommand
     }
 };
 
+static Strings defaultTemplateAttrPathsPrefixes{"templates."};
+static Strings defaultTemplateAttrPaths = {"templates.default", "defaultTemplate"};
+
 struct CmdFlakeInitCommon : virtual Args, EvalCommand
 {
     std::string templateUrl = "templates";
     Path destDir;
 
-    const Strings attrsPathPrefixes{"templates."};
     const LockFlags lockFlags{ .writeLockFile = false };
 
     CmdFlakeInitCommon()
@@ -669,8 +684,8 @@ struct CmdFlakeInitCommon : virtual Args, EvalCommand
                 completeFlakeRefWithFragment(
                     getEvalState(),
                     lockFlags,
-                    attrsPathPrefixes,
-                    {"defaultTemplate"},
+                    defaultTemplateAttrPathsPrefixes,
+                    defaultTemplateAttrPaths,
                     prefix);
             }}
         });
@@ -685,15 +700,21 @@ struct CmdFlakeInitCommon : virtual Args, EvalCommand
         auto [templateFlakeRef, templateName] = parseFlakeRefWithFragment(templateUrl, absPath("."));
 
         auto installable = InstallableFlake(nullptr,
-            evalState, std::move(templateFlakeRef),
-            Strings{templateName == "" ? "defaultTemplate" : templateName},
-            Strings(attrsPathPrefixes), lockFlags);
+            evalState, std::move(templateFlakeRef), templateName,
+            defaultTemplateAttrPaths,
+            defaultTemplateAttrPathsPrefixes,
+            lockFlags);
 
         auto [cursor, attrPath] = installable.getCursor(*evalState);
 
-        auto templateDir = cursor->getAttr("path")->getString();
+        auto templateDirAttr = cursor->getAttr("path");
+        auto templateDir = templateDirAttr->getString();
 
-        assert(store->isInStore(templateDir));
+        if (!store->isInStore(templateDir))
+            throw TypeError(
+                "'%s' was not found in the Nix store\n"
+                "If you've set '%s' to a string, try using a path instead.",
+                templateDir, templateDirAttr->getAttrPathStr());
 
         std::vector<Path> files;
 
@@ -728,6 +749,7 @@ struct CmdFlakeInitCommon : virtual Args, EvalCommand
                 else
                     throw Error("file '%s' has unsupported type", from2);
                 files.push_back(to2);
+                notice("wrote: %s", to2);
             }
         };
 
@@ -738,6 +760,11 @@ struct CmdFlakeInitCommon : virtual Args, EvalCommand
             for (auto & s : files) args.push_back(s);
             runProgram("git", true, args);
         }
+        auto welcomeText = cursor->maybeGetAttr("welcomeText");
+        if (welcomeText) {
+            notice("\n");
+            notice(renderMarkdownToTerminal(welcomeText->getString()));
+        }
     }
 };
 
diff --git a/src/nix/flake.md b/src/nix/flake.md
index accddd436..d59915eeb 100644
--- a/src/nix/flake.md
+++ b/src/nix/flake.md
@@ -209,6 +209,38 @@ Currently the `type` attribute can be one of the following:
   * `github:edolstra/dwarffs/unstable`
   * `github:edolstra/dwarffs/d3f2baba8f425779026c6ec04021b2e927f61e31`
 
+* `sourcehut`: Similar to `github`, is a more efficient way to fetch
+  SourceHut repositories. The following attributes are required:
+
+  * `owner`: The owner of the repository (including leading `~`).
+
+  * `repo`: The name of the repository.
+
+  Like `github`, these are downloaded as tarball archives.
+
+  The URL syntax for `sourcehut` flakes is:
+
+  `sourcehut:<owner>/<repo>(/<rev-or-ref>)?(\?<params>)?`
+
+  `<rev-or-ref>` works the same as `github`. Either a branch or tag name
+  (`ref`), or a commit hash (`rev`) can be specified.
+
+  Since SourceHut allows for self-hosting, you can specify `host` as
+  a parameter, to point to any instances other than `git.sr.ht`.
+
+  Currently, `ref` name resolution only works for Git repositories.
+  You can refer to Mercurial repositories by simply changing `host` to
+  `hg.sr.ht` (or any other Mercurial instance). With the caveat
+  that you must explicitly specify a commit hash (`rev`).
+
+  Some examples:
+
+  * `sourcehut:~misterio/nix-colors`
+  * `sourcehut:~misterio/nix-colors/main`
+  * `sourcehut:~misterio/nix-colors?host=git.example.org`
+  * `sourcehut:~misterio/nix-colors/182b4b8709b8ffe4e9774a4c5d6877bf6bb9a21c`
+  * `sourcehut:~misterio/nix-colors/21c1a380a6915d890d408e9f22203436a35bb2de?host=hg.sr.ht`
+
 * `indirect`: Indirections through the flake registry. These have the
   form
 
@@ -236,7 +268,7 @@ derivation):
 
   outputs = { self, nixpkgs }: {
 
-    defaultPackage.x86_64-linux =
+    packages.x86_64-linux.default =
       # Notice the reference to nixpkgs here.
       with import nixpkgs { system = "x86_64-linux"; };
       stdenv.mkDerivation {
diff --git a/src/nix/hash.cc b/src/nix/hash.cc
index 4535e4ab0..60d9593a7 100644
--- a/src/nix/hash.cc
+++ b/src/nix/hash.cc
@@ -177,7 +177,7 @@ static int compatNixHash(int argc, char * * argv)
         else if (*arg == "--base32") base32 = true;
         else if (*arg == "--truncate") truncate = true;
         else if (*arg == "--type") {
-            string s = getArg(*arg, arg, end);
+            std::string s = getArg(*arg, arg, end);
             ht = parseHashType(s);
         }
         else if (*arg == "--to-base16") op = opTo16;
diff --git a/src/nix/log.cc b/src/nix/log.cc
index fd3c1d787..72d02ef11 100644
--- a/src/nix/log.cc
+++ b/src/nix/log.cc
@@ -2,6 +2,7 @@
 #include "common-args.hh"
 #include "shared.hh"
 #include "store-api.hh"
+#include "log-store.hh"
 #include "progress-bar.hh"
 
 using namespace nix;
@@ -34,17 +35,24 @@ struct CmdLog : InstallableCommand
 
         RunPager pager;
         for (auto & sub : subs) {
+            auto * logSubP = dynamic_cast<LogStore *>(&*sub);
+            if (!logSubP) {
+                printInfo("Skipped '%s' which does not support retrieving build logs", sub->getUri());
+                continue;
+            }
+            auto & logSub = *logSubP;
+
             auto log = std::visit(overloaded {
                 [&](const DerivedPath::Opaque & bo) {
-                    return sub->getBuildLog(bo.path);
+                    return logSub.getBuildLog(bo.path);
                 },
                 [&](const DerivedPath::Built & bfd) {
-                    return sub->getBuildLog(bfd.drvPath);
+                    return logSub.getBuildLog(bfd.drvPath);
                 },
             }, b.raw());
             if (!log) continue;
             stopProgressBar();
-            printInfo("got build log for '%s' from '%s'", installable->what(), sub->getUri());
+            printInfo("got build log for '%s' from '%s'", installable->what(), logSub.getUri());
             std::cout << *log;
             return;
         }
diff --git a/src/nix/main.cc b/src/nix/main.cc
index b923f2535..6198681e7 100644
--- a/src/nix/main.cc
+++ b/src/nix/main.cc
@@ -117,7 +117,7 @@ struct NixArgs : virtual MultiCommand, virtual MixCommonArgs
         {"hash-path", {"hash", "path"}},
         {"ls-nar", {"nar", "ls"}},
         {"ls-store", {"store", "ls"}},
-        {"make-content-addressable", {"store", "make-content-addressable"}},
+        {"make-content-addressable", {"store", "make-content-addressed"}},
         {"optimise-store", {"store", "optimise"}},
         {"ping-store", {"store", "ping"}},
         {"sign-paths", {"store", "sign"}},
@@ -289,6 +289,7 @@ void mainWrapped(int argc, char * * argv)
     }
 
     if (argc == 2 && std::string(argv[1]) == "__dump-builtins") {
+        settings.experimentalFeatures = {Xp::Flakes, Xp::FetchClosure};
         evalSettings.pureEval = false;
         EvalState state({}, openStore("dummy://"));
         auto res = nlohmann::json::object();
diff --git a/src/nix/make-content-addressable.cc b/src/nix/make-content-addressable.cc
deleted file mode 100644
index 2e75a3b61..000000000
--- a/src/nix/make-content-addressable.cc
+++ /dev/null
@@ -1,102 +0,0 @@
-#include "command.hh"
-#include "store-api.hh"
-#include "references.hh"
-#include "common-args.hh"
-#include "json.hh"
-
-using namespace nix;
-
-struct CmdMakeContentAddressable : StorePathsCommand, MixJSON
-{
-    CmdMakeContentAddressable()
-    {
-        realiseMode = Realise::Outputs;
-    }
-
-    std::string description() override
-    {
-        return "rewrite a path or closure to content-addressed form";
-    }
-
-    std::string doc() override
-    {
-        return
-          #include "make-content-addressable.md"
-          ;
-    }
-
-    void run(ref<Store> store, StorePaths && storePaths) override
-    {
-        auto paths = store->topoSortPaths(StorePathSet(storePaths.begin(), storePaths.end()));
-
-        std::reverse(paths.begin(), paths.end());
-
-        std::map<StorePath, StorePath> remappings;
-
-        auto jsonRoot = json ? std::make_unique<JSONObject>(std::cout) : nullptr;
-        auto jsonRewrites = json ? std::make_unique<JSONObject>(jsonRoot->object("rewrites")) : nullptr;
-
-        for (auto & path : paths) {
-            auto pathS = store->printStorePath(path);
-            auto oldInfo = store->queryPathInfo(path);
-            std::string oldHashPart(path.hashPart());
-
-            StringSink sink;
-            store->narFromPath(path, sink);
-
-            StringMap rewrites;
-
-            StorePathSet references;
-            bool hasSelfReference = false;
-            for (auto & ref : oldInfo->references) {
-                if (ref == path)
-                    hasSelfReference = true;
-                else {
-                    auto i = remappings.find(ref);
-                    auto replacement = i != remappings.end() ? i->second : ref;
-                    // FIXME: warn about unremapped paths?
-                    if (replacement != ref)
-                        rewrites.insert_or_assign(store->printStorePath(ref), store->printStorePath(replacement));
-                    references.insert(std::move(replacement));
-                }
-            }
-
-            sink.s = rewriteStrings(sink.s, rewrites);
-
-            HashModuloSink hashModuloSink(htSHA256, oldHashPart);
-            hashModuloSink(sink.s);
-
-            auto narHash = hashModuloSink.finish().first;
-
-            ValidPathInfo info {
-                store->makeFixedOutputPath(FileIngestionMethod::Recursive, narHash, path.name(), references, hasSelfReference),
-                narHash,
-            };
-            info.references = std::move(references);
-            if (hasSelfReference) info.references.insert(info.path);
-            info.narSize = sink.s.size();
-            info.ca = FixedOutputHash {
-                .method = FileIngestionMethod::Recursive,
-                .hash = info.narHash,
-            };
-
-            if (!json)
-                notice("rewrote '%s' to '%s'", pathS, store->printStorePath(info.path));
-
-            auto source = sinkToSource([&](Sink & nextSink) {
-                RewritingSink rsink2(oldHashPart, std::string(info.path.hashPart()), nextSink);
-                rsink2(sink.s);
-                rsink2.flush();
-            });
-
-            store->addToStore(info, *source);
-
-            if (json)
-                jsonRewrites->attr(store->printStorePath(path), store->printStorePath(info.path));
-
-            remappings.insert_or_assign(std::move(path), std::move(info.path));
-        }
-    }
-};
-
-static auto rCmdMakeContentAddressable = registerCommand2<CmdMakeContentAddressable>({"store", "make-content-addressable"});
diff --git a/src/nix/make-content-addressed.cc b/src/nix/make-content-addressed.cc
new file mode 100644
index 000000000..34860c38f
--- /dev/null
+++ b/src/nix/make-content-addressed.cc
@@ -0,0 +1,55 @@
+#include "command.hh"
+#include "store-api.hh"
+#include "make-content-addressed.hh"
+#include "common-args.hh"
+#include "json.hh"
+
+using namespace nix;
+
+struct CmdMakeContentAddressed : virtual CopyCommand, virtual StorePathsCommand, MixJSON
+{
+    CmdMakeContentAddressed()
+    {
+        realiseMode = Realise::Outputs;
+    }
+
+    std::string description() override
+    {
+        return "rewrite a path or closure to content-addressed form";
+    }
+
+    std::string doc() override
+    {
+        return
+          #include "make-content-addressed.md"
+          ;
+    }
+
+    void run(ref<Store> srcStore, StorePaths && storePaths) override
+    {
+        auto dstStore = dstUri.empty() ? openStore() : openStore(dstUri);
+
+        auto remappings = makeContentAddressed(*srcStore, *dstStore,
+            StorePathSet(storePaths.begin(), storePaths.end()));
+
+        if (json) {
+            JSONObject jsonRoot(std::cout);
+            JSONObject jsonRewrites(jsonRoot.object("rewrites"));
+            for (auto & path : storePaths) {
+                auto i = remappings.find(path);
+                assert(i != remappings.end());
+                jsonRewrites.attr(srcStore->printStorePath(path), srcStore->printStorePath(i->second));
+            }
+        } else {
+            for (auto & path : storePaths) {
+                auto i = remappings.find(path);
+                assert(i != remappings.end());
+                notice("rewrote '%s' to '%s'",
+                    srcStore->printStorePath(path),
+                    srcStore->printStorePath(i->second));
+            }
+        }
+    }
+};
+
+static auto rCmdMakeContentAddressed = registerCommand2<CmdMakeContentAddressed>({"store", "make-content-addressed"});
diff --git a/src/nix/make-content-addressable.md b/src/nix/make-content-addressed.md
index 3dd847edc..215683e6d 100644
--- a/src/nix/make-content-addressable.md
+++ b/src/nix/make-content-addressed.md
@@ -5,7 +5,7 @@ R""(
 * Create a content-addressed representation of the closure of GNU Hello:
 
   ```console
-  # nix store make-content-addressable -r nixpkgs#hello
+  # nix store make-content-addressed nixpkgs#hello
   …
   rewrote '/nix/store/v5sv61sszx301i0x6xysaqzla09nksnd-hello-2.10' to '/nix/store/5skmmcb9svys5lj3kbsrjg7vf2irid63-hello-2.10'
   ```
@@ -29,7 +29,7 @@ R""(
   system closure:
 
   ```console
-  # nix store make-content-addressable -r /run/current-system
+  # nix store make-content-addressed /run/current-system
   ```
 
 # Description
diff --git a/src/nix/nix.md b/src/nix/nix.md
index 1dc59362d..0dacadee6 100644
--- a/src/nix/nix.md
+++ b/src/nix/nix.md
@@ -97,11 +97,9 @@ the Nix store. Here are the recognised types of installables:
     For example, if `/foo/bar/flake.nix` exists, then `/foo/bar/baz/` will resolve to
    `path:/foo/bar`
 
-
-
   If *attrpath* is omitted, Nix tries some default values; for most
-  subcommands, the default is `defaultPackage.`*system*
-  (e.g. `defaultPackage.x86_64-linux`), but some subcommands have
+  subcommands, the default is `packages.`*system*`.default`
+  (e.g. `packages.x86_64-linux.default`), but some subcommands have
   other defaults. If *attrpath* *is* specified, *attrpath* is
   interpreted as relative to one or more prefixes; for most
   subcommands, these are `packages.`*system*,
diff --git a/src/nix/path-info.cc b/src/nix/path-info.cc
index 3743d7504..d690fe594 100644
--- a/src/nix/path-info.cc
+++ b/src/nix/path-info.cc
@@ -97,7 +97,7 @@ struct CmdPathInfo : StorePathsCommand, MixJSON
 
             for (auto & storePath : storePaths) {
                 auto info = store->queryPathInfo(storePath);
-                auto storePathS = store->printStorePath(storePath);
+                auto storePathS = store->printStorePath(info->path);
 
                 std::cout << storePathS;
 
diff --git a/src/nix/prefetch.cc b/src/nix/prefetch.cc
index 094d2a519..f2dd44ba4 100644
--- a/src/nix/prefetch.cc
+++ b/src/nix/prefetch.cc
@@ -16,7 +16,7 @@ using namespace nix;
 
 /* If ‘url’ starts with ‘mirror://’, then resolve it using the list of
    mirrors defined in Nixpkgs. */
-string resolveMirrorUrl(EvalState & state, string url)
+std::string resolveMirrorUrl(EvalState & state, const std::string & url)
 {
     if (url.substr(0, 9) != "mirror://") return url;
 
@@ -38,8 +38,8 @@ string resolveMirrorUrl(EvalState & state, string url)
     if (mirrorList->value->listSize() < 1)
         throw Error("mirror URL '%s' did not expand to anything", url);
 
-    string mirror(state.forceString(*mirrorList->value->listElems()[0]));
-    return mirror + (hasSuffix(mirror, "/") ? "" : "/") + string(s, p + 1);
+    std::string mirror(state.forceString(*mirrorList->value->listElems()[0]));
+    return mirror + (hasSuffix(mirror, "/") ? "" : "/") + s.substr(p + 1);
 }
 
 std::tuple<StorePath, Hash> prefetchFile(
@@ -128,10 +128,10 @@ static int main_nix_prefetch_url(int argc, char * * argv)
 {
     {
         HashType ht = htSHA256;
-        std::vector<string> args;
+        std::vector<std::string> args;
         bool printPath = getEnv("PRINT_PATH") == "1";
         bool fromExpr = false;
-        string attrPath;
+        std::string attrPath;
         bool unpack = false;
         bool executable = false;
         std::optional<std::string> name;
@@ -147,7 +147,7 @@ static int main_nix_prefetch_url(int argc, char * * argv)
             else if (*arg == "--version")
                 printVersion("nix-prefetch-url");
             else if (*arg == "--type") {
-                string s = getArg(*arg, arg, end);
+                auto s = getArg(*arg, arg, end);
                 ht = parseHashType(s);
             }
             else if (*arg == "--print-path")
@@ -186,7 +186,7 @@ static int main_nix_prefetch_url(int argc, char * * argv)
 
         /* If -A is given, get the URL from the specified Nix
            expression. */
-        string url;
+        std::string url;
         if (!fromExpr) {
             if (args.empty())
                 throw UsageError("you must specify a URL");
diff --git a/src/nix/profile-list.md b/src/nix/profile-list.md
index 5c29c0b02..bdab9a208 100644
--- a/src/nix/profile-list.md
+++ b/src/nix/profile-list.md
@@ -8,7 +8,7 @@ R""(
   # nix profile list
   0 flake:nixpkgs#legacyPackages.x86_64-linux.spotify github:NixOS/nixpkgs/c23db78bbd474c4d0c5c3c551877523b4a50db06#legacyPackages.x86_64-linux.spotify /nix/store/akpdsid105phbbvknjsdh7hl4v3fhjkr-spotify-1.1.46.916.g416cacf1
   1 flake:nixpkgs#legacyPackages.x86_64-linux.zoom-us github:NixOS/nixpkgs/c23db78bbd474c4d0c5c3c551877523b4a50db06#legacyPackages.x86_64-linux.zoom-us /nix/store/89pmjmbih5qpi7accgacd17ybpgp4xfm-zoom-us-5.4.53350.1027
-  2 flake:blender-bin#defaultPackage.x86_64-linux github:edolstra/nix-warez/d09d7eea893dcb162e89bc67f6dc1ced14abfc27?dir=blender#defaultPackage.x86_64-linux /nix/store/zfgralhqjnam662kqsgq6isjw8lhrflz-blender-bin-2.91.0
+  2 flake:blender-bin#packages.x86_64-linux.default github:edolstra/nix-warez/d09d7eea893dcb162e89bc67f6dc1ced14abfc27?dir=blender#packages.x86_64-linux.default /nix/store/zfgralhqjnam662kqsgq6isjw8lhrflz-blender-bin-2.91.0
   ```
 
 # Description
diff --git a/src/nix/profile.cc b/src/nix/profile.cc
index 9b7c999af..b151e48d6 100644
--- a/src/nix/profile.cc
+++ b/src/nix/profile.cc
@@ -61,6 +61,26 @@ struct ProfileElement
     {
         return std::tuple(describe(), storePaths) < std::tuple(other.describe(), other.storePaths);
     }
+
+    void updateStorePaths(
+        ref<Store> evalStore,
+        ref<Store> store,
+        const BuiltPaths & builtPaths)
+    {
+        // FIXME: respect meta.outputsToInstall
+        storePaths.clear();
+        for (auto & buildable : builtPaths) {
+            std::visit(overloaded {
+                [&](const BuiltPath::Opaque & bo) {
+                    storePaths.insert(bo.path);
+                },
+                [&](const BuiltPath::Built & bfd) {
+                    for (auto & output : bfd.outputs)
+                        storePaths.insert(output.second);
+                },
+            }, buildable.raw());
+        }
+    }
 };
 
 struct ProfileManifest
@@ -77,18 +97,30 @@ struct ProfileManifest
             auto json = nlohmann::json::parse(readFile(manifestPath));
 
             auto version = json.value("version", 0);
-            if (version != 1)
-                throw Error("profile manifest '%s' has unsupported version %d", manifestPath, version);
+            std::string sUrl;
+            std::string sOriginalUrl;
+            switch(version){
+                case 1:
+                    sUrl = "uri";
+                    sOriginalUrl = "originalUri";
+                    break;
+                case 2:
+                    sUrl = "url";
+                    sOriginalUrl = "originalUrl";
+                    break;
+                default:
+                    throw Error("profile manifest '%s' has unsupported version %d", manifestPath, version);
+            }
 
             for (auto & e : json["elements"]) {
                 ProfileElement element;
                 for (auto & p : e["storePaths"])
                     element.storePaths.insert(state.store->parseStorePath((std::string) p));
                 element.active = e["active"];
-                if (e.value("uri", "") != "") {
+                if (e.value(sUrl,"") != "") {
                     element.source = ProfileElementSource{
-                        parseFlakeRef(e["originalUri"]),
-                        parseFlakeRef(e["uri"]),
+                        parseFlakeRef(e[sOriginalUrl]),
+                        parseFlakeRef(e[sUrl]),
                         e["attrPath"]
                     };
                 }
@@ -105,7 +137,7 @@ struct ProfileManifest
 
             for (auto & drvInfo : drvInfos) {
                 ProfileElement element;
-                element.storePaths = {state.store->parseStorePath(drvInfo.queryOutPath())};
+                element.storePaths = {drvInfo.queryOutPath()};
                 elements.emplace_back(std::move(element));
             }
         }
@@ -122,14 +154,14 @@ struct ProfileManifest
             obj["storePaths"] = paths;
             obj["active"] = element.active;
             if (element.source) {
-                obj["originalUri"] = element.source->originalRef.to_string();
-                obj["uri"] = element.source->resolvedRef.to_string();
+                obj["originalUrl"] = element.source->originalRef.to_string();
+                obj["url"] = element.source->resolvedRef.to_string();
                 obj["attrPath"] = element.source->attrPath;
             }
             array.push_back(obj);
         }
         nlohmann::json json;
-        json["version"] = 1;
+        json["version"] = 2;
         json["elements"] = array;
         return json.dump();
     }
@@ -214,6 +246,16 @@ struct ProfileManifest
     }
 };
 
+static std::map<Installable *, BuiltPaths>
+builtPathsPerInstallable(
+    const std::vector<std::pair<std::shared_ptr<Installable>, BuiltPath>> & builtPaths)
+{
+    std::map<Installable *, BuiltPaths> res;
+    for (auto & [installable, builtPath] : builtPaths)
+        res[installable.get()].push_back(builtPath);
+    return res;
+}
+
 struct CmdProfileInstall : InstallablesCommand, MixDefaultProfile
 {
     std::string description() override
@@ -232,54 +274,28 @@ struct CmdProfileInstall : InstallablesCommand, MixDefaultProfile
     {
         ProfileManifest manifest(*getEvalState(), *profile);
 
-        std::vector<DerivedPath> pathsToBuild;
+        auto builtPaths = builtPathsPerInstallable(
+            Installable::build2(
+                getEvalStore(), store, Realise::Outputs, installables, bmNormal));
 
         for (auto & installable : installables) {
+            ProfileElement element;
+
             if (auto installable2 = std::dynamic_pointer_cast<InstallableFlake>(installable)) {
+                // FIXME: make build() return this?
                 auto [attrPath, resolvedRef, drv] = installable2->toDerivation();
-
-                ProfileElement element;
-                if (!drv.outPath)
-                    throw UnimplementedError("CA derivations are not yet supported by 'nix profile'");
-                element.storePaths = {*drv.outPath}; // FIXME
                 element.source = ProfileElementSource{
                     installable2->flakeRef,
                     resolvedRef,
                     attrPath,
                 };
+            }
 
-                pathsToBuild.push_back(DerivedPath::Built{drv.drvPath, StringSet{drv.outputName}});
+            element.updateStorePaths(getEvalStore(), store, builtPaths[installable.get()]);
 
-                manifest.elements.emplace_back(std::move(element));
-            } else {
-                auto buildables = build(getEvalStore(), store, Realise::Outputs, {installable}, bmNormal);
-
-                for (auto & buildable : buildables) {
-                    ProfileElement element;
-
-                    std::visit(overloaded {
-                        [&](const BuiltPath::Opaque & bo) {
-                            pathsToBuild.push_back(bo);
-                            element.storePaths.insert(bo.path);
-                        },
-                        [&](const BuiltPath::Built & bfd) {
-                            // TODO: Why are we querying if we know the output
-                            // names already? Is it just to figure out what the
-                            // default one is?
-                            for (auto & output : store->queryDerivationOutputMap(bfd.drvPath)) {
-                                pathsToBuild.push_back(DerivedPath::Built{bfd.drvPath, {output.first}});
-                                element.storePaths.insert(output.second);
-                            }
-                        },
-                    }, buildable.raw());
-
-                    manifest.elements.emplace_back(std::move(element));
-                }
-            }
+            manifest.elements.push_back(std::move(element));
         }
 
-        store->buildPaths(pathsToBuild);
-
         updateProfile(manifest.build(store));
     }
 };
@@ -295,7 +311,11 @@ public:
         expectArgs("elements", &_matchers);
     }
 
-    typedef std::variant<size_t, Path, std::regex> Matcher;
+    struct RegexPattern {
+        std::string pattern;
+        std::regex  reg;
+    };
+    typedef std::variant<size_t, Path, RegexPattern> Matcher;
 
     std::vector<Matcher> getMatchers(ref<Store> store)
     {
@@ -307,7 +327,7 @@ public:
             else if (store->isStorePath(s))
                 res.push_back(s);
             else
-                res.push_back(std::regex(s, std::regex::extended | std::regex::icase));
+                res.push_back(RegexPattern{s,std::regex(s, std::regex::extended | std::regex::icase)});
         }
 
         return res;
@@ -320,9 +340,9 @@ public:
                 if (*n == pos) return true;
             } else if (auto path = std::get_if<Path>(&matcher)) {
                 if (element.storePaths.count(store.parseStorePath(*path))) return true;
-            } else if (auto regex = std::get_if<std::regex>(&matcher)) {
+            } else if (auto regex = std::get_if<RegexPattern>(&matcher)) {
                 if (element.source
-                    && std::regex_match(element.source->attrPath, *regex))
+                    && std::regex_match(element.source->attrPath, regex->reg))
                     return true;
             }
         }
@@ -355,16 +375,30 @@ struct CmdProfileRemove : virtual EvalCommand, MixDefaultProfile, MixProfileElem
 
         for (size_t i = 0; i < oldManifest.elements.size(); ++i) {
             auto & element(oldManifest.elements[i]);
-            if (!matches(*store, element, i, matchers))
+            if (!matches(*store, element, i, matchers)) {
                 newManifest.elements.push_back(std::move(element));
+            } else {
+                notice("removing '%s'", element.describe());
+            }
         }
 
-        // FIXME: warn about unused matchers?
-
+        auto removedCount = oldManifest.elements.size() - newManifest.elements.size();
         printInfo("removed %d packages, kept %d packages",
-            oldManifest.elements.size() - newManifest.elements.size(),
+            removedCount,
             newManifest.elements.size());
 
+        if (removedCount == 0) {
+            for (auto matcher: matchers) {
+                if (const size_t * index = std::get_if<size_t>(&matcher)){
+                    warn("'%d' is not a valid index", *index);
+                } else if (const Path * path = std::get_if<Path>(&matcher)){
+                    warn("'%s' does not match any paths", *path);
+                } else if (const RegexPattern * regex = std::get_if<RegexPattern>(&matcher)){
+                    warn("'%s' does not match any packages", regex->pattern);
+                }
+            }
+            warn ("Use 'nix profile list' to see the current profile.");
+        }
         updateProfile(newManifest.build(store));
     }
 };
@@ -389,47 +423,71 @@ struct CmdProfileUpgrade : virtual SourceExprCommand, MixDefaultProfile, MixProf
 
         auto matchers = getMatchers(store);
 
-        // FIXME: code duplication
-        std::vector<DerivedPath> pathsToBuild;
+        std::vector<std::shared_ptr<Installable>> installables;
+        std::vector<size_t> indices;
+
+        auto upgradedCount = 0;
 
         for (size_t i = 0; i < manifest.elements.size(); ++i) {
             auto & element(manifest.elements[i]);
             if (element.source
-                && !element.source->originalRef.input.isImmutable()
+                && !element.source->originalRef.input.isLocked()
                 && matches(*store, element, i, matchers))
             {
+                upgradedCount++;
+
                 Activity act(*logger, lvlChatty, actUnknown,
                     fmt("checking '%s' for updates", element.source->attrPath));
 
-                InstallableFlake installable(
+                auto installable = std::make_shared<InstallableFlake>(
                     this,
                     getEvalState(),
                     FlakeRef(element.source->originalRef),
-                    {element.source->attrPath},
-                    {},
+                    "",
+                    Strings{element.source->attrPath},
+                    Strings{},
                     lockFlags);
 
-                auto [attrPath, resolvedRef, drv] = installable.toDerivation();
+                auto [attrPath, resolvedRef, drv] = installable->toDerivation();
 
                 if (element.source->resolvedRef == resolvedRef) continue;
 
                 printInfo("upgrading '%s' from flake '%s' to '%s'",
                     element.source->attrPath, element.source->resolvedRef, resolvedRef);
 
-                if (!drv.outPath)
-                    throw UnimplementedError("CA derivations are not yet supported by 'nix profile'");
-                element.storePaths = {*drv.outPath}; // FIXME
                 element.source = ProfileElementSource{
-                    installable.flakeRef,
+                    installable->flakeRef,
                     resolvedRef,
                     attrPath,
                 };
 
-                pathsToBuild.push_back(DerivedPath::Built{drv.drvPath, {drv.outputName}});
+                installables.push_back(installable);
+                indices.push_back(i);
             }
         }
 
-        store->buildPaths(pathsToBuild);
+        if (upgradedCount == 0) {
+            for (auto & matcher : matchers) {
+                if (const size_t * index = std::get_if<size_t>(&matcher)){
+                    warn("'%d' is not a valid index", *index);
+                } else if (const Path * path = std::get_if<Path>(&matcher)){
+                    warn("'%s' does not match any paths", *path);
+                } else if (const RegexPattern * regex = std::get_if<RegexPattern>(&matcher)){
+                    warn("'%s' does not match any packages", regex->pattern);
+                }
+            }
+            warn ("Use 'nix profile list' to see the current profile.");
+        }
+
+        auto builtPaths = builtPathsPerInstallable(
+            Installable::build2(
+                getEvalStore(), store, Realise::Outputs, installables, bmNormal));
+
+        for (size_t i = 0; i < installables.size(); ++i) {
+            auto & installable = installables.at(i);
+            auto & element = manifest.elements[indices.at(i)];
+            element.updateStorePaths(getEvalStore(), store, builtPaths[installable.get()]);
+        }
 
         updateProfile(manifest.build(store));
     }
diff --git a/src/nix/profile.md b/src/nix/profile.md
index d3ddcd3d1..8dade051d 100644
--- a/src/nix/profile.md
+++ b/src/nix/profile.md
@@ -70,7 +70,7 @@ are installed in this version of the profile. It looks like this:
     {
       "active": true,
       "attrPath": "legacyPackages.x86_64-linux.zoom-us",
-      "originalUri": "flake:nixpkgs",
+      "originalUrl": "flake:nixpkgs",
       "storePaths": [
         "/nix/store/wbhg2ga8f3h87s9h5k0slxk0m81m4cxl-zoom-us-5.3.469451.0927"
       ],
@@ -84,11 +84,11 @@ are installed in this version of the profile. It looks like this:
 Each object in the array `elements` denotes an installed package and
 has the following fields:
 
-* `originalUri`: The [flake reference](./nix3-flake.md) specified by
+* `originalUrl`: The [flake reference](./nix3-flake.md) specified by
   the user at the time of installation (e.g. `nixpkgs`). This is also
   the flake reference that will be used by `nix profile upgrade`.
 
-* `uri`: The immutable flake reference to which `originalUri`
+* `uri`: The immutable flake reference to which `originalUrl`
   resolved.
 
 * `attrPath`: The flake output attribute that provided this
@@ -96,7 +96,7 @@ has the following fields:
   user specified, but the one resulting from applying the default
   attribute paths and prefixes; for instance, `hello` might resolve to
   `packages.x86_64-linux.hello` and the empty string to
-  `defaultPackage.x86_64-linux`.
+  `packages.x86_64-linux.default`.
 
 * `storePath`: The paths in the Nix store containing the package.
 
diff --git a/src/nix/run.cc b/src/nix/run.cc
index bae64ed39..25a8fa8d3 100644
--- a/src/nix/run.cc
+++ b/src/nix/run.cc
@@ -38,9 +38,12 @@ void runProgramInStore(ref<Store> store,
        unshare(CLONE_NEWUSER) doesn't work in a multithreaded program
        (which "nix" is), so we exec() a single-threaded helper program
        (chrootHelper() below) to do the work. */
-    auto store2 = store.dynamic_pointer_cast<LocalStore>();
+    auto store2 = store.dynamic_pointer_cast<LocalFSStore>();
 
-    if (store2 && store->storeDir != store2->getRealStoreDir()) {
+    if (!store2)
+        throw Error("store '%s' is not a local store so it does not support command execution", store->getUri());
+
+    if (store->storeDir != store2->getRealStoreDir()) {
         Strings helperArgs = { chrootHelperName, store->storeDir, store2->getRealStoreDir(), program };
         for (auto & arg : args) helperArgs.push_back(arg);
 
@@ -91,7 +94,7 @@ struct CmdShell : InstallablesCommand, MixEnvironment
 
     void run(ref<Store> store) override
     {
-        auto outPaths = toStorePaths(getEvalStore(), store, Realise::Outputs, OperateOn::Output, installables);
+        auto outPaths = Installable::toStorePaths(getEvalStore(), store, Realise::Outputs, OperateOn::Output, installables);
 
         auto accessor = store->getFSAccessor();
 
@@ -158,7 +161,10 @@ struct CmdRun : InstallableCommand
 
     Strings getDefaultFlakeAttrPaths() override
     {
-        Strings res{"defaultApp." + settings.thisSystem.get()};
+        Strings res{
+            "apps." + settings.thisSystem.get() + ".default",
+            "defaultApp." + settings.thisSystem.get(),
+        };
         for (auto & s : SourceExprCommand::getDefaultFlakeAttrPaths())
             res.push_back(s);
         return res;
@@ -176,6 +182,7 @@ struct CmdRun : InstallableCommand
     {
         auto state = getEvalState();
 
+        lockFlags.applyNixConfig = true;
         auto app = installable->toApp(*state).resolve(getEvalStore(), store);
 
         Strings allArgs{app.program};
diff --git a/src/nix/run.md b/src/nix/run.md
index cd3b978c0..a0f362076 100644
--- a/src/nix/run.md
+++ b/src/nix/run.md
@@ -58,9 +58,9 @@ For instance, if `name` is set to `hello-1.10`, `nix run` will run
 If no flake output attribute is given, `nix run` tries the following
 flake output attributes:
 
-* `defaultApp.<system>`
+* `apps.<system>.default`
 
-* `defaultPackage.<system>`
+* `packages.<system>.default`
 
 If an attribute *name* is given, `nix run` tries the following flake
 output attributes:
@@ -74,7 +74,7 @@ output attributes:
 # Apps
 
 An app is specified by a flake output attribute named
-`apps.<system>.<name>` or `defaultApp.<system>`. It looks like this:
+`apps.<system>.<name>`. It looks like this:
 
 ```nix
 apps.x86_64-linux.blender_2_79 = {
diff --git a/src/nix/show-derivation.cc b/src/nix/show-derivation.cc
index c614be68d..fb46b4dbf 100644
--- a/src/nix/show-derivation.cc
+++ b/src/nix/show-derivation.cc
@@ -40,7 +40,7 @@ struct CmdShowDerivation : InstallablesCommand
 
     void run(ref<Store> store) override
     {
-        auto drvPaths = toDerivations(store, installables, true);
+        auto drvPaths = Installable::toDerivations(store, installables, true);
 
         if (recursive) {
             StorePathSet closure;
@@ -65,19 +65,23 @@ struct CmdShowDerivation : InstallablesCommand
                     auto & outputName = _outputName; // work around clang bug
                     auto outputObj { outputsObj.object(outputName) };
                     std::visit(overloaded {
-                        [&](const DerivationOutputInputAddressed & doi) {
+                        [&](const DerivationOutput::InputAddressed & doi) {
                             outputObj.attr("path", store->printStorePath(doi.path));
                         },
-                        [&](const DerivationOutputCAFixed & dof) {
+                        [&](const DerivationOutput::CAFixed & dof) {
                             outputObj.attr("path", store->printStorePath(dof.path(*store, drv.name, outputName)));
                             outputObj.attr("hashAlgo", dof.hash.printMethodAlgo());
                             outputObj.attr("hash", dof.hash.hash.to_string(Base16, false));
                         },
-                        [&](const DerivationOutputCAFloating & dof) {
+                        [&](const DerivationOutput::CAFloating & dof) {
                             outputObj.attr("hashAlgo", makeFileIngestionPrefix(dof.method) + printHashType(dof.hashType));
                         },
-                        [&](const DerivationOutputDeferred &) {},
-                    }, output.output);
+                        [&](const DerivationOutput::Deferred &) {},
+                        [&](const DerivationOutput::Impure & doi) {
+                            outputObj.attr("hashAlgo", makeFileIngestionPrefix(doi.method) + printHashType(doi.hashType));
+                            outputObj.attr("impure", true);
+                        },
+                    }, output.raw());
                 }
             }
 
diff --git a/src/nix/store-copy-log.cc b/src/nix/store-copy-log.cc
index 079cd6b3e..2e288f743 100644
--- a/src/nix/store-copy-log.cc
+++ b/src/nix/store-copy-log.cc
@@ -1,6 +1,8 @@
 #include "command.hh"
 #include "shared.hh"
 #include "store-api.hh"
+#include "store-cast.hh"
+#include "log-store.hh"
 #include "sync.hh"
 #include "thread-pool.hh"
 
@@ -26,7 +28,10 @@ struct CmdCopyLog : virtual CopyCommand, virtual InstallablesCommand
 
     void run(ref<Store> srcStore) override
     {
+        auto & srcLogStore = require<LogStore>(*srcStore);
+
         auto dstStore = getDstStore();
+        auto & dstLogStore = require<LogStore>(*dstStore);
 
         StorePathSet drvPaths;
 
@@ -35,8 +40,8 @@ struct CmdCopyLog : virtual CopyCommand, virtual InstallablesCommand
                 drvPaths.insert(drvPath);
 
         for (auto & drvPath : drvPaths) {
-            if (auto log = srcStore->getBuildLog(drvPath))
-                dstStore->addBuildLog(drvPath, *log);
+            if (auto log = srcLogStore.getBuildLog(drvPath))
+                dstLogStore.addBuildLog(drvPath, *log);
             else
                 throw Error("build log for '%s' is not available", srcStore->printStorePath(drvPath));
         }
diff --git a/src/nix/store-delete.cc b/src/nix/store-delete.cc
index e4a3cb554..ca43f1530 100644
--- a/src/nix/store-delete.cc
+++ b/src/nix/store-delete.cc
@@ -2,6 +2,8 @@
 #include "common-args.hh"
 #include "shared.hh"
 #include "store-api.hh"
+#include "store-cast.hh"
+#include "gc-store.hh"
 
 using namespace nix;
 
@@ -32,12 +34,14 @@ struct CmdStoreDelete : StorePathsCommand
 
     void run(ref<Store> store, std::vector<StorePath> && storePaths) override
     {
+        auto & gcStore = require<GcStore>(*store);
+
         for (auto & path : storePaths)
             options.pathsToDelete.insert(path);
 
         GCResults results;
         PrintFreed freed(true, results);
-        store->collectGarbage(options, results);
+        gcStore.collectGarbage(options, results);
     }
 };
 
diff --git a/src/nix/store-gc.cc b/src/nix/store-gc.cc
index a2d74066e..8b9b5d164 100644
--- a/src/nix/store-gc.cc
+++ b/src/nix/store-gc.cc
@@ -2,6 +2,8 @@
 #include "common-args.hh"
 #include "shared.hh"
 #include "store-api.hh"
+#include "store-cast.hh"
+#include "gc-store.hh"
 
 using namespace nix;
 
@@ -33,10 +35,12 @@ struct CmdStoreGC : StoreCommand, MixDryRun
 
     void run(ref<Store> store) override
     {
+        auto & gcStore = require<GcStore>(*store);
+
         options.action = dryRun ? GCOptions::gcReturnDead : GCOptions::gcDeleteDead;
         GCResults results;
         PrintFreed freed(options.action == GCOptions::gcDeleteDead, results);
-        store->collectGarbage(options, results);
+        gcStore.collectGarbage(options, results);
     }
 };
 
diff --git a/src/nix/why-depends.cc b/src/nix/why-depends.cc
index 657df30d7..1d9ab28ba 100644
--- a/src/nix/why-depends.cc
+++ b/src/nix/why-depends.cc
@@ -82,9 +82,9 @@ struct CmdWhyDepends : SourceExprCommand
     void run(ref<Store> store) override
     {
         auto package = parseInstallable(store, _package);
-        auto packagePath = toStorePath(getEvalStore(), store, Realise::Outputs, operateOn, package);
+        auto packagePath = Installable::toStorePath(getEvalStore(), store, Realise::Outputs, operateOn, package);
         auto dependency = parseInstallable(store, _dependency);
-        auto dependencyPath = toStorePath(getEvalStore(), store, Realise::Derivation, operateOn, dependency);
+        auto dependencyPath = Installable::toStorePath(getEvalStore(), store, Realise::Derivation, operateOn, dependency);
         auto dependencyPathHash = dependencyPath.hashPart();
 
         StorePathSet closure;
@@ -157,11 +157,11 @@ struct CmdWhyDepends : SourceExprCommand
            closure (i.e., that have a non-infinite distance to
            'dependency'). Print every edge on a path between `package`
            and `dependency`. */
-        std::function<void(Node &, const string &, const string &)> printNode;
+        std::function<void(Node &, const std::string &, const std::string &)> printNode;
 
         struct BailOut { };
 
-        printNode = [&](Node & node, const string & firstPad, const string & tailPad) {
+        printNode = [&](Node & node, const std::string & firstPad, const std::string & tailPad) {
             auto pathS = store->printStorePath(node.path);
 
             assert(node.dist != inf);
@@ -171,12 +171,6 @@ struct CmdWhyDepends : SourceExprCommand
                     node.visited ? "\e[38;5;244m" : "",
                     firstPad != "" ? "→ " : "",
                     pathS);
-            } else {
-                logger->cout("%s%s%s%s" ANSI_NORMAL,
-                    firstPad,
-                    node.visited ? "\e[38;5;244m" : "",
-                    firstPad != "" ? treeLast : "",
-                    pathS);
             }
 
             if (node.path == dependencyPath && !all
@@ -184,7 +178,7 @@ struct CmdWhyDepends : SourceExprCommand
                 throw BailOut();
 
             if (node.visited) return;
-            node.visited = true;
+            if (precise) node.visited = true;
 
             /* Sort the references by distance to `dependency` to
                ensure that the shortest path is printed first. */
@@ -267,6 +261,16 @@ struct CmdWhyDepends : SourceExprCommand
                     if (!all) break;
                 }
 
+                if (!precise) {
+                    auto pathS = store->printStorePath(ref.second->path);
+                    logger->cout("%s%s%s%s" ANSI_NORMAL,
+                        firstPad,
+                        ref.second->visited ? "\e[38;5;244m" : "",
+                        last ? treeLast : treeConn,
+                        pathS);
+                    node.visited = true;
+                }
+
                 printNode(*ref.second,
                     tailPad + (last ? treeNull : treeLine),
                     tailPad + (last ? treeNull : treeLine));
@@ -275,6 +279,9 @@ struct CmdWhyDepends : SourceExprCommand
 
         RunPager pager;
         try {
+            if (!precise) {
+                logger->cout("%s", store->printStorePath(graph.at(packagePath).path));
+            }
             printNode(graph.at(packagePath), "", "");
         } catch (BailOut & ) { }
     }