Merge remote-tracking branch 'origin/master' into coerce-string

31 files changed, 339 insertions, 161 deletions

diff --git a/src/nix/app.cc b/src/nix/app.cc
index 821964f86..5658f2a52 100644
--- a/src/nix/app.cc
+++ b/src/nix/app.cc
@@ -37,11 +37,13 @@ struct InstallableDerivedPath : Installable
  * Return the rewrites that are needed to resolve a string whose context is
  * included in `dependencies`.
  */
-StringPairs resolveRewrites(Store & store, const BuiltPaths dependencies)
+StringPairs resolveRewrites(
+    Store & store,
+    const std::vector<BuiltPathWithResult> & dependencies)
 {
     StringPairs res;
     for (auto & dep : dependencies)
-        if (auto drvDep = std::get_if<BuiltPathBuilt>(&dep))
+        if (auto drvDep = std::get_if<BuiltPathBuilt>(&dep.path))
             for (auto & [ outputName, outputPath ] : drvDep->outputs)
                 res.emplace(
                     downstreamPlaceholder(store, drvDep->drvPath, outputName),
@@ -53,7 +55,10 @@ StringPairs resolveRewrites(Store & store, const BuiltPaths dependencies)
 /**
  * Resolve the given string assuming the given context.
  */
-std::string resolveString(Store & store, const std::string & toResolve, const BuiltPaths dependencies)
+std::string resolveString(
+    Store & store,
+    const std::string & toResolve,
+    const std::vector<BuiltPathWithResult> & dependencies)
 {
     auto rewrites = resolveRewrites(store, dependencies);
     return rewriteStrings(toResolve, rewrites);
@@ -66,7 +71,9 @@ UnresolvedApp Installable::toApp(EvalState & state)
 
     auto type = cursor->getAttr("type")->getString();
 
-    std::string expected = !attrPath.empty() && state.symbols[attrPath[0]] == "apps" ? "app" : "derivation";
+    std::string expected = !attrPath.empty() &&
+        (state.symbols[attrPath[0]] == "apps" || state.symbols[attrPath[0]] == "defaultApp")
+        ? "app" : "derivation";
     if (type != expected)
         throw Error("attribute '%s' should have type '%s'", cursor->getAttrPathStr(), expected);
 
diff --git a/src/nix/build.cc b/src/nix/build.cc
index 9c648d28e..94b169167 100644
--- a/src/nix/build.cc
+++ b/src/nix/build.cc
@@ -10,6 +10,37 @@
 
 using namespace nix;
 
+nlohmann::json derivedPathsToJSON(const DerivedPaths & paths, ref<Store> store)
+{
+    auto res = nlohmann::json::array();
+    for (auto & t : paths) {
+        std::visit([&res, store](const auto & t) {
+            res.push_back(t.toJSON(store));
+        }, t.raw());
+    }
+    return res;
+}
+
+nlohmann::json builtPathsWithResultToJSON(const std::vector<BuiltPathWithResult> & buildables, ref<Store> store)
+{
+    auto res = nlohmann::json::array();
+    for (auto & b : buildables) {
+        std::visit([&](const auto & t) {
+            auto j = t.toJSON(store);
+            if (b.result) {
+                j["startTime"] = b.result->startTime;
+                j["stopTime"] = b.result->stopTime;
+                if (b.result->cpuUser)
+                    j["cpuUser"] = ((double) b.result->cpuUser->count()) / 1000000;
+                if (b.result->cpuSystem)
+                    j["cpuSystem"] = ((double) b.result->cpuSystem->count()) / 1000000;
+            }
+            res.push_back(j);
+        }, b.path.raw());
+    }
+    return res;
+}
+
 struct CmdBuild : InstallablesCommand, MixDryRun, MixJSON, MixProfile
 {
     Path outLink = "result";
@@ -78,7 +109,7 @@ struct CmdBuild : InstallablesCommand, MixDryRun, MixJSON, MixProfile
             Realise::Outputs,
             installables, buildMode);
 
-        if (json) logger->cout("%s", derivedPathsWithHintsToJSON(buildables, store).dump());
+        if (json) logger->cout("%s", builtPathsWithResultToJSON(buildables, store).dump());
 
         if (outLink != "")
             if (auto store2 = store.dynamic_pointer_cast<LocalFSStore>())
@@ -98,7 +129,7 @@ struct CmdBuild : InstallablesCommand, MixDryRun, MixJSON, MixProfile
                                 store2->addPermRoot(output.second, absPath(symlink));
                             }
                         },
-                    }, buildable.raw());
+                    }, buildable.path.raw());
                 }
 
         if (printOutputPaths) {
@@ -113,11 +144,14 @@ struct CmdBuild : InstallablesCommand, MixDryRun, MixJSON, MixProfile
                             std::cout << store->printStorePath(output.second) << std::endl;
                         }
                     },
-                }, buildable.raw());
+                }, buildable.path.raw());
             }
         }
 
-        updateProfile(buildables);
+        BuiltPaths buildables2;
+        for (auto & b : buildables)
+            buildables2.push_back(b.path);
+        updateProfile(buildables2);
     }
 };
 
diff --git a/src/nix/daemon.cc b/src/nix/daemon.cc
index 940923d3b..c527fdb0a 100644
--- a/src/nix/daemon.cc
+++ b/src/nix/daemon.cc
@@ -257,7 +257,7 @@ static void daemonLoop()
         } catch (Interrupted & e) {
             return;
         } catch (Error & error) {
-            ErrorInfo ei = error.info();
+            auto ei = error.info();
             // FIXME: add to trace?
             ei.msg = hintfmt("error processing connection: %1%", ei.msg.str());
             logError(ei);
diff --git a/src/nix/daemon.md b/src/nix/daemon.md
index e97016a94..d5cdadf08 100644
--- a/src/nix/daemon.md
+++ b/src/nix/daemon.md
@@ -11,7 +11,7 @@ R""(
 # Description
 
 This command runs the Nix daemon, which is a required component in
-multi-user Nix installations. It performs build actions and other
+multi-user Nix installations. It runs build tasks and other
 operations on the Nix store on behalf of non-root users. Usually you
 don't run the daemon directly; instead it's managed by a service
 management framework such as `systemd`.
diff --git a/src/nix/develop.cc b/src/nix/develop.cc
index 4de109754..1d90d1dac 100644
--- a/src/nix/develop.cc
+++ b/src/nix/develop.cc
@@ -164,6 +164,14 @@ struct BuildEnvironment
     {
         return vars == other.vars && bashFunctions == other.bashFunctions;
     }
+
+    std::string getSystem() const
+    {
+        if (auto v = get(vars, "system"))
+            return getString(*v);
+        else
+            return settings.thisSystem;
+    }
 };
 
 const static std::string getEnvSh =
@@ -192,10 +200,12 @@ static StorePath getDerivationEnvironment(ref<Store> store, ref<Store> evalStore
     drv.env.erase("allowedRequisites");
     drv.env.erase("disallowedReferences");
     drv.env.erase("disallowedRequisites");
+    drv.env.erase("name");
 
     /* Rehash and write the derivation. FIXME: would be nice to use
        'buildDerivation', but that's privileged. */
     drv.name += "-env";
+    drv.env.emplace("name", drv.name);
     drv.inputSrcs.insert(std::move(getEnvShPath));
     if (settings.isExperimentalFeatureEnabled(Xp::CaDerivations)) {
         for (auto & output : drv.outputs) {
@@ -568,7 +578,7 @@ struct CmdDevelop : Common, MixEnvironment
             }
         }
 
-        runProgramInStore(store, shell, args);
+        runProgramInStore(store, shell, args, buildEnvironment.getSystem());
     }
 };
 
diff --git a/src/nix/eval.cc b/src/nix/eval.cc
index 23fef7c68..ccee074e9 100644
--- a/src/nix/eval.cc
+++ b/src/nix/eval.cc
@@ -4,10 +4,11 @@
 #include "store-api.hh"
 #include "eval.hh"
 #include "eval-inline.hh"
-#include "json.hh"
 #include "value-to-json.hh"
 #include "progress-bar.hh"
 
+#include <nlohmann/json.hpp>
+
 using namespace nix;
 
 struct CmdEval : MixJSON, InstallableCommand
@@ -115,9 +116,7 @@ struct CmdEval : MixJSON, InstallableCommand
         }
 
         else if (json) {
-            JSONPlaceholder jsonOut(std::cout);
-            printValueAsJSON(*state, true, *v, pos, jsonOut, context, false);
-            std::cout << std::endl;
+            std::cout << printValueAsJSON(*state, true, *v, pos, context, false).dump() << std::endl;
         }
 
         else {
diff --git a/src/nix/flake-update.md b/src/nix/flake-update.md
index 2ee8a707d..8c6042d94 100644
--- a/src/nix/flake-update.md
+++ b/src/nix/flake-update.md
@@ -16,7 +16,7 @@ R""(
 # Description
 
 This command recreates the lock file of a flake (`flake.lock`), thus
-updating the lock for every mutable input (like `nixpkgs`) to its
+updating the lock for every unlocked input (like `nixpkgs`) to its
 current version. This is equivalent to passing `--recreate-lock-file`
 to any command that operates on a flake. That is,
 
diff --git a/src/nix/flake.cc b/src/nix/flake.cc
index 3d90cfc05..06fd87ef2 100644
--- a/src/nix/flake.cc
+++ b/src/nix/flake.cc
@@ -11,7 +11,6 @@
 #include "attr-path.hh"
 #include "fetchers.hh"
 #include "registry.hh"
-#include "json.hh"
 #include "eval-cache.hh"
 #include "markdown.hh"
 
@@ -21,6 +20,7 @@
 
 using namespace nix;
 using namespace nix::flake;
+using json = nlohmann::json;
 
 class FlakeCommand : virtual Args, public MixFlakeOptions
 {
@@ -215,7 +215,7 @@ struct CmdFlakeMetadata : FlakeCommand, MixJSON
             if (!lockedFlake.lockFile.root->inputs.empty())
                 logger->cout(ANSI_BOLD "Inputs:" ANSI_NORMAL);
 
-            std::unordered_set<std::shared_ptr<Node>> visited;
+            std::set<ref<Node>> visited;
 
             std::function<void(const Node & node, const std::string & prefix)> recurse;
 
@@ -227,7 +227,7 @@ struct CmdFlakeMetadata : FlakeCommand, MixJSON
                     if (auto lockedNode = std::get_if<0>(&input.second)) {
                         logger->cout("%s" ANSI_BOLD "%s" ANSI_NORMAL ": %s",
                             prefix + (last ? treeLast : treeConn), input.first,
-                            *lockedNode ? (*lockedNode)->lockedRef : flake.lockedRef);
+                            (*lockedNode)->lockedRef);
 
                         bool firstVisit = visited.insert(*lockedNode).second;
 
@@ -917,35 +917,44 @@ struct CmdFlakeArchive : FlakeCommand, MixJSON, MixDryRun
     {
         auto flake = lockFlake();
 
-        auto jsonRoot = json ? std::optional<JSONObject>(std::cout) : std::nullopt;
-
         StorePathSet sources;
 
         sources.insert(flake.flake.sourceInfo->storePath);
-        if (jsonRoot)
-            jsonRoot->attr("path", store->printStorePath(flake.flake.sourceInfo->storePath));
 
         // FIXME: use graph output, handle cycles.
-        std::function<void(const Node & node, std::optional<JSONObject> & jsonObj)> traverse;
-        traverse = [&](const Node & node, std::optional<JSONObject> & jsonObj)
+        std::function<nlohmann::json(const Node & node)> traverse;
+        traverse = [&](const Node & node)
         {
-            auto jsonObj2 = jsonObj ? jsonObj->object("inputs") : std::optional<JSONObject>();
+            nlohmann::json jsonObj2 = json ? json::object() : nlohmann::json(nullptr);
             for (auto & [inputName, input] : node.inputs) {
                 if (auto inputNode = std::get_if<0>(&input)) {
-                    auto jsonObj3 = jsonObj2 ? jsonObj2->object(inputName) : std::optional<JSONObject>();
                     auto storePath =
                         dryRun
                         ? (*inputNode)->lockedRef.input.computeStorePath(*store)
                         : (*inputNode)->lockedRef.input.fetch(store).first.storePath;
-                    if (jsonObj3)
-                        jsonObj3->attr("path", store->printStorePath(storePath));
-                    sources.insert(std::move(storePath));
-                    traverse(**inputNode, jsonObj3);
+                    if (json) {
+                        auto& jsonObj3 = jsonObj2[inputName];
+                        jsonObj3["path"] = store->printStorePath(storePath);
+                        sources.insert(std::move(storePath));
+                        jsonObj3["inputs"] = traverse(**inputNode);
+                    } else {
+                        sources.insert(std::move(storePath));
+                        traverse(**inputNode);
+                    }
                 }
             }
+            return jsonObj2;
         };
 
-        traverse(*flake.lockFile.root, jsonRoot);
+        if (json) {
+            nlohmann::json jsonRoot = {
+                {"path", store->printStorePath(flake.flake.sourceInfo->storePath)},
+                {"inputs", traverse(*flake.lockFile.root)},
+            };
+            std::cout << jsonRoot.dump() << std::endl;
+        } else {
+            traverse(*flake.lockFile.root);
+        }
 
         if (!dryRun && !dstUri.empty()) {
             ref<Store> dstStore = dstUri.empty() ? openStore() : openStore(dstUri);
diff --git a/src/nix/flake.md b/src/nix/flake.md
index a1ab43281..810e9ebea 100644
--- a/src/nix/flake.md
+++ b/src/nix/flake.md
@@ -18,51 +18,56 @@ values such as packages or NixOS modules provided by the flake).
 Flake references (*flakerefs*) are a way to specify the location of a
 flake. These have two different forms:
 
-* An attribute set representation, e.g.
 
-  ```nix
-  {
-    type = "github";
-    owner = "NixOS";
-    repo = "nixpkgs";
-  }
-  ```
+## Attribute set representation
 
-  The only required attribute is `type`. The supported types are
-  listed below.
+Example:
 
-* A URL-like syntax, e.g.
+```nix
+{
+  type = "github";
+  owner = "NixOS";
+  repo = "nixpkgs";
+}
+```
 
-  ```
-  github:NixOS/nixpkgs
-  ```
+The only required attribute is `type`. The supported types are
+listed below.
 
-  These are used on the command line as a more convenient alternative
-  to the attribute set representation. For instance, in the command
+## URL-like syntax
 
-  ```console
-  # nix build github:NixOS/nixpkgs#hello
-  ```
+Example:
 
-  `github:NixOS/nixpkgs` is a flake reference (while `hello` is an
-  output attribute). They are also allowed in the `inputs` attribute
-  of a flake, e.g.
+```
+github:NixOS/nixpkgs
+```
 
-  ```nix
-  inputs.nixpkgs.url = github:NixOS/nixpkgs;
-  ```
+These are used on the command line as a more convenient alternative
+to the attribute set representation. For instance, in the command
 
-  is equivalent to
+```console
+# nix build github:NixOS/nixpkgs#hello
+```
 
-  ```nix
-  inputs.nixpkgs = {
-    type = "github";
-    owner = "NixOS";
-    repo = "nixpkgs";
-  };
-  ```
+`github:NixOS/nixpkgs` is a flake reference (while `hello` is an
+output attribute). They are also allowed in the `inputs` attribute
+of a flake, e.g.
+
+```nix
+inputs.nixpkgs.url = github:NixOS/nixpkgs;
+```
+
+is equivalent to
+
+```nix
+inputs.nixpkgs = {
+  type = "github";
+  owner = "NixOS";
+  repo = "nixpkgs";
+};
+```
 
-## Examples
+### Examples
 
 Here are some examples of flake references in their URL-like representation:
 
diff --git a/src/nix/local.mk b/src/nix/local.mk
index e4ec7634d..0f2f016ec 100644
--- a/src/nix/local.mk
+++ b/src/nix/local.mk
@@ -18,7 +18,7 @@ nix_CXXFLAGS += -I src/libutil -I src/libstore -I src/libfetchers -I src/libexpr
 
 nix_LIBS = libexpr libmain libfetchers libstore libutil libcmd
 
-nix_LDFLAGS = -pthread $(SODIUM_LIBS) $(EDITLINE_LIBS) $(BOOST_LDFLAGS) -llowdown
+nix_LDFLAGS = -pthread $(SODIUM_LIBS) $(EDITLINE_LIBS) $(BOOST_LDFLAGS) $(LOWDOWN_LIBS)
 
 $(foreach name, \
   nix-build nix-channel nix-collect-garbage nix-copy-closure nix-daemon nix-env nix-hash nix-instantiate nix-prefetch-url nix-shell nix-store, \
diff --git a/src/nix/ls.cc b/src/nix/ls.cc
index 07554994b..e964b01b3 100644
--- a/src/nix/ls.cc
+++ b/src/nix/ls.cc
@@ -3,7 +3,7 @@
 #include "fs-accessor.hh"
 #include "nar-accessor.hh"
 #include "common-args.hh"
-#include "json.hh"
+#include <nlohmann/json.hpp>
 
 using namespace nix;
 
@@ -91,10 +91,9 @@ struct MixLs : virtual Args, MixJSON
         if (path == "/") path = "";
 
         if (json) {
-            JSONPlaceholder jsonRoot(std::cout);
             if (showDirectory)
                 throw UsageError("'--directory' is useless with '--json'");
-            listNar(jsonRoot, accessor, path, recursive);
+            std::cout << listNar(accessor, path, recursive);
         } else
             listText(accessor);
     }
diff --git a/src/nix/main.cc b/src/nix/main.cc
index 7172b4bd2..d3d2f5b16 100644
--- a/src/nix/main.cc
+++ b/src/nix/main.cc
@@ -53,7 +53,6 @@ static bool haveInternet()
 }
 
 std::string programPath;
-char * * savedArgv;
 
 struct HelpRequested { };
 
@@ -270,7 +269,7 @@ void mainWrapped(int argc, char * * argv)
     programPath = argv[0];
     auto programName = std::string(baseNameOf(programPath));
 
-    if (argc > 0 && std::string_view(argv[0]) == "__build-remote") {
+    if (argc > 1 && std::string_view(argv[1]) == "__build-remote") {
         programName = "build-remote";
         argv++; argc--;
     }
diff --git a/src/nix/make-content-addressed.cc b/src/nix/make-content-addressed.cc
index 34860c38f..d86b90fc7 100644
--- a/src/nix/make-content-addressed.cc
+++ b/src/nix/make-content-addressed.cc
@@ -2,10 +2,13 @@
 #include "store-api.hh"
 #include "make-content-addressed.hh"
 #include "common-args.hh"
-#include "json.hh"
+
+#include <nlohmann/json.hpp>
 
 using namespace nix;
 
+using nlohmann::json;
+
 struct CmdMakeContentAddressed : virtual CopyCommand, virtual StorePathsCommand, MixJSON
 {
     CmdMakeContentAddressed()
@@ -25,6 +28,7 @@ struct CmdMakeContentAddressed : virtual CopyCommand, virtual StorePathsCommand,
           ;
     }
 
+    using StorePathsCommand::run;
     void run(ref<Store> srcStore, StorePaths && storePaths) override
     {
         auto dstStore = dstUri.empty() ? openStore() : openStore(dstUri);
@@ -33,13 +37,15 @@ struct CmdMakeContentAddressed : virtual CopyCommand, virtual StorePathsCommand,
             StorePathSet(storePaths.begin(), storePaths.end()));
 
         if (json) {
-            JSONObject jsonRoot(std::cout);
-            JSONObject jsonRewrites(jsonRoot.object("rewrites"));
+            auto jsonRewrites = json::object();
             for (auto & path : storePaths) {
                 auto i = remappings.find(path);
                 assert(i != remappings.end());
-                jsonRewrites.attr(srcStore->printStorePath(path), srcStore->printStorePath(i->second));
+                jsonRewrites[srcStore->printStorePath(path)] = srcStore->printStorePath(i->second);
             }
+            auto json = json::object();
+            json["rewrites"] = jsonRewrites;
+            std::cout << json.dump();
         } else {
             for (auto & path : storePaths) {
                 auto i = remappings.find(path);
diff --git a/src/nix/nix.md b/src/nix/nix.md
index d48682a94..db60c59ff 100644
--- a/src/nix/nix.md
+++ b/src/nix/nix.md
@@ -115,12 +115,11 @@ the Nix store. Here are the recognised types of installables:
 
 * **Store derivations**: `/nix/store/p7gp6lxdg32h4ka1q398wd9r2zkbbz2v-hello-2.10.drv`
 
-  Store derivations are store paths with extension `.drv` and are a
-  low-level representation of a build-time dependency graph used
-  internally by Nix. By default, if you pass a store derivation to a
-  `nix` subcommand, it will operate on the *output paths* of the
-  derivation. For example, `nix path-info` prints information about
-  the output paths:
+  By default, if you pass a [store derivation] path to a `nix` subcommand, the command will operate on the [output path]s of the derivation.
+
+  [output path]: ../../glossary.md#gloss-output-path
+
+  For example, `nix path-info` prints information about the output paths:
 
   ```console
   # nix path-info --json /nix/store/p7gp6lxdg32h4ka1q398wd9r2zkbbz2v-hello-2.10.drv
@@ -164,6 +163,13 @@ operate are determined as follows:
   …
   ```
 
+  and likewise, using a store path to a "drv" file to specify the derivation:
+
+  ```console
+  # nix build '/nix/store/gzaflydcr6sb3567hap9q6srzx8ggdgg-glibc-2.33-78.drv^dev,static'
+  …
+  ```
+
 * You can also specify that *all* outputs should be used using the
   syntax *installable*`^*`. For example, the following shows the size
   of all outputs of the `glibc` package in the binary cache:
@@ -177,6 +183,12 @@ operate are determined as follows:
   /nix/store/q6580lr01jpcsqs4r5arlh4ki2c1m9rv-glibc-2.33-123-dev             44200560
   ```
 
+  and likewise, using a store path to a "drv" file to specify the derivation:
+
+  ```console
+  # nix path-info -S '/nix/store/gzaflydcr6sb3567hap9q6srzx8ggdgg-glibc-2.33-78.drv^*'
+  …
+  ```
 * If you didn't specify the desired outputs, but the derivation has an
   attribute `meta.outputsToInstall`, Nix will use those outputs. For
   example, since the package `nixpkgs#libxml2` has this attribute:
@@ -189,6 +201,11 @@ operate are determined as follows:
   a command like `nix shell nixpkgs#libxml2` will provide only those
   two outputs by default.
 
+  Note that a [store derivation] (given by its `.drv` file store path) doesn't have
+  any attributes like `meta`, and thus this case doesn't apply to it.
+
+  [store derivation]: ../../glossary.md#gloss-store-derivation
+
 * Otherwise, Nix will use all outputs of the derivation.
 
 # Nix stores
diff --git a/src/nix/path-from-hash-part.cc b/src/nix/path-from-hash-part.cc
new file mode 100644
index 000000000..7f7cda8d3
--- /dev/null
+++ b/src/nix/path-from-hash-part.cc
@@ -0,0 +1,39 @@
+#include "command.hh"
+#include "store-api.hh"
+
+using namespace nix;
+
+struct CmdPathFromHashPart : StoreCommand
+{
+    std::string hashPart;
+
+    CmdPathFromHashPart()
+    {
+        expectArgs({
+            .label = "hash-part",
+            .handler = {&hashPart},
+        });
+    }
+
+    std::string description() override
+    {
+        return "get a store path from its hash part";
+    }
+
+    std::string doc() override
+    {
+        return
+          #include "path-from-hash-part.md"
+          ;
+    }
+
+    void run(ref<Store> store) override
+    {
+        if (auto storePath = store->queryPathFromHashPart(hashPart))
+            logger->cout(store->printStorePath(*storePath));
+        else
+            throw Error("there is no store path corresponding to '%s'", hashPart);
+    }
+};
+
+static auto rCmdPathFromHashPart = registerCommand2<CmdPathFromHashPart>({"store", "path-from-hash-part"});
diff --git a/src/nix/path-from-hash-part.md b/src/nix/path-from-hash-part.md
new file mode 100644
index 000000000..788e13ab6
--- /dev/null
+++ b/src/nix/path-from-hash-part.md
@@ -0,0 +1,20 @@
+R""(
+
+# Examples
+
+* Return the full store path with the given hash part:
+
+  ```console
+  # nix store path-from-hash-part --store https://cache.nixos.org/ 0i2jd68mp5g6h2sa5k9c85rb80sn8hi9
+  /nix/store/0i2jd68mp5g6h2sa5k9c85rb80sn8hi9-hello-2.10
+  ```
+
+# Description
+
+Given the hash part of a store path (that is, the 32 characters
+following `/nix/store/`), return the full store path. This is
+primarily useful in the implementation of binary caches, where a
+request for a `.narinfo` file only supplies the hash part
+(e.g. `https://cache.nixos.org/0i2jd68mp5g6h2sa5k9c85rb80sn8hi9.narinfo`).
+
+)""
diff --git a/src/nix/path-info.cc b/src/nix/path-info.cc
index d690fe594..613c5b191 100644
--- a/src/nix/path-info.cc
+++ b/src/nix/path-info.cc
@@ -1,12 +1,13 @@
 #include "command.hh"
 #include "shared.hh"
 #include "store-api.hh"
-#include "json.hh"
 #include "common-args.hh"
 
 #include <algorithm>
 #include <array>
 
+#include <nlohmann/json.hpp>
+
 using namespace nix;
 
 struct CmdPathInfo : StorePathsCommand, MixJSON
@@ -86,11 +87,10 @@ struct CmdPathInfo : StorePathsCommand, MixJSON
             pathLen = std::max(pathLen, store->printStorePath(storePath).size());
 
         if (json) {
-            JSONPlaceholder jsonRoot(std::cout);
-            store->pathInfoToJSON(jsonRoot,
+            std::cout << store->pathInfoToJSON(
                 // FIXME: preserve order?
                 StorePathSet(storePaths.begin(), storePaths.end()),
-                true, showClosureSize, SRI, AllowInvalid);
+                true, showClosureSize, SRI, AllowInvalid).dump();
         }
 
         else {
diff --git a/src/nix/path-info.md b/src/nix/path-info.md
index 7a1714ba4..b30898ac0 100644
--- a/src/nix/path-info.md
+++ b/src/nix/path-info.md
@@ -68,7 +68,9 @@ R""(
   ]
   ```
 
-* Print the path of the store derivation produced by `nixpkgs#hello`:
+* Print the path of the [store derivation] produced by `nixpkgs#hello`:
+
+  [store derivation]: ../../glossary.md#gloss-store-derivation
 
   ```console
   # nix path-info --derivation nixpkgs#hello
diff --git a/src/nix/profile-list.md b/src/nix/profile-list.md
index bdab9a208..fa786162f 100644
--- a/src/nix/profile-list.md
+++ b/src/nix/profile-list.md
@@ -20,11 +20,11 @@ following fields:
 * An integer that can be used to unambiguously identify the package in
   invocations of `nix profile remove` and `nix profile upgrade`.
 
-* The original ("mutable") flake reference and output attribute path
+* The original ("unlocked") flake reference and output attribute path
   used at installation time.
 
-* The immutable flake reference to which the mutable flake reference
-  was resolved.
+* The locked flake reference to which the unlocked flake reference was
+  resolved.
 
 * The store path(s) of the package.
 
diff --git a/src/nix/profile-upgrade.md b/src/nix/profile-upgrade.md
index e06e74abe..39cca428b 100644
--- a/src/nix/profile-upgrade.md
+++ b/src/nix/profile-upgrade.md
@@ -2,7 +2,7 @@ R""(
 
 # Examples
 
-* Upgrade all packages that were installed using a mutable flake
+* Upgrade all packages that were installed using an unlocked flake
   reference:
 
   ```console
@@ -32,9 +32,9 @@ the package was installed.
 
 > **Warning**
 >
-> This only works if you used a *mutable* flake reference at
+> This only works if you used an *unlocked* flake reference at
 > installation time, e.g. `nixpkgs#hello`. It does not work if you
-> used an *immutable* flake reference
+> used a *locked* flake reference
 > (e.g. `github:NixOS/nixpkgs/13d0c311e3ae923a00f734b43fd1d35b47d8943a#hello`),
 > since in that case the "latest version" is always the same.
 
diff --git a/src/nix/profile.cc b/src/nix/profile.cc
index 3814e7d5a..11910523d 100644
--- a/src/nix/profile.cc
+++ b/src/nix/profile.cc
@@ -253,11 +253,11 @@ struct ProfileManifest
 
 static std::map<Installable *, BuiltPaths>
 builtPathsPerInstallable(
-    const std::vector<std::pair<std::shared_ptr<Installable>, BuiltPath>> & builtPaths)
+    const std::vector<std::pair<std::shared_ptr<Installable>, BuiltPathWithResult>> & builtPaths)
 {
     std::map<Installable *, BuiltPaths> res;
     for (auto & [installable, builtPath] : builtPaths)
-        res[installable.get()].push_back(builtPath);
+        res[installable.get()].push_back(builtPath.path);
     return res;
 }
 
diff --git a/src/nix/profile.md b/src/nix/profile.md
index be3c5ba1a..273e02280 100644
--- a/src/nix/profile.md
+++ b/src/nix/profile.md
@@ -88,8 +88,7 @@ has the following fields:
   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 `originalUrl`
-  resolved.
+* `uri`: The locked flake reference to which `originalUrl` resolved.
 
 * `attrPath`: The flake output attribute that provided this
   package. Note that this is not necessarily the attribute that the
diff --git a/src/nix/registry.cc b/src/nix/registry.cc
index c496f94f8..b5bdfba95 100644
--- a/src/nix/registry.cc
+++ b/src/nix/registry.cc
@@ -183,14 +183,12 @@ struct CmdRegistryPin : RegistryCommand, EvalCommand
 
     void run(nix::ref<nix::Store> store) override
     {
-        if (locked.empty()) {
-            locked = url;
-        }
+        if (locked.empty()) locked = url;
         auto registry = getRegistry();
         auto ref = parseFlakeRef(url);
-        auto locked_ref = parseFlakeRef(locked);
+        auto lockedRef = parseFlakeRef(locked);
         registry->remove(ref.input);
-        auto [tree, resolved] = locked_ref.resolve(store).input.fetch(store);
+        auto [tree, resolved] = lockedRef.resolve(store).input.fetch(store);
         fetchers::Attrs extraAttrs;
         if (ref.subdir != "") extraAttrs["dir"] = ref.subdir;
         registry->add(ref.input, resolved, extraAttrs);
diff --git a/src/nix/repl.md b/src/nix/repl.md
index 23ef0f4e6..c5113be61 100644
--- a/src/nix/repl.md
+++ b/src/nix/repl.md
@@ -36,7 +36,7 @@ R""(
   Loading Installable ''...
   Added 1 variables.
 
-  # nix repl --extra_experimental_features 'flakes repl-flake' nixpkgs
+  # nix repl --extra-experimental-features 'flakes repl-flake' nixpkgs
   Loading Installable 'flake:nixpkgs#'...
   Added 5 variables.
 
diff --git a/src/nix/run.cc b/src/nix/run.cc
index 45d2dfd0d..6fca68047 100644
--- a/src/nix/run.cc
+++ b/src/nix/run.cc
@@ -9,6 +9,7 @@
 #include "fs-accessor.hh"
 #include "progress-bar.hh"
 #include "eval.hh"
+#include "build/personality.hh"
 
 #if __linux__
 #include <sys/mount.h>
@@ -24,7 +25,8 @@ namespace nix {
 
 void runProgramInStore(ref<Store> store,
     const std::string & program,
-    const Strings & args)
+    const Strings & args,
+    std::optional<std::string_view> system)
 {
     stopProgressBar();
 
@@ -44,7 +46,7 @@ void runProgramInStore(ref<Store> store,
         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 };
+        Strings helperArgs = { chrootHelperName, store->storeDir, store2->getRealStoreDir(), std::string(system.value_or("")), program };
         for (auto & arg : args) helperArgs.push_back(arg);
 
         execv(getSelfExe().value_or("nix").c_str(), stringsToCharPtrs(helperArgs).data());
@@ -52,6 +54,9 @@ void runProgramInStore(ref<Store> store,
         throw SysError("could not execute chroot helper");
     }
 
+    if (system)
+        setPersonality(*system);
+
     execvp(program.c_str(), stringsToCharPtrs(args).data());
 
     throw SysError("unable to execute '%s'", program);
@@ -199,6 +204,7 @@ void chrootHelper(int argc, char * * argv)
     int p = 1;
     std::string storeDir = argv[p++];
     std::string realStoreDir = argv[p++];
+    std::string system = argv[p++];
     std::string cmd = argv[p++];
     Strings args;
     while (p < argc)
@@ -262,6 +268,9 @@ void chrootHelper(int argc, char * * argv)
     writeFile("/proc/self/uid_map", fmt("%d %d %d", uid, uid, 1));
     writeFile("/proc/self/gid_map", fmt("%d %d %d", gid, gid, 1));
 
+    if (system != "")
+        setPersonality(system);
+
     execvp(cmd.c_str(), stringsToCharPtrs(args).data());
 
     throw SysError("unable to exec '%s'", cmd);
diff --git a/src/nix/run.hh b/src/nix/run.hh
index 6180a87dd..fed360158 100644
--- a/src/nix/run.hh
+++ b/src/nix/run.hh
@@ -6,6 +6,7 @@ namespace nix {
 
 void runProgramInStore(ref<Store> store,
     const std::string & program,
-    const Strings & args);
+    const Strings & args,
+    std::optional<std::string_view> system = std::nullopt);
 
 }
diff --git a/src/nix/search.cc b/src/nix/search.cc
index bdd45cbed..d2a31607d 100644
--- a/src/nix/search.cc
+++ b/src/nix/search.cc
@@ -5,7 +5,6 @@
 #include "names.hh"
 #include "get-drvs.hh"
 #include "common-args.hh"
-#include "json.hh"
 #include "shared.hh"
 #include "eval-cache.hh"
 #include "attr-path.hh"
@@ -13,8 +12,10 @@
 
 #include <regex>
 #include <fstream>
+#include <nlohmann/json.hpp>
 
 using namespace nix;
+using json = nlohmann::json;
 
 std::string wrap(std::string prefix, std::string s)
 {
@@ -84,7 +85,8 @@ struct CmdSearch : InstallableCommand, MixJSON
 
         auto state = getEvalState();
 
-        auto jsonOut = json ? std::make_unique<JSONObject>(std::cout) : nullptr;
+        std::optional<nlohmann::json> jsonOut;
+        if (json) jsonOut = json::object();
 
         uint64_t results = 0;
 
@@ -151,10 +153,11 @@ struct CmdSearch : InstallableCommand, MixJSON
                     {
                         results++;
                         if (json) {
-                            auto jsonElem = jsonOut->object(attrPath2);
-                            jsonElem.attr("pname", name.name);
-                            jsonElem.attr("version", name.version);
-                            jsonElem.attr("description", description);
+                            (*jsonOut)[attrPath2] = {
+                                {"pname", name.name},
+                                {"version", name.version},
+                                {"description", description},
+                            };
                         } else {
                             auto name2 = hiliteMatches(name.name, nameMatches, ANSI_GREEN, "\e[0;2m");
                             if (results > 1) logger->cout("");
@@ -193,6 +196,10 @@ struct CmdSearch : InstallableCommand, MixJSON
         for (auto & cursor : installable->getCursors(*state))
             visit(*cursor, cursor->getAttrPath(), true);
 
+        if (json) {
+            std::cout << jsonOut->dump() << std::endl;
+        }
+
         if (!json && !results)
             throw Error("no results for the given search term(s)!");
     }
diff --git a/src/nix/show-derivation.cc b/src/nix/show-derivation.cc
index fb46b4dbf..af2e676a4 100644
--- a/src/nix/show-derivation.cc
+++ b/src/nix/show-derivation.cc
@@ -5,10 +5,11 @@
 #include "common-args.hh"
 #include "store-api.hh"
 #include "archive.hh"
-#include "json.hh"
 #include "derivations.hh"
+#include <nlohmann/json.hpp>
 
 using namespace nix;
+using json = nlohmann::json;
 
 struct CmdShowDerivation : InstallablesCommand
 {
@@ -48,77 +49,63 @@ struct CmdShowDerivation : InstallablesCommand
             drvPaths = std::move(closure);
         }
 
-        {
-
-        JSONObject jsonRoot(std::cout, true);
+        json jsonRoot = json::object();
 
         for (auto & drvPath : drvPaths) {
             if (!drvPath.isDerivation()) continue;
 
-            auto drvObj(jsonRoot.object(store->printStorePath(drvPath)));
+            json& drvObj = jsonRoot[store->printStorePath(drvPath)];
 
             auto drv = store->readDerivation(drvPath);
 
             {
-                auto outputsObj(drvObj.object("outputs"));
+                json& outputsObj = drvObj["outputs"];
+                outputsObj = json::object();
                 for (auto & [_outputName, output] : drv.outputs) {
                     auto & outputName = _outputName; // work around clang bug
-                    auto outputObj { outputsObj.object(outputName) };
+                    auto& outputObj = outputsObj[outputName];
+                    outputObj = json::object();
                     std::visit(overloaded {
                         [&](const DerivationOutput::InputAddressed & doi) {
-                            outputObj.attr("path", store->printStorePath(doi.path));
+                            outputObj["path"] = store->printStorePath(doi.path);
                         },
                         [&](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));
+                            outputObj["path"] = store->printStorePath(dof.path(*store, drv.name, outputName));
+                            outputObj["hashAlgo"] = dof.hash.printMethodAlgo();
+                            outputObj["hash"] = dof.hash.hash.to_string(Base16, false);
                         },
                         [&](const DerivationOutput::CAFloating & dof) {
-                            outputObj.attr("hashAlgo", makeFileIngestionPrefix(dof.method) + printHashType(dof.hashType));
+                            outputObj["hashAlgo"] = makeFileIngestionPrefix(dof.method) + printHashType(dof.hashType);
                         },
                         [&](const DerivationOutput::Deferred &) {},
                         [&](const DerivationOutput::Impure & doi) {
-                            outputObj.attr("hashAlgo", makeFileIngestionPrefix(doi.method) + printHashType(doi.hashType));
-                            outputObj.attr("impure", true);
+                            outputObj["hashAlgo"] = makeFileIngestionPrefix(doi.method) + printHashType(doi.hashType);
+                            outputObj["impure"] = true;
                         },
                     }, output.raw());
                 }
             }
 
             {
-                auto inputsList(drvObj.list("inputSrcs"));
+                auto& inputsList = drvObj["inputSrcs"];
+                inputsList = json::array();
                 for (auto & input : drv.inputSrcs)
-                    inputsList.elem(store->printStorePath(input));
-            }
-
-            {
-                auto inputDrvsObj(drvObj.object("inputDrvs"));
-                for (auto & input : drv.inputDrvs) {
-                    auto inputList(inputDrvsObj.list(store->printStorePath(input.first)));
-                    for (auto & outputId : input.second)
-                        inputList.elem(outputId);
-                }
+                    inputsList.emplace_back(store->printStorePath(input));
             }
 
-            drvObj.attr("system", drv.platform);
-            drvObj.attr("builder", drv.builder);
-
             {
-                auto argsList(drvObj.list("args"));
-                for (auto & arg : drv.args)
-                    argsList.elem(arg);
+                auto& inputDrvsObj = drvObj["inputDrvs"];
+                inputDrvsObj = json::object();
+                for (auto & input : drv.inputDrvs)
+                    inputDrvsObj[store->printStorePath(input.first)] = input.second;
             }
 
-            {
-                auto envObj(drvObj.object("env"));
-                for (auto & var : drv.env)
-                    envObj.attr(var.first, var.second);
-            }
+            drvObj["system"] = drv.platform;
+            drvObj["builder"] = drv.builder;
+            drvObj["args"] = drv.args;
+            drvObj["env"] = drv.env;
         }
-
-        }
-
-        std::cout << "\n";
+        std::cout << jsonRoot.dump(2) << std::endl;
     }
 };
 
diff --git a/src/nix/show-derivation.md b/src/nix/show-derivation.md
index aa863899c..2cd93aa62 100644
--- a/src/nix/show-derivation.md
+++ b/src/nix/show-derivation.md
@@ -2,9 +2,11 @@ R""(
 
 # Examples
 
-* Show the store derivation that results from evaluating the Hello
+* Show the [store derivation] that results from evaluating the Hello
   package:
 
+  [store derivation]: ../../glossary.md#gloss-store-derivation
+
   ```console
   # nix show-derivation nixpkgs#hello
   {
@@ -37,7 +39,7 @@ R""(
 # Description
 
 This command prints on standard output a JSON representation of the
-store derivations to which *installables* evaluate. Store derivations
+[store derivation]s to which *installables* evaluate. Store derivations
 are used internally by Nix. They are store paths with extension `.drv`
 that represent the build-time dependency graph to which a Nix
 expression evaluates.
diff --git a/src/nix/store-copy-log.md b/src/nix/store-copy-log.md
index 19ae57079..0937250f2 100644
--- a/src/nix/store-copy-log.md
+++ b/src/nix/store-copy-log.md
@@ -18,7 +18,9 @@ R""(
   (The flag `--substituters ''` avoids querying
   `https://cache.nixos.org` for the log.)
 
-* To copy the log for a specific store derivation via SSH:
+* To copy the log for a specific [store derivation] via SSH:
+
+  [store derivation]: ../../glossary.md#gloss-store-derivation
 
   ```console
   # nix store copy-log --to ssh-ng://machine /nix/store/ilgm50plpmcgjhcp33z6n4qbnpqfhxym-glibc-2.33-59.drv
diff --git a/src/nix/why-depends.cc b/src/nix/why-depends.cc
index 1d9ab28ba..723017497 100644
--- a/src/nix/why-depends.cc
+++ b/src/nix/why-depends.cc
@@ -83,20 +83,47 @@ struct CmdWhyDepends : SourceExprCommand
     {
         auto package = parseInstallable(store, _package);
         auto packagePath = Installable::toStorePath(getEvalStore(), store, Realise::Outputs, operateOn, package);
+
+        /* We don't need to build `dependency`. We try to get the store
+         * path if it's already known, and if not, then it's not a dependency.
+         *
+         * Why? If `package` does depends on `dependency`, then getting the
+         * store path of `package` above necessitated having the store path
+         * of `dependency`. The contrapositive is, if the store path of
+         * `dependency` is not already known at this point (i.e. it's a CA
+         * derivation which hasn't been built), then `package` did not need it
+         * to build.
+         */
         auto dependency = parseInstallable(store, _dependency);
-        auto dependencyPath = Installable::toStorePath(getEvalStore(), store, Realise::Derivation, operateOn, dependency);
-        auto dependencyPathHash = dependencyPath.hashPart();
+        auto derivedDependency = dependency->toDerivedPath();
+        auto optDependencyPath = std::visit(overloaded {
+            [](const DerivedPath::Opaque & nodrv) -> std::optional<StorePath> {
+                return { nodrv.path };
+            },
+            [&](const DerivedPath::Built & hasdrv) -> std::optional<StorePath> {
+                if (hasdrv.outputs.size() != 1) {
+                    throw Error("argument '%s' should evaluate to one store path", dependency->what());
+                }
+                auto outputMap = store->queryPartialDerivationOutputMap(hasdrv.drvPath);
+                auto maybePath = outputMap.find(*hasdrv.outputs.begin());
+                if (maybePath == outputMap.end()) {
+                    throw Error("unexpected end of iterator");
+                }
+                return maybePath->second;
+            },
+        }, derivedDependency.raw());
 
         StorePathSet closure;
         store->computeFSClosure({packagePath}, closure, false, false);
 
-        if (!closure.count(dependencyPath)) {
-            printError("'%s' does not depend on '%s'",
-                store->printStorePath(packagePath),
-                store->printStorePath(dependencyPath));
+        if (!optDependencyPath.has_value() || !closure.count(*optDependencyPath)) {
+            printError("'%s' does not depend on '%s'", package->what(), dependency->what());
             return;
         }
 
+        auto dependencyPath = *optDependencyPath;
+        auto dependencyPathHash = dependencyPath.hashPart();
+
         stopProgressBar(); // FIXME
 
         auto accessor = store->getFSAccessor();