Merge remote-tracking branch 'upstream/master' into no-stringly-typed-derivation-output

29 files changed, 232 insertions, 77 deletions

diff --git a/doc/manual/advanced-topics/diff-hook.xml b/doc/manual/advanced-topics/diff-hook.xml
index fb4bf819f..f01ab71b3 100644
--- a/doc/manual/advanced-topics/diff-hook.xml
+++ b/doc/manual/advanced-topics/diff-hook.xml
@@ -70,7 +70,7 @@ path just built.</para>
 
   <screen>
 $ nix-build ./deterministic.nix -A stable
-these derivations will be built:
+this derivation will be built:
   /nix/store/z98fasz2jqy9gs0xbvdj939p27jwda38-stable.drv
 building '/nix/store/z98fasz2jqy9gs0xbvdj939p27jwda38-stable.drv'...
 /nix/store/yyxlzw3vqaas7wfp04g0b1xg51f2czgq-stable
@@ -85,7 +85,7 @@ checking outputs of '/nix/store/z98fasz2jqy9gs0xbvdj939p27jwda38-stable.drv'...
 
   <screen>
 $ nix-build ./deterministic.nix -A unstable
-these derivations will be built:
+this derivation will be built:
   /nix/store/cgl13lbj1w368r5z8gywipl1ifli7dhk-unstable.drv
 building '/nix/store/cgl13lbj1w368r5z8gywipl1ifli7dhk-unstable.drv'...
 /nix/store/krpqk0l9ib0ibi1d2w52z293zw455cap-unstable
@@ -193,7 +193,7 @@ repeat = 1
     An example output of this configuration:
     <screen>
 $ nix-build ./test.nix -A unstable
-these derivations will be built:
+this derivation will be built:
   /nix/store/ch6llwpr2h8c3jmnf3f2ghkhx59aa97f-unstable.drv
 building '/nix/store/ch6llwpr2h8c3jmnf3f2ghkhx59aa97f-unstable.drv' (round 1/2)...
 building '/nix/store/ch6llwpr2h8c3jmnf3f2ghkhx59aa97f-unstable.drv' (round 2/2)...
diff --git a/doc/manual/advanced-topics/post-build-hook.xml b/doc/manual/advanced-topics/post-build-hook.xml
index acfe9e3cc..6cc286ee1 100644
--- a/doc/manual/advanced-topics/post-build-hook.xml
+++ b/doc/manual/advanced-topics/post-build-hook.xml
@@ -122,7 +122,7 @@ post-build-hook = /etc/nix/upload-to-cache.sh
 
   <screen>
 $ nix-build -E '(import &lt;nixpkgs&gt; {}).writeText "example" (builtins.toString builtins.currentTime)'
-these derivations will be built:
+this derivation will be built:
   /nix/store/s4pnfbkalzy5qz57qs6yybna8wylkig6-example.drv
 building '/nix/store/s4pnfbkalzy5qz57qs6yybna8wylkig6-example.drv'...
 running post-build-hook '/home/grahamc/projects/github.com/NixOS/nix/post-hook.sh'...
diff --git a/doc/manual/command-ref/nix-env.xml b/doc/manual/command-ref/nix-env.xml
index 2b95b6819..55f25d959 100644
--- a/doc/manual/command-ref/nix-env.xml
+++ b/doc/manual/command-ref/nix-env.xml
@@ -516,7 +516,7 @@ source:
 $ nix-env -f '&lt;nixpkgs>' -iA hello --dry-run
 (dry run; not doing anything)
 installing ‘hello-2.10’
-these paths will be fetched (0.04 MiB download, 0.19 MiB unpacked):
+this path will be fetched (0.04 MiB download, 0.19 MiB unpacked):
   /nix/store/wkhdf9jinag5750mqlax6z2zbwhqb76n-hello-2.10
   <replaceable>...</replaceable></screen>
 
diff --git a/doc/manual/installation/env-variables.xml b/doc/manual/installation/env-variables.xml
index e2b8fc867..cc52f5b4a 100644
--- a/doc/manual/installation/env-variables.xml
+++ b/doc/manual/installation/env-variables.xml
@@ -39,7 +39,7 @@ bundle.</para>
   <step><para>Set the environment variable and install Nix</para>
     <screen>
 $ export NIX_SSL_CERT_FILE=/etc/ssl/my-certificate-bundle.crt
-$ sh &lt;(curl https://nixos.org/nix/install)
+$ sh &lt;(curl -L https://nixos.org/nix/install)
 </screen></step>
 
   <step><para>In the shell profile and rc files (for example,
diff --git a/doc/manual/installation/installing-binary.xml b/doc/manual/installation/installing-binary.xml
index 8d548f0ea..d25c46b85 100644
--- a/doc/manual/installation/installing-binary.xml
+++ b/doc/manual/installation/installing-binary.xml
@@ -12,7 +12,7 @@
 </para>
 
 <screen>
-  $ sh &lt;(curl https://nixos.org/nix/install)
+  $ sh &lt;(curl -L https://nixos.org/nix/install)
 </screen>
 
 <para>
@@ -39,7 +39,7 @@
     To explicitly select a single-user installation on your system:
 
     <screen>
-  sh &lt;(curl https://nixos.org/nix/install) --no-daemon
+  sh &lt;(curl -L https://nixos.org/nix/install) --no-daemon
 </screen>
   </para>
 
diff --git a/doc/manual/introduction/quick-start.xml b/doc/manual/introduction/quick-start.xml
index 1ce6c8d50..1992c14ed 100644
--- a/doc/manual/introduction/quick-start.xml
+++ b/doc/manual/introduction/quick-start.xml
@@ -15,7 +15,7 @@ to subsequent chapters.</para>
 <step><para>Install single-user Nix by running the following:
 
 <screen>
-$ bash &lt;(curl https://nixos.org/nix/install)
+$ bash &lt;(curl -L https://nixos.org/nix/install)
 </screen>
 
 This will install Nix in <filename>/nix</filename>. The install script
diff --git a/shell.nix b/shell.nix
index e3b422c7c..17aaa05ed 100644
--- a/shell.nix
+++ b/shell.nix
@@ -7,7 +7,7 @@ with import ./release-common.nix { inherit pkgs; };
 (if useClang then clangStdenv else stdenv).mkDerivation {
   name = "nix";
 
-  buildInputs = buildDeps ++ propagatedDeps ++ perlDeps ++ [ pkgs.rustfmt ];
+  buildInputs = buildDeps ++ propagatedDeps ++ perlDeps;
 
   inherit configureFlags;
 
diff --git a/src/libexpr/attr-path.cc b/src/libexpr/attr-path.cc
index 8980bc09d..2e2a17b14 100644
--- a/src/libexpr/attr-path.cc
+++ b/src/libexpr/attr-path.cc
@@ -6,11 +6,11 @@
 namespace nix {
 
 
-static Strings parseAttrPath(const string & s)
+static Strings parseAttrPath(std::string_view s)
 {
     Strings res;
     string cur;
-    string::const_iterator i = s.begin();
+    auto i = s.begin();
     while (i != s.end()) {
         if (*i == '.') {
             res.push_back(cur);
@@ -32,6 +32,15 @@ static Strings parseAttrPath(const string & s)
 }
 
 
+std::vector<Symbol> parseAttrPath(EvalState & state, std::string_view s)
+{
+    std::vector<Symbol> res;
+    for (auto & a : parseAttrPath(s))
+        res.push_back(state.symbols.create(a));
+    return res;
+}
+
+
 std::pair<Value *, Pos> findAlongAttrPath(EvalState & state, const string & attrPath,
     Bindings & autoArgs, Value & vIn)
 {
diff --git a/src/libexpr/attr-path.hh b/src/libexpr/attr-path.hh
index fce160da7..d9d74ab2d 100644
--- a/src/libexpr/attr-path.hh
+++ b/src/libexpr/attr-path.hh
@@ -16,4 +16,6 @@ std::pair<Value *, Pos> findAlongAttrPath(EvalState & state, const string & attr
 /* Heuristic to find the filename and lineno or a nix value. */
 Pos findDerivationFilename(EvalState & state, Value & v, std::string what);
 
+std::vector<Symbol> parseAttrPath(EvalState & state, std::string_view s);
+
 }
diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index 8e71db2b8..b90a64357 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -161,12 +161,12 @@ const Value *getPrimOp(const Value &v) {
 }
 
 
-string showType(const Value & v)
+string showType(ValueType type)
 {
-    switch (v.type) {
+    switch (type) {
         case tInt: return "an integer";
-        case tBool: return "a boolean";
-        case tString: return v.string.context ? "a string with context" : "a string";
+        case tBool: return "a Boolean";
+        case tString: return "a string";
         case tPath: return "a path";
         case tNull: return "null";
         case tAttrs: return "a set";
@@ -175,14 +175,27 @@ string showType(const Value & v)
         case tApp: return "a function application";
         case tLambda: return "a function";
         case tBlackhole: return "a black hole";
+        case tPrimOp: return "a built-in function";
+        case tPrimOpApp: return "a partially applied built-in function";
+        case tExternal: return "an external value";
+        case tFloat: return "a float";
+    }
+    abort();
+}
+
+
+string showType(const Value & v)
+{
+    switch (v.type) {
+        case tString: return v.string.context ? "a string with context" : "a string";
         case tPrimOp:
             return fmt("the built-in function '%s'", string(v.primOp->name));
         case tPrimOpApp:
             return fmt("the partially applied built-in function '%s'", string(getPrimOp(v)->primOp->name));
         case tExternal: return v.external->showType();
-        case tFloat: return "a float";
+    default:
+        return showType(v.type);
     }
-    abort();
 }
 
 
@@ -323,6 +336,7 @@ EvalState::EvalState(const Strings & _searchPath, ref<Store> store)
     , sOutputHash(symbols.create("outputHash"))
     , sOutputHashAlgo(symbols.create("outputHashAlgo"))
     , sOutputHashMode(symbols.create("outputHashMode"))
+    , sRecurseForDerivations(symbols.create("recurseForDerivations"))
     , repair(NoRepair)
     , store(store)
     , baseEnv(allocEnv(128))
@@ -471,14 +485,21 @@ Value * EvalState::addConstant(const string & name, Value & v)
 Value * EvalState::addPrimOp(const string & name,
     size_t arity, PrimOpFun primOp)
 {
+    auto name2 = string(name, 0, 2) == "__" ? string(name, 2) : name;
+    Symbol sym = symbols.create(name2);
+
+    /* Hack to make constants lazy: turn them into a application of
+       the primop to a dummy value. */
     if (arity == 0) {
+        auto vPrimOp = allocValue();
+        vPrimOp->type = tPrimOp;
+        vPrimOp->primOp = new PrimOp(primOp, 1, sym);
         Value v;
-        primOp(*this, noPos, nullptr, v);
+        mkApp(v, *vPrimOp, *vPrimOp);
         return addConstant(name, v);
     }
+
     Value * v = allocValue();
-    string name2 = string(name, 0, 2) == "__" ? string(name, 2) : name;
-    Symbol sym = symbols.create(name2);
     v->type = tPrimOp;
     v->primOp = new PrimOp(primOp, arity, sym);
     staticBaseEnv.vars[symbols.create(name)] = baseEnvDispl;
diff --git a/src/libexpr/eval.hh b/src/libexpr/eval.hh
index 1485dc7fe..863365259 100644
--- a/src/libexpr/eval.hh
+++ b/src/libexpr/eval.hh
@@ -18,7 +18,7 @@ namespace nix {
 
 class Store;
 class EvalState;
-struct StorePath;
+class StorePath;
 enum RepairFlag : bool;
 
 
@@ -74,7 +74,8 @@ public:
         sSystem, sOverrides, sOutputs, sOutputName, sIgnoreNulls,
         sFile, sLine, sColumn, sFunctor, sToString,
         sRight, sWrong, sStructuredAttrs, sBuilder, sArgs,
-        sOutputHash, sOutputHashAlgo, sOutputHashMode;
+        sOutputHash, sOutputHashAlgo, sOutputHashMode,
+        sRecurseForDerivations;
     Symbol sDerivationNix;
 
     /* If set, force copying files to the Nix store even if they
@@ -324,6 +325,7 @@ private:
 
 
 /* Return a string representing the type of the value `v'. */
+string showType(ValueType type);
 string showType(const Value & v);
 
 /* Decode a context string ‘!<name>!<path>’ into a pair <path,
diff --git a/src/libexpr/get-drvs.cc b/src/libexpr/get-drvs.cc
index ca9c547fa..a4937e722 100644
--- a/src/libexpr/get-drvs.cc
+++ b/src/libexpr/get-drvs.cc
@@ -348,7 +348,7 @@ static void getDerivations(EvalState & state, Value & vIn,
                    should we recurse into it?  => Only if it has a
                    `recurseForDerivations = true' attribute. */
                 if (i->value->type == tAttrs) {
-                    Bindings::iterator j = i->value->attrs->find(state.symbols.create("recurseForDerivations"));
+                    Bindings::iterator j = i->value->attrs->find(state.sRecurseForDerivations);
                     if (j != i->value->attrs->end() && state.forceBool(*j->value, *j->pos))
                         getDerivations(state, *i->value, pathPrefix2, autoArgs, drvs, done, ignoreAssertionFailures);
                 }
diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index bf3c17997..fe5358962 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -50,20 +50,20 @@ void EvalState::realiseContext(const PathSet & context)
     std::vector<StorePathWithOutputs> drvs;
 
     for (auto & i : context) {
-        std::pair<string, string> decoded = decodeContext(i);
-        auto ctx = store->parseStorePath(decoded.first);
+        auto [ctxS, outputName] = decodeContext(i);
+        auto ctx = store->parseStorePath(ctxS);
         if (!store->isValidPath(ctx))
             throw InvalidPathError(store->printStorePath(ctx));
-        if (!decoded.second.empty() && ctx.isDerivation()) {
-            drvs.push_back(StorePathWithOutputs{ctx, {decoded.second}});
+        if (!outputName.empty() && ctx.isDerivation()) {
+            drvs.push_back(StorePathWithOutputs{ctx, {outputName}});
 
             /* Add the output of this derivation to the allowed
                paths. */
             if (allowedPaths) {
-                auto drv = store->derivationFromPath(store->parseStorePath(decoded.first));
-                DerivationOutputs::iterator i = drv.outputs.find(decoded.second);
+                auto drv = store->derivationFromPath(ctx);
+                DerivationOutputs::iterator i = drv.outputs.find(outputName);
                 if (i == drv.outputs.end())
-                    throw Error("derivation '%s' does not have an output named '%s'", decoded.first, decoded.second);
+                    throw Error("derivation '%s' does not have an output named '%s'", ctxS, outputName);
                 allowedPaths->insert(store->printStorePath(i->second.path));
             }
         }
@@ -79,6 +79,7 @@ void EvalState::realiseContext(const PathSet & context)
     StorePathSet willBuild, willSubstitute, unknown;
     unsigned long long downloadSize, narSize;
     store->queryMissing(drvs, willBuild, willSubstitute, unknown, downloadSize, narSize);
+
     store->buildPaths(drvs);
 }
 
@@ -2208,10 +2209,11 @@ static void prim_splitVersion(EvalState & state, const Pos & pos, Value * * args
 RegisterPrimOp::PrimOps * RegisterPrimOp::primOps;
 
 
-RegisterPrimOp::RegisterPrimOp(std::string name, size_t arity, PrimOpFun fun)
+RegisterPrimOp::RegisterPrimOp(std::string name, size_t arity, PrimOpFun fun,
+    std::optional<std::string> requiredFeature)
 {
     if (!primOps) primOps = new PrimOps;
-    primOps->emplace_back(name, arity, fun);
+    primOps->push_back({name, arity, fun, requiredFeature});
 }
 
 
@@ -2403,7 +2405,8 @@ void EvalState::createBaseEnv()
 
     if (RegisterPrimOp::primOps)
         for (auto & primOp : *RegisterPrimOp::primOps)
-            addPrimOp(std::get<0>(primOp), std::get<1>(primOp), std::get<2>(primOp));
+            if (!primOp.requiredFeature || settings.isExperimentalFeatureEnabled(*primOp.requiredFeature))
+                addPrimOp(primOp.name, primOp.arity, primOp.primOp);
 
     /* Now that we've added all primops, sort the `builtins' set,
        because attribute lookups expect it to be sorted. */
diff --git a/src/libexpr/primops.hh b/src/libexpr/primops.hh
index 05d0792ef..75c460ecf 100644
--- a/src/libexpr/primops.hh
+++ b/src/libexpr/primops.hh
@@ -7,12 +7,25 @@ namespace nix {
 
 struct RegisterPrimOp
 {
-    typedef std::vector<std::tuple<std::string, size_t, PrimOpFun>> PrimOps;
+    struct Info
+    {
+        std::string name;
+        size_t arity;
+        PrimOpFun primOp;
+        std::optional<std::string> requiredFeature;
+    };
+
+    typedef std::vector<Info> PrimOps;
     static PrimOps * primOps;
+
     /* You can register a constant by passing an arity of 0. fun
        will get called during EvalState initialization, so there
        may be primops not yet added and builtins is not yet sorted. */
-    RegisterPrimOp(std::string name, size_t arity, PrimOpFun fun);
+    RegisterPrimOp(
+        std::string name,
+        size_t arity,
+        PrimOpFun fun,
+        std::optional<std::string> requiredFeature = {});
 };
 
 /* These primops are disabled without enableNativeCode, but plugins
diff --git a/src/libmain/shared.cc b/src/libmain/shared.cc
index dc6d5e413..1cb422967 100644
--- a/src/libmain/shared.cc
+++ b/src/libmain/shared.cc
@@ -48,7 +48,10 @@ void printMissing(ref<Store> store, const StorePathSet & willBuild,
     unsigned long long downloadSize, unsigned long long narSize, Verbosity lvl)
 {
     if (!willBuild.empty()) {
-        printMsg(lvl, "these derivations will be built:");
+        if (willBuild.size() == 1)
+            printMsg(lvl, fmt("this derivation will be built:"));
+        else
+            printMsg(lvl, fmt("these %d derivations will be built:", willBuild.size()));
         auto sorted = store->topoSortPaths(willBuild);
         reverse(sorted.begin(), sorted.end());
         for (auto & i : sorted)
@@ -56,9 +59,18 @@ void printMissing(ref<Store> store, const StorePathSet & willBuild,
     }
 
     if (!willSubstitute.empty()) {
-        printMsg(lvl, fmt("these paths will be fetched (%.2f MiB download, %.2f MiB unpacked):",
-                downloadSize / (1024.0 * 1024.0),
-                narSize / (1024.0 * 1024.0)));
+        const float downloadSizeMiB = downloadSize / (1024.f * 1024.f);
+        const float narSizeMiB = narSize / (1024.f * 1024.f);
+        if (willSubstitute.size() == 1) {
+            printMsg(lvl, fmt("this path will be fetched (%.2f MiB download, %.2f MiB unpacked):",
+                downloadSizeMiB,
+                narSizeMiB));
+        } else {
+            printMsg(lvl, fmt("these %d paths will be fetched (%.2f MiB download, %.2f MiB unpacked):",
+                willSubstitute.size(),
+                downloadSizeMiB,
+                narSizeMiB));
+        }
         for (auto & i : willSubstitute)
             printMsg(lvl, fmt("  %s", store->printStorePath(i)));
     }
diff --git a/src/libstore/binary-cache-store.cc b/src/libstore/binary-cache-store.cc
index f8eff508c..9f52ddafa 100644
--- a/src/libstore/binary-cache-store.cc
+++ b/src/libstore/binary-cache-store.cc
@@ -388,8 +388,6 @@ void BinaryCacheStore::addSignatures(const StorePath & storePath, const StringSe
 
     narInfo->sigs.insert(sigs.begin(), sigs.end());
 
-    auto narInfoFile = narInfoFileFor(narInfo->path);
-
     writeNarInfo(narInfo);
 }
 
diff --git a/src/libstore/build.cc b/src/libstore/build.cc
index 077217b79..a33a9434a 100644
--- a/src/libstore/build.cc
+++ b/src/libstore/build.cc
@@ -86,7 +86,7 @@ struct HookInstance;
 
 
 /* A pointer to a goal. */
-class Goal;
+struct Goal;
 class DerivationGoal;
 typedef std::shared_ptr<Goal> GoalPtr;
 typedef std::weak_ptr<Goal> WeakGoalPtr;
@@ -1195,6 +1195,12 @@ void DerivationGoal::haveDerivation()
 
     parsedDrv = std::make_unique<ParsedDerivation>(drvPath, *drv);
 
+    if (parsedDrv->contentAddressed()) {
+        settings.requireExperimentalFeature("ca-derivations");
+        throw Error("ca-derivations isn't implemented yet");
+    }
+
+
     /* We are first going to try to create the invalid output paths
        through substitutes.  If that doesn't work, we'll build
        them. */
diff --git a/src/libstore/filetransfer.cc b/src/libstore/filetransfer.cc
index c954ace7f..531b85af8 100644
--- a/src/libstore/filetransfer.cc
+++ b/src/libstore/filetransfer.cc
@@ -72,6 +72,7 @@ struct curlFileTransfer : public FileTransfer
 
         curl_off_t writtenToSink = 0;
 
+        inline static const std::set<long> successfulStatuses {200, 201, 204, 206, 304, 0 /* other protocol */};
         /* Get the HTTP status code, or 0 for other protocols. */
         long getHTTPStatus()
         {
@@ -98,7 +99,7 @@ struct curlFileTransfer : public FileTransfer
 
                     /* Only write data to the sink if this is a
                        successful response. */
-                    if (httpStatus == 0 || httpStatus == 200 || httpStatus == 201 || httpStatus == 206) {
+                    if (successfulStatuses.count(httpStatus)) {
                         writtenToSink += len;
                         this->request.dataCallback((char *) data, len);
                     }
@@ -352,8 +353,7 @@ struct curlFileTransfer : public FileTransfer
             if (writeException)
                 failEx(writeException);
 
-            else if (code == CURLE_OK &&
-                (httpStatus == 200 || httpStatus == 201 || httpStatus == 204 || httpStatus == 206 || httpStatus == 304 || httpStatus == 0 /* other protocol */))
+            else if (code == CURLE_OK && successfulStatuses.count(httpStatus))
             {
                 result.cached = httpStatus == 304;
                 act.progress(result.bodySize, result.bodySize);
diff --git a/src/libstore/parsed-derivations.cc b/src/libstore/parsed-derivations.cc
index 24f848e46..c7797b730 100644
--- a/src/libstore/parsed-derivations.cc
+++ b/src/libstore/parsed-derivations.cc
@@ -117,4 +117,9 @@ bool ParsedDerivation::substitutesAllowed() const
     return getBoolAttr("allowSubstitutes", true);
 }
 
+bool ParsedDerivation::contentAddressed() const
+{
+    return getBoolAttr("__contentAddressed", false);
+}
+
 }
diff --git a/src/libstore/parsed-derivations.hh b/src/libstore/parsed-derivations.hh
index 7621342d7..d24d1eb4f 100644
--- a/src/libstore/parsed-derivations.hh
+++ b/src/libstore/parsed-derivations.hh
@@ -34,6 +34,8 @@ public:
     bool willBuildLocally() const;
 
     bool substitutesAllowed() const;
+
+    bool contentAddressed() const;
 };
 
 }
diff --git a/src/libstore/remote-store.cc b/src/libstore/remote-store.cc
index fc5ab5865..f5f2ab7fd 100644
--- a/src/libstore/remote-store.cc
+++ b/src/libstore/remote-store.cc
@@ -228,7 +228,7 @@ struct ConnectionHandle
 
     ~ConnectionHandle()
     {
-        if (!daemonException && std::uncaught_exception()) {
+        if (!daemonException && std::uncaught_exceptions()) {
             handle.markBad();
             debug("closing daemon connection because of an exception");
         }
diff --git a/src/libstore/store-api.cc b/src/libstore/store-api.cc
index 9a6c9671c..982fc22b6 100644
--- a/src/libstore/store-api.cc
+++ b/src/libstore/store-api.cc
@@ -61,7 +61,7 @@ StorePathWithOutputs Store::followLinksToStorePathWithOutputs(std::string_view p
 
 /* Store paths have the following form:
 
-   <store>/<h>-<name>
+   <realized-path> = <store>/<h>-<name>
 
    where
 
@@ -85,11 +85,14 @@ StorePathWithOutputs Store::followLinksToStorePathWithOutputs(std::string_view p
    <type> = one of:
      "text:<r1>:<r2>:...<rN>"
        for plain text files written to the store using
-       addTextToStore(); <r1> ... <rN> are the references of the
-       path.
-     "source"
+       addTextToStore(); <r1> ... <rN> are the store paths referenced
+       by this path, in the form described by <realized-path>
+     "source:<r1>:<r2>:...:<rN>:self"
        for paths copied to the store using addToStore() when recursive
-       = true and hashAlgo = "sha256"
+       = true and hashAlgo = "sha256". Just like in the text case, we
+       can have the store paths referenced by the path.
+       Additionally, we can have an optional :self label to denote self
+       reference.
      "output:<id>"
        for either the outputs created by derivations, OR paths copied
        to the store using addToStore() with recursive != true or
@@ -117,6 +120,12 @@ StorePathWithOutputs Store::followLinksToStorePathWithOutputs(std::string_view p
              the contents of the path (or expected contents of the
              path for fixed-output derivations)
 
+   Note that since an output derivation has always type output, while
+   something added by addToStore can have type output or source depending
+   on the hash, this means that the same input can be hashed differently
+   if added to the store via addToStore or via a derivation, in the sha256
+   recursive case.
+
    It would have been nicer to handle fixed-output derivations under
    "source", e.g. have something like "source:<rec><algo>", but we're
    stuck with this for now...
diff --git a/src/libutil/ansicolor.hh b/src/libutil/ansicolor.hh
index 8ae07b092..a38c2d798 100644
--- a/src/libutil/ansicolor.hh
+++ b/src/libutil/ansicolor.hh
@@ -11,5 +11,7 @@ namespace nix {
 #define ANSI_GREEN "\e[32;1m"
 #define ANSI_YELLOW "\e[33;1m"
 #define ANSI_BLUE "\e[34;1m"
+#define ANSI_MAGENTA "\e[35m;1m"
+#define ANSI_CYAN "\e[36m;1m"
 
 }
diff --git a/src/libutil/json.cc b/src/libutil/json.cc
index 74e37b4c4..01331947e 100644
--- a/src/libutil/json.cc
+++ b/src/libutil/json.cc
@@ -173,7 +173,7 @@ JSONObject JSONPlaceholder::object()
 
 JSONPlaceholder::~JSONPlaceholder()
 {
-    assert(!first || std::uncaught_exception());
+    assert(!first || std::uncaught_exceptions());
 }
 
 }
diff --git a/src/libutil/tests/compression.cc b/src/libutil/tests/compression.cc
new file mode 100644
index 000000000..5b7a2c5b9
--- /dev/null
+++ b/src/libutil/tests/compression.cc
@@ -0,0 +1,78 @@
+#include "compression.hh"
+#include <gtest/gtest.h>
+
+namespace nix {
+
+    /* ----------------------------------------------------------------------------
+     * compress / decompress
+     * --------------------------------------------------------------------------*/
+
+    TEST(compress, compressWithUnknownMethod) {
+        ASSERT_THROW(compress("invalid-method", "something-to-compress"), UnknownCompressionMethod);
+    }
+
+    TEST(compress, noneMethodDoesNothingToTheInput) {
+        ref<std::string> o = compress("none", "this-is-a-test");
+
+        ASSERT_EQ(*o, "this-is-a-test");
+    }
+
+    TEST(decompress, decompressXzCompressed) {
+        auto method = "xz";
+        auto str = "slfja;sljfklsa;jfklsjfkl;sdjfkl;sadjfkl;sdjf;lsdfjsadlf";
+        ref<std::string> o = decompress(method, *compress(method, str));
+
+        ASSERT_EQ(*o, str);
+    }
+
+    TEST(decompress, decompressBzip2Compressed) {
+        auto method = "bzip2";
+        auto str = "slfja;sljfklsa;jfklsjfkl;sdjfkl;sadjfkl;sdjf;lsdfjsadlf";
+        ref<std::string> o = decompress(method, *compress(method, str));
+
+        ASSERT_EQ(*o, str);
+    }
+
+    TEST(decompress, decompressBrCompressed) {
+        auto method = "br";
+        auto str = "slfja;sljfklsa;jfklsjfkl;sdjfkl;sadjfkl;sdjf;lsdfjsadlf";
+        ref<std::string> o = decompress(method, *compress(method, str));
+
+        ASSERT_EQ(*o, str);
+    }
+
+    TEST(decompress, decompressInvalidInputThrowsCompressionError) {
+        auto method = "bzip2";
+        auto str = "this is a string that does not qualify as valid bzip2 data";
+
+        ASSERT_THROW(decompress(method, str), CompressionError);
+    }
+
+    /* ----------------------------------------------------------------------------
+     * compression sinks
+     * --------------------------------------------------------------------------*/
+
+    TEST(makeCompressionSink, noneSinkDoesNothingToInput) {
+        StringSink strSink;
+        auto inputString = "slfja;sljfklsa;jfklsjfkl;sdjfkl;sadjfkl;sdjf;lsdfjsadlf";
+        auto sink = makeCompressionSink("none", strSink);
+        (*sink)(inputString);
+        sink->finish();
+
+        ASSERT_STREQ((*strSink.s).c_str(), inputString);
+    }
+
+    TEST(makeCompressionSink, compressAndDecompress) {
+        StringSink strSink;
+        auto inputString = "slfja;sljfklsa;jfklsjfkl;sdjfkl;sadjfkl;sdjf;lsdfjsadlf";
+        auto decompressionSink = makeDecompressionSink("bzip2", strSink);
+        auto sink = makeCompressionSink("bzip2", *decompressionSink);
+
+        (*sink)(inputString);
+        sink->finish();
+        decompressionSink->finish();
+
+        ASSERT_STREQ((*strSink.s).c_str(), inputString);
+    }
+
+}
diff --git a/src/libutil/util.cc b/src/libutil/util.cc
index 667dd2edb..1268b146a 100644
--- a/src/libutil/util.cc
+++ b/src/libutil/util.cc
@@ -35,7 +35,7 @@
 #endif
 
 
-extern char * * environ;
+extern char * * environ __attribute__((weak));
 
 
 namespace nix {
@@ -1199,7 +1199,7 @@ void _interrupted()
     /* Block user interrupts while an exception is being handled.
        Throwing an exception while another exception is being handled
        kills the program! */
-    if (!interruptThrown && !std::uncaught_exception()) {
+    if (!interruptThrown && !std::uncaught_exceptions()) {
         interruptThrown = true;
         throw Interrupted("interrupted by the user");
     }
diff --git a/src/nix-build/nix-build.cc b/src/nix-build/nix-build.cc
index a224d635d..f77de56ea 100755
--- a/src/nix-build/nix-build.cc
+++ b/src/nix-build/nix-build.cc
@@ -21,7 +21,7 @@
 using namespace nix;
 using namespace std::string_literals;
 
-extern char * * environ;
+extern char * * environ __attribute__((weak));
 
 /* Recreate the effect of the perl shellwords function, breaking up a
  * string into arguments like a shell word, including escapes
diff --git a/src/nix/command.cc b/src/nix/command.cc
index d62626c26..3651a9e9c 100644
--- a/src/nix/command.cc
+++ b/src/nix/command.cc
@@ -4,7 +4,7 @@
 #include "nixexpr.hh"
 #include "profiles.hh"
 
-extern char * * environ;
+extern char * * environ __attribute__((weak));
 
 namespace nix {
 
diff --git a/src/nix/repl.cc b/src/nix/repl.cc
index 4bcaaeebf..617d49614 100644
--- a/src/nix/repl.cc
+++ b/src/nix/repl.cc
@@ -19,6 +19,7 @@ extern "C" {
 }
 #endif
 
+#include "ansicolor.hh"
 #include "shared.hh"
 #include "eval.hh"
 #include "eval-inline.hh"
@@ -37,14 +38,6 @@ extern "C" {
 
 namespace nix {
 
-#define ESC_RED "\033[31m"
-#define ESC_GRE "\033[32m"
-#define ESC_YEL "\033[33m"
-#define ESC_BLU "\033[34;1m"
-#define ESC_MAG "\033[35m"
-#define ESC_CYA "\033[36m"
-#define ESC_END "\033[0m"
-
 struct NixRepl : gc
 {
     string curDir;
@@ -645,25 +638,25 @@ std::ostream & NixRepl::printValue(std::ostream & str, Value & v, unsigned int m
     switch (v.type) {
 
     case tInt:
-        str << ESC_CYA << v.integer << ESC_END;
+        str << ANSI_CYAN << v.integer << ANSI_NORMAL;
         break;
 
     case tBool:
-        str << ESC_CYA << (v.boolean ? "true" : "false") << ESC_END;
+        str << ANSI_CYAN << (v.boolean ? "true" : "false") << ANSI_NORMAL;
         break;
 
     case tString:
-        str << ESC_YEL;
+        str << ANSI_YELLOW;
         printStringValue(str, v.string.s);
-        str << ESC_END;
+        str << ANSI_NORMAL;
         break;
 
     case tPath:
-        str << ESC_GRE << v.path << ESC_END; // !!! escaping?
+        str << ANSI_GREEN << v.path << ANSI_NORMAL; // !!! escaping?
         break;
 
     case tNull:
-        str << ESC_CYA "null" ESC_END;
+        str << ANSI_CYAN "null" ANSI_NORMAL;
         break;
 
     case tAttrs: {
@@ -699,7 +692,7 @@ std::ostream & NixRepl::printValue(std::ostream & str, Value & v, unsigned int m
                     try {
                         printValue(str, *i.second, maxDepth - 1, seen);
                     } catch (AssertionError & e) {
-                        str << ESC_RED "«error: " << e.msg() << "»" ESC_END;
+                        str << ANSI_RED "«error: " << e.msg() << "»" ANSI_NORMAL;
                     }
                 str << "; ";
             }
@@ -725,7 +718,7 @@ std::ostream & NixRepl::printValue(std::ostream & str, Value & v, unsigned int m
                     try {
                         printValue(str, *v.listElems()[n], maxDepth - 1, seen);
                     } catch (AssertionError & e) {
-                        str << ESC_RED "«error: " << e.msg() << "»" ESC_END;
+                        str << ANSI_RED "«error: " << e.msg() << "»" ANSI_NORMAL;
                     }
                 str << " ";
             }
@@ -737,16 +730,16 @@ std::ostream & NixRepl::printValue(std::ostream & str, Value & v, unsigned int m
     case tLambda: {
         std::ostringstream s;
         s << v.lambda.fun->pos;
-        str << ESC_BLU "«lambda @ " << filterANSIEscapes(s.str()) << "»" ESC_END;
+        str << ANSI_BLUE "«lambda @ " << filterANSIEscapes(s.str()) << "»" ANSI_NORMAL;
         break;
     }
 
     case tPrimOp:
-        str << ESC_MAG "«primop»" ESC_END;
+        str << ANSI_MAGENTA "«primop»" ANSI_NORMAL;
         break;
 
     case tPrimOpApp:
-        str << ESC_BLU "«primop-app»" ESC_END;
+        str << ANSI_BLUE "«primop-app»" ANSI_NORMAL;
         break;
 
     case tFloat:
@@ -754,7 +747,7 @@ std::ostream & NixRepl::printValue(std::ostream & str, Value & v, unsigned int m
         break;
 
     default:
-        str << ESC_RED "«unknown»" ESC_END;
+        str << ANSI_RED "«unknown»" ANSI_NORMAL;
         break;
     }