Merge remote-tracking branch 'origin/master' into source-path

21 files changed, 235 insertions, 202 deletions

diff --git a/src/libexpr/attr-path.cc b/src/libexpr/attr-path.cc
index 8ae4270e6..ab654c1b0 100644
--- a/src/libexpr/attr-path.cc
+++ b/src/libexpr/attr-path.cc
@@ -118,7 +118,7 @@ std::pair<SourcePath, uint32_t> findPackageFilename(EvalState & state, Value & v
 
     // FIXME: is it possible to extract the Pos object instead of doing this
     //        toString + parsing?
-    PathSet context;
+    NixStringContext context;
     auto path = state.coerceToPath(noPos, *v2, context, "while evaluating the 'meta.position' attribute of a derivation");
 
     auto fn = path.path.abs();
diff --git a/src/libexpr/eval-cache.cc b/src/libexpr/eval-cache.cc
index ec4ad2f5e..ac646af8a 100644
--- a/src/libexpr/eval-cache.cc
+++ b/src/libexpr/eval-cache.cc
@@ -47,7 +47,7 @@ struct AttrDb
     {
         auto state(_state->lock());
 
-        Path cacheDir = getCacheDir() + "/nix/eval-cache-v4";
+        Path cacheDir = getCacheDir() + "/nix/eval-cache-v5";
         createDirs(cacheDir);
 
         Path dbPath = cacheDir + "/" + fingerprint.to_string(Base16, false) + ".sqlite";
@@ -300,7 +300,7 @@ struct AttrDb
                 NixStringContext context;
                 if (!queryAttribute.isNull(3))
                     for (auto & s : tokenizeString<std::vector<std::string>>(queryAttribute.getStr(3), ";"))
-                        context.push_back(NixStringContextElem::parse(cfg, s));
+                        context.insert(NixStringContextElem::parse(s));
                 return {{rowId, string_t{queryAttribute.getStr(2), context}}};
             }
             case AttrType::Bool:
@@ -621,9 +621,11 @@ string_t AttrCursor::getStringWithContext()
 
     auto & v = forceValue();
 
-    if (v.type() == nString)
-        return {v.string.s, v.getContext(*root->state.store)};
-    else if (v.type() == nPath)
+    if (v.type() == nString) {
+        NixStringContext context;
+        copyContext(v, context);
+        return {v.string.s, std::move(context)};
+    } else if (v.type() == nPath)
         return {v.path().to_string(), {}};
     else
         root->state.error("'%s' is not a string but %s", getAttrPathStr()).debugThrow<TypeError>();
diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index d6daf2727..e2b455b91 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -610,8 +610,7 @@ void EvalState::allowAndSetStorePathString(const StorePath & storePath, Value &
 {
     allowPath(storePath);
 
-    auto path = store->printStorePath(storePath);
-    v.mkString(path, PathSet({path}));
+    mkStorePathString(storePath, v);
 }
 
 SourcePath EvalState::checkSourcePath(const SourcePath & path_)
@@ -693,7 +692,7 @@ void EvalState::checkURI(const std::string & uri)
 }
 
 
-Path EvalState::toRealPath(const Path & path, const PathSet & context)
+Path EvalState::toRealPath(const Path & path, const NixStringContext & context)
 {
     // FIXME: check whether 'path' is in 'context'.
     return
@@ -945,25 +944,25 @@ void Value::mkString(std::string_view s)
 }
 
 
-static void copyContextToValue(Value & v, const PathSet & context)
+static void copyContextToValue(Value & v, const NixStringContext & context)
 {
     if (!context.empty()) {
         size_t n = 0;
         v.string.context = (const char * *)
             allocBytes((context.size() + 1) * sizeof(char *));
         for (auto & i : context)
-            v.string.context[n++] = dupString(i.c_str());
+            v.string.context[n++] = dupString(i.to_string().c_str());
         v.string.context[n] = 0;
     }
 }
 
-void Value::mkString(std::string_view s, const PathSet & context)
+void Value::mkString(std::string_view s, const NixStringContext & context)
 {
     mkString(s);
     copyContextToValue(*this, context);
 }
 
-void Value::mkStringMove(const char * s, const PathSet & context)
+void Value::mkStringMove(const char * s, const NixStringContext & context)
 {
     mkString(s);
     copyContextToValue(*this, context);
@@ -1039,6 +1038,16 @@ void EvalState::mkPos(Value & v, PosIdx p)
 }
 
 
+void EvalState::mkStorePathString(const StorePath & p, Value & v)
+{
+    v.mkString(
+        store->printStorePath(p),
+        NixStringContext {
+            NixStringContextElem::Opaque { .path = p },
+        });
+}
+
+
 /* Create a thunk for the delayed computation of the given expression
    in the given environment.  But if the expression is a variable,
    then look it up right away.  This significantly reduces the number
@@ -1901,7 +1910,7 @@ void EvalState::concatLists(Value & v, size_t nrLists, Value * * lists, const Po
 
 void ExprConcatStrings::eval(EvalState & state, Env & env, Value & v)
 {
-    PathSet context;
+    NixStringContext context;
     std::vector<BackedStringView> s;
     size_t sSize = 0;
     NixInt n = 0;
@@ -2110,26 +2119,15 @@ std::string_view EvalState::forceString(Value & v, const PosIdx pos, std::string
 }
 
 
-void copyContext(const Value & v, PathSet & context)
+void copyContext(const Value & v, NixStringContext & context)
 {
     if (v.string.context)
         for (const char * * p = v.string.context; *p; ++p)
-            context.insert(*p);
+            context.insert(NixStringContextElem::parse(*p));
 }
 
 
-NixStringContext Value::getContext(const Store & store)
-{
-    NixStringContext res;
-    assert(internalType == tString);
-    if (string.context)
-        for (const char * * p = string.context; *p; ++p)
-            res.push_back(NixStringContextElem::parse(store, *p));
-    return res;
-}
-
-
-std::string_view EvalState::forceString(Value & v, PathSet & context, const PosIdx pos, std::string_view errorCtx)
+std::string_view EvalState::forceString(Value & v, NixStringContext & context, const PosIdx pos, std::string_view errorCtx)
 {
     auto s = forceString(v, pos, errorCtx);
     copyContext(v, context);
@@ -2159,7 +2157,7 @@ bool EvalState::isDerivation(Value & v)
 
 
 std::optional<std::string> EvalState::tryAttrsToString(const PosIdx pos, Value & v,
-    PathSet & context, bool coerceMore, bool copyToStore)
+    NixStringContext & context, bool coerceMore, bool copyToStore)
 {
     auto i = v.attrs->find(sToString);
     if (i != v.attrs->end()) {
@@ -2176,7 +2174,7 @@ std::optional<std::string> EvalState::tryAttrsToString(const PosIdx pos, Value &
 BackedStringView EvalState::coerceToString(
     const PosIdx pos,
     Value & v,
-    PathSet & context,
+    NixStringContext & context,
     std::string_view errorCtx,
     bool coerceMore,
     bool copyToStore,
@@ -2258,7 +2256,7 @@ BackedStringView EvalState::coerceToString(
 }
 
 
-StorePath EvalState::copyPathToStore(PathSet & context, const SourcePath & path)
+StorePath EvalState::copyPathToStore(NixStringContext & context, const SourcePath & path)
 {
     if (nix::isDerivation(path.path.abs()))
         error("file names are not allowed to end in '%1%'", drvExtension).debugThrow<EvalError>();
@@ -2275,12 +2273,14 @@ StorePath EvalState::copyPathToStore(PathSet & context, const SourcePath & path)
             return dstPath;
         }();
 
-    context.insert(store->printStorePath(dstPath));
+    context.insert(NixStringContextElem::Opaque {
+        .path = dstPath
+    });
     return dstPath;
 }
 
 
-SourcePath EvalState::coerceToPath(const PosIdx pos, Value & v, PathSet & context, std::string_view errorCtx)
+SourcePath EvalState::coerceToPath(const PosIdx pos, Value & v, NixStringContext & context, std::string_view errorCtx)
 {
     auto path = coerceToString(pos, v, context, errorCtx, false, false, true).toOwned();
     if (path == "" || path[0] != '/')
@@ -2289,7 +2289,7 @@ SourcePath EvalState::coerceToPath(const PosIdx pos, Value & v, PathSet & contex
 }
 
 
-StorePath EvalState::coerceToStorePath(const PosIdx pos, Value & v, PathSet & context, std::string_view errorCtx)
+StorePath EvalState::coerceToStorePath(const PosIdx pos, Value & v, NixStringContext & context, std::string_view errorCtx)
 {
     auto path = coerceToString(pos, v, context, errorCtx, false, false, true).toOwned();
     if (auto storePath = store->maybeParseStorePath(path))
@@ -2496,7 +2496,7 @@ void EvalState::printStats()
 }
 
 
-std::string ExternalValueBase::coerceToString(const Pos & pos, PathSet & context, bool copyMore, bool copyToStore) const
+std::string ExternalValueBase::coerceToString(const Pos & pos, NixStringContext & context, bool copyMore, bool copyToStore) const
 {
     throw TypeError({
         .msg = hintfmt("cannot coerce %1% to a string", showType())
diff --git a/src/libexpr/eval.hh b/src/libexpr/eval.hh
index dea8b4a3a..bb3ac2b22 100644
--- a/src/libexpr/eval.hh
+++ b/src/libexpr/eval.hh
@@ -57,7 +57,7 @@ void printEnvBindings(const SymbolTable & st, const StaticEnv & se, const Env &
 
 std::unique_ptr<ValMap> mapStaticEnvBindings(const SymbolTable & st, const StaticEnv & se, const Env & env);
 
-void copyContext(const Value & v, PathSet & context);
+void copyContext(const Value & v, NixStringContext & context);
 
 
 std::string printValue(const EvalState & state, const Value & v);
@@ -330,7 +330,7 @@ public:
      * intended to distinguish between import-from-derivation and
      * sources stored in the actual /nix/store.
      */
-    Path toRealPath(const Path & path, const PathSet & context);
+    Path toRealPath(const Path & path, const NixStringContext & context);
 
     /**
      * Parse a Nix expression from the specified file.
@@ -426,7 +426,7 @@ public:
      */
     void forceFunction(Value & v, const PosIdx pos, std::string_view errorCtx);
     std::string_view forceString(Value & v, const PosIdx pos, std::string_view errorCtx);
-    std::string_view forceString(Value & v, PathSet & context, const PosIdx pos, std::string_view errorCtx);
+    std::string_view forceString(Value & v, NixStringContext & context, const PosIdx pos, std::string_view errorCtx);
     std::string_view forceStringNoCtx(Value & v, const PosIdx pos, std::string_view errorCtx);
 
     [[gnu::noinline]]
@@ -442,7 +442,7 @@ public:
     bool isDerivation(Value & v);
 
     std::optional<std::string> tryAttrsToString(const PosIdx pos, Value & v,
-        PathSet & context, bool coerceMore = false, bool copyToStore = true);
+        NixStringContext & context, bool coerceMore = false, bool copyToStore = true);
 
     /**
      * String coercion.
@@ -452,12 +452,12 @@ public:
      * booleans and lists to a string.  If `copyToStore` is set,
      * referenced paths are copied to the Nix store as a side effect.
      */
-    BackedStringView coerceToString(const PosIdx pos, Value & v, PathSet & context,
+    BackedStringView coerceToString(const PosIdx pos, Value & v, NixStringContext & context,
         std::string_view errorCtx,
         bool coerceMore = false, bool copyToStore = true,
         bool canonicalizePath = true);
 
-    StorePath copyPathToStore(PathSet & context, const SourcePath & path);
+    StorePath copyPathToStore(NixStringContext & context, const SourcePath & path);
 
     /**
      * Path coercion.
@@ -466,12 +466,12 @@ public:
      * path.  The result is guaranteed to be a canonicalised, absolute
      * path.  Nothing is copied to the store.
      */
-    SourcePath coerceToPath(const PosIdx pos, Value & v, PathSet & context, std::string_view errorCtx);
+    SourcePath coerceToPath(const PosIdx pos, Value & v, NixStringContext & context, std::string_view errorCtx);
 
     /**
      * Like coerceToPath, but the result must be a store path.
      */
-    StorePath coerceToStorePath(const PosIdx pos, Value & v, PathSet & context, std::string_view errorCtx);
+    StorePath coerceToStorePath(const PosIdx pos, Value & v, NixStringContext & context, std::string_view errorCtx);
 
 public:
 
@@ -576,6 +576,12 @@ public:
     void mkThunk_(Value & v, Expr * expr);
     void mkPos(Value & v, PosIdx pos);
 
+    /* Create a string representing a store path.
+
+       The string is the printed store path with a context containing a single
+       `Opaque` element of that store path. */
+    void mkStorePathString(const StorePath & storePath, Value & v);
+
     void concatLists(Value & v, size_t nrLists, Value * * lists, const PosIdx pos, std::string_view errorCtx);
 
     /**
@@ -587,7 +593,7 @@ public:
      * Realise the given context, and return a mapping from the placeholders
      * used to construct the associated value to their final store path
      */
-    [[nodiscard]] StringMap realiseContext(const PathSet & context);
+    [[nodiscard]] StringMap realiseContext(const NixStringContext & context);
 
 private:
 
diff --git a/src/libexpr/flake/config.cc b/src/libexpr/flake/config.cc
index 89ddbde7e..e89014862 100644
--- a/src/libexpr/flake/config.cc
+++ b/src/libexpr/flake/config.cc
@@ -31,7 +31,7 @@ static void writeTrustedList(const TrustedList & trustedList)
 
 void ConfigFile::apply()
 {
-    std::set<std::string> whitelist{"bash-prompt", "bash-prompt-prefix", "bash-prompt-suffix", "flake-registry"};
+    std::set<std::string> whitelist{"bash-prompt", "bash-prompt-prefix", "bash-prompt-suffix", "flake-registry", "commit-lockfile-summary"};
 
     for (auto & [name, value] : settings) {
 
diff --git a/src/libexpr/flake/flake.cc b/src/libexpr/flake/flake.cc
index ccf868361..60bb6a71e 100644
--- a/src/libexpr/flake/flake.cc
+++ b/src/libexpr/flake/flake.cc
@@ -265,7 +265,7 @@ static Flake getFlake(
                     state.symbols[setting.name],
                     std::string(state.forceStringNoCtx(*setting.value, setting.pos, "")));
             else if (setting.value->type() == nPath) {
-                PathSet emptyContext = {};
+                NixStringContext emptyContext = {};
                 flake.config.settings.emplace(
                     state.symbols[setting.name],
                     state.coerceToString(setting.pos, *setting.value, emptyContext, "", false, true, true) .toOwned());
diff --git a/src/libexpr/get-drvs.cc b/src/libexpr/get-drvs.cc
index 1602fbffb..506a63677 100644
--- a/src/libexpr/get-drvs.cc
+++ b/src/libexpr/get-drvs.cc
@@ -71,7 +71,7 @@ std::optional<StorePath> DrvInfo::queryDrvPath() const
 {
     if (!drvPath && attrs) {
         Bindings::iterator i = attrs->find(state->sDrvPath);
-        PathSet context;
+        NixStringContext context;
         if (i == attrs->end())
             drvPath = {std::nullopt};
         else
@@ -93,7 +93,7 @@ StorePath DrvInfo::queryOutPath() const
 {
     if (!outPath && attrs) {
         Bindings::iterator i = attrs->find(state->sOutPath);
-        PathSet context;
+        NixStringContext context;
         if (i != attrs->end())
             outPath = state->coerceToStorePath(i->pos, *i->value, context, "while evaluating the output path of a derivation");
     }
@@ -124,7 +124,7 @@ DrvInfo::Outputs DrvInfo::queryOutputs(bool withPaths, bool onlyOutputsToInstall
                     /* And evaluate its ‘outPath’ attribute. */
                     Bindings::iterator outPath = out->value->attrs->find(state->sOutPath);
                     if (outPath == out->value->attrs->end()) continue; // FIXME: throw error?
-                    PathSet context;
+                    NixStringContext context;
                     outputs.emplace(output, state->coerceToStorePath(outPath->pos, *outPath->value, context, "while evaluating an output path of a derivation"));
                 } else
                     outputs.emplace(output, std::nullopt);
diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index 60bf45147..cea5b4202 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -38,17 +38,16 @@ namespace nix {
 InvalidPathError::InvalidPathError(const Path & path) :
     EvalError("path '%s' is not valid", path), path(path) {}
 
-StringMap EvalState::realiseContext(const PathSet & context)
+StringMap EvalState::realiseContext(const NixStringContext & context)
 {
     std::vector<DerivedPath::Built> drvs;
     StringMap res;
 
-    for (auto & c_ : context) {
+    for (auto & c : context) {
         auto ensureValid = [&](const StorePath & p) {
             if (!store->isValidPath(p))
                 debugThrowLastTrace(InvalidPathError(store->printStorePath(p)));
         };
-        auto c = NixStringContextElem::parse(*store, c_);
         std::visit(overloaded {
             [&](const NixStringContextElem::Built & b) {
                 drvs.push_back(DerivedPath::Built {
@@ -112,7 +111,7 @@ struct RealisePathFlags {
 
 static SourcePath realisePath(EvalState & state, const PosIdx pos, Value & v, const RealisePathFlags flags = {})
 {
-    PathSet context;
+    NixStringContext context;
 
     auto path = state.coerceToPath(noPos, v, context, "while realising the context of a path");
 
@@ -158,7 +157,12 @@ static void mkOutputString(
             /* FIXME: we need to depend on the basic derivation, not
                derivation */
             : downstreamPlaceholder(*state.store, drvPath, o.first),
-        {"!" + o.first + "!" + state.store->printStorePath(drvPath)});
+        NixStringContext {
+            NixStringContextElem::Built {
+                .drvPath = drvPath,
+                .output = o.first,
+            }
+        });
 }
 
 /* Load and evaluate an expression from path specified by the
@@ -178,17 +182,18 @@ static void import(EvalState & state, const PosIdx pos, Value & vPath, Value * v
         return storePath;
     };
 
-    if (auto optStorePath = isValidDerivationInStore()) {
-        auto storePath = *optStorePath;
-        Derivation drv = state.store->readDerivation(storePath);
+    if (auto storePath = isValidDerivationInStore()) {
+        Derivation drv = state.store->readDerivation(*storePath);
         auto attrs = state.buildBindings(3 + drv.outputs.size());
-        attrs.alloc(state.sDrvPath).mkString(path2, {"=" + path2});
+        attrs.alloc(state.sDrvPath).mkString(path2, {
+            NixStringContextElem::DrvDeep { .drvPath = *storePath },
+        });
         attrs.alloc(state.sName).mkString(drv.env["name"]);
         auto & outputsVal = attrs.alloc(state.sOutputs);
         state.mkList(outputsVal, drv.outputs.size());
 
         for (const auto & [i, o] : enumerate(drv.outputs)) {
-            mkOutputString(state, attrs, storePath, drv, o);
+            mkOutputString(state, attrs, *storePath, drv, o);
             (outputsVal.listElems()[i] = state.allocValue())->mkString(o.first);
         }
 
@@ -359,7 +364,7 @@ void prim_exec(EvalState & state, const PosIdx pos, Value * * args, Value & v)
     auto count = args[0]->listSize();
     if (count == 0)
         state.error("at least one argument to 'exec' required").atPos(pos).debugThrow<EvalError>();
-    PathSet context;
+    NixStringContext context;
     auto program = state.coerceToString(pos, *elems[0], context,
             "while evaluating the first element of the argument passed to builtins.exec",
             false, false).toOwned();
@@ -769,7 +774,7 @@ static RegisterPrimOp primop_abort({
     )",
     .fun = [](EvalState & state, const PosIdx pos, Value * * args, Value & v)
     {
-        PathSet context;
+        NixStringContext context;
         auto s = state.coerceToString(pos, *args[0], context,
                 "while evaluating the error message passed to builtins.abort").toOwned();
         state.debugThrowLastTrace(Abort("evaluation aborted with the following error message: '%1%'", s));
@@ -788,7 +793,7 @@ static RegisterPrimOp primop_throw({
     )",
     .fun = [](EvalState & state, const PosIdx pos, Value * * args, Value & v)
     {
-      PathSet context;
+      NixStringContext context;
       auto s = state.coerceToString(pos, *args[0], context,
               "while evaluating the error message passed to builtin.throw").toOwned();
       state.debugThrowLastTrace(ThrownError(s));
@@ -801,7 +806,7 @@ static void prim_addErrorContext(EvalState & state, const PosIdx pos, Value * *
         state.forceValue(*args[1], pos);
         v = *args[1];
     } catch (Error & e) {
-        PathSet context;
+        NixStringContext context;
         auto message = state.coerceToString(pos, *args[0], context,
                 "while evaluating the error message passed to builtins.addErrorContext",
                 false, false).toOwned();
@@ -1087,7 +1092,7 @@ drvName, Bindings * attrs, Value & v)
     Derivation drv;
     drv.name = drvName;
 
-    PathSet context;
+    NixStringContext context;
 
     bool contentAddressed = false;
     bool isImpure = false;
@@ -1233,8 +1238,7 @@ drvName, Bindings * attrs, Value & v)
     /* Everything in the context of the strings in the derivation
        attributes should be added as dependencies of the resulting
        derivation. */
-    for (auto & c_ : context) {
-        auto c = NixStringContextElem::parse(*state.store, c_);
+    for (auto & c : context) {
         std::visit(overloaded {
             /* Since this allows the builder to gain access to every
                path in the dependency graph of the derivation (including
@@ -1294,7 +1298,13 @@ drvName, Bindings * attrs, Value & v)
         auto h = newHashAllowEmpty(*outputHash, parseHashTypeOpt(outputHashAlgo));
 
         auto method = ingestionMethod.value_or(FileIngestionMethod::Flat);
-        auto outPath = state.store->makeFixedOutputPath(method, h, drvName);
+        auto outPath = state.store->makeFixedOutputPath(drvName, FixedOutputInfo {
+            .hash = {
+                .method = method,
+                .hash = h,
+            },
+            .references = {},
+        });
         drv.env["out"] = state.store->printStorePath(outPath);
         drv.outputs.insert_or_assign("out",
             DerivationOutput::CAFixed {
@@ -1387,7 +1397,9 @@ drvName, Bindings * attrs, Value & v)
     }
 
     auto result = state.buildBindings(1 + drv.outputs.size());
-    result.alloc(state.sDrvPath).mkString(drvPathS, {"=" + drvPathS});
+    result.alloc(state.sDrvPath).mkString(drvPathS, {
+        NixStringContextElem::DrvDeep { .drvPath = drvPath },
+    });
     for (auto & i : drv.outputs)
         mkOutputString(state, result, drvPath, drv, i);
 
@@ -1432,7 +1444,7 @@ static RegisterPrimOp primop_placeholder({
 /* Convert the argument to a path.  !!! obsolete? */
 static void prim_toPath(EvalState & state, const PosIdx pos, Value * * args, Value & v)
 {
-    PathSet context;
+    NixStringContext context;
     auto path = state.coerceToPath(pos, *args[0], context, "while evaluating the first argument passed to builtins.toPath");
     v.mkString(path.path.abs(), context);
 }
@@ -1463,7 +1475,7 @@ static void prim_storePath(EvalState & state, const PosIdx pos, Value * * args,
             .errPos = state.positions[pos]
         }));
 
-    PathSet context;
+    NixStringContext context;
     auto path = state.checkSourcePath(state.coerceToPath(pos, *args[0], context, "while evaluating the first argument passed to builtins.storePath")).path;
     /* Resolve symlinks in ‘path’, unless ‘path’ itself is a symlink
        directly in the store.  The latter condition is necessary so
@@ -1478,7 +1490,7 @@ static void prim_storePath(EvalState & state, const PosIdx pos, Value * * args,
     auto path2 = state.store->toStorePath(path.abs()).first;
     if (!settings.readOnlyMode)
         state.store->ensurePath(path2);
-    context.insert(state.store->printStorePath(path2));
+    context.insert(NixStringContextElem::Opaque { .path = path2 });
     v.mkString(path.abs(), context);
 }
 
@@ -1534,7 +1546,7 @@ static RegisterPrimOp primop_pathExists({
    following the last slash. */
 static void prim_baseNameOf(EvalState & state, const PosIdx pos, Value * * args, Value & v)
 {
-    PathSet context;
+    NixStringContext context;
     v.mkString(baseNameOf(*state.coerceToString(pos, *args[0], context,
             "while evaluating the first argument passed to builtins.baseNameOf",
             false, false)), context);
@@ -1556,12 +1568,12 @@ static RegisterPrimOp primop_baseNameOf({
    of the argument. */
 static void prim_dirOf(EvalState & state, const PosIdx pos, Value * * args, Value & v)
 {
-    PathSet context;
     state.forceValue(*args[0], pos);
     if (args[0]->type() == nPath) {
         auto path = args[0]->path();
         v.mkPath(path.path.isRoot() ? path : path.parent());
     } else {
+        NixStringContext context;
         auto path = state.coerceToString(pos, *args[0], context,
             "while evaluating the first argument passed to 'builtins.dirOf'",
             false, false);
@@ -1599,7 +1611,12 @@ static void prim_readFile(EvalState & state, const PosIdx pos, Value * * args, V
         refsSink << s;
         refs = refsSink.getResultPaths();
     }
-    auto context = state.store->printStorePathSet(refs);
+    NixStringContext context;
+    for (auto && p : std::move(refs)) {
+        context.insert(NixStringContextElem::Opaque {
+            .path = std::move((StorePath &&)p),
+        });
+    }
     v.mkString(s, context);
 }
 
@@ -1630,7 +1647,7 @@ static void prim_findFile(EvalState & state, const PosIdx pos, Value * * args, V
 
         i = getAttr(state, state.sPath, v2->attrs, "in an element of the __nixPath");
 
-        PathSet context;
+        NixStringContext context;
         auto path = state.coerceToString(pos, *i->value, context,
                 "while evaluating the `path` attribute of an element of the list passed to builtins.findFile",
                 false, false).toOwned();
@@ -1781,7 +1798,7 @@ static RegisterPrimOp primop_readDir({
 static void prim_toXML(EvalState & state, const PosIdx pos, Value * * args, Value & v)
 {
     std::ostringstream out;
-    PathSet context;
+    NixStringContext context;
     printValueAsXML(state, true, false, *args[0], out, context, pos);
     v.mkString(out.str(), context);
 }
@@ -1889,7 +1906,7 @@ static RegisterPrimOp primop_toXML({
 static void prim_toJSON(EvalState & state, const PosIdx pos, Value * * args, Value & v)
 {
     std::ostringstream out;
-    PathSet context;
+    NixStringContext context;
     printValueAsJSON(state, true, *args[0], pos, out, context);
     v.mkString(out.str(), context);
 }
@@ -1939,22 +1956,23 @@ static RegisterPrimOp primop_fromJSON({
    as an input by derivations. */
 static void prim_toFile(EvalState & state, const PosIdx pos, Value * * args, Value & v)
 {
-    PathSet context;
+    NixStringContext context;
     std::string name(state.forceStringNoCtx(*args[0], pos, "while evaluating the first argument passed to builtins.toFile"));
     std::string contents(state.forceString(*args[1], context, pos, "while evaluating the second argument passed to builtins.toFile"));
 
     StorePathSet refs;
 
-    for (auto path : context) {
-        if (path.at(0) != '/')
+    for (auto c : context) {
+        if (auto p = std::get_if<NixStringContextElem::Opaque>(&c))
+            refs.insert(p->path);
+        else
             state.debugThrowLastTrace(EvalError({
                 .msg = hintfmt(
                     "in 'toFile': the file named '%1%' must not contain a reference "
                     "to a derivation but contains (%2%)",
-                    name, path),
+                    name, c.to_string()),
                 .errPos = state.positions[pos]
             }));
-        refs.insert(state.store->parseStorePath(path));
     }
 
     auto storePath = settings.readOnlyMode
@@ -2055,7 +2073,7 @@ static void addPath(
     FileIngestionMethod method,
     const std::optional<Hash> expectedHash,
     Value & v,
-    const PathSet & context)
+    const NixStringContext & context)
 {
     try {
         // FIXME: handle CA derivation outputs (where path needs to
@@ -2103,7 +2121,13 @@ static void addPath(
 
         std::optional<StorePath> expectedStorePath;
         if (expectedHash)
-            expectedStorePath = state.store->makeFixedOutputPath(method, *expectedHash, name);
+            expectedStorePath = state.store->makeFixedOutputPath(name, FixedOutputInfo {
+                .hash = {
+                    .method = method,
+                    .hash = *expectedHash,
+                },
+                .references = {},
+            });
 
         if (!expectedHash || !state.store->isValidPath(*expectedStorePath)) {
             StorePath dstPath = settings.readOnlyMode
@@ -2123,7 +2147,7 @@ static void addPath(
 
 static void prim_filterSource(EvalState & state, const PosIdx pos, Value * * args, Value & v)
 {
-    PathSet context;
+    NixStringContext context;
     auto path = state.coerceToPath(pos, *args[1], context,
         "while evaluating the second argument (the path to filter) passed to builtins.filterSource");
     state.forceFunction(*args[0], pos, "while evaluating the first argument passed to builtins.filterSource");
@@ -2192,7 +2216,7 @@ static void prim_path(EvalState & state, const PosIdx pos, Value * * args, Value
     Value * filterFun = nullptr;
     auto method = FileIngestionMethod::Recursive;
     std::optional<Hash> expectedHash;
-    PathSet context;
+    NixStringContext context;
 
     state.forceAttrs(*args[0], pos, "while evaluating the argument passed to 'builtins.path'");
 
@@ -3528,7 +3552,7 @@ static RegisterPrimOp primop_lessThan({
    `"/nix/store/whatever..."'. */
 static void prim_toString(EvalState & state, const PosIdx pos, Value * * args, Value & v)
 {
-    PathSet context;
+    NixStringContext context;
     auto s = state.coerceToString(pos, *args[0], context,
             "while evaluating the first argument passed to builtins.toString",
             true, false);
@@ -3567,7 +3591,7 @@ static void prim_substring(EvalState & state, const PosIdx pos, Value * * args,
 {
     int start = state.forceInt(*args[0], pos, "while evaluating the first argument (the start offset) passed to builtins.substring");
     int len = state.forceInt(*args[1], pos, "while evaluating the second argument (the substring length) passed to builtins.substring");
-    PathSet context;
+    NixStringContext context;
     auto s = state.coerceToString(pos, *args[2], context, "while evaluating the third argument (the string) passed to builtins.substring");
 
     if (start < 0)
@@ -3601,7 +3625,7 @@ static RegisterPrimOp primop_substring({
 
 static void prim_stringLength(EvalState & state, const PosIdx pos, Value * * args, Value & v)
 {
-    PathSet context;
+    NixStringContext context;
     auto s = state.coerceToString(pos, *args[0], context, "while evaluating the argument passed to builtins.stringLength");
     v.mkInt(s->size());
 }
@@ -3627,7 +3651,7 @@ static void prim_hashString(EvalState & state, const PosIdx pos, Value * * args,
             .errPos = state.positions[pos]
         }));
 
-    PathSet context; // discarded
+    NixStringContext context; // discarded
     auto s = state.forceString(*args[1], context, pos, "while evaluating the second argument passed to builtins.hashString");
 
     v.mkString(hashString(*ht, s).to_string(Base16, false));
@@ -3673,7 +3697,7 @@ void prim_match(EvalState & state, const PosIdx pos, Value * * args, Value & v)
 
         auto regex = state.regexCache->get(re);
 
-        PathSet context;
+        NixStringContext context;
         const auto str = state.forceString(*args[1], context, pos, "while evaluating the second argument passed to builtins.match");
 
         std::cmatch match;
@@ -3753,7 +3777,7 @@ void prim_split(EvalState & state, const PosIdx pos, Value * * args, Value & v)
 
         auto regex = state.regexCache->get(re);
 
-        PathSet context;
+        NixStringContext context;
         const auto str = state.forceString(*args[1], context, pos, "while evaluating the second argument passed to builtins.split");
 
         auto begin = std::cregex_iterator(str.begin(), str.end(), regex);
@@ -3850,7 +3874,7 @@ static RegisterPrimOp primop_split({
 
 static void prim_concatStringsSep(EvalState & state, const PosIdx pos, Value * * args, Value & v)
 {
-    PathSet context;
+    NixStringContext context;
 
     auto sep = state.forceString(*args[0], context, pos, "while evaluating the first argument (the separator string) passed to builtins.concatStringsSep");
     state.forceList(*args[1], pos, "while evaluating the second argument (the list of strings to concat) passed to builtins.concatStringsSep");
@@ -3890,15 +3914,15 @@ static void prim_replaceStrings(EvalState & state, const PosIdx pos, Value * * a
     for (auto elem : args[0]->listItems())
         from.emplace_back(state.forceString(*elem, pos, "while evaluating one of the strings to replace passed to builtins.replaceStrings"));
 
-    std::vector<std::pair<std::string, PathSet>> to;
+    std::vector<std::pair<std::string, NixStringContext>> to;
     to.reserve(args[1]->listSize());
     for (auto elem : args[1]->listItems()) {
-        PathSet ctx;
+        NixStringContext ctx;
         auto s = state.forceString(*elem, ctx, pos, "while evaluating one of the replacement strings passed to builtins.replaceStrings");
         to.emplace_back(s, std::move(ctx));
     }
 
-    PathSet context;
+    NixStringContext context;
     auto s = state.forceString(*args[2], context, pos, "while evaluating the third argument passed to builtins.replaceStrings");
 
     std::string res;
diff --git a/src/libexpr/primops/context.cc b/src/libexpr/primops/context.cc
index db43e5771..07bf400cf 100644
--- a/src/libexpr/primops/context.cc
+++ b/src/libexpr/primops/context.cc
@@ -7,7 +7,7 @@ namespace nix {
 
 static void prim_unsafeDiscardStringContext(EvalState & state, const PosIdx pos, Value * * args, Value & v)
 {
-    PathSet context;
+    NixStringContext context;
     auto s = state.coerceToString(pos, *args[0], context, "while evaluating the argument passed to builtins.unsafeDiscardStringContext");
     v.mkString(*s);
 }
@@ -17,7 +17,7 @@ static RegisterPrimOp primop_unsafeDiscardStringContext("__unsafeDiscardStringCo
 
 static void prim_hasContext(EvalState & state, const PosIdx pos, Value * * args, Value & v)
 {
-    PathSet context;
+    NixStringContext context;
     state.forceString(*args[0], context, pos, "while evaluating the argument passed to builtins.hasContext");
     v.mkBool(!context.empty());
 }
@@ -33,17 +33,18 @@ static RegisterPrimOp primop_hasContext("__hasContext", 1, prim_hasContext);
    drv.inputDrvs. */
 static void prim_unsafeDiscardOutputDependency(EvalState & state, const PosIdx pos, Value * * args, Value & v)
 {
-    PathSet context;
+    NixStringContext context;
     auto s = state.coerceToString(pos, *args[0], context, "while evaluating the argument passed to builtins.unsafeDiscardOutputDependency");
 
-    PathSet context2;
-    for (auto && p : context) {
-        auto c = NixStringContextElem::parse(*state.store, p);
+    NixStringContext context2;
+    for (auto && c : context) {
         if (auto * ptr = std::get_if<NixStringContextElem::DrvDeep>(&c)) {
-            context2.emplace(state.store->printStorePath(ptr->drvPath));
+            context2.emplace(NixStringContextElem::Opaque {
+                .path = ptr->drvPath
+            });
         } else {
             /* Can reuse original item */
-            context2.emplace(std::move(p));
+            context2.emplace(std::move(c));
         }
     }
 
@@ -79,22 +80,21 @@ static void prim_getContext(EvalState & state, const PosIdx pos, Value * * args,
         bool allOutputs = false;
         Strings outputs;
     };
-    PathSet context;
+    NixStringContext context;
     state.forceString(*args[0], context, pos, "while evaluating the argument passed to builtins.getContext");
     auto contextInfos = std::map<StorePath, ContextInfo>();
-    for (const auto & p : context) {
-        NixStringContextElem ctx = NixStringContextElem::parse(*state.store, p);
+    for (auto && i : context) {
         std::visit(overloaded {
-            [&](NixStringContextElem::DrvDeep & d) {
-                contextInfos[d.drvPath].allOutputs = true;
+            [&](NixStringContextElem::DrvDeep && d) {
+                contextInfos[std::move(d.drvPath)].allOutputs = true;
             },
-            [&](NixStringContextElem::Built & b) {
-                contextInfos[b.drvPath].outputs.emplace_back(std::move(b.output));
+            [&](NixStringContextElem::Built && b) {
+                contextInfos[std::move(b.drvPath)].outputs.emplace_back(std::move(b.output));
             },
-            [&](NixStringContextElem::Opaque & o) {
-                contextInfos[o.path].path = true;
+            [&](NixStringContextElem::Opaque && o) {
+                contextInfos[std::move(o.path)].path = true;
             },
-        }, ctx.raw());
+        }, ((NixStringContextElem &&) i).raw());
     }
 
     auto attrs = state.buildBindings(contextInfos.size());
@@ -129,7 +129,7 @@ static RegisterPrimOp primop_getContext("__getContext", 1, prim_getContext);
 */
 static void prim_appendContext(EvalState & state, const PosIdx pos, Value * * args, Value & v)
 {
-    PathSet context;
+    NixStringContext context;
     auto orig = state.forceString(*args[0], context, noPos, "while evaluating the first argument passed to builtins.appendContext");
 
     state.forceAttrs(*args[1], pos, "while evaluating the second argument passed to builtins.appendContext");
@@ -143,13 +143,16 @@ static void prim_appendContext(EvalState & state, const PosIdx pos, Value * * ar
                 .msg = hintfmt("context key '%s' is not a store path", name),
                 .errPos = state.positions[i.pos]
             });
+        auto namePath = state.store->parseStorePath(name);
         if (!settings.readOnlyMode)
-            state.store->ensurePath(state.store->parseStorePath(name));
+            state.store->ensurePath(namePath);
         state.forceAttrs(*i.value, i.pos, "while evaluating the value of a string context");
         auto iter = i.value->attrs->find(sPath);
         if (iter != i.value->attrs->end()) {
             if (state.forceBool(*iter->value, iter->pos, "while evaluating the `path` attribute of a string context"))
-                context.emplace(name);
+                context.emplace(NixStringContextElem::Opaque {
+                    .path = namePath,
+                });
         }
 
         iter = i.value->attrs->find(sAllOutputs);
@@ -161,7 +164,9 @@ static void prim_appendContext(EvalState & state, const PosIdx pos, Value * * ar
                         .errPos = state.positions[i.pos]
                     });
                 }
-                context.insert(concatStrings("=", name));
+                context.emplace(NixStringContextElem::DrvDeep {
+                    .drvPath = namePath,
+                });
             }
         }
 
@@ -176,7 +181,10 @@ static void prim_appendContext(EvalState & state, const PosIdx pos, Value * * ar
             }
             for (auto elem : iter->value->listItems()) {
                 auto outputName = state.forceStringNoCtx(*elem, iter->pos, "while evaluating an output name within a string context");
-                context.insert(concatStrings("!", outputName, "!", name));
+                context.emplace(NixStringContextElem::Built {
+                    .drvPath = namePath,
+                    .output = std::string { outputName },
+                });
             }
         }
     }
diff --git a/src/libexpr/primops/fetchClosure.cc b/src/libexpr/primops/fetchClosure.cc
index 0dfa97fa3..4cf1f1e0b 100644
--- a/src/libexpr/primops/fetchClosure.cc
+++ b/src/libexpr/primops/fetchClosure.cc
@@ -18,7 +18,7 @@ static void prim_fetchClosure(EvalState & state, const PosIdx pos, Value * * arg
         const auto & attrName = state.symbols[attr.name];
 
         if (attrName == "fromPath") {
-            PathSet context;
+            NixStringContext context;
             fromPath = state.coerceToStorePath(attr.pos, *attr.value, context,
                     "while evaluating the 'fromPath' attribute passed to builtins.fetchClosure");
         }
@@ -27,7 +27,7 @@ static void prim_fetchClosure(EvalState & state, const PosIdx pos, Value * * arg
             state.forceValue(*attr.value, attr.pos);
             toCA = true;
             if (attr.value->type() != nString || attr.value->string.s != std::string("")) {
-                PathSet context;
+                NixStringContext context;
                 toPath = state.coerceToStorePath(attr.pos, *attr.value, context,
                         "while evaluating the 'toPath' attribute passed to builtins.fetchClosure");
             }
@@ -114,8 +114,7 @@ static void prim_fetchClosure(EvalState & state, const PosIdx pos, Value * * arg
             });
     }
 
-    auto toPathS = state.store->printStorePath(*toPath);
-    v.mkString(toPathS, {toPathS});
+    state.mkStorePathString(*toPath, v);
 }
 
 static RegisterPrimOp primop_fetchClosure({
diff --git a/src/libexpr/primops/fetchMercurial.cc b/src/libexpr/primops/fetchMercurial.cc
index c41bd60b6..2c0d98e74 100644
--- a/src/libexpr/primops/fetchMercurial.cc
+++ b/src/libexpr/primops/fetchMercurial.cc
@@ -13,7 +13,7 @@ static void prim_fetchMercurial(EvalState & state, const PosIdx pos, Value * * a
     std::optional<Hash> rev;
     std::optional<std::string> ref;
     std::string_view name = "source";
-    PathSet context;
+    NixStringContext context;
 
     state.forceValue(*args[0], pos);
 
@@ -73,8 +73,7 @@ static void prim_fetchMercurial(EvalState & state, const PosIdx pos, Value * * a
     auto [tree, input2] = input.fetch(state.store);
 
     auto attrs2 = state.buildBindings(8);
-    auto storePath = state.store->printStorePath(tree.storePath);
-    attrs2.alloc(state.sOutPath).mkString(storePath, {storePath});
+    state.mkStorePathString(tree.storePath, attrs2.alloc(state.sOutPath));
     if (input2.getRef())
         attrs2.alloc("branch").mkString(*input2.getRef());
     // Backward compatibility: set 'rev' to
diff --git a/src/libexpr/primops/fetchTree.cc b/src/libexpr/primops/fetchTree.cc
index 0d0e00fa5..cd7039025 100644
--- a/src/libexpr/primops/fetchTree.cc
+++ b/src/libexpr/primops/fetchTree.cc
@@ -24,9 +24,8 @@ void emitTreeAttrs(
 
     auto attrs = state.buildBindings(8);
 
-    auto storePath = state.store->printStorePath(tree.storePath);
 
-    attrs.alloc(state.sOutPath).mkString(storePath, {storePath});
+    state.mkStorePathString(tree.storePath, attrs.alloc(state.sOutPath));
 
     // FIXME: support arbitrary input attributes.
 
@@ -107,7 +106,7 @@ static void fetchTree(
     const FetchTreeParams & params = FetchTreeParams{}
 ) {
     fetchers::Input input;
-    PathSet context;
+    NixStringContext context;
 
     state.forceValue(*args[0], pos);
 
@@ -243,10 +242,15 @@ static void fetch(EvalState & state, const PosIdx pos, Value * * args, Value & v
 
     // early exit if pinned and already in the store
     if (expectedHash && expectedHash->type == htSHA256) {
-        auto expectedPath =
-            unpack
-            ? state.store->makeFixedOutputPath(FileIngestionMethod::Recursive, *expectedHash, name, {})
-            : state.store->makeFixedOutputPath(FileIngestionMethod::Flat, *expectedHash, name, {});
+        auto expectedPath = state.store->makeFixedOutputPath(
+            name,
+            FixedOutputInfo {
+                .hash = {
+                    .method = unpack ? FileIngestionMethod::Recursive : FileIngestionMethod::Flat,
+                    .hash = *expectedHash,
+                },
+                .references = {}
+            });
 
         if (state.store->isValidPath(expectedPath)) {
             state.allowAndSetStorePathString(expectedPath, v);
diff --git a/src/libexpr/tests/json.cc b/src/libexpr/tests/json.cc
index 411bc0ac3..7586bdd9b 100644
--- a/src/libexpr/tests/json.cc
+++ b/src/libexpr/tests/json.cc
@@ -8,7 +8,7 @@ namespace nix {
         protected:
             std::string getJSONValue(Value& value) {
                 std::stringstream ss;
-                PathSet ps;
+                NixStringContext ps;
                 printValueAsJSON(state, true, value, noPos, ss, ps);
                 return ss.str();
             }
diff --git a/src/libexpr/tests/value/context.cc b/src/libexpr/tests/value/context.cc
index 083359b7a..27d6920b0 100644
--- a/src/libexpr/tests/value/context.cc
+++ b/src/libexpr/tests/value/context.cc
@@ -8,69 +8,62 @@
 
 namespace nix {
 
-// Testing of trivial expressions
-struct NixStringContextElemTest : public LibExprTest {
-   const Store & store() const {
-       return *LibExprTest::store;
-   }
-};
-
-TEST_F(NixStringContextElemTest, empty_invalid) {
+TEST(NixStringContextElemTest, empty_invalid) {
     EXPECT_THROW(
-        NixStringContextElem::parse(store(), ""),
+        NixStringContextElem::parse(""),
         BadNixStringContextElem);
 }
 
-TEST_F(NixStringContextElemTest, single_bang_invalid) {
+TEST(NixStringContextElemTest, single_bang_invalid) {
     EXPECT_THROW(
-        NixStringContextElem::parse(store(), "!"),
+        NixStringContextElem::parse("!"),
         BadNixStringContextElem);
 }
 
-TEST_F(NixStringContextElemTest, double_bang_invalid) {
+TEST(NixStringContextElemTest, double_bang_invalid) {
     EXPECT_THROW(
-        NixStringContextElem::parse(store(), "!!/"),
+        NixStringContextElem::parse("!!/"),
         BadStorePath);
 }
 
-TEST_F(NixStringContextElemTest, eq_slash_invalid) {
+TEST(NixStringContextElemTest, eq_slash_invalid) {
     EXPECT_THROW(
-        NixStringContextElem::parse(store(), "=/"),
+        NixStringContextElem::parse("=/"),
         BadStorePath);
 }
 
-TEST_F(NixStringContextElemTest, slash_invalid) {
+TEST(NixStringContextElemTest, slash_invalid) {
     EXPECT_THROW(
-        NixStringContextElem::parse(store(), "/"),
+        NixStringContextElem::parse("/"),
         BadStorePath);
 }
 
-TEST_F(NixStringContextElemTest, opaque) {
-    std::string_view opaque = "/nix/store/g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-x";
-    auto elem = NixStringContextElem::parse(store(), opaque);
+TEST(NixStringContextElemTest, opaque) {
+    std::string_view opaque = "g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-x";
+    auto elem = NixStringContextElem::parse(opaque);
     auto * p = std::get_if<NixStringContextElem::Opaque>(&elem);
     ASSERT_TRUE(p);
-    ASSERT_EQ(p->path, store().parseStorePath(opaque));
-    ASSERT_EQ(elem.to_string(store()), opaque);
+    ASSERT_EQ(p->path, StorePath { opaque });
+    ASSERT_EQ(elem.to_string(), opaque);
 }
 
-TEST_F(NixStringContextElemTest, drvDeep) {
-    std::string_view drvDeep = "=/nix/store/g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-x.drv";
-    auto elem = NixStringContextElem::parse(store(), drvDeep);
+TEST(NixStringContextElemTest, drvDeep) {
+    std::string_view drvDeep = "=g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-x.drv";
+    auto elem = NixStringContextElem::parse(drvDeep);
     auto * p = std::get_if<NixStringContextElem::DrvDeep>(&elem);
     ASSERT_TRUE(p);
-    ASSERT_EQ(p->drvPath, store().parseStorePath(drvDeep.substr(1)));
-    ASSERT_EQ(elem.to_string(store()), drvDeep);
+    ASSERT_EQ(p->drvPath, StorePath { drvDeep.substr(1) });
+    ASSERT_EQ(elem.to_string(), drvDeep);
 }
 
-TEST_F(NixStringContextElemTest, built) {
-    std::string_view built = "!foo!/nix/store/g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-x.drv";
-    auto elem = NixStringContextElem::parse(store(), built);
+TEST(NixStringContextElemTest, built) {
+    std::string_view built = "!foo!g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-x.drv";
+    auto elem = NixStringContextElem::parse(built);
     auto * p = std::get_if<NixStringContextElem::Built>(&elem);
     ASSERT_TRUE(p);
     ASSERT_EQ(p->output, "foo");
-    ASSERT_EQ(p->drvPath, store().parseStorePath(built.substr(5)));
-    ASSERT_EQ(elem.to_string(store()), built);
+    ASSERT_EQ(p->drvPath, StorePath { built.substr(5) });
+    ASSERT_EQ(elem.to_string(), built);
 }
 
 }
@@ -116,12 +109,12 @@ Gen<NixStringContextElem> Arbitrary<NixStringContextElem>::arbitrary()
 
 namespace nix {
 
-RC_GTEST_FIXTURE_PROP(
+RC_GTEST_PROP(
     NixStringContextElemTest,
     prop_round_rip,
     (const NixStringContextElem & o))
 {
-    RC_ASSERT(o == NixStringContextElem::parse(store(), o.to_string(store())));
+    RC_ASSERT(o == NixStringContextElem::parse(o.to_string()));
 }
 
 }
diff --git a/src/libexpr/value-to-json.cc b/src/libexpr/value-to-json.cc
index d40a77302..4996a5bde 100644
--- a/src/libexpr/value-to-json.cc
+++ b/src/libexpr/value-to-json.cc
@@ -11,7 +11,7 @@
 namespace nix {
 using json = nlohmann::json;
 json printValueAsJSON(EvalState & state, bool strict,
-    Value & v, const PosIdx pos, PathSet & context, bool copyToStore)
+    Value & v, const PosIdx pos, NixStringContext & context, bool copyToStore)
 {
     checkInterrupt();
 
@@ -95,13 +95,13 @@ json printValueAsJSON(EvalState & state, bool strict,
 }
 
 void printValueAsJSON(EvalState & state, bool strict,
-    Value & v, const PosIdx pos, std::ostream & str, PathSet & context, bool copyToStore)
+    Value & v, const PosIdx pos, std::ostream & str, NixStringContext & context, bool copyToStore)
 {
     str << printValueAsJSON(state, strict, v, pos, context, copyToStore);
 }
 
 json ExternalValueBase::printValueAsJSON(EvalState & state, bool strict,
-    PathSet & context, bool copyToStore) const
+    NixStringContext & context, bool copyToStore) const
 {
     state.debugThrowLastTrace(TypeError("cannot convert %1% to JSON", showType()));
 }
diff --git a/src/libexpr/value-to-json.hh b/src/libexpr/value-to-json.hh
index 713356c7f..47ac90313 100644
--- a/src/libexpr/value-to-json.hh
+++ b/src/libexpr/value-to-json.hh
@@ -11,9 +11,9 @@
 namespace nix {
 
 nlohmann::json printValueAsJSON(EvalState & state, bool strict,
-    Value & v, const PosIdx pos, PathSet & context, bool copyToStore = true);
+    Value & v, const PosIdx pos, NixStringContext & context, bool copyToStore = true);
 
 void printValueAsJSON(EvalState & state, bool strict,
-    Value & v, const PosIdx pos, std::ostream & str, PathSet & context, bool copyToStore = true);
+    Value & v, const PosIdx pos, std::ostream & str, NixStringContext & context, bool copyToStore = true);
 
 }
diff --git a/src/libexpr/value-to-xml.cc b/src/libexpr/value-to-xml.cc
index 4e87ac4b6..2539ad1c1 100644
--- a/src/libexpr/value-to-xml.cc
+++ b/src/libexpr/value-to-xml.cc
@@ -18,7 +18,7 @@ static XMLAttrs singletonAttrs(const std::string & name, const std::string & val
 
 
 static void printValueAsXML(EvalState & state, bool strict, bool location,
-    Value & v, XMLWriter & doc, PathSet & context, PathSet & drvsSeen,
+    Value & v, XMLWriter & doc, NixStringContext & context, PathSet & drvsSeen,
     const PosIdx pos);
 
 
@@ -32,7 +32,7 @@ static void posToXML(EvalState & state, XMLAttrs & xmlAttrs, const Pos & pos)
 
 
 static void showAttrs(EvalState & state, bool strict, bool location,
-    Bindings & attrs, XMLWriter & doc, PathSet & context, PathSet & drvsSeen)
+    Bindings & attrs, XMLWriter & doc, NixStringContext & context, PathSet & drvsSeen)
 {
     StringSet names;
 
@@ -54,7 +54,7 @@ static void showAttrs(EvalState & state, bool strict, bool location,
 
 
 static void printValueAsXML(EvalState & state, bool strict, bool location,
-    Value & v, XMLWriter & doc, PathSet & context, PathSet & drvsSeen,
+    Value & v, XMLWriter & doc, NixStringContext & context, PathSet & drvsSeen,
     const PosIdx pos)
 {
     checkInterrupt();
@@ -166,7 +166,7 @@ static void printValueAsXML(EvalState & state, bool strict, bool location,
 
 
 void ExternalValueBase::printValueAsXML(EvalState & state, bool strict,
-    bool location, XMLWriter & doc, PathSet & context, PathSet & drvsSeen,
+    bool location, XMLWriter & doc, NixStringContext & context, PathSet & drvsSeen,
     const PosIdx pos) const
 {
     doc.writeEmptyElement("unevaluated");
@@ -174,7 +174,7 @@ void ExternalValueBase::printValueAsXML(EvalState & state, bool strict,
 
 
 void printValueAsXML(EvalState & state, bool strict, bool location,
-    Value & v, std::ostream & out, PathSet & context, const PosIdx pos)
+    Value & v, std::ostream & out, NixStringContext & context, const PosIdx pos)
 {
     XMLWriter doc(true, out);
     XMLOpenElement root(doc, "expr");
diff --git a/src/libexpr/value-to-xml.hh b/src/libexpr/value-to-xml.hh
index ace7ead0f..6d702c0f2 100644
--- a/src/libexpr/value-to-xml.hh
+++ b/src/libexpr/value-to-xml.hh
@@ -10,6 +10,6 @@
 namespace nix {
 
 void printValueAsXML(EvalState & state, bool strict, bool location,
-    Value & v, std::ostream & out, PathSet & context, const PosIdx pos);
+    Value & v, std::ostream & out, NixStringContext & context, const PosIdx pos);
 
 }
diff --git a/src/libexpr/value.hh b/src/libexpr/value.hh
index d524c4869..89c0c36fd 100644
--- a/src/libexpr/value.hh
+++ b/src/libexpr/value.hh
@@ -101,7 +101,7 @@ class ExternalValueBase
      * Coerce the value to a string. Defaults to uncoercable, i.e. throws an
      * error.
      */
-    virtual std::string coerceToString(const Pos & pos, PathSet & context, bool copyMore, bool copyToStore) const;
+    virtual std::string coerceToString(const Pos & pos, NixStringContext & context, bool copyMore, bool copyToStore) const;
 
     /**
      * Compare to another value of the same type. Defaults to uncomparable,
@@ -113,13 +113,13 @@ class ExternalValueBase
      * Print the value as JSON. Defaults to unconvertable, i.e. throws an error
      */
     virtual nlohmann::json printValueAsJSON(EvalState & state, bool strict,
-        PathSet & context, bool copyToStore = true) const;
+        NixStringContext & context, bool copyToStore = true) const;
 
     /**
      * Print the value as XML. Defaults to unevaluated
      */
     virtual void printValueAsXML(EvalState & state, bool strict, bool location,
-        XMLWriter & doc, PathSet & context, PathSet & drvsSeen,
+        XMLWriter & doc, NixStringContext & context, PathSet & drvsSeen,
         const PosIdx pos) const;
 
     virtual ~ExternalValueBase()
@@ -269,9 +269,9 @@ public:
 
     void mkString(std::string_view s);
 
-    void mkString(std::string_view s, const PathSet & context);
+    void mkString(std::string_view s, const NixStringContext & context);
 
-    void mkStringMove(const char * s, const PathSet & context);
+    void mkStringMove(const char * s, const NixStringContext & context);
 
     inline void mkString(const Symbol & s)
     {
@@ -400,8 +400,6 @@ public:
      */
     bool isTrivial() const;
 
-    NixStringContext getContext(const Store &);
-
     auto listItems()
     {
         struct ListIterable
diff --git a/src/libexpr/value/context.cc b/src/libexpr/value/context.cc
index 61d9c53df..f76fc76e4 100644
--- a/src/libexpr/value/context.cc
+++ b/src/libexpr/value/context.cc
@@ -1,11 +1,10 @@
 #include "value/context.hh"
-#include "store-api.hh"
 
 #include <optional>
 
 namespace nix {
 
-NixStringContextElem NixStringContextElem::parse(const Store & store, std::string_view s0)
+NixStringContextElem NixStringContextElem::parse(std::string_view s0)
 {
     std::string_view s = s0;
 
@@ -25,41 +24,41 @@ NixStringContextElem NixStringContextElem::parse(const Store & store, std::strin
                 "String content element beginning with '!' should have a second '!'");
         }
         return NixStringContextElem::Built {
-            .drvPath = store.parseStorePath(s.substr(index + 1)),
+            .drvPath = StorePath { s.substr(index + 1) },
             .output = std::string(s.substr(0, index)),
         };
     }
     case '=': {
         return NixStringContextElem::DrvDeep {
-            .drvPath = store.parseStorePath(s.substr(1)),
+            .drvPath = StorePath { s.substr(1) },
         };
     }
     default: {
         return NixStringContextElem::Opaque {
-            .path = store.parseStorePath(s),
+            .path = StorePath { s },
         };
     }
     }
 }
 
-std::string NixStringContextElem::to_string(const Store & store) const {
+std::string NixStringContextElem::to_string() const {
     return std::visit(overloaded {
         [&](const NixStringContextElem::Built & b) {
             std::string res;
             res += '!';
             res += b.output;
             res += '!';
-            res += store.printStorePath(b.drvPath);
+            res += b.drvPath.to_string();
             return res;
         },
         [&](const NixStringContextElem::DrvDeep & d) {
             std::string res;
             res += '=';
-            res += store.printStorePath(d.drvPath);
+            res += d.drvPath.to_string();
             return res;
         },
         [&](const NixStringContextElem::Opaque & o) {
-            return store.printStorePath(o.path);
+            return std::string { o.path.to_string() };
         },
     }, raw());
 }
diff --git a/src/libexpr/value/context.hh b/src/libexpr/value/context.hh
index 8719602d8..287ae08a9 100644
--- a/src/libexpr/value/context.hh
+++ b/src/libexpr/value/context.hh
@@ -26,8 +26,6 @@ public:
     }
 };
 
-class Store;
-
 /**
  * Plain opaque path to some store object.
  *
@@ -80,12 +78,15 @@ struct NixStringContextElem : _NixStringContextElem_Raw {
     using DrvDeep = NixStringContextElem_DrvDeep;
     using Built = NixStringContextElem_Built;
 
-    inline const Raw & raw() const {
+    inline const Raw & raw() const & {
         return static_cast<const Raw &>(*this);
     }
-    inline Raw & raw() {
+    inline Raw & raw() & {
         return static_cast<Raw &>(*this);
     }
+    inline Raw && raw() && {
+        return static_cast<Raw &&>(*this);
+    }
 
     /**
      * Decode a context string, one of:
@@ -93,10 +94,10 @@ struct NixStringContextElem : _NixStringContextElem_Raw {
      * - ‘=<path>’
      * - ‘!<name>!<path>’
      */
-    static NixStringContextElem parse(const Store & store, std::string_view s);
-    std::string to_string(const Store & store) const;
+    static NixStringContextElem parse(std::string_view s);
+    std::string to_string() const;
 };
 
-typedef std::vector<NixStringContextElem> NixStringContext;
+typedef std::set<NixStringContextElem> NixStringContext;
 
 }