treewide: Use StringSet alias consistently instead of std::set<std::string>

The intention is to switch to transparent comparators from N3657 for ordered set containers for strings and using the alias consistently would simplify things.
2025-06-25 10:41:16 +02:00 · 2025-05-02 17:40:29 +00:00 · 2025-05-02 17:40:29 +00:00 · d8c97d8073
commit d8c97d8073
parent a976a46ee8
55 changed files with 111 additions and 109 deletions
--- a/src/build-remote/build-remote.cc
+++ b/src/build-remote/build-remote.cc
@ -42,7 +42,7 @@ static AutoCloseFD openSlotLock(const Machine & m, uint64_t slot)
    return openLockFile(fmt("%s/%s-%d", currentLoad, escapeUri(m.storeUri.render()), slot), true);
 }

-static bool allSupportedLocally(Store & store, const std::set<std::string>& requiredFeatures) {
+static bool allSupportedLocally(Store & store, const StringSet& requiredFeatures) {
    for (auto & feature : requiredFeatures)
        if (!store.systemFeatures.get().count(feature)) return false;
    return true;
@ -113,7 +113,7 @@ static int main_build_remote(int argc, char * * argv)
            auto amWilling = readInt(source);
            auto neededSystem = readString(source);
            drvPath = store->parseStorePath(readString(source));
-            auto requiredFeatures = readStrings<std::set<std::string>>(source);
+            auto requiredFeatures = readStrings<StringSet>(source);

            /* It would be possible to build locally after some builds clear out,
               so don't show the warning now: */
--- a/src/libcmd/command.cc
+++ b/src/libcmd/command.cc
@ -40,7 +40,7 @@ nlohmann::json NixMultiCommand::toJSON()
 void NixMultiCommand::run()
 {
    if (!command) {
-        std::set<std::string> subCommandTextLines;
+        StringSet subCommandTextLines;
        for (auto & [name, _] : commands)
            subCommandTextLines.insert(fmt("- `%s`", name));
        std::string markdownError =
--- a/src/libcmd/include/nix/cmd/command.hh
+++ b/src/libcmd/include/nix/cmd/command.hh
@ -363,7 +363,7 @@ void completeFlakeRefWithFragment(
    const Strings & defaultFlakeAttrPaths,
    std::string_view prefix);

-std::string showVersions(const std::set<std::string> & versions);
+std::string showVersions(const StringSet & versions);

 void printClosureDiff(
    ref<Store> store, const StorePath & beforePath, const StorePath & afterPath, std::string_view indent);
--- a/src/libcmd/installable-attr-path.cc
+++ b/src/libcmd/installable-attr-path.cc
@ -72,7 +72,7 @@ DerivedPathsWithInfo InstallableAttrPath::toDerivedPaths()

        auto newOutputs = std::visit(overloaded {
            [&](const ExtendedOutputsSpec::Default & d) -> OutputsSpec {
-                std::set<std::string> outputsToInstall;
+                StringSet outputsToInstall;
                for (auto & output : packageInfo.queryOutputs(false, true))
                    outputsToInstall.insert(output.first);
                if (outputsToInstall.empty())
--- a/src/libcmd/installable-flake.cc
+++ b/src/libcmd/installable-flake.cc
@ -117,7 +117,7 @@ DerivedPathsWithInfo InstallableFlake::toDerivedPaths()
            .drvPath = makeConstantStorePathRef(std::move(drvPath)),
            .outputs = std::visit(overloaded {
                [&](const ExtendedOutputsSpec::Default & d) -> OutputsSpec {
-                    std::set<std::string> outputsToInstall;
+                    StringSet outputsToInstall;
                    if (auto aOutputSpecified = attr->maybeGetAttr(state->sOutputSpecified)) {
                        if (aOutputSpecified->getBool()) {
                            if (auto aOutputName = attr->maybeGetAttr("outputName"))
--- a/src/libexpr/attr-path.cc
+++ b/src/libexpr/attr-path.cc
@ -74,7 +74,7 @@ std::pair<Value *, PosIdx> findAlongAttrPath(EvalState & state, const std::strin

            auto a = v->attrs()->get(state.symbols.create(attr));
            if (!a) {
-                std::set<std::string> attrNames;
+                StringSet attrNames;
                for (auto & attr : *v->attrs())
                    attrNames.insert(std::string(state.symbols[attr.name]));

--- a/src/libexpr/eval-cache.cc
+++ b/src/libexpr/eval-cache.cc
@ -492,7 +492,7 @@ Value & AttrCursor::forceValue()
 Suggestions AttrCursor::getSuggestionsForAttr(Symbol name)
 {
    auto attrNames = getAttrs();
-    std::set<std::string> strAttrNames;
+    StringSet strAttrNames;
    for (auto & name : attrNames)
        strAttrNames.insert(std::string(root->state.symbols[name]));

--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@ -1446,7 +1446,7 @@ void ExprSelect::eval(EvalState & state, Env & env, Value & v)
            } else {
                state.forceAttrs(*vAttrs, pos, "while selecting an attribute");
                if (!(j = vAttrs->attrs()->get(name))) {
-                    std::set<std::string> allAttrNames;
+                    StringSet allAttrNames;
                    for (auto & attr : *vAttrs->attrs())
                        allAttrNames.insert(std::string(state.symbols[attr.name]));
                    auto suggestions = Suggestions::bestMatches(allAttrNames, state.symbols[name]);
@ -1603,7 +1603,7 @@ void EvalState::callFunction(Value & fun, std::span<Value *> args, Value & vRes,
                       user. */
                    for (auto & i : *args[0]->attrs())
                        if (!lambda.formals->has(i.name)) {
-                            std::set<std::string> formalNames;
+                            StringSet formalNames;
                            for (auto & formal : lambda.formals->formals)
                                formalNames.insert(std::string(symbols[formal.name]));
                            auto suggestions = Suggestions::bestMatches(formalNames, symbols[i.name]);
--- a/src/libfetchers/mercurial.cc
+++ b/src/libfetchers/mercurial.cc
@ -194,7 +194,7 @@ struct MercurialInputScheme : InputScheme

                input.attrs.insert_or_assign("ref", chomp(runHg({ "branch", "-R", actualUrl })));

-                auto files = tokenizeString<std::set<std::string>>(
+                auto files = tokenizeString<StringSet>(
                    runHg({ "status", "-R", actualUrl, "--clean", "--modified", "--added", "--no-status", "--print0" }), "\0"s);

                Path actualPath(absPath(actualUrl));
--- a/src/libfetchers/tarball.cc
+++ b/src/libfetchers/tarball.cc
@ -224,7 +224,7 @@ ref<SourceAccessor> downloadTarball(
 // An input scheme corresponding to a curl-downloadable resource.
 struct CurlInputScheme : InputScheme
 {
-    const std::set<std::string> transportUrlSchemes = {"file", "http", "https"};
+    const StringSet transportUrlSchemes = {"file", "http", "https"};

    bool hasTarballExtension(std::string_view path) const
    {
@ -236,7 +236,7 @@ struct CurlInputScheme : InputScheme

    virtual bool isValidURL(const ParsedURL & url, bool requireTree) const = 0;

-    static const std::set<std::string> specialParams;
+    static const StringSet specialParams;

    std::optional<Input> inputFromURL(
        const Settings & settings,
--- a/src/libflake/config.cc
+++ b/src/libflake/config.cc
@ -32,7 +32,7 @@ static void writeTrustedList(const TrustedList & trustedList)

 void ConfigFile::apply(const Settings & flakeSettings)
 {
-    std::set<std::string> whitelist{"bash-prompt", "bash-prompt-prefix", "bash-prompt-suffix", "flake-registry", "commit-lock-file-summary", "commit-lockfile-summary"};
+    StringSet whitelist{"bash-prompt", "bash-prompt-prefix", "bash-prompt-suffix", "flake-registry", "commit-lock-file-summary", "commit-lockfile-summary"};

    for (auto & [name, value] : settings) {

--- a/src/libflake/flake.cc
+++ b/src/libflake/flake.cc
@ -323,7 +323,7 @@ static FlakeRef applySelfAttrs(
 {
    auto newRef(ref);

-    std::set<std::string> allowedAttrs{"submodules", "lfs"};
+    StringSet allowedAttrs{"submodules", "lfs"};

    for (auto & attr : flake.selfAttrs) {
        if (!allowedAttrs.contains(attr.first))
--- a/src/libmain/plugin.cc
+++ b/src/libmain/plugin.cc
@ -19,7 +19,7 @@ struct PluginFilesSetting : public BaseSetting<Paths>
        const Paths & def,
        const std::string & name,
        const std::string & description,
-        const std::set<std::string> & aliases = {})
+        const StringSet & aliases = {})
        : BaseSetting<Paths>(def, true, name, description, aliases)
    {
        options->addSetting(this);
--- a/src/libstore-tests/common-protocol.cc
+++ b/src/libstore-tests/common-protocol.cc
@ -154,7 +154,7 @@ CHARACTERIZATION_TEST(
 CHARACTERIZATION_TEST(
    set,
    "set",
-    (std::tuple<std::set<std::string>, std::set<std::string>, std::set<std::string>, std::set<std::set<std::string>>> {
+    (std::tuple<StringSet, StringSet, StringSet, std::set<StringSet>> {
        { },
        { "" },
        { "", "foo", "bar" },
--- a/src/libstore-tests/outputs-spec.cc
+++ b/src/libstore-tests/outputs-spec.cc
@ -7,7 +7,7 @@
 namespace nix {

 TEST(OutputsSpec, no_empty_names) {
-    ASSERT_DEATH(OutputsSpec::Names { std::set<std::string> { } }, "");
+    ASSERT_DEATH(OutputsSpec::Names { StringSet { } }, "");
 }

 #define TEST_DONT_PARSE(NAME, STR)           \
--- a/src/libstore-tests/serve-protocol.cc
+++ b/src/libstore-tests/serve-protocol.cc
@ -374,7 +374,7 @@ VERSIONED_CHARACTERIZATION_TEST(
    set,
    "set",
    defaultVersion,
-    (std::tuple<std::set<std::string>, std::set<std::string>, std::set<std::string>, std::set<std::set<std::string>>> {
+    (std::tuple<StringSet, StringSet, StringSet, std::set<StringSet>> {
        { },
        { "" },
        { "", "foo", "bar" },
--- a/src/libstore-tests/worker-protocol.cc
+++ b/src/libstore-tests/worker-protocol.cc
@ -574,7 +574,7 @@ VERSIONED_CHARACTERIZATION_TEST(
    set,
    "set",
    defaultVersion,
-    (std::tuple<std::set<std::string>, std::set<std::string>, std::set<std::string>, std::set<std::set<std::string>>> {
+    (std::tuple<StringSet, StringSet, StringSet, std::set<StringSet>> {
        { },
        { "" },
        { "", "foo", "bar" },
--- a/src/libstore/derived-path-map.cc
+++ b/src/libstore/derived-path-map.cc
@ -55,17 +55,17 @@ typename DerivedPathMap<V>::ChildNode * DerivedPathMap<V>::findSlot(const Single
 namespace nix {

 template<>
-bool DerivedPathMap<std::set<std::string>>::ChildNode::operator == (
-    const DerivedPathMap<std::set<std::string>>::ChildNode &) const noexcept = default;
+bool DerivedPathMap<StringSet>::ChildNode::operator == (
+    const DerivedPathMap<StringSet>::ChildNode &) const noexcept = default;

 // TODO libc++ 16 (used by darwin) missing `std::map::operator <=>`, can't do yet.
 #if 0
 template<>
-std::strong_ordering DerivedPathMap<std::set<std::string>>::ChildNode::operator <=> (
-    const DerivedPathMap<std::set<std::string>>::ChildNode &) const noexcept = default;
+std::strong_ordering DerivedPathMap<StringSet>::ChildNode::operator <=> (
+    const DerivedPathMap<StringSet>::ChildNode &) const noexcept = default;
 #endif

-template struct DerivedPathMap<std::set<std::string>>::ChildNode;
-template struct DerivedPathMap<std::set<std::string>>;
+template struct DerivedPathMap<StringSet>::ChildNode;
+template struct DerivedPathMap<StringSet>;

 };
--- a/src/libstore/dummy-store.cc
+++ b/src/libstore/dummy-store.cc
@ -22,7 +22,7 @@ struct DummyStoreConfig : virtual StoreConfig {
          ;
    }

-    static std::set<std::string> uriSchemes() {
+    static StringSet uriSchemes() {
        return {"dummy"};
    }
 };
--- a/src/libstore/include/nix/store/derived-path-map.hh
+++ b/src/libstore/include/nix/store/derived-path-map.hh
@ -91,20 +91,20 @@ struct DerivedPathMap {
 };

 template<>
-bool DerivedPathMap<std::set<std::string>>::ChildNode::operator == (
-    const DerivedPathMap<std::set<std::string>>::ChildNode &) const noexcept;
+bool DerivedPathMap<StringSet>::ChildNode::operator == (
+    const DerivedPathMap<StringSet>::ChildNode &) const noexcept;

 // TODO libc++ 16 (used by darwin) missing `std::map::operator <=>`, can't do yet.
 #if 0
 template<>
-std::strong_ordering DerivedPathMap<std::set<std::string>>::ChildNode::operator <=> (
-    const DerivedPathMap<std::set<std::string>>::ChildNode &) const noexcept;
+std::strong_ordering DerivedPathMap<StringSet>::ChildNode::operator <=> (
+    const DerivedPathMap<StringSet>::ChildNode &) const noexcept;

 template<>
-inline auto DerivedPathMap<std::set<std::string>>::operator <=> (const DerivedPathMap<std::set<std::string>> &) const noexcept = default;
+inline auto DerivedPathMap<StringSet>::operator <=> (const DerivedPathMap<StringSet> &) const noexcept = default;
 #endif

-extern template struct DerivedPathMap<std::set<std::string>>::ChildNode;
-extern template struct DerivedPathMap<std::set<std::string>>;
+extern template struct DerivedPathMap<StringSet>::ChildNode;
+extern template struct DerivedPathMap<StringSet>;

 }
--- a/src/libstore/include/nix/store/globals.hh
+++ b/src/libstore/include/nix/store/globals.hh
@ -24,7 +24,7 @@ struct MaxBuildJobsSetting : public BaseSetting<unsigned int>
        unsigned int def,
        const std::string & name,
        const std::string & description,
-        const std::set<std::string> & aliases = {})
+        const StringSet & aliases = {})
        : BaseSetting<unsigned int>(def, true, name, description, aliases)
    {
        options->addSetting(this);
--- a/src/libstore/include/nix/store/http-binary-cache-store.hh
+++ b/src/libstore/include/nix/store/http-binary-cache-store.hh
@ -15,10 +15,10 @@ struct HttpBinaryCacheStoreConfig : virtual BinaryCacheStoreConfig
        return "HTTP Binary Cache Store";
    }

-    static std::set<std::string> uriSchemes()
+    static StringSet uriSchemes()
    {
        static bool forceHttp = getEnv("_NIX_FORCE_HTTP") == "1";
-        auto ret = std::set<std::string>({"http", "https"});
+        auto ret = StringSet({"http", "https"});
        if (forceHttp)
            ret.insert("file");
        return ret;
--- a/src/libstore/include/nix/store/legacy-ssh-store.hh
+++ b/src/libstore/include/nix/store/legacy-ssh-store.hh
@ -37,7 +37,7 @@ struct LegacySSHStoreConfig : virtual CommonSSHStoreConfig

    const std::string name() override { return "SSH Store"; }

-    static std::set<std::string> uriSchemes() { return {"ssh"}; }
+    static StringSet uriSchemes() { return {"ssh"}; }

    std::string doc() override;
 };
--- a/src/libstore/include/nix/store/local-binary-cache-store.hh
+++ b/src/libstore/include/nix/store/local-binary-cache-store.hh
@ -15,7 +15,7 @@ struct LocalBinaryCacheStoreConfig : virtual BinaryCacheStoreConfig
        return "Local Binary Cache Store";
    }

-    static std::set<std::string> uriSchemes();
+    static StringSet uriSchemes();

    std::string doc() override;
 };
--- a/src/libstore/include/nix/store/local-overlay-store.hh
+++ b/src/libstore/include/nix/store/local-overlay-store.hh
@ -63,7 +63,7 @@ struct LocalOverlayStoreConfig : virtual LocalStoreConfig
        return ExperimentalFeature::LocalOverlayStore;
    }

-    static std::set<std::string> uriSchemes()
+    static StringSet uriSchemes()
    {
        return { "local-overlay" };
    }
--- a/src/libstore/include/nix/store/local-store.hh
+++ b/src/libstore/include/nix/store/local-store.hh
@ -67,7 +67,7 @@ struct LocalStoreConfig : virtual LocalFSStoreConfig

    const std::string name() override { return "Local Store"; }

-    static std::set<std::string> uriSchemes()
+    static StringSet uriSchemes()
    { return {"local"}; }

    std::string doc() override;
--- a/src/libstore/include/nix/store/machines.hh
+++ b/src/libstore/include/nix/store/machines.hh
@ -15,12 +15,12 @@ typedef std::vector<Machine> Machines;
 struct Machine {

    const StoreReference storeUri;
-    const std::set<std::string> systemTypes;
+    const StringSet systemTypes;
    const std::string sshKey;
    const unsigned int maxJobs;
    const float speedFactor;
-    const std::set<std::string> supportedFeatures;
-    const std::set<std::string> mandatoryFeatures;
+    const StringSet supportedFeatures;
+    const StringSet mandatoryFeatures;
    const std::string sshPublicHostKey;
    bool enabled = true;

@ -34,12 +34,12 @@ struct Machine {
     * @return Whether `features` is a subset of the union of `supportedFeatures` and
     * `mandatoryFeatures`.
     */
-    bool allSupported(const std::set<std::string> & features) const;
+    bool allSupported(const StringSet & features) const;

    /**
     * @return Whether `mandatoryFeatures` is a subset of `features`.
     */
-    bool mandatoryMet(const std::set<std::string> & features) const;
+    bool mandatoryMet(const StringSet & features) const;

    Machine(
        const std::string & storeUri,
@ -75,7 +75,7 @@ struct Machine {
     * with `@` are interpreted as paths to other configuration files in
     * the same format.
     */
-    static Machines parseConfig(const std::set<std::string> & defaultSystems, const std::string & config);
+    static Machines parseConfig(const StringSet & defaultSystems, const std::string & config);
 };

 /**
--- a/src/libstore/include/nix/store/path-with-outputs.hh
+++ b/src/libstore/include/nix/store/path-with-outputs.hh
@ -19,7 +19,7 @@ struct StoreDirConfig;
 struct StorePathWithOutputs
 {
    StorePath path;
-    std::set<std::string> outputs;
+    StringSet outputs;

    std::string to_string(const StoreDirConfig & store) const;

--- a/src/libstore/include/nix/store/s3-binary-cache-store.hh
+++ b/src/libstore/include/nix/store/s3-binary-cache-store.hh
@ -98,7 +98,7 @@ public:
        return "S3 Binary Cache Store";
    }

-    static std::set<std::string> uriSchemes()
+    static StringSet uriSchemes()
    {
        return {"s3"};
    }
--- a/src/libstore/include/nix/store/ssh-store.hh
+++ b/src/libstore/include/nix/store/ssh-store.hh
@ -23,7 +23,7 @@ struct SSHStoreConfig : virtual RemoteStoreConfig, virtual CommonSSHStoreConfig
        return "Experimental SSH Store";
    }

-    static std::set<std::string> uriSchemes()
+    static StringSet uriSchemes()
    {
        return {"ssh-ng"};
    }
@ -45,7 +45,7 @@ struct MountedSSHStoreConfig : virtual SSHStoreConfig, virtual LocalFSStoreConfi
        return "Experimental SSH Store with filesystem mounted";
    }

-    static std::set<std::string> uriSchemes()
+    static StringSet uriSchemes()
    {
        return {"mounted-ssh-ng"};
    }
--- a/src/libstore/include/nix/store/store-api.hh
+++ b/src/libstore/include/nix/store/store-api.hh
@ -888,7 +888,7 @@ std::list<ref<Store>> getDefaultSubstituters();

 struct StoreFactory
 {
-    std::set<std::string> uriSchemes;
+    StringSet uriSchemes;
    /**
     * The `authorityPath` parameter is `<authority>/<path>`, or really
     * whatever comes after `<scheme>://` and before `?<query-params>`.
--- a/src/libstore/include/nix/store/uds-remote-store.hh
+++ b/src/libstore/include/nix/store/uds-remote-store.hh
@ -38,7 +38,7 @@ protected:
    static constexpr char const * scheme = "unix";

 public:
-    static std::set<std::string> uriSchemes()
+    static StringSet uriSchemes()
    { return {scheme}; }
 };

--- a/src/libstore/local-binary-cache-store.cc
+++ b/src/libstore/local-binary-cache-store.cc
@ -119,7 +119,7 @@ bool LocalBinaryCacheStore::fileExists(const std::string & path)
    return pathExists(binaryCacheDir + "/" + path);
 }

-std::set<std::string> LocalBinaryCacheStoreConfig::uriSchemes()
+StringSet LocalBinaryCacheStoreConfig::uriSchemes()
 {
    if (getEnv("_NIX_FORCE_HTTP") == "1")
        return {};
--- a/src/libstore/local-store.cc
+++ b/src/libstore/local-store.cc
@ -535,7 +535,7 @@ void LocalStore::upgradeDBSchema(State & state)
 {
    state.db.exec("create table if not exists SchemaMigrations (migration text primary key not null);");

-    std::set<std::string> schemaMigrations;
+    StringSet schemaMigrations;

    {
        SQLiteStmt querySchemaMigrations;
--- a/src/libstore/machines.cc
+++ b/src/libstore/machines.cc
@ -47,7 +47,7 @@ bool Machine::systemSupported(const std::string & system) const
    return system == "builtin" || (systemTypes.count(system) > 0);
 }

-bool Machine::allSupported(const std::set<std::string> & features) const
+bool Machine::allSupported(const StringSet & features) const
 {
    return std::all_of(features.begin(), features.end(),
        [&](const std::string & feature) {
@ -56,7 +56,7 @@ bool Machine::allSupported(const std::set<std::string> & features) const
        });
 }

-bool Machine::mandatoryMet(const std::set<std::string> & features) const
+bool Machine::mandatoryMet(const StringSet & features) const
 {
    return std::all_of(mandatoryFeatures.begin(), mandatoryFeatures.end(),
        [&](const std::string & feature) {
@ -134,7 +134,7 @@ static std::vector<std::string> expandBuilderLines(const std::string & builders)
    return result;
 }

-static Machine parseBuilderLine(const std::set<std::string> & defaultSystems, const std::string & line)
+static Machine parseBuilderLine(const StringSet & defaultSystems, const std::string & line)
 {
    const auto tokens = tokenizeString<std::vector<std::string>>(line);

@ -178,7 +178,7 @@ static Machine parseBuilderLine(const std::set<std::string> & defaultSystems, co
        // `storeUri`
        tokens[0],
        // `systemTypes`
-        isSet(1) ? tokenizeString<std::set<std::string>>(tokens[1], ",") : defaultSystems,
+        isSet(1) ? tokenizeString<StringSet>(tokens[1], ",") : defaultSystems,
        // `sshKey`
        isSet(2) ? tokens[2] : "",
        // `maxJobs`
@ -186,15 +186,15 @@ static Machine parseBuilderLine(const std::set<std::string> & defaultSystems, co
        // `speedFactor`
        isSet(4) ? parseFloatField(4) : 1.0f,
        // `supportedFeatures`
-        isSet(5) ? tokenizeString<std::set<std::string>>(tokens[5], ",") : std::set<std::string>{},
+        isSet(5) ? tokenizeString<StringSet>(tokens[5], ",") : StringSet{},
        // `mandatoryFeatures`
-        isSet(6) ? tokenizeString<std::set<std::string>>(tokens[6], ",") : std::set<std::string>{},
+        isSet(6) ? tokenizeString<StringSet>(tokens[6], ",") : StringSet{},
        // `sshPublicHostKey`
        isSet(7) ? ensureBase64(7) : ""
    };
 }

-static Machines parseBuilderLines(const std::set<std::string> & defaultSystems, const std::vector<std::string> & builders)
+static Machines parseBuilderLines(const StringSet & defaultSystems, const std::vector<std::string> & builders)
 {
    Machines result;
    std::transform(
@ -203,7 +203,7 @@ static Machines parseBuilderLines(const std::set<std::string> & defaultSystems,
    return result;
 }

-Machines Machine::parseConfig(const std::set<std::string> & defaultSystems, const std::string & s)
+Machines Machine::parseConfig(const StringSet & defaultSystems, const std::string & s)
 {
    const auto builderLines = expandBuilderLines(s);
    return parseBuilderLines(defaultSystems, builderLines);
--- a/src/libstore/path-with-outputs.cc
+++ b/src/libstore/path-with-outputs.cc
@ -82,9 +82,9 @@ std::pair<std::string_view, StringSet> parsePathWithOutputs(std::string_view s)
 {
    size_t n = s.find("!");
    return n == s.npos
-        ? std::make_pair(s, std::set<std::string>())
+        ? std::make_pair(s, StringSet())
        : std::make_pair(s.substr(0, n),
-            tokenizeString<std::set<std::string>>(s.substr(n + 1), ","));
+            tokenizeString<StringSet>(s.substr(n + 1), ","));
 }


--- a/src/libutil/args.cc
+++ b/src/libutil/args.cc
@ -593,7 +593,7 @@ MultiCommand::MultiCommand(std::string_view commandName, const Commands & comman
            assert(!command);
            auto i = commands.find(s);
            if (i == commands.end()) {
-                std::set<std::string> commandNames;
+                StringSet commandNames;
                for (auto & [name, _] : commands)
                    commandNames.insert(name);
                auto suggestions = Suggestions::bestMatches(commandNames, s);
--- a/src/libutil/configuration.cc
+++ b/src/libutil/configuration.cc
@ -220,7 +220,7 @@ void Config::convertToArgs(Args & args, const std::string & category)
 AbstractSetting::AbstractSetting(
    const std::string & name,
    const std::string & description,
-    const std::set<std::string> & aliases,
+    const StringSet & aliases,
    std::optional<ExperimentalFeature> experimentalFeature)
    : name(name)
    , description(stripIndentation(description))
@ -428,7 +428,7 @@ PathSetting::PathSetting(Config * options,
    const Path & def,
    const std::string & name,
    const std::string & description,
-    const std::set<std::string> & aliases)
+    const StringSet & aliases)
    : BaseSetting<Path>(def, true, name, description, aliases)
 {
    options->addSetting(this);
@ -444,7 +444,7 @@ OptionalPathSetting::OptionalPathSetting(Config * options,
    const std::optional<Path> & def,
    const std::string & name,
    const std::string & description,
-    const std::set<std::string> & aliases)
+    const StringSet & aliases)
    : BaseSetting<std::optional<Path>>(def, true, name, description, aliases)
 {
    options->addSetting(this);
--- a/src/libutil/experimental-features.cc
+++ b/src/libutil/experimental-features.cc
@ -358,7 +358,7 @@ nlohmann::json documentExperimentalFeatures()
    return (nlohmann::json) res;
 }

-std::set<ExperimentalFeature> parseFeatures(const std::set<std::string> & rawFeatures)
+std::set<ExperimentalFeature> parseFeatures(const StringSet & rawFeatures)
 {
    std::set<ExperimentalFeature> res;
    for (auto & rawFeature : rawFeatures)
--- a/src/libutil/hash.cc
+++ b/src/libutil/hash.cc
@ -32,9 +32,9 @@ static size_t regularHashSize(HashAlgorithm type) {
 }


-const std::set<std::string> hashAlgorithms = {"blake3", "md5", "sha1", "sha256", "sha512" };
+const StringSet hashAlgorithms = {"blake3", "md5", "sha1", "sha256", "sha512" };

-const std::set<std::string> hashFormats = {"base64", "nix32", "base16", "sri" };
+const StringSet hashFormats = {"base64", "nix32", "base16", "sri" };

 Hash::Hash(HashAlgorithm algo, const ExperimentalFeatureSettings & xpSettings) : algo(algo)
 {
--- a/src/libutil/include/nix/util/args.hh
+++ b/src/libutil/include/nix/util/args.hh
@ -179,7 +179,7 @@ public:
        using ptr = std::shared_ptr<Flag>;

        std::string longName;
-        std::set<std::string> aliases;
+        StringSet aliases;
        char shortName = 0;
        std::string description;
        std::string category;
@ -263,7 +263,7 @@ protected:
    virtual Strings::iterator rewriteArgs(Strings & args, Strings::iterator pos)
    { return pos; }

-    std::set<std::string> hiddenCategories;
+    StringSet hiddenCategories;

    /**
     * Called after all command line flags before the first non-flag
--- a/src/libutil/include/nix/util/configuration.hh
+++ b/src/libutil/include/nix/util/configuration.hh
@ -179,7 +179,7 @@ public:

    const std::string name;
    const std::string description;
-    const std::set<std::string> aliases;
+    const StringSet aliases;

    int created = 123;

@ -192,7 +192,7 @@ protected:
    AbstractSetting(
        const std::string & name,
        const std::string & description,
-        const std::set<std::string> & aliases,
+        const StringSet & aliases,
        std::optional<ExperimentalFeature> experimentalFeature = std::nullopt);

    virtual ~AbstractSetting();
@ -251,7 +251,7 @@ public:
        const bool documentDefault,
        const std::string & name,
        const std::string & description,
-        const std::set<std::string> & aliases = {},
+        const StringSet & aliases = {},
        std::optional<ExperimentalFeature> experimentalFeature = std::nullopt)
        : AbstractSetting(name, description, aliases, experimentalFeature)
        , value(def)
@ -323,7 +323,7 @@ public:
        const T & def,
        const std::string & name,
        const std::string & description,
-        const std::set<std::string> & aliases = {},
+        const StringSet & aliases = {},
        const bool documentDefault = true,
        std::optional<ExperimentalFeature> experimentalFeature = std::nullopt)
        : BaseSetting<T>(def, documentDefault, name, description, aliases, std::move(experimentalFeature))
@ -349,7 +349,7 @@ public:
        const Path & def,
        const std::string & name,
        const std::string & description,
-        const std::set<std::string> & aliases = {});
+        const StringSet & aliases = {});

    Path parse(const std::string & str) const override;

@ -371,7 +371,7 @@ public:
        const std::optional<Path> & def,
        const std::string & name,
        const std::string & description,
-        const std::set<std::string> & aliases = {});
+        const StringSet & aliases = {});

    std::optional<Path> parse(const std::string & str) const override;

--- a/src/libutil/include/nix/util/experimental-features.hh
+++ b/src/libutil/include/nix/util/experimental-features.hh
@ -76,7 +76,7 @@ std::ostream & operator<<(
 * Parse a set of strings to the corresponding set of experimental
 * features, ignoring (but warning for) any unknown feature.
 */
-std::set<ExperimentalFeature> parseFeatures(const std::set<std::string> &);
+std::set<ExperimentalFeature> parseFeatures(const StringSet &);

 /**
 * An experimental feature was required for some (experimental)
--- a/src/libutil/include/nix/util/hash.hh
+++ b/src/libutil/include/nix/util/hash.hh
@ -20,7 +20,7 @@ const int sha1HashSize = 20;
 const int sha256HashSize = 32;
 const int sha512HashSize = 64;

-extern const std::set<std::string> hashAlgorithms;
+extern const StringSet hashAlgorithms;

 extern const std::string nix32Chars;

@ -40,7 +40,7 @@ enum struct HashFormat : int {
    SRI
 };

-extern const std::set<std::string> hashFormats;
+extern const StringSet hashFormats;

 struct Hash
 {
--- a/src/libutil/include/nix/util/strings.hh
+++ b/src/libutil/include/nix/util/strings.hh
@ -1,5 +1,7 @@
 #pragma once

+#include "nix/util/types.hh"
+
 #include <list>
 #include <set>
 #include <string_view>
@ -30,7 +32,7 @@ template<class C>
 C tokenizeString(std::string_view s, std::string_view separators = " \t\n\r");

 extern template std::list<std::string> tokenizeString(std::string_view s, std::string_view separators);
-extern template std::set<std::string> tokenizeString(std::string_view s, std::string_view separators);
+extern template StringSet tokenizeString(std::string_view s, std::string_view separators);
 extern template std::vector<std::string> tokenizeString(std::string_view s, std::string_view separators);

 /**
@ -44,7 +46,7 @@ template<typename C>
 C splitString(std::string_view s, std::string_view separators);

 extern template std::list<std::string> splitString(std::string_view s, std::string_view separators);
-extern template std::set<std::string> splitString(std::string_view s, std::string_view separators);
+extern template StringSet splitString(std::string_view s, std::string_view separators);
 extern template std::vector<std::string> splitString(std::string_view s, std::string_view separators);

 /**
@ -54,7 +56,7 @@ template<class C>
 std::string concatStringsSep(const std::string_view sep, const C & ss);

 extern template std::string concatStringsSep(std::string_view, const std::list<std::string> &);
-extern template std::string concatStringsSep(std::string_view, const std::set<std::string> &);
+extern template std::string concatStringsSep(std::string_view, const StringSet &);
 extern template std::string concatStringsSep(std::string_view, const std::vector<std::string> &);
 extern template std::string concatStringsSep(std::string_view, const boost::container::small_vector<std::string, 64> &);

@ -85,7 +87,7 @@ template<class C>
 dropEmptyInitThenConcatStringsSep(const std::string_view sep, const C & ss);

 extern template std::string dropEmptyInitThenConcatStringsSep(std::string_view, const std::list<std::string> &);
-extern template std::string dropEmptyInitThenConcatStringsSep(std::string_view, const std::set<std::string> &);
+extern template std::string dropEmptyInitThenConcatStringsSep(std::string_view, const StringSet &);
 extern template std::string dropEmptyInitThenConcatStringsSep(std::string_view, const std::vector<std::string> &);

 /**
--- a/src/libutil/include/nix/util/suggestions.hh
+++ b/src/libutil/include/nix/util/suggestions.hh
@ -35,7 +35,7 @@ public:
    ) const;

    static Suggestions bestMatches (
-        const std::set<std::string> & allMatches,
+        const StringSet & allMatches,
        std::string_view query
    );

--- a/src/libutil/strings.cc
+++ b/src/libutil/strings.cc
@ -26,18 +26,18 @@ __attribute__((no_sanitize("undefined"))) std::string_view toView(const std::ost
 }

 template std::list<std::string> tokenizeString(std::string_view s, std::string_view separators);
-template std::set<std::string> tokenizeString(std::string_view s, std::string_view separators);
+template StringSet tokenizeString(std::string_view s, std::string_view separators);
 template std::vector<std::string> tokenizeString(std::string_view s, std::string_view separators);

 template std::list<std::string> splitString(std::string_view s, std::string_view separators);
-template std::set<std::string> splitString(std::string_view s, std::string_view separators);
+template StringSet splitString(std::string_view s, std::string_view separators);
 template std::vector<std::string> splitString(std::string_view s, std::string_view separators);

 template std::list<OsString>
 basicSplitString(std::basic_string_view<OsChar> s, std::basic_string_view<OsChar> separators);

 template std::string concatStringsSep(std::string_view, const std::list<std::string> &);
-template std::string concatStringsSep(std::string_view, const std::set<std::string> &);
+template std::string concatStringsSep(std::string_view, const StringSet &);
 template std::string concatStringsSep(std::string_view, const std::vector<std::string> &);
 template std::string concatStringsSep(std::string_view, const boost::container::small_vector<std::string, 64> &);

@ -49,7 +49,7 @@ typedef std::string_view strings_4[4];
 template std::string concatStringsSep(std::string_view, const strings_4 &);

 template std::string dropEmptyInitThenConcatStringsSep(std::string_view, const std::list<std::string> &);
-template std::string dropEmptyInitThenConcatStringsSep(std::string_view, const std::set<std::string> &);
+template std::string dropEmptyInitThenConcatStringsSep(std::string_view, const StringSet &);
 template std::string dropEmptyInitThenConcatStringsSep(std::string_view, const std::vector<std::string> &);

 /**
--- a/src/libutil/suggestions.cc
+++ b/src/libutil/suggestions.cc
@ -38,7 +38,7 @@ int levenshteinDistance(std::string_view first, std::string_view second)
 }

 Suggestions Suggestions::bestMatches (
-    const std::set<std::string> & allMatches,
+    const StringSet & allMatches,
    std::string_view query)
 {
    std::set<Suggestion> res;
--- a/src/nix-build/nix-build.cc
+++ b/src/nix-build/nix-build.cc
@ -147,7 +147,7 @@ static void main_nix_build(int argc, char * * argv)
    std::string outLink = "./result";

    // List of environment variables kept for --pure
-    std::set<std::string> keepVars{
+    StringSet keepVars{
        "HOME", "XDG_RUNTIME_DIR", "USER", "LOGNAME", "DISPLAY",
        "WAYLAND_DISPLAY", "WAYLAND_SOCKET", "PATH", "TERM", "IN_NIX_SHELL",
        "NIX_SHELL_PRESERVE_PROMPT", "TZ", "PAGER", "NIX_BUILD_SHELL", "SHLVL",
--- a/src/nix-env/nix-env.cc
+++ b/src/nix-env/nix-env.cc
@ -238,9 +238,9 @@ static void checkSelectorUse(DrvNames & selectors)

 namespace {

-std::set<std::string> searchByPrefix(const PackageInfos & allElems, std::string_view prefix) {
+StringSet searchByPrefix(const PackageInfos & allElems, std::string_view prefix) {
    constexpr std::size_t maxResults = 3;
-    std::set<std::string> result;
+    StringSet result;
    for (const auto & packageInfo : allElems) {
        const auto drvName = DrvName { packageInfo.queryName() };
        if (hasPrefix(drvName.name, prefix)) {
--- a/src/nix/develop.cc
+++ b/src/nix/develop.cc
@ -67,7 +67,7 @@ struct BuildEnvironment
    {
        BuildEnvironment res;

-        std::set<std::string> exported;
+        StringSet exported;

        for (auto & [name, info] : json["variables"].items()) {
            std::string type = info["type"];
@ -151,7 +151,7 @@ struct BuildEnvironment
        return structuredAttrs->second;
    }

-    void toBash(std::ostream & out, const std::set<std::string> & ignoreVars) const
+    void toBash(std::ostream & out, const StringSet & ignoreVars) const
    {
        for (auto & [name, value] : vars) {
            if (!ignoreVars.count(name)) {
@ -308,7 +308,7 @@ static StorePath getDerivationEnvironment(ref<Store> store, ref<Store> evalStore

 struct Common : InstallableCommand, MixProfile
 {
-    std::set<std::string> ignoreVars{
+    StringSet ignoreVars{
        "BASHOPTS",
        "HOME", // FIXME: don't ignore in pure mode?
        "NIX_BUILD_TOP",
--- a/src/nix/diff-closures.cc
+++ b/src/nix/diff-closures.cc
@ -47,10 +47,10 @@ GroupedPaths getClosureInfo(ref<Store> store, const StorePath & toplevel)
    return groupedPaths;
 }

-std::string showVersions(const std::set<std::string> & versions)
+std::string showVersions(const StringSet & versions)
 {
    if (versions.empty()) return "∅";
-    std::set<std::string> versions2;
+    StringSet versions2;
    for (auto & version : versions)
        versions2.insert(version.empty() ? "ε" : version);
    return concatStringsSep(", ", versions2);
@ -65,7 +65,7 @@ void printClosureDiff(
    auto beforeClosure = getClosureInfo(store, beforePath);
    auto afterClosure = getClosureInfo(store, afterPath);

-    std::set<std::string> allNames;
+    StringSet allNames;
    for (auto & [name, _] : beforeClosure) allNames.insert(name);
    for (auto & [name, _] : afterClosure) allNames.insert(name);

@ -87,11 +87,11 @@ void printClosureDiff(
        auto sizeDelta = (int64_t) afterSize - (int64_t) beforeSize;
        auto showDelta = std::abs(sizeDelta) >= 8 * 1024;

-        std::set<std::string> removed, unchanged;
+        StringSet removed, unchanged;
        for (auto & [version, _] : beforeVersions)
            if (!afterVersions.count(version)) removed.insert(version); else unchanged.insert(version);

-        std::set<std::string> added;
+        StringSet added;
        for (auto & [version, _] : afterVersions)
            if (!beforeVersions.count(version)) added.insert(version);

--- a/src/nix/flake.cc
+++ b/src/nix/flake.cc
@ -386,7 +386,7 @@ struct CmdFlakeCheck : FlakeCommand
            }
        };

-        std::set<std::string> omittedSystems;
+        StringSet omittedSystems;

        // FIXME: rewrite to use EvalCache.

--- a/src/nix/profile.cc
+++ b/src/nix/profile.cc
@ -67,7 +67,7 @@ struct ProfileElement
     * Return a string representing an installable corresponding to the current
     * element, either a flakeref or a plain store path
     */
-    std::set<std::string> toInstallables(Store & store)
+    StringSet toInstallables(Store & store)
    {
        if (source)
            return {source->to_string()};
@ -600,7 +600,7 @@ public:
        });
    }

-    std::set<std::string> getMatchingElementNames(ProfileManifest & manifest) {
+    StringSet getMatchingElementNames(ProfileManifest & manifest) {
        if (_matchers.empty()) {
            throw UsageError("No packages specified.");
        }
@ -614,7 +614,7 @@ public:
            return {};
        }

-        std::set<std::string> result;
+        StringSet result;
        for (auto & matcher : _matchers) {
            bool foundMatch = false;
            for (auto & [name, element] : manifest.elements) {
--- a/src/nix/why-depends.cc
+++ b/src/nix/why-depends.cc
@ -193,7 +193,7 @@ struct CmdWhyDepends : SourceExprCommand, MixOperateOnOptions
            /* Sort the references by distance to `dependency` to
               ensure that the shortest path is printed first. */
            std::multimap<size_t, Node *> refs;
-            std::set<std::string> hashes;
+            StringSet hashes;

            for (auto & ref : node.refs) {
                if (ref == node.path && packagePath != dependencyPath) continue;