Refactor: rename C++ concatStringsSep -> dropEmptyInitThenConcatStringsSep

src/build-remote/build-remote.cc

@@ -206,15 +206,15 @@ static int main_build_remote(int argc, char * * argv)
                         error
                             % drvstr
                             % neededSystem
-                            % concatStringsSep<StringSet>(", ", requiredFeatures)
+                            % dropEmptyInitThenConcatStringsSep<StringSet>(", ", requiredFeatures)
                             % machines.size();
 
                         for (auto & m : machines)
                             error
-                                % concatStringsSep<StringSet>(", ", m.systemTypes)
+                                % dropEmptyInitThenConcatStringsSep<StringSet>(", ", m.systemTypes)
                                 % m.maxJobs
-                                % concatStringsSep<StringSet>(", ", m.supportedFeatures)
+                                % dropEmptyInitThenConcatStringsSep<StringSet>(", ", m.supportedFeatures)
-                                % concatStringsSep<StringSet>(", ", m.mandatoryFeatures);
+                                % dropEmptyInitThenConcatStringsSep<StringSet>(", ", m.mandatoryFeatures);
 
                         printMsg(couldBuildLocally ? lvlChatty : lvlWarn, error.str());
 

src/libcmd/command.cc

@@ -42,7 +42,7 @@ void NixMultiCommand::run()
         for (auto & [name, _] : commands)
             subCommandTextLines.insert(fmt("- `%s`", name));
         std::string markdownError = fmt("`nix %s` requires a sub-command. Available sub-commands:\n\n%s\n",
-                commandName, concatStringsSep("\n", subCommandTextLines));
+                commandName, dropEmptyInitThenConcatStringsSep("\n", subCommandTextLines));
         throw UsageError(renderMarkdownToTerminal(markdownError));
     }
     command->second->run();

src/libcmd/installables.cc

@@ -374,7 +374,7 @@ void completeFlakeRefWithFragment(
                         auto attrPath2 = (*attr)->getAttrPath(attr2);
                         /* Strip the attrpath prefix. */
                         attrPath2.erase(attrPath2.begin(), attrPath2.begin() + attrPathPrefix.size());
-                        completions.add(flakeRefS + "#" + prefixRoot + concatStringsSep(".", evalState->symbols.resolve(attrPath2)));
+                        completions.add(flakeRefS + "#" + prefixRoot + dropEmptyInitThenConcatStringsSep(".", evalState->symbols.resolve(attrPath2)));
                     }
                 }
             }
@@ -630,7 +630,7 @@ static void throwBuildErrors(
                 }
                 failedPaths.insert(failedResult->path.to_string(store));
             }
-            throw Error("build of %s failed", concatStringsSep(", ", quoteStrings(failedPaths)));
+            throw Error("build of %s failed", dropEmptyInitThenConcatStringsSep(", ", quoteStrings(failedPaths)));
         }
     }
 }

src/libcmd/repl.cc

@@ -625,7 +625,7 @@ ProcessLineResult NixRepl::processLine(std::string line)
 
                 markdown +=
                     "**Synopsis:** `builtins." + (std::string) (*doc->name) + "` "
-                    + concatStringsSep(" ", args) + "\n\n";
+                    + dropEmptyInitThenConcatStringsSep(" ", args) + "\n\n";
             }
 
             markdown += stripIndentation(doc->doc);

src/libexpr/eval-cache.cc

@@ -225,7 +225,7 @@ struct AttrDb
                 (key.first)
                 (symbols[key.second])
                 (AttrType::ListOfStrings)
-                (concatStringsSep("\t", l)).exec();
+                (dropEmptyInitThenConcatStringsSep("\t", l)).exec();
 
             return state->db.getLastInsertedRowId();
         });
@@ -435,12 +435,12 @@ std::vector<Symbol> AttrCursor::getAttrPath(Symbol name) const
 
 std::string AttrCursor::getAttrPathStr() const
 {
-    return concatStringsSep(".", root->state.symbols.resolve(getAttrPath()));
+    return dropEmptyInitThenConcatStringsSep(".", root->state.symbols.resolve(getAttrPath()));
 }
 
 std::string AttrCursor::getAttrPathStr(Symbol name) const
 {
-    return concatStringsSep(".", root->state.symbols.resolve(getAttrPath(name)));
+    return dropEmptyInitThenConcatStringsSep(".", root->state.symbols.resolve(getAttrPath(name)));
 }
 
 Value & AttrCursor::forceValue()

src/libflake/flake/config.cc

@@ -47,7 +47,7 @@ void ConfigFile::apply(const Settings & flakeSettings)
         else if (auto* b = std::get_if<Explicit<bool>>(&value))
             valueS = b->t ? "true" : "false";
         else if (auto ss = std::get_if<std::vector<std::string>>(&value))
-            valueS = concatStringsSep(" ", *ss); // FIXME: evil
+            valueS = dropEmptyInitThenConcatStringsSep(" ", *ss); // FIXME: evil
         else
             assert(false);
 

src/libflake/flake/lockfile.cc

@@ -61,7 +61,7 @@ static std::shared_ptr<Node> doFind(const ref<Node>& root, const InputPath & pat
         std::vector<std::string> cycle;
         std::transform(found, visited.cend(), std::back_inserter(cycle), printInputPath);
         cycle.push_back(printInputPath(path));
-        throw Error("follow cycle detected: [%s]", concatStringsSep(" -> ", cycle));
+        throw Error("follow cycle detected: [%s]", dropEmptyInitThenConcatStringsSep(" -> ", cycle));
     }
     visited.push_back(path);
 
@@ -367,7 +367,7 @@ void check();
 
 std::string printInputPath(const InputPath & path)
 {
-    return concatStringsSep("/", path);
+    return dropEmptyInitThenConcatStringsSep("/", path);
 }
 
 }

src/libmain/shared.cc

@@ -301,11 +301,11 @@ void printVersion(const std::string & programName)
 #endif
         cfg.push_back("signed-caches");
         std::cout << "System type: " << settings.thisSystem << "\n";
-        std::cout << "Additional system types: " << concatStringsSep(", ", settings.extraPlatforms.get()) << "\n";
+        std::cout << "Additional system types: " << dropEmptyInitThenConcatStringsSep(", ", settings.extraPlatforms.get()) << "\n";
-        std::cout << "Features: " << concatStringsSep(", ", cfg) << "\n";
+        std::cout << "Features: " << dropEmptyInitThenConcatStringsSep(", ", cfg) << "\n";
         std::cout << "System configuration file: " << settings.nixConfDir + "/nix.conf" << "\n";
         std::cout << "User configuration files: " <<
-            concatStringsSep(":", settings.nixUserConfFiles)
+            dropEmptyInitThenConcatStringsSep(":", settings.nixUserConfFiles)
             << "\n";
         std::cout << "Store directory: " << settings.nixStore << "\n";
         std::cout << "State directory: " << settings.nixStateDir << "\n";

src/libstore/build/derivation-goal.cc

@@ -895,7 +895,7 @@ void runPostBuildHook(
     std::map<std::string, std::string> hookEnvironment = getEnv();
 
     hookEnvironment.emplace("DRV_PATH", store.printStorePath(drvPath));
-    hookEnvironment.emplace("OUT_PATHS", chomp(concatStringsSep(" ", store.printStorePathSet(outputPaths))));
+    hookEnvironment.emplace("OUT_PATHS", chomp(dropEmptyInitThenConcatStringsSep(" ", store.printStorePathSet(outputPaths))));
     hookEnvironment.emplace("NIX_CONFIG", globalConfig.toKeyValue());
 
     struct LogSink : Sink {
@@ -1505,7 +1505,7 @@ std::pair<bool, SingleDrvOutputs> DerivationGoal::checkPathValidity()
     if (!wantedOutputsLeft.empty())
         throw Error("derivation '%s' does not have wanted outputs %s",
             worker.store.printStorePath(drvPath),
-            concatStringsSep(", ", quoteStrings(wantedOutputsLeft)));
+            dropEmptyInitThenConcatStringsSep(", ", quoteStrings(wantedOutputsLeft)));
 
     bool allValid = true;
     for (auto & [_, status] : initialOutputs) {

src/libstore/build/entry-points.cc

@@ -42,7 +42,7 @@ void Store::buildPaths(const std::vector<DerivedPath> & reqs, BuildMode buildMod
         throw std::move(*ex);
     } else if (!failed.empty()) {
         if (ex) logError(ex->info());
-        throw Error(worker.failingExitStatus(), "build of %s failed", concatStringsSep(", ", quoteStrings(failed)));
+        throw Error(worker.failingExitStatus(), "build of %s failed", dropEmptyInitThenConcatStringsSep(", ", quoteStrings(failed)));
     }
 }
 

src/libstore/globals.cc

@@ -82,7 +82,7 @@ Settings::Settings()
         Strings ss;
         for (auto & p : tokenizeString<Strings>(*s, ":"))
             ss.push_back("@" + p);
-        builders = concatStringsSep(" ", ss);
+        builders = dropEmptyInitThenConcatStringsSep(" ", ss);
     }
 
 #if defined(__linux__) && defined(SANDBOX_SHELL)

src/libstore/local-store.cc

@@ -656,7 +656,7 @@ void LocalStore::registerDrvOutput(const Realisation & info)
                 combinedSignatures.insert(info.signatures.begin(),
                     info.signatures.end());
                 state->stmts->UpdateRealisedOutput.use()
-                    (concatStringsSep(" ", combinedSignatures))
+                    (dropEmptyInitThenConcatStringsSep(" ", combinedSignatures))
                     (info.id.strHash())
                     (info.id.outputName)
                     .exec();
@@ -675,7 +675,7 @@ void LocalStore::registerDrvOutput(const Realisation & info)
                 (info.id.strHash())
                 (info.id.outputName)
                 (printStorePath(info.outPath))
-                (concatStringsSep(" ", info.signatures))
+                (dropEmptyInitThenConcatStringsSep(" ", info.signatures))
                 .exec();
         }
         for (auto & [outputId, depPath] : info.dependentRealisations) {
@@ -729,7 +729,7 @@ uint64_t LocalStore::addValidPath(State & state,
         (info.deriver ? printStorePath(*info.deriver) : "", (bool) info.deriver)
         (info.narSize, info.narSize != 0)
         (info.ultimate ? 1 : 0, info.ultimate)
-        (concatStringsSep(" ", info.sigs), !info.sigs.empty())
+        (dropEmptyInitThenConcatStringsSep(" ", info.sigs), !info.sigs.empty())
         (renderContentAddress(info.ca), (bool) info.ca)
         .exec();
     uint64_t id = state.db.getLastInsertedRowId();
@@ -833,7 +833,7 @@ void LocalStore::updatePathInfo(State & state, const ValidPathInfo & info)
         (info.narSize, info.narSize != 0)
         (info.narHash.to_string(HashFormat::Base16, true))
         (info.ultimate ? 1 : 0, info.ultimate)
-        (concatStringsSep(" ", info.sigs), !info.sigs.empty())
+        (dropEmptyInitThenConcatStringsSep(" ", info.sigs), !info.sigs.empty())
         (renderContentAddress(info.ca), (bool) info.ca)
         (printStorePath(info.path))
         .exec();

src/libstore/misc.cc

@@ -464,7 +464,7 @@ OutputPathMap resolveDerivedPath(Store & store, const DerivedPath::Built & bfd)
     if (!outputsLeft.empty())
         throw Error("derivation '%s' does not have an outputs %s",
             store.printStorePath(drvPath),
-            concatStringsSep(", ", quoteStrings(std::get<OutputsSpec::Names>(bfd.outputs.raw))));
+            dropEmptyInitThenConcatStringsSep(", ", quoteStrings(std::get<OutputsSpec::Names>(bfd.outputs.raw))));
     return outputMap;
 }
 

src/libstore/nar-info-disk-cache.cc

@@ -337,9 +337,9 @@ public:
                     (narInfo ? narInfo->fileSize : 0, narInfo != 0 && narInfo->fileSize)
                     (info->narHash.to_string(HashFormat::Nix32, true))
                     (info->narSize)
-                    (concatStringsSep(" ", info->shortRefs()))
+                    (dropEmptyInitThenConcatStringsSep(" ", info->shortRefs()))
                     (info->deriver ? std::string(info->deriver->to_string()) : "", (bool) info->deriver)
-                    (concatStringsSep(" ", info->sigs))
+                    (dropEmptyInitThenConcatStringsSep(" ", info->sigs))
                     (renderContentAddress(info->ca))
                     (time(0)).exec();
 

src/libstore/nar-info.cc

@@ -111,7 +111,7 @@ std::string NarInfo::to_string(const Store & store) const
     res += "NarHash: " + narHash.to_string(HashFormat::Nix32, true) + "\n";
     res += "NarSize: " + std::to_string(narSize) + "\n";
 
-    res += "References: " + concatStringsSep(" ", shortRefs()) + "\n";
+    res += "References: " + dropEmptyInitThenConcatStringsSep(" ", shortRefs()) + "\n";
 
     if (deriver)
         res += "Deriver: " + std::string(deriver->to_string()) + "\n";

src/libstore/outputs-spec.cc

@@ -83,7 +83,7 @@ std::string OutputsSpec::to_string() const
             return "*";
         },
         [&](const OutputsSpec::Names & outputNames) -> std::string {
-            return concatStringsSep(",", outputNames);
+            return dropEmptyInitThenConcatStringsSep(",", outputNames);
         },
     }, raw);
 }

src/libstore/path-info.cc

@@ -30,7 +30,7 @@ std::string ValidPathInfo::fingerprint(const Store & store) const
             "1;" + store.printStorePath(path) + ";"
             + narHash.to_string(HashFormat::Nix32, true) + ";"
             + std::to_string(narSize) + ";"
-        + concatStringsSep(",", store.printStorePathSet(references));
+        + dropEmptyInitThenConcatStringsSep(",", store.printStorePathSet(references));
 }
 
 

src/libstore/path-with-outputs.cc

@@ -9,7 +9,7 @@ std::string StorePathWithOutputs::to_string(const StoreDirConfig & store) const
 {
     return outputs.empty()
         ? store.printStorePath(path)
-        : store.printStorePath(path) + "!" + concatStringsSep(",", outputs);
+        : store.printStorePath(path) + "!" + dropEmptyInitThenConcatStringsSep(",", outputs);
 }
 
 

src/libstore/store-api.cc

@@ -1208,7 +1208,7 @@ std::string StoreDirConfig::showPaths(const StorePathSet & paths)
 
 std::string showPaths(const PathSet & paths)
 {
-    return concatStringsSep(", ", quoteStrings(paths));
+    return dropEmptyInitThenConcatStringsSep(", ", quoteStrings(paths));
 }
 
 

src/libstore/unix/build/hook-instance.cc

@@ -8,7 +8,7 @@ namespace nix {
 
 HookInstance::HookInstance()
 {
-    debug("starting build hook '%s'", concatStringsSep(" ", settings.buildHook.get()));
+    debug("starting build hook '%s'", dropEmptyInitThenConcatStringsSep(" ", settings.buildHook.get()));
 
     auto buildHookArgs = settings.buildHook.get();
 

src/libstore/unix/build/local-derivation-goal.cc

@@ -496,10 +496,10 @@ void LocalDerivationGoal::startBuilder()
     if (!parsedDrv->canBuildLocally(worker.store))
         throw Error("a '%s' with features {%s} is required to build '%s', but I am a '%s' with features {%s}",
             drv->platform,
-            concatStringsSep(", ", parsedDrv->getRequiredSystemFeatures()),
+            dropEmptyInitThenConcatStringsSep(", ", parsedDrv->getRequiredSystemFeatures()),
             worker.store.printStorePath(drvPath),
             settings.thisSystem,
-            concatStringsSep<StringSet>(", ", worker.store.systemFeatures));
+            dropEmptyInitThenConcatStringsSep<StringSet>(", ", worker.store.systemFeatures));
 
     /* Create a temporary directory where the build will take
        place. */
@@ -840,7 +840,7 @@ void LocalDerivationGoal::startBuilder()
 
     /* Run the builder. */
     printMsg(lvlChatty, "executing builder '%1%'", drv->builder);
-    printMsg(lvlChatty, "using builder args '%1%'", concatStringsSep(" ", drv->args));
+    printMsg(lvlChatty, "using builder args '%1%'", dropEmptyInitThenConcatStringsSep(" ", drv->args));
     for (auto & i : drv->env)
         printMsg(lvlVomit, "setting builder env variable '%1%'='%2%'", i.first, i.second);
 
@@ -1063,7 +1063,7 @@ void LocalDerivationGoal::startBuilder()
                 e.addTrace({}, "while waiting for the build environment for '%s' to initialize (%s, previous messages: %s)",
                     worker.store.printStorePath(drvPath),
                     statusToString(status),
-                    concatStringsSep("|", msgs));
+                    dropEmptyInitThenConcatStringsSep("|", msgs));
                 throw;
             }
         }();

src/libutil/config.cc

@@ -152,7 +152,7 @@ static void parseConfigFiles(const std::string & contents, const std::string & p
 
         parsedContents.push_back({
             std::move(name),
-            concatStringsSep(" ", Strings(i, tokens.end())),
+            dropEmptyInitThenConcatStringsSep(" ", Strings(i, tokens.end())),
         });
     };
 }
@@ -318,7 +318,7 @@ template<> void BaseSetting<Strings>::appendOrSet(Strings newValue, bool append)
 
 template<> std::string BaseSetting<Strings>::to_string() const
 {
-    return concatStringsSep(" ", value);
+    return dropEmptyInitThenConcatStringsSep(" ", value);
 }
 
 template<> StringSet BaseSetting<StringSet>::parse(const std::string & str) const
@@ -334,7 +334,7 @@ template<> void BaseSetting<StringSet>::appendOrSet(StringSet newValue, bool app
 
 template<> std::string BaseSetting<StringSet>::to_string() const
 {
-    return concatStringsSep(" ", value);
+    return dropEmptyInitThenConcatStringsSep(" ", value);
 }
 
 template<> std::set<ExperimentalFeature> BaseSetting<std::set<ExperimentalFeature>>::parse(const std::string & str) const
@@ -362,7 +362,7 @@ template<> std::string BaseSetting<std::set<ExperimentalFeature>>::to_string() c
     StringSet stringifiedXpFeatures;
     for (const auto & feature : value)
         stringifiedXpFeatures.insert(std::string(showExperimentalFeature(feature)));
-    return concatStringsSep(" ", stringifiedXpFeatures);
+    return dropEmptyInitThenConcatStringsSep(" ", stringifiedXpFeatures);
 }
 
 template<> StringMap BaseSetting<StringMap>::parse(const std::string & str) const

src/libutil/util.hh

@@ -37,7 +37,7 @@ template<class C> C tokenizeString(std::string_view s, std::string_view separato
  * elements.
  */
 template<class C>
-std::string concatStringsSep(const std::string_view sep, const C & ss)
+std::string dropEmptyInitThenConcatStringsSep(const std::string_view sep, const C & ss)
 {
     size_t size = 0;
     // need a cast to string_view since this is also called with Symbols
@@ -56,7 +56,7 @@ auto concatStrings(Parts && ... parts)
     -> std::enable_if_t<(... && std::is_convertible_v<Parts, std::string_view>), std::string>
 {
     std::string_view views[sizeof...(parts)] = { parts... };
-    return concatStringsSep({}, views);
+    return dropEmptyInitThenConcatStringsSep({}, views);
 }
 
 

src/nix/develop.cc

@@ -608,7 +608,7 @@ struct CmdDevelop : Common, MixEnvironment
             std::vector<std::string> args;
             for (auto s : command)
                 args.push_back(shellEscape(s));
-            script += fmt("exec %s\n", concatStringsSep(" ", args));
+            script += fmt("exec %s\n", dropEmptyInitThenConcatStringsSep(" ", args));
         }
 
         else {

src/nix/diff-closures.cc

@@ -49,7 +49,7 @@ std::string showVersions(const std::set<std::string> & versions)
     std::set<std::string> versions2;
     for (auto & version : versions)
         versions2.insert(version.empty() ? "ε" : version);
-    return concatStringsSep(", ", versions2);
+    return dropEmptyInitThenConcatStringsSep(", ", versions2);
 }
 
 void printClosureDiff(
@@ -97,7 +97,7 @@ void printClosureDiff(
                 items.push_back(fmt("%s → %s", showVersions(removed), showVersions(added)));
             if (showDelta)
                 items.push_back(fmt("%s%+.1f KiB" ANSI_NORMAL, sizeDelta > 0 ? ANSI_RED : ANSI_GREEN, sizeDelta / 1024.0));
-            logger->cout("%s%s: %s", indent, name, concatStringsSep(", ", items));
+            logger->cout("%s%s: %s", indent, name, dropEmptyInitThenConcatStringsSep(", ", items));
         }
     }
 }

src/nix/env.cc

@@ -94,7 +94,7 @@ struct CmdShell : InstallablesCommand, MixEnvironment
 
         auto unixPath = tokenizeString<Strings>(getEnv("PATH").value_or(""), ":");
         unixPath.insert(unixPath.begin(), pathAdditions.begin(), pathAdditions.end());
-        auto unixPathString = concatStringsSep(":", unixPath);
+        auto unixPathString = dropEmptyInitThenConcatStringsSep(":", unixPath);
         setEnv("PATH", unixPathString.c_str());
 
         Strings args;

src/nix/flake.cc

@@ -805,7 +805,7 @@ struct CmdFlakeCheck : FlakeCommand
             warn(
                 "The check omitted these incompatible systems: %s\n"
                 "Use '--all-systems' to check all.",
-                concatStringsSep(", ", omittedSystems)
+                dropEmptyInitThenConcatStringsSep(", ", omittedSystems)
             );
         };
     };
@@ -1211,7 +1211,7 @@ struct CmdFlakeShow : FlakeCommand, MixJSON
             auto attrPathS = state->symbols.resolve(attrPath);
 
             Activity act(*logger, lvlInfo, actUnknown,
-                fmt("evaluating '%s'", concatStringsSep(".", attrPathS)));
+                fmt("evaluating '%s'", dropEmptyInitThenConcatStringsSep(".", attrPathS)));
 
             try {
                 auto recurse = [&]()
@@ -1291,7 +1291,7 @@ struct CmdFlakeShow : FlakeCommand, MixJSON
                         if (!json)
                             logger->cout(fmt("%s " ANSI_WARNING "omitted" ANSI_NORMAL " (use '--all-systems' to show)", headerPrefix));
                         else {
-                            logger->warn(fmt("%s omitted (use '--all-systems' to show)", concatStringsSep(".", attrPathS)));
+                            logger->warn(fmt("%s omitted (use '--all-systems' to show)", dropEmptyInitThenConcatStringsSep(".", attrPathS)));
                         }
                     } else {
                         if (visitor.isDerivation())
@@ -1315,13 +1315,13 @@ struct CmdFlakeShow : FlakeCommand, MixJSON
                         if (!json)
                             logger->cout(fmt("%s " ANSI_WARNING "omitted" ANSI_NORMAL " (use '--legacy' to show)", headerPrefix));
                         else {
-                            logger->warn(fmt("%s omitted (use '--legacy' to show)", concatStringsSep(".", attrPathS)));
+                            logger->warn(fmt("%s omitted (use '--legacy' to show)", dropEmptyInitThenConcatStringsSep(".", attrPathS)));
                         }
                     } else if (!showAllSystems && std::string(attrPathS[1]) != localSystem) {
                         if (!json)
                             logger->cout(fmt("%s " ANSI_WARNING "omitted" ANSI_NORMAL " (use '--all-systems' to show)", headerPrefix));
                         else {
-                            logger->warn(fmt("%s omitted (use '--all-systems' to show)", concatStringsSep(".", attrPathS)));
+                            logger->warn(fmt("%s omitted (use '--all-systems' to show)", dropEmptyInitThenConcatStringsSep(".", attrPathS)));
                         }
                     } else {
                         if (visitor.isDerivation())

src/nix/main.cc

@@ -185,7 +185,7 @@ struct NixArgs : virtual MultiCommand, virtual MixCommonArgs, virtual RootArgs
         auto & info = i->second;
         if (info.status == AliasStatus::Deprecated) {
             warn("'%s' is a deprecated alias for '%s'",
-                arg, concatStringsSep(" ", info.replacement));
+                arg, dropEmptyInitThenConcatStringsSep(" ", info.replacement));
         }
         pos = args.erase(pos);
         for (auto j = info.replacement.rbegin(); j != info.replacement.rend(); ++j)
@@ -238,7 +238,7 @@ struct NixArgs : virtual MultiCommand, virtual MixCommonArgs, virtual RootArgs
    lowdown. */
 static void showHelp(std::vector<std::string> subcommand, NixArgs & toplevel)
 {
-    auto mdName = subcommand.empty() ? "nix" : fmt("nix3-%s", concatStringsSep("-", subcommand));
+    auto mdName = subcommand.empty() ? "nix" : fmt("nix3-%s", dropEmptyInitThenConcatStringsSep("-", subcommand));
 
     evalSettings.restrictEval = false;
     evalSettings.pureEval = false;
@@ -273,7 +273,7 @@ static void showHelp(std::vector<std::string> subcommand, NixArgs & toplevel)
 
     auto attr = vRes->attrs()->get(state.symbols.create(mdName + ".md"));
     if (!attr)
-        throw UsageError("Nix has no subcommand '%s'", concatStringsSep("", subcommand));
+        throw UsageError("Nix has no subcommand '%s'", dropEmptyInitThenConcatStringsSep("", subcommand));
 
     auto markdown = state.forceString(*attr->value, noPos, "while evaluating the lowdown help text");
 

src/nix/path-info.cc

@@ -185,7 +185,7 @@ struct CmdPathInfo : StorePathsCommand, MixJSON
                     if (info->ultimate) ss.push_back("ultimate");
                     if (info->ca) ss.push_back("ca:" + renderContentAddress(*info->ca));
                     for (auto & sig : info->sigs) ss.push_back(sig);
-                    std::cout << concatStringsSep(" ", ss);
+                    std::cout << dropEmptyInitThenConcatStringsSep(" ", ss);
                 }
 
                 std::cout << std::endl;

src/nix/profile.cc

@@ -58,7 +58,7 @@ struct ProfileElement
         StringSet names;
         for (auto & path : storePaths)
             names.insert(DrvName(path.name()).name);
-        return concatStringsSep(", ", names);
+        return dropEmptyInitThenConcatStringsSep(", ", names);
     }
 
     /**
@@ -472,7 +472,7 @@ struct CmdProfileInstall : InstallablesCommand, MixDefaultProfile
                 originalConflictingFilePath,
                 newConflictingFilePath,
                 originalEntryName,
-                concatStringsSep(" ", newConflictingRefs),
+                dropEmptyInitThenConcatStringsSep(" ", newConflictingRefs),
                 conflictError.priority,
                 conflictError.priority - 1,
                 conflictError.priority + 1
@@ -813,7 +813,7 @@ struct CmdProfileList : virtual EvalCommand, virtual StoreCommand, MixDefaultPro
                     logger->cout("Original flake URL: %s", element.source->originalRef.to_string());
                     logger->cout("Locked flake URL:   %s", element.source->lockedRef.to_string());
                 }
-                logger->cout("Store paths:        %s", concatStringsSep(" ", store->printStorePathSet(element.storePaths)));
+                logger->cout("Store paths:        %s", dropEmptyInitThenConcatStringsSep(" ", store->printStorePathSet(element.storePaths)));
             }
         }
     }

src/nix/search.cc

@@ -96,7 +96,7 @@ struct CmdSearch : InstallableValueCommand, MixJSON
             auto attrPathS = state->symbols.resolve(attrPath);
 
             Activity act(*logger, lvlInfo, actUnknown,
-                fmt("evaluating '%s'", concatStringsSep(".", attrPathS)));
+                fmt("evaluating '%s'", dropEmptyInitThenConcatStringsSep(".", attrPathS)));
             try {
                 auto recurse = [&]()
                 {
@@ -115,7 +115,7 @@ struct CmdSearch : InstallableValueCommand, MixJSON
                     auto aDescription = aMeta ? aMeta->maybeGetAttr(state->sDescription) : nullptr;
                     auto description = aDescription ? aDescription->getString() : "";
                     std::replace(description.begin(), description.end(), '\n', ' ');
-                    auto attrPath2 = concatStringsSep(".", attrPathS);
+                    auto attrPath2 = dropEmptyInitThenConcatStringsSep(".", attrPathS);
 
                     std::vector<std::smatch> attrPathMatches;
                     std::vector<std::smatch> descriptionMatches;

tests/unit/libutil/references.cc

@@ -15,7 +15,7 @@ struct RewriteParams {
             strRewrites.insert(from + "->" + to);
         return os <<
             "OriginalString: " << bar.originalString << std::endl <<
-            "Rewrites: " << concatStringsSep(",", strRewrites) << std::endl <<
+            "Rewrites: " << dropEmptyInitThenConcatStringsSep(",", strRewrites) << std::endl <<
             "Expected result: " << bar.finalString;
     }
 };

tests/unit/libutil/tests.cc

@@ -227,32 +227,32 @@ namespace nix {
     }
 
     /* ----------------------------------------------------------------------------
-     * concatStringsSep
+     * dropEmptyInitThenConcatStringsSep
      * --------------------------------------------------------------------------*/
 
-    TEST(concatStringsSep, buildCommaSeparatedString) {
+    TEST(dropEmptyInitThenConcatStringsSep, buildCommaSeparatedString) {
         Strings strings;
         strings.push_back("this");
         strings.push_back("is");
         strings.push_back("great");
 
-        ASSERT_EQ(concatStringsSep(",", strings), "this,is,great");
+        ASSERT_EQ(dropEmptyInitThenConcatStringsSep(",", strings), "this,is,great");
     }
 
-    TEST(concatStringsSep, buildStringWithEmptySeparator) {
+    TEST(dropEmptyInitThenConcatStringsSep, buildStringWithEmptySeparator) {
         Strings strings;
         strings.push_back("this");
         strings.push_back("is");
         strings.push_back("great");
 
-        ASSERT_EQ(concatStringsSep("", strings), "thisisgreat");
+        ASSERT_EQ(dropEmptyInitThenConcatStringsSep("", strings), "thisisgreat");
     }
 
-    TEST(concatStringsSep, buildSingleString) {
+    TEST(dropEmptyInitThenConcatStringsSep, buildSingleString) {
         Strings strings;
         strings.push_back("this");
 
-        ASSERT_EQ(concatStringsSep(",", strings), "this");
+        ASSERT_EQ(dropEmptyInitThenConcatStringsSep(",", strings), "this");
     }
 
     /* ----------------------------------------------------------------------------