style(3p/nix): Add braces around single-line for-loops

These were not caught by the previous clang-tidy invocation, but were
instead sorted out using amber[0] as such:

    ambr --regex 'for (\(.+\))\s([a-z].*;)' 'for $1 { $2 }'

[0]: https://github.com/dalance/amber

third_party/nix/src/libutil/args.cc

@@ -153,7 +153,9 @@ bool Args::processArgs(const Strings& args, bool finish) {
   if ((exp.arity == 0 && finish) ||
       (exp.arity > 0 && args.size() == exp.arity)) {
     std::vector<std::string> ss;
-    for (auto& s : args) ss.push_back(s);
+    for (auto& s : args) {
+      ss.push_back(s);
+    }
     exp.handler(std::move(ss));
     expectedArgs.pop_front();
     res = true;
@@ -189,7 +191,9 @@ Strings argvToStrings(int argc, char** argv) {
 std::string renderLabels(const Strings& labels) {
   std::string res;
   for (auto label : labels) {
-    for (auto& c : label) c = std::toupper(c);
+    for (auto& c : label) {
+      c = std::toupper(c);
+    }
     res += " <" + label + ">";
   }
   return res;
@@ -197,7 +201,9 @@ std::string renderLabels(const Strings& labels) {
 
 void printTable(std::ostream& out, const Table2& table) {
   size_t max = 0;
-  for (auto& row : table) max = std::max(max, row.first.size());
+  for (auto& row : table) {
+    max = std::max(max, row.first.size());
+  }
   for (auto& row : table) {
     out << "  " << row.first << std::string(max - row.first.size() + 2, ' ')
         << row.second << "\n";

third_party/nix/src/libutil/config.cc

@@ -61,7 +61,9 @@ void AbstractConfig::warnUnknownSettings() {
 
 void AbstractConfig::reapplyUnknownSettings() {
   auto unknownSettings2 = std::move(unknownSettings);
-  for (auto& s : unknownSettings2) set(s.first, s.second);
+  for (auto& s : unknownSettings2) {
+    set(s.first, s.second);
+  }
 }
 
 void Config::getSettings(std::map<std::string, SettingInfo>& res,
@@ -138,7 +140,9 @@ void AbstractConfig::applyConfigFile(const Path& path) {
 }
 
 void Config::resetOverriden() {
-  for (auto& s : _settings) s.second.setting->overriden = false;
+  for (auto& s : _settings) {
+    s.second.setting->overriden = false;
+  }
 }
 
 void Config::toJSON(JSONObject& out) {
@@ -250,7 +254,9 @@ std::string BaseSetting<Strings>::to_string() {
 template <>
 void BaseSetting<Strings>::toJSON(JSONPlaceholder& out) {
   JSONList list(out.list());
-  for (auto& s : value) list.elem(s);
+  for (auto& s : value) {
+    list.elem(s);
+  }
 }
 
 template <>
@@ -266,7 +272,9 @@ std::string BaseSetting<StringSet>::to_string() {
 template <>
 void BaseSetting<StringSet>::toJSON(JSONPlaceholder& out) {
   JSONList list(out.list());
-  for (auto& s : value) list.elem(s);
+  for (auto& s : value) {
+    list.elem(s);
+  }
 }
 
 template class BaseSetting<int>;
@@ -308,11 +316,15 @@ void GlobalConfig::getSettings(std::map<std::string, SettingInfo>& res,
 }
 
 void GlobalConfig::resetOverriden() {
-  for (auto& config : *configRegistrations) config->resetOverriden();
+  for (auto& config : *configRegistrations) {
+    config->resetOverriden();
+  }
 }
 
 void GlobalConfig::toJSON(JSONObject& out) {
-  for (auto& config : *configRegistrations) config->toJSON(out);
+  for (auto& config : *configRegistrations) {
+    config->toJSON(out);
+  }
 }
 
 void GlobalConfig::convertToArgs(Args& args, const std::string& category) {

third_party/nix/src/libutil/thread-pool.hh

@@ -125,7 +125,9 @@ void processGraph(ThreadPool& pool, const std::set<T>& nodes,
     }
   };
 
-  for (auto& node : nodes) pool.enqueue(std::bind(worker, std::ref(node)));
+  for (auto& node : nodes) {
+    pool.enqueue(std::bind(worker, std::ref(node)));
+  }
 
   pool.process();
 

third_party/nix/src/libutil/util.cc

@@ -69,7 +69,9 @@ std::map<std::string, std::string> getEnv() {
 }
 
 void clearEnv() {
-  for (auto& name : getEnv()) unsetenv(name.first.c_str());
+  for (auto& name : getEnv()) {
+    unsetenv(name.first.c_str());
+  }
 }
 
 void replaceEnv(std::map<std::string, std::string> newEnv) {
@@ -903,7 +905,9 @@ pid_t startProcess(std::function<void()> fun, const ProcessOptions& options) {
 
 std::vector<char*> stringsToCharPtrs(const Strings& ss) {
   std::vector<char*> res;
-  for (auto& s : ss) res.push_back((char*)s.c_str());
+  for (auto& s : ss) {
+    res.push_back((char*)s.c_str());
+  }
   res.push_back(0);
   return res;
 }
@@ -1215,7 +1219,9 @@ bool hasSuffix(const string& s, const string& suffix) {
 
 std::string toLower(const std::string& s) {
   std::string r(s);
-  for (auto& c : r) c = std::tolower(c);
+  for (auto& c : r) {
+    c = std::tolower(c);
+  }
   return r;
 }