refactor(3p/nix): Apply clang-tidy's readability-* fixes r/788

This applies the readability fixes listed here:

https://clang.llvm.org/extra/clang-tidy/checks/list.html

15 files changed, 79 insertions, 73 deletions

diff --git a/third_party/nix/src/nix/build.cc b/third_party/nix/src/nix/build.cc
index 0738821a89..9ab2d27e0f 100644
--- a/third_party/nix/src/nix/build.cc
+++ b/third_party/nix/src/nix/build.cc
@@ -47,11 +47,11 @@ struct CmdBuild : MixDryRun, InstallablesCommand {
     for (size_t i = 0; i < buildables.size(); ++i) {
       auto& b(buildables[i]);
 
-      if (outLink != "") {
+      if (!outLink.empty()) {
         for (auto& output : b.outputs) {
           if (auto store2 = store.dynamic_pointer_cast<LocalFSStore>()) {
             std::string symlink = outLink;
-            if (i) {
+            if (i != 0u) {
               symlink += fmt("-%d", i);
             }
             if (output.first != "out") {
diff --git a/third_party/nix/src/nix/command.cc b/third_party/nix/src/nix/command.cc
index b0efcb823d..439f22dc3b 100644
--- a/third_party/nix/src/nix/command.cc
+++ b/third_party/nix/src/nix/command.cc
@@ -80,9 +80,8 @@ bool MultiCommand::processFlag(Strings::iterator& pos, Strings::iterator end) {
 bool MultiCommand::processArgs(const Strings& args, bool finish) {
   if (command) {
     return command->processArgs(args, finish);
-  } else {
-    return Args::processArgs(args, finish);
   }
+  return Args::processArgs(args, finish);
 }
 
 StoreCommand::StoreCommand() = default;
@@ -119,7 +118,7 @@ void StorePathsCommand::run(ref<Store> store) {
   Paths storePaths;
 
   if (all) {
-    if (installables.size()) {
+    if (!installables.empty() != 0u) {
       throw UsageError("'--all' does not expect arguments");
     }
     for (auto& p : store->queryAllValidPaths()) {
diff --git a/third_party/nix/src/nix/doctor.cc b/third_party/nix/src/nix/doctor.cc
index 44ce2d9292..95bf8a922e 100644
--- a/third_party/nix/src/nix/doctor.cc
+++ b/third_party/nix/src/nix/doctor.cc
@@ -7,7 +7,7 @@
 using namespace nix;
 
 std::string formatProtocol(unsigned int proto) {
-  if (proto) {
+  if (proto != 0u) {
     auto major = GET_PROTOCOL_MAJOR(proto) >> 8;
     auto minor = GET_PROTOCOL_MINOR(proto);
     return (format("%1%.%2%") % major % minor).str();
@@ -41,7 +41,7 @@ struct CmdDoctor : StoreCommand {
     }
   }
 
-  bool checkNixInPath() {
+  static bool checkNixInPath() {
     PathSet dirs;
 
     for (auto& dir : tokenizeString<Strings>(getEnv("PATH"), ":")) {
@@ -64,7 +64,7 @@ struct CmdDoctor : StoreCommand {
     return true;
   }
 
-  bool checkProfileRoots(ref<Store> store) {
+  static bool checkProfileRoots(ref<Store> store) {
     PathSet dirs;
 
     for (auto& dir : tokenizeString<Strings>(getEnv("PATH"), ":")) {
@@ -106,7 +106,7 @@ struct CmdDoctor : StoreCommand {
     return true;
   }
 
-  bool checkStoreProtocol(unsigned int storeProto) {
+  static bool checkStoreProtocol(unsigned int storeProto) {
     unsigned int clientProto = GET_PROTOCOL_MAJOR(SERVE_PROTOCOL_VERSION) ==
                                        GET_PROTOCOL_MAJOR(storeProto)
                                    ? SERVE_PROTOCOL_VERSION
diff --git a/third_party/nix/src/nix/installables.cc b/third_party/nix/src/nix/installables.cc
index 06419f1f12..f6cba6d3b6 100644
--- a/third_party/nix/src/nix/installables.cc
+++ b/third_party/nix/src/nix/installables.cc
@@ -23,7 +23,7 @@ SourceExprCommand::SourceExprCommand() {
 }
 
 Value* SourceExprCommand::getSourceExpr(EvalState& state) {
-  if (vSourceExpr) {
+  if (vSourceExpr != nullptr) {
     return vSourceExpr;
   }
 
@@ -31,7 +31,7 @@ Value* SourceExprCommand::getSourceExpr(EvalState& state) {
 
   vSourceExpr = state.allocValue();
 
-  if (file != "") {
+  if (!file.empty()) {
     state.evalFile(lookupFileArg(state, file), *vSourceExpr);
 
   } else {
@@ -46,7 +46,7 @@ Value* SourceExprCommand::getSourceExpr(EvalState& state) {
     std::unordered_set<std::string> seen;
 
     auto addEntry = [&](const std::string& name) {
-      if (name == "") {
+      if (name.empty()) {
         return;
       }
       if (!seen.insert(name).second) {
@@ -135,7 +135,7 @@ struct InstallableValue : Installable {
       drvPaths.insert(b.drvPath);
 
       auto outputName = drv.queryOutputName();
-      if (outputName == "") {
+      if (outputName.empty()) {
         throw Error("derivation '%s' lacks an 'outputName' attribute",
                     b.drvPath);
       }
@@ -153,9 +153,8 @@ struct InstallableValue : Installable {
         b.outputs.insert(b2.outputs.begin(), b2.outputs.end());
       }
       return {b};
-    } else {
-      return res;
     }
+    return res;
   }
 };
 
@@ -204,7 +203,7 @@ static std::vector<std::shared_ptr<Installable>> parseInstallables(
   std::vector<std::shared_ptr<Installable>> result;
 
   if (ss.empty() && useDefaultInstallables) {
-    if (cmd.file == "") {
+    if (cmd.file.empty()) {
       cmd.file = ".";
     }
     ss = {""};
@@ -222,7 +221,7 @@ static std::vector<std::shared_ptr<Installable>> parseInstallables(
       }
     }
 
-    else if (s == "" || std::regex_match(s, attrPathRegex)) {
+    else if (s.empty() || std::regex_match(s, attrPathRegex)) {
       result.push_back(std::make_shared<InstallableAttrPath>(cmd, s));
 
     } else {
@@ -254,7 +253,7 @@ Buildables build(ref<Store> store, RealiseMode mode,
 
   for (auto& i : installables) {
     for (auto& b : i->toBuildables()) {
-      if (b.drvPath != "") {
+      if (!b.drvPath.empty()) {
         StringSet outputNames;
         for (auto& output : b.outputs) {
           outputNames.insert(output.first);
diff --git a/third_party/nix/src/nix/log.cc b/third_party/nix/src/nix/log.cc
index 86f133e94a..63d3554cc2 100644
--- a/third_party/nix/src/nix/log.cc
+++ b/third_party/nix/src/nix/log.cc
@@ -40,7 +40,7 @@ struct CmdLog : InstallableCommand {
 
     RunPager pager;
     for (auto& sub : subs) {
-      auto log = b.drvPath != "" ? sub->getBuildLog(b.drvPath) : nullptr;
+      auto log = !b.drvPath.empty() ? sub->getBuildLog(b.drvPath) : nullptr;
       for (auto& output : b.outputs) {
         if (log) {
           break;
diff --git a/third_party/nix/src/nix/main.cc b/third_party/nix/src/nix/main.cc
index 54285bfa93..11ba3f8410 100644
--- a/third_party/nix/src/nix/main.cc
+++ b/third_party/nix/src/nix/main.cc
@@ -27,14 +27,14 @@ namespace nix {
 static bool haveInternet() {
   struct ifaddrs* addrs;
 
-  if (getifaddrs(&addrs)) {
+  if (getifaddrs(&addrs) != 0) {
     return true;
   }
 
   Finally free([&]() { freeifaddrs(addrs); });
 
-  for (auto i = addrs; i; i = i->ifa_next) {
-    if (!i->ifa_addr) {
+  for (auto i = addrs; i != nullptr; i = i->ifa_next) {
+    if (i->ifa_addr == nullptr) {
       continue;
     }
     if (i->ifa_addr->sa_family == AF_INET) {
diff --git a/third_party/nix/src/nix/path-info.cc b/third_party/nix/src/nix/path-info.cc
index b871c45f1c..e94dcc9628 100644
--- a/third_party/nix/src/nix/path-info.cc
+++ b/third_party/nix/src/nix/path-info.cc
@@ -113,7 +113,7 @@ struct CmdPathInfo : StorePathsCommand, MixJSON {
           if (info->ultimate) {
             ss.push_back("ultimate");
           }
-          if (info->ca != "") {
+          if (!info->ca.empty()) {
             ss.push_back("ca:" + info->ca);
           }
           for (auto& sig : info->sigs) {
diff --git a/third_party/nix/src/nix/repl.cc b/third_party/nix/src/nix/repl.cc
index 9567ad4315..81e940dd3a 100644
--- a/third_party/nix/src/nix/repl.cc
+++ b/third_party/nix/src/nix/repl.cc
@@ -62,7 +62,7 @@ struct NixRepl {
   ~NixRepl();
   void mainLoop(const std::vector<std::string>& files);
   StringSet completePrefix(string prefix);
-  bool getLine(string& input, const std::string& prompt);
+  static bool getLine(string& input, const std::string& prompt);
   Path getDerivationPath(Value& v);
   bool processLine(string line);
   void loadFile(const Path& path);
@@ -145,11 +145,12 @@ static char* completionCallback(char* s, int* match) {
   if (possible.size() == 1) {
     *match = 1;
     auto* res = strdup(possible.begin()->c_str() + strlen(s));
-    if (!res) {
+    if (res == nullptr) {
       throw Error("allocation failure");
     }
     return res;
-  } else if (possible.size() > 1) {
+  }
+  if (possible.size() > 1) {
     auto checkAllHaveSameAt = [&](size_t pos) {
       auto& first = *possible.begin();
       for (auto& p : possible) {
@@ -167,7 +168,7 @@ static char* completionCallback(char* s, int* match) {
     if (len > 0) {
       *match = 1;
       auto* res = strdup(std::string(*possible.begin(), start, len).c_str());
-      if (!res) {
+      if (res == nullptr) {
         throw Error("allocation failure");
       }
       return res;
@@ -266,10 +267,9 @@ void NixRepl::mainLoop(const std::vector<std::string>& files) {
         // For parse errors on incomplete input, we continue waiting for the
         // next line of input without clearing the input so far.
         continue;
-      } else {
-        LOG(ERROR) << error << (settings.showTrace ? e.prefix() : "")
-                   << e.msg();
       }
+      LOG(ERROR) << error << (settings.showTrace ? e.prefix() : "") << e.msg();
+
     } catch (Error& e) {
       LOG(ERROR) << error << (settings.showTrace ? e.prefix() : "") << e.msg();
     } catch (Interrupted& e) {
@@ -284,29 +284,31 @@ void NixRepl::mainLoop(const std::vector<std::string>& files) {
 }
 
 bool NixRepl::getLine(string& input, const std::string& prompt) {
-  struct sigaction act, old;
-  sigset_t savedSignalMask, set;
+  struct sigaction act;
+  struct sigaction old;
+  sigset_t savedSignalMask;
+  sigset_t set;
 
   auto setupSignals = [&]() {
     act.sa_handler = sigintHandler;
     sigfillset(&act.sa_mask);
     act.sa_flags = 0;
-    if (sigaction(SIGINT, &act, &old)) {
+    if (sigaction(SIGINT, &act, &old) != 0) {
       throw SysError("installing handler for SIGINT");
     }
 
     sigemptyset(&set);
     sigaddset(&set, SIGINT);
-    if (sigprocmask(SIG_UNBLOCK, &set, &savedSignalMask)) {
+    if (sigprocmask(SIG_UNBLOCK, &set, &savedSignalMask) != 0) {
       throw SysError("unblocking SIGINT");
     }
   };
   auto restoreSignals = [&]() {
-    if (sigprocmask(SIG_SETMASK, &savedSignalMask, nullptr)) {
+    if (sigprocmask(SIG_SETMASK, &savedSignalMask, nullptr) != 0) {
       throw SysError("restoring signals");
     }
 
-    if (sigaction(SIGINT, &old, nullptr)) {
+    if (sigaction(SIGINT, &old, nullptr) != 0) {
       throw SysError("restoring handler for SIGINT");
     }
   };
@@ -316,13 +318,13 @@ bool NixRepl::getLine(string& input, const std::string& prompt) {
   Finally doFree([&]() { free(s); });
   restoreSignals();
 
-  if (g_signal_received) {
+  if (g_signal_received != 0) {
     g_signal_received = 0;
     input.clear();
     return true;
   }
 
-  if (!s) {
+  if (s == nullptr) {
     return false;
   }
   input += s;
@@ -334,7 +336,8 @@ StringSet NixRepl::completePrefix(string prefix) {
   StringSet completions;
 
   size_t start = prefix.find_last_of(" \n\r\t(){}[]");
-  std::string prev, cur;
+  std::string prev;
+  std::string cur;
   if (start == std::string::npos) {
     prev = "";
     cur = prefix;
@@ -343,13 +346,14 @@ StringSet NixRepl::completePrefix(string prefix) {
     cur = std::string(prefix, start + 1);
   }
 
-  size_t slash, dot;
+  size_t slash;
+  size_t dot;
 
   if ((slash = cur.rfind('/')) != string::npos) {
     try {
       auto dir = std::string(cur, 0, slash);
       auto prefix2 = std::string(cur, slash + 1);
-      for (auto& entry : readDirectory(dir == "" ? "/" : dir)) {
+      for (auto& entry : readDirectory(dir.empty() ? "/" : dir)) {
         if (entry.name[0] != '.' && hasPrefix(entry.name, prefix2)) {
           completions.insert(prev + dir + "/" + entry.name);
         }
@@ -418,7 +422,7 @@ static int runProgram(const string& program, const Strings& args) {
 }
 
 bool isVarName(const string& s) {
-  if (s.size() == 0) {
+  if (s.empty()) {
     return false;
   }
   char c = s[0];
@@ -441,18 +445,19 @@ Path NixRepl::getDerivationPath(Value& v) {
         "expression does not evaluate to a derivation, so I can't build it");
   }
   Path drvPath = drvInfo->queryDrvPath();
-  if (drvPath == "" || !state.store->isValidPath(drvPath)) {
+  if (drvPath.empty() || !state.store->isValidPath(drvPath)) {
     throw Error("expression did not evaluate to a valid derivation");
   }
   return drvPath;
 }
 
 bool NixRepl::processLine(string line) {
-  if (line == "") {
+  if (line.empty()) {
     return true;
   }
 
-  string command, arg;
+  string command;
+  string arg;
 
   if (line[0] == ':') {
     size_t p = line.find_first_of(" \n\r\t");
@@ -505,7 +510,9 @@ bool NixRepl::processLine(string line) {
     std::cout << showType(v) << std::endl;
 
   } else if (command == ":u") {
-    Value v, f, result;
+    Value v;
+    Value f;
+    Value result;
     evalString(arg, v);
     evalString(
         "drv: (import <nixpkgs> {}).runCommand \"shell\" { buildInputs = [ drv "
@@ -553,7 +560,7 @@ bool NixRepl::processLine(string line) {
   else if (command == ":q" || command == ":quit") {
     return false;
 
-  } else if (command != "") {
+  } else if (!command.empty()) {
     throw Error(format("unknown command '%1%'") % command);
 
   } else {
@@ -580,7 +587,8 @@ bool NixRepl::processLine(string line) {
 void NixRepl::loadFile(const Path& path) {
   loadedFiles.remove(path);
   loadedFiles.push_back(path);
-  Value v, v2;
+  Value v;
+  Value v2;
   state.evalFile(lookupFileArg(state, path), v);
   state.autoCallFunction(*autoArgs, v, v2);
   addAttrsToScope(v2);
@@ -652,7 +660,7 @@ std::ostream& NixRepl::printValue(std::ostream& str, Value& v,
 
 std::ostream& printStringValue(std::ostream& str, const char* string) {
   str << "\"";
-  for (const char* i = string; *i; i++) {
+  for (const char* i = string; *i != 0; i++) {
     if (*i == '\"' || *i == '\\') {
       str << "\\" << *i;
     } else if (*i == '\n') {
diff --git a/third_party/nix/src/nix/run.cc b/third_party/nix/src/nix/run.cc
index 5459c38952..9827360f0a 100644
--- a/third_party/nix/src/nix/run.cc
+++ b/third_party/nix/src/nix/run.cc
@@ -96,7 +96,7 @@ struct CmdRun : InstallablesCommand {
       std::map<std::string, std::string> kept;
       for (auto& var : keep) {
         auto s = getenv(var.c_str());
-        if (s) {
+        if (s != nullptr) {
           kept[var] = s;
         }
       }
@@ -133,9 +133,7 @@ struct CmdRun : InstallablesCommand {
         continue;
       }
 
-      if (true) {
-        unixPath.push_front(path + "/bin");
-      }
+      { unixPath.push_front(path + "/bin"); }
 
       auto propPath = path + "/nix-support/propagated-user-env-packages";
       if (accessor->stat(propPath).type == FSAccessor::tRegular) {
@@ -249,7 +247,7 @@ void chrootHelper(int argc, char** argv) {
     }
 
     char* cwd = getcwd(nullptr, 0);
-    if (!cwd) {
+    if (cwd == nullptr) {
       throw SysError("getting current directory");
     }
     Finally freeCwd([&]() { free(cwd); });
diff --git a/third_party/nix/src/nix/search.cc b/third_party/nix/src/nix/search.cc
index 78a1f21bc1..5f6def2202 100644
--- a/third_party/nix/src/nix/search.cc
+++ b/third_party/nix/src/nix/search.cc
@@ -160,11 +160,11 @@ struct CmdSearch : SourceExprCommand, MixJSON {
             }
           }
 
-          if (cache) {
+          if (cache != nullptr) {
             cache->attr("type", "derivation");
             cache->attr("name", drv.queryName());
             cache->attr("system", drv.querySystem());
-            if (description != "") {
+            if (!description.empty()) {
               auto meta(cache->object("meta"));
               meta.attr("description", description);
             }
@@ -190,11 +190,12 @@ struct CmdSearch : SourceExprCommand, MixJSON {
 
           for (auto& i : *v->attrs) {
             auto cache2 =
-                cache ? std::make_unique<JSONObject>(cache->object(i.name))
-                      : nullptr;
+                cache != nullptr
+                    ? std::make_unique<JSONObject>(cache->object(i.name))
+                    : nullptr;
             doExpr(i.value,
-                   attrPath == "" ? (std::string)i.name
-                                  : attrPath + "." + (std::string)i.name,
+                   attrPath.empty() ? (std::string)i.name
+                                    : attrPath + "." + (std::string)i.name,
                    toplevel2 || fromCache, cache2 ? cache2.get() : nullptr);
           }
         }
@@ -256,7 +257,7 @@ struct CmdSearch : SourceExprCommand, MixJSON {
       }
     }
 
-    if (results.size() == 0) {
+    if (results.empty()) {
       throw Error("no results for the given search term(s)!");
     }
 
diff --git a/third_party/nix/src/nix/show-derivation.cc b/third_party/nix/src/nix/show-derivation.cc
index 4a604c2c22..b821a9ee12 100644
--- a/third_party/nix/src/nix/show-derivation.cc
+++ b/third_party/nix/src/nix/show-derivation.cc
@@ -63,7 +63,7 @@ struct CmdShowDerivation : InstallablesCommand {
           for (auto& output : drv.outputs) {
             auto outputObj(outputsObj.object(output.first));
             outputObj.attr("path", output.second.path);
-            if (output.second.hash != "") {
+            if (!output.second.hash.empty()) {
               outputObj.attr("hashAlgo", output.second.hashAlgo);
               outputObj.attr("hash", output.second.hash);
             }
diff --git a/third_party/nix/src/nix/sigs.cc b/third_party/nix/src/nix/sigs.cc
index eb99fc8ee5..420296a802 100644
--- a/third_party/nix/src/nix/sigs.cc
+++ b/third_party/nix/src/nix/sigs.cc
@@ -71,7 +71,7 @@ struct CmdCopySigs : StorePathsCommand {
           }
 
           for (auto& sig : info2->sigs) {
-            if (!info->sigs.count(sig)) {
+            if (info->sigs.count(sig) == 0u) {
               newSigs.insert(sig);
             }
           }
@@ -132,7 +132,7 @@ struct CmdSignPaths : StorePathsCommand {
       info2.sign(secretKey);
       assert(!info2.sigs.empty());
 
-      if (!info->sigs.count(*info2.sigs.begin())) {
+      if (info->sigs.count(*info2.sigs.begin()) == 0u) {
         store->addSignatures(storePath, info2.sigs);
         added++;
       }
diff --git a/third_party/nix/src/nix/upgrade-nix.cc b/third_party/nix/src/nix/upgrade-nix.cc
index dd11da0087..b225aac2d7 100644
--- a/third_party/nix/src/nix/upgrade-nix.cc
+++ b/third_party/nix/src/nix/upgrade-nix.cc
@@ -52,7 +52,7 @@ struct CmdUpgradeNix : MixDryRun, StoreCommand {
   void run(ref<Store> store) override {
     evalSettings.pureEval = true;
 
-    if (profileDir == "") {
+    if (profileDir.empty()) {
       profileDir = getProfileDir(store);
     }
 
@@ -97,7 +97,7 @@ struct CmdUpgradeNix : MixDryRun, StoreCommand {
   }
 
   /* Return the profile in which Nix is installed. */
-  Path getProfileDir(ref<Store> store) {
+  static Path getProfileDir(ref<Store> store) {
     Path where;
 
     for (auto& dir : tokenizeString<Strings>(getEnv("PATH"), ":")) {
@@ -107,7 +107,7 @@ struct CmdUpgradeNix : MixDryRun, StoreCommand {
       }
     }
 
-    if (where == "") {
+    if (where.empty()) {
       throw Error(
           "couldn't figure out how Nix is installed, so I can't upgrade it");
     }
diff --git a/third_party/nix/src/nix/verify.cc b/third_party/nix/src/nix/verify.cc
index 6b74761ba7..63dd181e07 100644
--- a/third_party/nix/src/nix/verify.cc
+++ b/third_party/nix/src/nix/verify.cc
@@ -94,7 +94,7 @@ struct CmdVerify : StorePathsCommand {
         if (!noTrust) {
           bool good = false;
 
-          if (info->ultimate && !sigsNeeded) {
+          if (info->ultimate && (sigsNeeded == 0u)) {
             good = true;
 
           } else {
@@ -104,7 +104,7 @@ struct CmdVerify : StorePathsCommand {
 
             auto doSigs = [&](StringSet sigs) {
               for (auto sig : sigs) {
-                if (sigsSeen.count(sig)) {
+                if (sigsSeen.count(sig) != 0u) {
                   continue;
                 }
                 sigsSeen.insert(sig);
@@ -162,7 +162,8 @@ struct CmdVerify : StorePathsCommand {
 
     pool.process();
 
-    throw Exit((corrupted ? 1 : 0) | (untrusted ? 2 : 0) | (failed ? 4 : 0));
+    throw Exit((corrupted != 0u ? 1 : 0) | (untrusted != 0u ? 2 : 0) |
+               (failed != 0u ? 4 : 0));
   }
 };
 
diff --git a/third_party/nix/src/nix/why-depends.cc b/third_party/nix/src/nix/why-depends.cc
index baf27a6951..bbbfd1fe01 100644
--- a/third_party/nix/src/nix/why-depends.cc
+++ b/third_party/nix/src/nix/why-depends.cc
@@ -18,7 +18,7 @@ static std::string hilite(const std::string& s, size_t pos, size_t len,
 static std::string filterPrintable(const std::string& s) {
   std::string res;
   for (char c : s) {
-    res += isprint(c) ? c : '.';
+    res += isprint(c) != 0 ? c : '.';
   }
   return res;
 }
@@ -70,7 +70,7 @@ struct CmdWhyDepends : SourceExprCommand {
     PathSet closure;
     store->computeFSClosure({packagePath}, closure, false, false);
 
-    if (!closure.count(dependencyPath)) {
+    if (closure.count(dependencyPath) == 0u) {
       LOG(WARNING) << "'" << package->what() << "' does not depend on '"
                    << dependency->what() << "'";
       return;
@@ -146,7 +146,7 @@ struct CmdWhyDepends : SourceExprCommand {
       assert(node.dist != inf);
       std::cout << fmt("%s%s%s%s" ANSI_NORMAL "\n", firstPad,
                        node.visited ? "\e[38;5;244m" : "",
-                       firstPad != "" ? "=> " : "", node.path);
+                       !firstPad.empty() ? "=> " : "", node.path);
 
       if (node.path == dependencyPath && !all &&
           packagePath != dependencyPath) {