style(3p/nix): Remove 'using std::*' from types.hh

It is considered bad form to use things from includes in headers, as
these directives propagate to everywhere else and can make it
confusing.

types.hh (which is includes almost literally everywhere) had some of
these directives, which this commit removes.

third_party/nix/src/nix-store/dotgraph.cc

@@ -9,23 +9,23 @@ using std::cout;
 
 namespace nix {
 
-static string dotQuote(const string& s) { return "\"" + s + "\""; }
+static std::string dotQuote(const std::string& s) { return "\"" + s + "\""; }
 
-static string nextColour() {
+static std::string nextColour() {
   static int n = 0;
-  static string colours[] = {"black", "red",     "green",
-                             "blue",  "magenta", "burlywood"};
-  return colours[n++ % (sizeof(colours) / sizeof(string))];
+  static std::string colours[] = {"black", "red",     "green",
+                                  "blue",  "magenta", "burlywood"};
+  return colours[n++ % (sizeof(colours) / sizeof(std::string))];
 }
 
-static string makeEdge(const string& src, const string& dst) {
+static std::string makeEdge(const std::string& src, const std::string& dst) {
   format f = format("%1% -> %2% [color = %3%];\n") % dotQuote(src) %
              dotQuote(dst) % dotQuote(nextColour());
   return f.str();
 }
 
-static string makeNode(const string& id, const string& label,
-                       const string& colour) {
+static std::string makeNode(const std::string& id, const std::string& label,
+                            const std::string& colour) {
   format f = format(
                  "%1% [label = %2%, shape = box, "
                  "style = filled, fillcolor = %3%];\n") %
@@ -33,15 +33,15 @@ static string makeNode(const string& id, const string& label,
   return f.str();
 }
 
-static string symbolicName(const string& path) {
-  string p = baseNameOf(path);
-  return string(p, p.find('-') + 1);
+static std::string symbolicName(const std::string& path) {
+  std::string p = baseNameOf(path);
+  return std::string(p, p.find('-') + 1);
 }
 
 #if 0
-string pathLabel(const Path & nePath, const string & elemPath)
+std::string pathLabel(const Path & nePath, const std::string & elemPath)
 {
-    return (string) nePath + "-" + elemPath;
+    return (std::string) nePath + "-" + elemPath;
 }
 
 

third_party/nix/src/nix-store/graphml.cc

@@ -10,23 +10,23 @@ using std::cout;
 
 namespace nix {
 
-static inline const string& xmlQuote(const string& s) {
+static inline const std::string& xmlQuote(const std::string& s) {
   // Luckily, store paths shouldn't contain any character that needs to be
   // quoted.
   return s;
 }
 
-static string symbolicName(const string& path) {
-  string p = baseNameOf(path);
-  return string(p, p.find('-') + 1);
+static std::string symbolicName(const std::string& path) {
+  std::string p = baseNameOf(path);
+  return std::string(p, p.find('-') + 1);
 }
 
-static string makeEdge(const string& src, const string& dst) {
+static std::string makeEdge(const std::string& src, const std::string& dst) {
   return fmt("  <edge source=\"%1%\" target=\"%2%\"/>\n", xmlQuote(src),
              xmlQuote(dst));
 }
 
-static string makeNode(const ValidPathInfo& info) {
+static std::string makeNode(const ValidPathInfo& info) {
   return fmt(
       "  <node id=\"%1%\">\n"
       "    <data key=\"narSize\">%2%</data>\n"

third_party/nix/src/nix-store/nix-store.cc

@@ -252,8 +252,8 @@ static void opPrintFixedPath(Strings opFlags, Strings opArgs) {
 
   auto i = opArgs.begin();
   HashType hashAlgo = parseHashType(*i++);
-  string hash = *i++;
-  string name = *i++;
+  std::string hash = *i++;
+  std::string name = *i++;
 
   cout << format("%1%\n") %
               store->makeFixedOutputPath(recursive, Hash(hash, hashAlgo), name);
@@ -279,12 +279,12 @@ static PathSet maybeUseOutputs(const Path& storePath, bool useOutput,
    graph.  Topological sorting is used to keep the tree relatively
    flat. */
 
-const string treeConn = "+---";
-const string treeLine = "|   ";
-const string treeNull = "    ";
+const std::string treeConn = "+---";
+const std::string treeLine = "|   ";
+const std::string treeNull = "    ";
 
-static void printTree(const Path& path, const string& firstPad,
-                      const string& tailPad, PathSet& done) {
+static void printTree(const Path& path, const std::string& firstPad,
+                      const std::string& tailPad, PathSet& done) {
   if (done.find(path) != done.end()) {
     cout << format("%1%%2% [...]\n") % firstPad % path;
     return;
@@ -334,7 +334,7 @@ static void opQuery(Strings opFlags, Strings opArgs) {
   bool useOutput = false;
   bool includeOutputs = false;
   bool forceRealise = false;
-  string bindingName;
+  std::string bindingName;
 
   for (auto& i : opFlags) {
     QueryType prev = query;
@@ -776,7 +776,7 @@ static void opDump(Strings opFlags, Strings opArgs) {
   }
 
   FdSink sink(STDOUT_FILENO);
-  string path = *opArgs.begin();
+  std::string path = *opArgs.begin();
   dumpPath(path, sink);
   sink.flush();
 }
@@ -1154,9 +1154,9 @@ static void opGenerateBinaryCacheKey(Strings opFlags, Strings opArgs) {
     throw UsageError("three arguments expected");
   }
   auto i = opArgs.begin();
-  string keyName = *i++;
-  string secretKeyFile = *i++;
-  string publicKeyFile = *i++;
+  std::string keyName = *i++;
+  std::string secretKeyFile = *i++;
+  std::string publicKeyFile = *i++;
 
 #if HAVE_SODIUM
   if (sodium_init() == -1) {
@@ -1169,13 +1169,13 @@ static void opGenerateBinaryCacheKey(Strings opFlags, Strings opArgs) {
     throw Error("key generation failed");
   }
 
-  writeFile(publicKeyFile,
-            keyName + ":" +
-                base64Encode(string((char*)pk, crypto_sign_PUBLICKEYBYTES)));
+  writeFile(publicKeyFile, keyName + ":" +
+                               base64Encode(std::string(
+                                   (char*)pk, crypto_sign_PUBLICKEYBYTES)));
   umask(0077);
-  writeFile(secretKeyFile,
-            keyName + ":" +
-                base64Encode(string((char*)sk, crypto_sign_SECRETKEYBYTES)));
+  writeFile(secretKeyFile, keyName + ":" +
+                               base64Encode(std::string(
+                                   (char*)sk, crypto_sign_SECRETKEYBYTES)));
 #else
   throw Error(
       "Nix was not compiled with libsodium, required for signed binary cache "