Reformat for 4-space indentation

Specifically, with
  clang-format --style='{ IndentWidth: 4, BreakBeforeBraces: Mozilla, ColumnLimit: 120, PointerAlignment: Middle }'
which was the clang-format invocation that produced the fewest diffs on
the nix source out of ~20 that I tried.

nixos/modules/installer/tools/nixos-option/libnix-copy-paste.cc

@@ -21,61 +21,63 @@ using nix::Strings;
 using std::string;
 
 // From nix/src/libexpr/attr-path.cc
-Strings parseAttrPath(const string &s) {
-  Strings res;
-  string cur;
-  string::const_iterator i = s.begin();
-  while (i != s.end()) {
-    if (*i == '.') {
-      res.push_back(cur);
-      cur.clear();
-    } else if (*i == '"') {
-      ++i;
-      while (1) {
-        if (i == s.end())
-          throw Error(format("missing closing quote in selection path '%1%'") %
-                      s);
-        if (*i == '"')
-          break;
-        cur.push_back(*i++);
-      }
-    } else
-      cur.push_back(*i);
-    ++i;
-  }
-  if (!cur.empty())
-    res.push_back(cur);
-  return res;
+Strings parseAttrPath(const string & s)
+{
+    Strings res;
+    string cur;
+    string::const_iterator i = s.begin();
+    while (i != s.end()) {
+        if (*i == '.') {
+            res.push_back(cur);
+            cur.clear();
+        } else if (*i == '"') {
+            ++i;
+            while (1) {
+                if (i == s.end())
+                    throw Error(format("missing closing quote in selection path '%1%'") % s);
+                if (*i == '"')
+                    break;
+                cur.push_back(*i++);
+            }
+        } else
+            cur.push_back(*i);
+        ++i;
+    }
+    if (!cur.empty())
+        res.push_back(cur);
+    return res;
 }
 
 // From nix/src/nix/repl.cc
-bool isVarName(const string &s) {
-  if (s.size() == 0)
-    return false;
-  char c = s[0];
-  if ((c >= '0' && c <= '9') || c == '-' || c == '\'')
-    return false;
-  for (auto &i : s)
-    if (!((i >= 'a' && i <= 'z') || (i >= 'A' && i <= 'Z') ||
-          (i >= '0' && i <= '9') || i == '_' || i == '-' || i == '\''))
-      return false;
-  return true;
+bool isVarName(const string & s)
+{
+    if (s.size() == 0)
+        return false;
+    char c = s[0];
+    if ((c >= '0' && c <= '9') || c == '-' || c == '\'')
+        return false;
+    for (auto & i : s)
+        if (!((i >= 'a' && i <= 'z') || (i >= 'A' && i <= 'Z') || (i >= '0' && i <= '9') || i == '_' || i == '-' ||
+              i == '\''))
+            return false;
+    return true;
 }
 
 // From nix/src/nix/repl.cc
-std::ostream &printStringValue(std::ostream &str, const char *string) {
-  str << "\"";
-  for (const char *i = string; *i; i++)
-    if (*i == '\"' || *i == '\\')
-      str << "\\" << *i;
-    else if (*i == '\n')
-      str << "\\n";
-    else if (*i == '\r')
-      str << "\\r";
-    else if (*i == '\t')
-      str << "\\t";
-    else
-      str << *i;
-  str << "\"";
-  return str;
+std::ostream & printStringValue(std::ostream & str, const char * string)
+{
+    str << "\"";
+    for (const char * i = string; *i; i++)
+        if (*i == '\"' || *i == '\\')
+            str << "\\" << *i;
+        else if (*i == '\n')
+            str << "\\n";
+        else if (*i == '\r')
+            str << "\\r";
+        else if (*i == '\t')
+            str << "\\t";
+        else
+            str << *i;
+    str << "\"";
+    return str;
 }

nixos/modules/installer/tools/nixos-option/libnix-copy-paste.hh

@@ -4,6 +4,6 @@
 #include <nix/types.hh>
 #include <string>
 
-nix::Strings parseAttrPath(const std::string &s);
-bool isVarName(const std::string &s);
-std::ostream &printStringValue(std::ostream &str, const char *string);
+nix::Strings parseAttrPath(const std::string & s);
+bool isVarName(const std::string & s);
+std::ostream & printStringValue(std::ostream & str, const char * string);