daemon: Remove ‘singleton’ and replace ‘typedef’ with ‘using’ in ‘types.hh’

* nix/libutil/util.hh (singleton): Remove.
* nix/libstore/build.cc (DerivationGoal::startBuilder)
(SubstitutionGoal::tryNext, SubstitutionGoal::tryToRun)
(LocalStore::ensurePath, LocalStore::repairPath): Use normal
construction function instead of ‘singleton’.
* nix/libstore/local-store.cc (LocalStore::addToStoreFromDump)
(LocalStore::addTextToStore, LocalStore::importPath): Likewise.
* nix/nix-daemon/nix-daemon.cc (performOp): Likewise.

Change-Id: If0d929407c09482f3b506a1c51dfda70e29696dd
Signed-off-by: Ludovic Courtès <ludo@gnu.org>

2 files changed, 8 insertions, 9 deletions

diff --git a/nix/libstore/build.cc b/nix/libstore/build.cc
index 993876c6d10..47e93d1a211 100644
--- a/nix/libstore/build.cc
+++ b/nix/libstore/build.cc
@@ -2041,8 +2041,7 @@ void DerivationGoal::startBuilder()
     /* parent */
     pid.setSeparatePG(true);
     builderOut.writeSide.close();
-    worker.childStarted(shared_from_this(), pid,
-        singleton<set<int> >(builderOut.readSide), true, true);
+    worker.childStarted(shared_from_this(), pid, std::set<int>{builderOut.readSide}, true, true);
 
     /* Check if setting up the build environment failed. */
     string msg = readLine(builderOut.readSide);
@@ -3168,7 +3167,7 @@ void SubstitutionGoal::tryNext()
     trace("trying substituter");
 
     SubstitutablePathInfos infos;
-    PathSet dummy(singleton<PathSet>(storePath));
+    PathSet dummy{storePath};
     worker.store.querySubstitutablePathInfos(dummy, infos);
     SubstitutablePathInfos::iterator k = infos.find(storePath);
     if (k == infos.end()) {
@@ -3243,7 +3242,7 @@ void SubstitutionGoal::tryToRun()
 
     /* Acquire a lock on the output path. */
     outputLock = std::shared_ptr<PathLocks>(new PathLocks);
-    if (!outputLock->lockPaths(singleton<PathSet>(storePath), "", false)) {
+    if (!outputLock->lockPaths(PathSet{storePath}, "", false)) {
         worker.waitForAWhile(shared_from_this());
         return;
     }
@@ -3842,7 +3841,7 @@ void LocalStore::ensurePath(const Path & path)
 
     Worker worker(*this);
     GoalPtr goal = worker.makeSubstitutionGoal(path);
-    Goals goals = singleton<Goals>(goal);
+    Goals goals{goal};
 
     worker.run(goals);
 
@@ -3855,7 +3854,7 @@ void LocalStore::repairPath(const Path & path)
 {
     Worker worker(*this);
     GoalPtr goal = worker.makeSubstitutionGoal(path, true);
-    Goals goals = singleton<Goals>(goal);
+    Goals goals{goal};
 
     worker.run(goals);
 
diff --git a/nix/libstore/local-store.cc b/nix/libstore/local-store.cc
index f6540c2117d..d544253add8 100644
--- a/nix/libstore/local-store.cc
+++ b/nix/libstore/local-store.cc
@@ -1015,7 +1015,7 @@ Path LocalStore::addToStoreFromDump(const string & dump, const string & name,
         /* The first check above is an optimisation to prevent
            unnecessary lock acquisition. */
 
-        PathLocks outputLock(singleton<PathSet, Path>(dstPath));
+        PathLocks outputLock{ PathSet{dstPath} };
 
         if (repair || !isValidPath(dstPath)) {
 
@@ -1084,7 +1084,7 @@ Path LocalStore::addTextToStore(const string & name, const string & s,
 
     if (repair || !isValidPath(dstPath)) {
 
-        PathLocks outputLock(singleton<PathSet, Path>(dstPath));
+        PathLocks outputLock{ PathSet{dstPath} };
 
         if (repair || !isValidPath(dstPath)) {
 
@@ -1380,7 +1380,7 @@ Path LocalStore::importPath(bool requireSignature, Source & source)
            lock on this path). */
         Strings locksHeld = tokenizeString<Strings>(getEnv("NIX_HELD_LOCKS"));
         if (find(locksHeld.begin(), locksHeld.end(), dstPath) == locksHeld.end())
-            outputLock.lockPaths(singleton<PathSet, Path>(dstPath));
+            outputLock.lockPaths(PathSet{dstPath});
 
         if (!isValidPath(dstPath)) {