treewide: replace lock_guard with scoped_lock

SonarLint reports the latter to be better:

std::scoped_lock basically provides the same feature as std::lock_guard,
but is more generic: It can lock several mutexes at the same time, with a
deadlock prevention mechanism (see {rule:cpp:S5524}). The equivalent code
to perform simultaneous locking with std::lock_guard is significantly more
complex. Therefore, it is simpler to use std::scoped_lock all the time,
even when locking only one mutex (there will be no performance impact).

Signed-off-by: Rosen Penev <rosenp@gmail.com>

src/storage/plugins/CurlStorage.cxx

@@ -131,7 +131,7 @@ protected:
 	}
 
 	void LockSetDone() {
-		const std::lock_guard<Mutex> lock(mutex);
+		const std::scoped_lock<Mutex> lock(mutex);
 		SetDone();
 	}
 
@@ -149,7 +149,7 @@ private:
 
 	/* virtual methods from CurlResponseHandler */
 	void OnError(std::exception_ptr e) noexcept final {
-		const std::lock_guard<Mutex> lock(mutex);
+		const std::scoped_lock<Mutex> lock(mutex);
 		postponed_error = std::move(e);
 		SetDone();
 	}

src/storage/plugins/NfsStorage.cxx

@@ -139,7 +139,7 @@ private:
 	void SetState(State _state) noexcept {
 		assert(GetEventLoop().IsInside());
 
-		const std::lock_guard<Mutex> protect(mutex);
+		const std::scoped_lock<Mutex> protect(mutex);
 		state = _state;
 		cond.notify_all();
 	}
@@ -147,7 +147,7 @@ private:
 	void SetState(State _state, std::exception_ptr &&e) noexcept {
 		assert(GetEventLoop().IsInside());
 
-		const std::lock_guard<Mutex> protect(mutex);
+		const std::scoped_lock<Mutex> protect(mutex);
 		state = _state;
 		last_exception = std::move(e);
 		cond.notify_all();

src/storage/plugins/SmbclientStorage.cxx

@@ -102,7 +102,7 @@ GetInfo(SmbclientContext &ctx, Mutex &mutex, const char *path)
 	struct stat st;
 
 	{
-		const std::lock_guard<Mutex> protect(mutex);
+		const std::scoped_lock<Mutex> protect(mutex);
 		if (ctx.Stat(path, st) != 0)
 			throw MakeErrno("Failed to access file");
 	}
@@ -137,7 +137,7 @@ SmbclientStorage::OpenDirectory(std::string_view uri_utf8)
 	SMBCFILE *handle;
 
 	{
-		const std::lock_guard<Mutex> protect(mutex);
+		const std::scoped_lock<Mutex> protect(mutex);
 		handle = ctx.OpenDirectory(mapped.c_str());
 	}
 
@@ -158,14 +158,14 @@ SkipNameFS(PathTraitsFS::const_pointer name) noexcept
 
 SmbclientDirectoryReader::~SmbclientDirectoryReader()
 {
-	const std::lock_guard<Mutex> lock(storage.mutex);
+	const std::scoped_lock<Mutex> lock(storage.mutex);
 	storage.ctx.CloseDirectory(handle);
 }
 
 const char *
 SmbclientDirectoryReader::Read() noexcept
 {
-	const std::lock_guard<Mutex> protect(storage.mutex);
+	const std::scoped_lock<Mutex> protect(storage.mutex);
 
 	while (auto e = storage.ctx.ReadDirectory(handle)) {
 		name = e->name;

src/storage/plugins/UdisksStorage.cxx

@@ -159,7 +159,7 @@ UdisksStorage::SetMountPoint(Path mount_point)
 void
 UdisksStorage::LockSetMountPoint(Path mount_point)
 {
-	const std::lock_guard<Mutex> lock(mutex);
+	const std::scoped_lock<Mutex> lock(mutex);
 	SetMountPoint(mount_point);
 }
 
@@ -191,7 +191,7 @@ UdisksStorage::OnListReply(ODBus::Message reply) noexcept
 			return;
 		}
 	} catch (...) {
-		const std::lock_guard<Mutex> lock(mutex);
+		const std::scoped_lock<Mutex> lock(mutex);
 		mount_error = std::current_exception();
 		want_mount = false;
 		cond.notify_all();
@@ -247,7 +247,7 @@ try {
 	mount_request.Send(connection, *msg.Get(),
 			   [this](auto o) { return OnMountNotify(std::move(o)); });
 } catch (...) {
-	const std::lock_guard<Mutex> lock(mutex);
+	const std::scoped_lock<Mutex> lock(mutex);
 	mount_error = std::current_exception();
 	want_mount = false;
 	cond.notify_all();
@@ -266,7 +266,7 @@ try {
 	const char *mount_path = i.GetString();
 	LockSetMountPoint(Path::FromFS(mount_path));
 } catch (...) {
-	const std::lock_guard<Mutex> lock(mutex);
+	const std::scoped_lock<Mutex> lock(mutex);
 	mount_error = std::current_exception();
 	want_mount = false;
 	cond.notify_all();
@@ -304,7 +304,7 @@ try {
 	mount_request.Send(connection, *msg.Get(),
 			   [this](auto u) { return OnUnmountNotify(std::move(u)); });
 } catch (...) {
-	const std::lock_guard<Mutex> lock(mutex);
+	const std::scoped_lock<Mutex> lock(mutex);
 	mount_error = std::current_exception();
 	mounted_storage.reset();
 	cond.notify_all();
@@ -316,12 +316,12 @@ try {
 	using namespace ODBus;
 	reply.CheckThrowError();
 
-	const std::lock_guard<Mutex> lock(mutex);
+	const std::scoped_lock<Mutex> lock(mutex);
 	mount_error = {};
 	mounted_storage.reset();
 	cond.notify_all();
 } catch (...) {
-	const std::lock_guard<Mutex> lock(mutex);
+	const std::scoped_lock<Mutex> lock(mutex);
 	mount_error = std::current_exception();
 	mounted_storage.reset();
 	cond.notify_all();