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/input/cache/Item.cxx

@@ -37,14 +37,14 @@ InputCacheItem::~InputCacheItem() noexcept
 void
 InputCacheItem::AddLease(InputCacheLease &lease) noexcept
 {
-	const std::lock_guard<Mutex> lock(mutex);
+	const std::scoped_lock<Mutex> lock(mutex);
 	leases.push_back(lease);
 }
 
 void
 InputCacheItem::RemoveLease(InputCacheLease &lease) noexcept
 {
-	const std::lock_guard<Mutex> lock(mutex);
+	const std::scoped_lock<Mutex> lock(mutex);
 	auto i = leases.iterator_to(lease);
 	if (i == next_lease)
 		++next_lease;

src/input/cache/Item.hxx

@@ -63,7 +63,7 @@ public:
 	using BufferingInputStream::size;
 
 	bool IsInUse() const noexcept {
-		const std::lock_guard<Mutex> lock(mutex);
+		const std::scoped_lock<Mutex> lock(mutex);
 		return !leases.empty();
 	}
 

src/input/cache/Stream.cxx

@@ -36,7 +36,7 @@ CacheInputStream::Check()
 	const ScopeUnlock unlock(mutex);
 
 	auto &i = GetCacheItem();
-	const std::lock_guard<Mutex> protect(i.mutex);
+	const std::scoped_lock<Mutex> protect(i.mutex);
 
 	i.Check();
 }
@@ -60,7 +60,7 @@ CacheInputStream::IsAvailable() const noexcept
 	const ScopeUnlock unlock(mutex);
 
 	auto &i = GetCacheItem();
-	const std::lock_guard<Mutex> protect(i.mutex);
+	const std::scoped_lock<Mutex> protect(i.mutex);
 
 	return i.IsAvailable(_offset);
 }
@@ -76,7 +76,7 @@ CacheInputStream::Read(std::unique_lock<Mutex> &lock,
 
 	{
 		const ScopeUnlock unlock(mutex);
-		const std::lock_guard<Mutex> protect(i.mutex);
+		const std::scoped_lock<Mutex> protect(i.mutex);
 
 		nbytes = i.Read(lock, _offset, ptr, read_size);
 	}
@@ -91,6 +91,6 @@ CacheInputStream::OnInputCacheAvailable() noexcept
 	auto &i = GetCacheItem();
 	const ScopeUnlock unlock(i.mutex);
 
-	const std::lock_guard<Mutex> protect(mutex);
+	const std::scoped_lock<Mutex> protect(mutex);
 	InvokeOnAvailable();
 }