Auto increase inlined capacity whenever it does not affect class' size.

PiperOrigin-RevId: 487292771
Change-Id: I2454e28fe91017fb2954a4ad194712fcafe893d2

1 files changed, 11 insertions, 2 deletions

diff --git a/absl/container/internal/inlined_vector.h b/absl/container/internal/inlined_vector.h
index 48f31c2e..0398f530 100644
--- a/absl/container/internal/inlined_vector.h
+++ b/absl/container/internal/inlined_vector.h
@@ -379,7 +379,9 @@ class Storage {
     return data_.allocated.allocated_capacity;
   }
 
-  SizeType<A> GetInlinedCapacity() const { return static_cast<SizeType<A>>(N); }
+  SizeType<A> GetInlinedCapacity() const {
+    return static_cast<SizeType<A>>(kOptimalInlinedSize);
+  }
 
   StorageView<A> MakeStorageView() {
     return GetIsAllocated() ? StorageView<A>{GetAllocatedData(), GetSize(),
@@ -483,8 +485,15 @@ class Storage {
     SizeType<A> allocated_capacity;
   };
 
+  // `kOptimalInlinedSize` is an automatically adjusted inlined capacity of the
+  // `InlinedVector`. Sometimes, it is possible to increase the capacity (from
+  // the user requested `N`) without increasing the size of the `InlinedVector`.
+  static constexpr size_t kOptimalInlinedSize =
+      (std::max)(N, sizeof(Allocated) / sizeof(ValueType<A>));
+
   struct Inlined {
-    alignas(ValueType<A>) char inlined_data[sizeof(ValueType<A>[N])];
+    alignas(ValueType<A>) char inlined_data[sizeof(
+        ValueType<A>[kOptimalInlinedSize])];
   };
 
   union Data {