From e767c39d8ce8f5c148d01cc00e576d37ddd5bdd2 Mon Sep 17 00:00:00 2001
From: KRM7 <70973547+KRM7@users.noreply.github.com>
Date: Sat, 10 Feb 2024 15:53:25 +0100
Subject: [PATCH] add stack_buffer_size method

---
 src/small_unique_ptr.hpp  |  7 +++++++
 test/small_unique_ptr.cpp | 20 +++++++++++++++++++-
 2 files changed, 26 insertions(+), 1 deletion(-)

diff --git a/src/small_unique_ptr.hpp b/src/small_unique_ptr.hpp
index cea0f29..f31cb09 100644
--- a/src/small_unique_ptr.hpp
+++ b/src/small_unique_ptr.hpp
@@ -351,6 +351,13 @@ class small_unique_ptr : private detail::small_unique_ptr_base<T>
         return small_unique_ptr::small_unique_ptr_base::is_stack_allocated();
     }
 
+    [[nodiscard]]
+    static constexpr std::size_t stack_buffer_size() noexcept
+    {
+        if constexpr (detail::is_always_heap_allocated_v<T>) return 0;
+        else return detail::buffer_size_v<T>;
+    }
+
     [[nodiscard]]
     constexpr pointer get() const noexcept
     {
diff --git a/test/small_unique_ptr.cpp b/test/small_unique_ptr.cpp
index 71485be..724d750 100644
--- a/test/small_unique_ptr.cpp
+++ b/test/small_unique_ptr.cpp
@@ -108,8 +108,23 @@ TEST_CASE("object_size", "[small_unique_ptr]")
 
     STATIC_REQUIRE(alignof(small_unique_ptr<SmallIntrusive>) == detail::small_ptr_size);
     STATIC_REQUIRE(alignof(small_unique_ptr<LargeIntrusive>) == alignof(void*));
+}
+
+TEST_CASE("stack_buffer_size", "[small_unique_ptr]")
+{
+    STATIC_REQUIRE(small_unique_ptr<SmallPOD>::stack_buffer_size() == sizeof(SmallPOD));
+    STATIC_REQUIRE(small_unique_ptr<LargePOD>::stack_buffer_size() == 0);
+
+    STATIC_REQUIRE(small_unique_ptr<LargeDerived>::stack_buffer_size() == 0);
+    STATIC_REQUIRE(small_unique_ptr<LargeIntrusive>::stack_buffer_size() == 0);
 
-    STATIC_REQUIRE(detail::buffer_size_v<BaseIntrusive> > detail::buffer_size_v<Base>);
+    STATIC_REQUIRE(small_unique_ptr<SmallIntrusive>::stack_buffer_size() > small_unique_ptr<SmallDerived>::stack_buffer_size());
+}
+
+TEST_CASE("stack_buffer_size_archdep", "[small_unique_ptr][!mayfail]")
+{  
+    REQUIRE(small_unique_ptr<SmallDerived>::stack_buffer_size() == 48);
+    REQUIRE(small_unique_ptr<SmallIntrusive>::stack_buffer_size() == 56);
 }
 
 TEMPLATE_TEST_CASE("construction", "[small_unique_ptr]", SmallPOD, LargePOD, Base, SmallDerived, LargeDerived, BaseIntrusive, SmallIntrusive, LargeIntrusive)
@@ -171,6 +186,9 @@ TEST_CASE("is_stack_allocated", "[small_unique_ptr]")
     small_unique_ptr<LargePOD> p6 = make_unique_small<LargePOD>();
     REQUIRE(p5.is_stack_allocated());
     REQUIRE(!p6.is_stack_allocated());
+
+    small_unique_ptr<SmallPOD> np(nullptr);
+    REQUIRE(!np.is_stack_allocated());
 }
 
 TEST_CASE("comparisons", "[small_unique_ptr]")