add rust support (#113)

* add rust support

* move aligned_size to sizeclass.h

* add static qualifier

* adjust CMakeLists.txt, may broke CI tests

* fix msvc's complaining on c++17

* use SNMALLOC_FAST_PATH as the decorator of aligned_size

* adapt new alignment algorithm and add related test

Co-authored-by: mjp41 <mattpark@microsoft.com>

* fix test cases for msvc

* add extra test for size == 0

* treat memory block of same sizeclass as the same

* fix formatting problem

* remove extra declarations

Co-authored-by: Matthew Parkinson <mjp41@users.noreply.github.com>

src/mem/sizeclass.h

@@ -174,4 +174,16 @@ namespace snmalloc
     return relative;
   }
 #endif
+
+  SNMALLOC_FAST_PATH static size_t aligned_size(size_t alignment, size_t size)
+  {
+    // Client responsible for checking alignment is not zero
+    assert(alignment != 0);
+    // Client responsible for checking alignment is not above SUPERSLAB_SIZE
+    assert(alignment <= SUPERSLAB_SIZE);
+    // Client responsible for checking alignment is a power of two
+    assert(bits::next_pow2(alignment) == alignment);
+
+    return ((alignment - 1) | (size - 1)) + 1;
+  }
 } // namespace snmalloc