feat: add `is_compact_layout_v` concept

src/core/common_code/common_code.h

@@ -63,8 +63,8 @@
 #include <string>
 #include <cstdint>
 #include <optional>
-#include <type_traits>
 
+#include "utils/utility.h"
 #include "raw_code/raw_code_fwd.h"
 #include "short_code/short_code_fwd.h"
 
@@ -194,9 +194,9 @@ private:
 };
 
 static_assert(sizeof(CommonCode) == 8);
+static_assert(is_compact_layout_v<CommonCode>);
 static_assert(std::is_standard_layout_v<CommonCode>);
 static_assert(std::is_trivially_copyable_v<CommonCode>);
-static_assert(std::has_unique_object_representations_v<CommonCode>);
 
 } // namespace klotski::codec
 

src/core/group/group.h

@@ -245,9 +245,9 @@ private:
 };
 
 static_assert(sizeof(GroupUnion) == 1);
+static_assert(is_compact_layout_v<GroupUnion>);
 static_assert(std::is_standard_layout_v<GroupUnion>);
 static_assert(std::is_trivially_copyable_v<GroupUnion>);
-static_assert(std::has_unique_object_representations_v<GroupUnion>);
 
 } // namespace klotski::group
 
@@ -371,9 +371,9 @@ private:
 };
 
 static_assert(sizeof(Group) == 4);
+static_assert(is_compact_layout_v<Group>);
 static_assert(std::is_standard_layout_v<Group>);
 static_assert(std::is_trivially_copyable_v<Group>);
-static_assert(std::has_unique_object_representations_v<Group>);
 
 } // namespace klotski::group
 
@@ -432,9 +432,9 @@ private:
 };
 
 static_assert(sizeof(CaseInfo) == 8);
+static_assert(is_compact_layout_v<CaseInfo>);
 static_assert(std::is_standard_layout_v<CaseInfo>);
 static_assert(std::is_trivially_copyable_v<CaseInfo>);
-static_assert(std::has_unique_object_representations_v<CaseInfo>);
 
 } // namespace klotski::group
 

src/core/raw_code/raw_code.h

@@ -66,8 +66,8 @@
 #include <string>
 #include <cstdint>
 #include <optional>
-#include <type_traits>
 
+#include "utils/utility.h"
 #include "common_code/common_code_fwd.h"
 
 namespace klotski::codec {
@@ -171,9 +171,9 @@ private:
 };
 
 static_assert(sizeof(RawCode) == 8);
+static_assert(is_compact_layout_v<RawCode>);
 static_assert(std::is_standard_layout_v<RawCode>);
 static_assert(std::is_trivially_copyable_v<RawCode>);
-static_assert(std::has_unique_object_representations_v<RawCode>);
 
 } // namespace klotski::codec
 

src/core/short_code/short_code.h

@@ -187,9 +187,9 @@ private:
 };
 
 static_assert(sizeof(ShortCode) == 4);
+static_assert(is_compact_layout_v<ShortCode>);
 static_assert(std::is_standard_layout_v<ShortCode>);
 static_assert(std::is_trivially_copyable_v<ShortCode>);
-static_assert(std::has_unique_object_representations_v<ShortCode>);
 
 } // namespace klotski::codec
 

src/core/utils/utility.h

@@ -6,6 +6,7 @@
 #include <cstdint>
 #include <numeric>
 #include <functional>
+#include <type_traits>
 
 // ----------------------------------------------------------------------------------------- //
 
@@ -62,6 +63,13 @@
 
 namespace klotski {
 
+template <typename T>
+#ifndef __cpp_lib_has_unique_object_representations
+concept is_compact_layout_v = true;
+#else
+concept is_compact_layout_v = std::has_unique_object_representations_v<T>;
+#endif
+
 /// Calculate the sum of an array of integers.
 template <typename T, size_t N>
 requires std::is_integral_v<T>