wip

include/sg14/aa_inplace_vector.h

@@ -360,9 +360,10 @@ struct SG14_INPLACE_VECTOR_TRIVIALLY_RELOCATABLE_IF((sg14::aaipv::be_trivially_r
     // There is a feature-test macro for "conditionally trivial SMFs," namely
     // (__cpp_concepts >= 202002L); but in fact neither GCC 11.4 nor AppleClang 15
     // set that macro, despite supporting the feature (at least well enough to
-    // compile this code). So just check (__cplusplus >= 202002L) instead.
+    // compile this code). We could check (__cplusplus >= 202002L) instead,
+    // except that MSVC doesn't always set *that*! So check nothing, at least for now.
     //
-    static_assert(__cplusplus >= 202002L, "Allocator-aware inplace_vector requires that the compiler support conditionally trivial SMFs");
+    static_assert(true, "Allocator-aware inplace_vector requires that the compiler support conditionally trivial SMFs");
 
     static constexpr bool CopyCtorIsDefaultable =
         ((std::is_trivially_copy_constructible_v<T> &&

test/aa_inplace_vector_smallsize_test.cpp

@@ -26,11 +26,22 @@ namespace smallsize {
 
 TEST(IPV_TEST_NAME, SizeAndAlignment)
 {
+#ifdef _MSC_VER
+    // Our `ipv_alloc_holder` has a single [[no_unique_address]] member.
+    // Even using [[msvc::no_unique_address]], MSVC fails to treat
+    // `ipv_alloc_holder` as an empty base for the purposes of optimization,
+    // which means it occupies an extra byte compared to the Itanium ABI.
+    //
+    static constexpr bool msvc = true;
+#else
+    static constexpr bool msvc = false;
+#endif
+
     static_assert(sizeof(sg14::inplace_vector<char, 22>) == 32);
     static_assert(alignof(sg14::inplace_vector<char, 22>) == 8);
     static_assert(sizeof(sg14::pmr::inplace_vector<char, 22>) == 40);
     static_assert(alignof(sg14::pmr::inplace_vector<char, 22>) == 8);
-    static_assert(sizeof(smallsize::inplace_vector<char, 22>) == 23);
+    static_assert(sizeof(smallsize::inplace_vector<char, 22>) == (msvc ? 24 : 23));
     static_assert(alignof(smallsize::inplace_vector<char, 22>) == 1);
 
     static_assert(sizeof(smallsize::inplace_vector<char, 2>) == 3);