ext/-test-/RUBY_ALIGNOF: add minimalistic test

Check if RUBY_ALIGNOF(double) is the alignment to store a double inside
of a struct.

1 files changed, 15 insertions, 0 deletions

diff --git a/ext/-test-/RUBY_ALIGNOF/cpp.cpp b/ext/-test-/RUBY_ALIGNOF/cpp.cpp
new file mode 100644
index 0000000000..ea1211c38c
--- /dev/null
+++ b/ext/-test-/RUBY_ALIGNOF/cpp.cpp
@@ -0,0 +1,15 @@
+#include "ruby.h"
+#include <cstddef>
+
+struct T {
+    char _;
+    double t;
+};
+
+RBIMPL_STATIC_ASSERT(RUBY_ALIGNOF, RUBY_ALIGNOF(double) == offsetof(T, t));
+
+extern "C" void
+Init_RUBY_ALIGNOF()
+{
+    // Windows linker mandates this symbol to exist.
+}