[intro.object] Fix alignment in example

Makes the storage in the example properly aligned,
and explicitly states size assumption.

Author: frederick-vs-ja

source/basic.tex

@@ -3207,6 +3207,8 @@
 \end{note}
 \begin{example}
 \begin{codeblock}
+// assumes that \tcode{sizeof(int)} is equal to 4
+
 template<typename ...T>
 struct AlignedUnion {
   alignas(T...) unsigned char data[max(sizeof(T)...)];
@@ -3221,7 +3223,7 @@
 
 struct A { unsigned char a[32]; };
 struct B { unsigned char b[16]; };
-A a;
+alignas(int) A a;
 B *b = new (a.a + 8) B;                 // \tcode{a.a} provides storage for \tcode{*b}
 int *p = new (b->b + 4) int;            // \tcode{b->b} provides storage for \tcode{*p}
                                         // \tcode{a.a} does not provide storage for \tcode{*p} (directly),