From 0016af5f13702feb92f6323417fb9fe495e964d0 Mon Sep 17 00:00:00 2001 From: Alex Burka Date: Mon, 13 Jun 2016 17:54:39 -0400 Subject: [PATCH] not just a single field --- src/doc/book/ffi.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/src/doc/book/ffi.md b/src/doc/book/ffi.md index 5a2ec86c12f5..07b8d8e0da8a 100644 --- a/src/doc/book/ffi.md +++ b/src/doc/book/ffi.md @@ -580,7 +580,7 @@ However, the language provides a workaround. As a special case, an `enum` is eligible for the "nullable pointer optimization" if it contains exactly two variants, one of which contains no data and the other contains -a single field of one of the non-nullable types listed above (or a struct containing such a type). +a field of one of the non-nullable types listed above (or a struct containing such a type). This means it is represented as a single pointer, and the non-data variant is represented as a null pointer. This is called an "optimization", but unlike other optimizations it is guaranteed to apply to eligible types.