Ignore rust snippets, and add section referencing CLI args and library methods

1 files changed, 15 insertions, 3 deletions

diff --git a/book/src/using-unions.md b/book/src/using-unions.md
index 3f74b2ff..66ba6d13 100644
--- a/book/src/using-unions.md
+++ b/book/src/using-unions.md
@@ -25,11 +25,23 @@ typedef union {
 } greek_t;
 ```
 
+## Relevant Bindgen Options
+
+### Library
+
+* [`bindgen::Builder::no_unstable_rust()`](https://docs.rs/bindgen/0.25.3/bindgen/struct.Builder.html#method.no_unstable_rust)
+* [`bindgen::Builder::derive_default()`](https://docs.rs/bindgen/0.25.3/bindgen/struct.Builder.html#method.derive_default)
+
+### Command Line
+
+* `--no-unstable-rust`
+* `--with-derive-default`
+
 ## Using the unstable `union` version
 
 With `struct`s generated by bindgen from C, it is possible to initialize fields in a "normal" rust way:
 
-```rust
+```rust,ignore
 mod bindings;
 
 fn main() {
@@ -42,7 +54,7 @@ fn main() {
 
 When using the unstable `union` type, there are two choices for initialization: Zeroed, and with a specific variant.
 
-```rust
+```rust,ignore
 #![feature(untagged_unions)]
 mod bindings_unstable;
 
@@ -75,7 +87,7 @@ For versions of Rust that do not support the new `union` type, bindgen will gene
 
 Interacting with these unions is slightly different than the new `union` types. Whenever a variant of the union is accessed, it must be done through a reference.
 
-```rust
+```rust,ignore
 mod bindings;
 
 fn stable() {