switch defaults from generating unstable Rust to generating stable Rust

- changing the Builder::no_unstable_rust method to the Builder::unstable_rust method
- changing the --no-unstable-rust flag to a --unstable-rust flag in src/options.rs
- changing bindgen-flags header in the test headers to remove the --no-unstable-rust flag

Fixes #757

12 files changed, 18 insertions, 26 deletions

diff --git a/bindgen-integration/build.rs b/bindgen-integration/build.rs
index b715486c..7107d04b 100644
--- a/bindgen-integration/build.rs
+++ b/bindgen-integration/build.rs
@@ -28,7 +28,6 @@ fn main() {
     let macros = Arc::new(RwLock::new(HashSet::new()));
 
     let bindings = Builder::default()
-        .no_unstable_rust()
         .enable_cxx_namespaces()
         .raw_line("pub use self::root::*;")
         .header("cpp/Test.h")
diff --git a/book/src/tutorial-3.md b/book/src/tutorial-3.md
index a6a7135e..41197aa0 100644
--- a/book/src/tutorial-3.md
+++ b/book/src/tutorial-3.md
@@ -22,10 +22,6 @@ fn main() {
     // to bindgen, and lets you build up options for
     // the resulting bindings.
     let bindings = bindgen::Builder::default()
-        // Do not generate unstable Rust code that
-        // requires a nightly rustc and enabling
-        // unstable features.
-        .no_unstable_rust()
         // The input header we would like to generate
         // bindings for.
         .header("wrapper.h")
diff --git a/book/src/using-unions.md b/book/src/using-unions.md
index 66ba6d13..9ee10a92 100644
--- a/book/src/using-unions.md
+++ b/book/src/using-unions.md
@@ -1,6 +1,8 @@
 # Using the Union Types Generated by Bindgen
 
-**NOTE:** As of Rust version 1.17, Rust does not have a stable `union` type. Issue [#32836](https://github.com/rust-lang/rust/issues/32836) tracks the stabilization of a `union` type in Rust. By default, bindgen will generate the preliminary unstable `union` type, unless the flag `--no-unstable-rust` flag is used.
+**NOTE:** As of Rust version 1.17, Rust does not have a stable `union` type. Issue [#32836](https://github.com/rust-lang/rust/issues/32836) tracks the stabilization of a `union` type in Rust. 
+
+By using the flag `--unstable-rust`, bindgen will generate the preliminary unstable `union` type.
 
 In general, most interactions with unions (either reading or writing) are unsafe.
 
@@ -29,12 +31,12 @@ typedef union {
 
 ### Library
 
-* [`bindgen::Builder::no_unstable_rust()`](https://docs.rs/bindgen/0.25.3/bindgen/struct.Builder.html#method.no_unstable_rust)
+* [`bindgen::Builder::unstable_rust()`](https://docs.rs/bindgen/0.25.3/bindgen/struct.Builder.html#method.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`
+* `--unstable-rust`
 * `--with-derive-default`
 
 ## Using the unstable `union` version
@@ -129,4 +131,4 @@ error[E0308]: mismatched types
    |
    = note: expected type `bindings::__BindgenUnionField<bindings::alpha_t>`
               found type `bindings::alpha_t`
-```
\ No newline at end of file
+```
diff --git a/src/lib.rs b/src/lib.rs
index cd5cf8e1..a1446754 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -333,7 +333,7 @@ impl Builder {
         }
 
         if !self.options.unstable_rust {
-            output_vector.push("--no-unstable-rust".into());
+            output_vector.push("--unstable-rust".into());
         }
 
         self.options
@@ -736,8 +736,8 @@ impl Builder {
     }
 
     /// Avoid generating any unstable Rust, such as Rust unions, in the generated bindings.
-    pub fn no_unstable_rust(mut self) -> Builder {
-        self.options.unstable_rust = false;
+    pub fn unstable_rust(mut self, doit: bool) -> Self {
+        self.options.unstable_rust = doit;
         self
     }
 
@@ -959,7 +959,7 @@ impl Default for BindgenOptions {
             derive_default: false,
             enable_cxx_namespaces: false,
             disable_name_namespacing: false,
-            unstable_rust: true,
+            unstable_rust: false,
             use_core: false,
             ctypes_prefix: None,
             namespaced_constants: true,
diff --git a/src/options.rs b/src/options.rs
index bbf9c0dd..fc0dd247 100644
--- a/src/options.rs
+++ b/src/options.rs
@@ -135,9 +135,9 @@ pub fn builder_from_flags<I>
             Arg::with_name("no-prepend-enum-name")
                 .long("no-prepend-enum-name")
                 .help("Do not prepend the enum name to bitfield or constant variants."),
-            Arg::with_name("no-unstable-rust")
-                .long("no-unstable-rust")
-                .help("Do not generate unstable Rust code.")
+            Arg::with_name("unstable-rust")
+                .long("unstable-rust")
+                .help("Generate unstable Rust code.")
                 .multiple(true), // FIXME: Pass legacy test suite
             Arg::with_name("opaque-type")
                 .long("opaque-type")
@@ -325,8 +325,8 @@ pub fn builder_from_flags<I>
         builder = builder.ignore_methods();
     }
 
-    if matches.is_present("no-unstable-rust") {
-        builder = builder.no_unstable_rust();
+    if matches.is_present("unstable-rust") {
+        builder = builder.unstable_rust(true);
     }
 
     if matches.is_present("no-convert-floats") {
diff --git a/tests/headers/jsval_layout_opaque.hpp b/tests/headers/jsval_layout_opaque.hpp
index 85c5be63..8f36f77d 100644
--- a/tests/headers/jsval_layout_opaque.hpp
+++ b/tests/headers/jsval_layout_opaque.hpp
@@ -1,4 +1,4 @@
-// bindgen-flags: --no-unstable-rust -- -std=c++11
+// bindgen-flags: -- -std=c++11
 
 /**
  * These typedefs are hacky, but keep our tests consistent across 64-bit
diff --git a/tests/headers/only_bitfields.hpp b/tests/headers/only_bitfields.hpp
index 84db0586..793bc66b 100644
--- a/tests/headers/only_bitfields.hpp
+++ b/tests/headers/only_bitfields.hpp
@@ -1,4 +1,3 @@
-// bindgen-flags: --no-unstable-rust
 class C {
     bool a: 1;
     bool b: 7;
diff --git a/tests/headers/struct_with_bitfields.h b/tests/headers/struct_with_bitfields.h
index 107fb136..ece512cd 100644
--- a/tests/headers/struct_with_bitfields.h
+++ b/tests/headers/struct_with_bitfields.h
@@ -1,4 +1,3 @@
-// bindgen-flags: --no-unstable-rust
 struct bitfield {
     unsigned short
     a   :1,
diff --git a/tests/headers/union_with_anon_struct_bitfield.h b/tests/headers/union_with_anon_struct_bitfield.h
index 24c7dce8..9668ce40 100644
--- a/tests/headers/union_with_anon_struct_bitfield.h
+++ b/tests/headers/union_with_anon_struct_bitfield.h
@@ -1,4 +1,3 @@
-// bindgen-flags: --no-unstable-rust
 union foo {
     int a;
     struct {
diff --git a/tests/headers/weird_bitfields.hpp b/tests/headers/weird_bitfields.hpp
index 755681c1..68cbf4a5 100644
--- a/tests/headers/weird_bitfields.hpp
+++ b/tests/headers/weird_bitfields.hpp
@@ -1,4 +1,3 @@
-// bindgen-flags: --no-unstable-rust
 // You can guess where this is taken from...
 enum nsStyleSVGOpacitySource {
   eStyleSVGOpacitySource_Normal,
diff --git a/tests/test-one.sh b/tests/test-one.sh
index ac466164..16fe1f12 100755
--- a/tests/test-one.sh
+++ b/tests/test-one.sh
@@ -24,7 +24,7 @@ TEST_BINDINGS_BINARY=$(mktemp -t bindings.XXXXXX)
 FLAGS="$(grep "// bindgen-flags: " "$TEST" || echo)"
 FLAGS="${FLAGS/\/\/ bindgen\-flags:/}"
 # Prepend the default flags added in test.rs's `create_bindgen_builder`.
-FLAGS="--no-unstable-rust --with-derive-default --raw-line '' --raw-line '#![allow(dead_code, non_snake_case, non_camel_case_types, non_upper_case_globals)]' --raw-line '' $FLAGS"
+FLAGS="--with-derive-default --raw-line '' --raw-line '#![allow(dead_code, non_snake_case, non_camel_case_types, non_upper_case_globals)]' --raw-line '' $FLAGS"
 
 
 eval ./target/debug/bindgen \
diff --git a/tests/tests.rs b/tests/tests.rs
index 46f83155..c1d79954 100644
--- a/tests/tests.rs
+++ b/tests/tests.rs
@@ -146,7 +146,7 @@ fn create_bindgen_builder(header: &PathBuf) -> Result<Option<Builder>, Error> {
         .chain(flags.into_iter());
 
     builder_from_flags(args)
-        .map(|(builder, _, _)| Some(builder.no_unstable_rust()))
+        .map(|(builder, _, _)| Some(builder))
 }
 
 macro_rules! test_header {
@@ -177,7 +177,6 @@ include!(concat!(env!("OUT_DIR"), "/tests.rs"));
 fn test_header_contents() {
     let bindings = builder()
         .header_contents("test.h", "int foo(const char* a);")
-        .no_unstable_rust()
         .generate()
         .unwrap()
         .to_string();