Added catch_unwind to catch panic at generator due to missing or incorrect flags

Author: dengjeffrey

src/chooser.rs

@@ -3,10 +3,11 @@
 pub use ir::int::IntKind;
 pub use ir::enum_ty::{EnumVariantValue, EnumVariantCustomBehavior};
 use std::fmt;
+use std::panic::UnwindSafe;
 
 /// A trait to allow configuring different kinds of types in different
 /// situations.
-pub trait TypeChooser: fmt::Debug {
+pub trait TypeChooser: fmt::Debug + UnwindSafe {
     /// The integer kind an integer macro should have, given a name and the
     /// value of that macro, or `None` if you want the default to be chosen.
     fn int_macro(&self, _name: &str, _value: i64) -> Option<IntKind> {

src/lib.rs

@@ -555,6 +555,11 @@ pub struct BindgenOptions {
     pub objc_extern_crate: bool,
 }
 
+/// TODO(emilio): This is sort of a lie (see the error message that results from
+/// removing this), but since we don't share references across panic boundaries
+/// it's ok.
+impl ::std::panic::UnwindSafe for BindgenOptions {}
+
 impl BindgenOptions {
     fn build(&mut self) {
         self.whitelisted_vars.build();

src/main.rs

@@ -8,6 +8,7 @@ extern crate rustc_serialize;
 
 use bindgen::clang_version;
 use std::env;
+use std::panic;
 
 mod options;
 use options::builder_from_flags;
@@ -44,8 +45,24 @@ pub fn main() {
 
     match builder_from_flags(bind_args.into_iter()) {
         Ok((builder, output)) => {
-            let mut bindings = builder.generate()
-                .expect("Unable to generate bindings");
+
+            let builder_result =
+                panic::catch_unwind(||
+                    builder.generate().expect("Unable to generate bindings")
+                );
+
+            if builder_result.is_err() {
+                println!("Bindgen unexpectedly panicked");
+                println!("This may be caused by one of the known-unsupported \
+                          things (https://github.com/servo/rust-bindgen#c), \
+                          please modify the bindgen flags to work around it as \
+                          described in https://github.com/servo/rust-bindgen#c");
+                println!("Otherwise, please file an issue at \
+                         https://github.com/servo/rust-bindgen/issues/new");
+                std::process::exit(1);
+            }
+
+            let mut bindings = builder_result.unwrap();
             bindings.write(output)
                 .expect("Unable to write output");
             bindings.write_dummy_uses()