Honor and expose the derive_debug option.

Fixes #432

5 files changed, 55 insertions, 1 deletions

diff --git a/src/ir/item.rs b/src/ir/item.rs
index ac2d122e..7b18b331 100644
--- a/src/ir/item.rs
+++ b/src/ir/item.rs
@@ -219,7 +219,7 @@ impl CanDeriveDebug for Item {
     type Extra = ();
 
     fn can_derive_debug(&self, ctx: &BindgenContext, _: ()) -> bool {
-        match self.kind {
+        ctx.options().derive_debug && match self.kind {
             ItemKind::Type(ref ty) => {
                 if self.is_opaque(ctx) {
                     ty.layout(ctx)
diff --git a/src/lib.rs b/src/lib.rs
index 88da1a48..bb621718 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -268,6 +268,12 @@ impl Builder {
         self
     }
 
+    /// Set whether `Debug` should be derived by default.
+    pub fn derive_debug(mut self, doit: bool) -> Self {
+        self.options.derive_debug = doit;
+        self
+    }
+
     /// Emit Clang AST.
     pub fn emit_clang_ast(mut self) -> Builder {
         self.options.emit_ast = true;
diff --git a/src/options.rs b/src/options.rs
index 3456bfea..c5c80d63 100644
--- a/src/options.rs
+++ b/src/options.rs
@@ -31,6 +31,9 @@ pub fn builder_from_flags<I>(args: I)
                 .takes_value(true)
                 .multiple(true)
                 .number_of_values(1),
+            Arg::with_name("no-derive-debug")
+                .long("no-derive-debug")
+                .help("Avoid deriving Debug on any type."),
             Arg::with_name("builtins")
                 .long("builtins")
                 .help("Output bindings for builtin definitions, e.g. \
@@ -181,6 +184,10 @@ pub fn builder_from_flags<I>(args: I)
         builder = builder.emit_builtins();
     }
 
+    if matches.is_present("no-derive-debug") {
+        builder = builder.derive_debug(false);
+    }
+
     if let Some(prefix) = matches.value_of("ctypes-prefix") {
         builder = builder.ctypes_prefix(prefix);
     }
diff --git a/tests/expectations/tests/no-derive-debug.rs b/tests/expectations/tests/no-derive-debug.rs
new file mode 100644
index 00000000..e45b2678
--- /dev/null
+++ b/tests/expectations/tests/no-derive-debug.rs
@@ -0,0 +1,26 @@
+/* automatically generated by rust-bindgen */
+
+
+#![allow(non_snake_case)]
+
+#[repr(C)] #[derive(Copy, Clone)] pub struct foo { bar: ::std::os::raw::c_int, }
+
+/**
+ * bar should compile. It will normally derive debug, but our blacklist of foo
+ * and replacement for another type that doesn't implement it would prevent it
+ * from building if --no-derive-debug didn't work.
+ */
+#[repr(C)]
+#[derive(Copy)]
+pub struct bar {
+    pub foo: foo,
+    pub baz: ::std::os::raw::c_int,
+}
+#[test]
+fn bindgen_test_layout_bar() {
+    assert_eq!(::std::mem::size_of::<bar>() , 8usize);
+    assert_eq!(::std::mem::align_of::<bar>() , 4usize);
+}
+impl Clone for bar {
+    fn clone(&self) -> Self { *self }
+}
diff --git a/tests/headers/no-derive-debug.h b/tests/headers/no-derive-debug.h
new file mode 100644
index 00000000..4a49e404
--- /dev/null
+++ b/tests/headers/no-derive-debug.h
@@ -0,0 +1,15 @@
+// bindgen-flags: --no-derive-debug --blacklist-type foo --raw-line "#[repr(C)] #[derive(Copy, Clone)] pub struct foo { bar: ::std::os::raw::c_int, }"
+
+struct foo {
+  int bar;
+};
+
+/**
+ * bar should compile. It will normally derive debug, but our blacklist of foo
+ * and replacement for another type that doesn't implement it would prevent it
+ * from building if --no-derive-debug didn't work.
+ */
+struct bar {
+  struct foo foo;
+  int baz;
+};