Add a C naming option (#2045)

Closes #2045.
Fixes #1252.

2 files changed, 111 insertions, 0 deletions

diff --git a/tests/expectations/tests/c_naming.rs b/tests/expectations/tests/c_naming.rs
new file mode 100644
index 00000000..041e75ea
--- /dev/null
+++ b/tests/expectations/tests/c_naming.rs
@@ -0,0 +1,92 @@
+#![allow(
+    dead_code,
+    non_snake_case,
+    non_camel_case_types,
+    non_upper_case_globals
+)]
+
+#[repr(C)]
+#[derive(Debug, Default, Copy, Clone)]
+pub struct struct_a {
+    pub a: ::std::os::raw::c_int,
+}
+#[test]
+fn bindgen_test_layout_struct_a() {
+    assert_eq!(
+        ::std::mem::size_of::<struct_a>(),
+        4usize,
+        concat!("Size of: ", stringify!(struct_a))
+    );
+    assert_eq!(
+        ::std::mem::align_of::<struct_a>(),
+        4usize,
+        concat!("Alignment of ", stringify!(struct_a))
+    );
+    assert_eq!(
+        unsafe { &(*(::std::ptr::null::<struct_a>())).a as *const _ as usize },
+        0usize,
+        concat!(
+            "Offset of field: ",
+            stringify!(struct_a),
+            "::",
+            stringify!(a)
+        )
+    );
+}
+pub type a = *const struct_a;
+#[repr(C)]
+#[derive(Copy, Clone)]
+pub union union_b {
+    pub a: ::std::os::raw::c_int,
+    pub b: ::std::os::raw::c_int,
+}
+#[test]
+fn bindgen_test_layout_union_b() {
+    assert_eq!(
+        ::std::mem::size_of::<union_b>(),
+        4usize,
+        concat!("Size of: ", stringify!(union_b))
+    );
+    assert_eq!(
+        ::std::mem::align_of::<union_b>(),
+        4usize,
+        concat!("Alignment of ", stringify!(union_b))
+    );
+    assert_eq!(
+        unsafe { &(*(::std::ptr::null::<union_b>())).a as *const _ as usize },
+        0usize,
+        concat!(
+            "Offset of field: ",
+            stringify!(union_b),
+            "::",
+            stringify!(a)
+        )
+    );
+    assert_eq!(
+        unsafe { &(*(::std::ptr::null::<union_b>())).b as *const _ as usize },
+        0usize,
+        concat!(
+            "Offset of field: ",
+            stringify!(union_b),
+            "::",
+            stringify!(b)
+        )
+    );
+}
+impl Default for union_b {
+    fn default() -> Self {
+        unsafe { ::std::mem::zeroed() }
+    }
+}
+pub type b = union_b;
+pub const enum_c_A: enum_c = 0;
+pub type enum_c = ::std::os::raw::c_uint;
+extern "C" {
+    pub fn takes_a(arg: a);
+}
+extern "C" {
+    pub fn takes_b(arg: b);
+}
+extern "C" {
+    pub fn takes_c(arg: enum_c);
+}
diff --git a/tests/headers/c_naming.h b/tests/headers/c_naming.h
new file mode 100644
index 00000000..fd84c271
--- /dev/null
+++ b/tests/headers/c_naming.h
@@ -0,0 +1,19 @@
+// bindgen-flags: --c-naming
+
+typedef const struct a {
+    int a;
+} *a;
+
+union b {
+    int a;
+    int b;
+};
+typedef union b b;
+
+enum c {
+    A,
+};
+
+void takes_a(a arg) {}
+void takes_b(b arg) {}
+void takes_c(enum c arg) {}