Support "C-unwind" ABI

Closes #864

src/bindgen/utilities.rs

@@ -263,7 +263,7 @@ impl SynAbiHelpers for Option<syn::Abi> {
     fn is_c(&self) -> bool {
         if let Some(ref abi) = *self {
             if let Some(ref lit_string) = abi.name {
-                return lit_string.value() == "C";
+                return matches!(lit_string.value().as_str(), "C" | "C-unwind");
             }
         }
         false
@@ -280,7 +280,7 @@ impl SynAbiHelpers for Option<syn::Abi> {
 impl SynAbiHelpers for syn::Abi {
     fn is_c(&self) -> bool {
         if let Some(ref lit_string) = self.name {
-            lit_string.value() == "C"
+            matches!(lit_string.value().as_str(), "C" | "C-unwind")
         } else {
             false
         }

tests/expectations/abi_string.c

@@ -0,0 +1,8 @@
+#include <stdarg.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+void c(void);
+
+void c_unwind(void);

tests/expectations/abi_string.compat.c

@@ -0,0 +1,16 @@
+#include <stdarg.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif // __cplusplus
+
+void c(void);
+
+void c_unwind(void);
+
+#ifdef __cplusplus
+} // extern "C"
+#endif // __cplusplus

tests/expectations/abi_string.cpp

@@ -0,0 +1,13 @@
+#include <cstdarg>
+#include <cstdint>
+#include <cstdlib>
+#include <ostream>
+#include <new>
+
+extern "C" {
+
+void c();
+
+void c_unwind();
+
+} // extern "C"

tests/expectations/abi_string.pyx

@@ -0,0 +1,11 @@
+from libc.stdint cimport int8_t, int16_t, int32_t, int64_t, intptr_t
+from libc.stdint cimport uint8_t, uint16_t, uint32_t, uint64_t, uintptr_t
+cdef extern from *:
+  ctypedef bint bool
+  ctypedef struct va_list
+
+cdef extern from *:
+
+  void c();
+
+  void c_unwind();

tests/rust/abi_string.rs

@@ -0,0 +1,5 @@
+#[no_mangle]
+pub extern "C" fn c() {}
+
+#[no_mangle]
+pub extern "C-unwind" fn c_unwind() {}