ir: Support pointers to zsts.

Fixes #654

tests/expectations/zst.both.c

@@ -0,0 +1,11 @@
+#include <stdarg.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+typedef struct TraitObject {
+  void *data;
+  void *vtable;
+} TraitObject;
+
+void *root(const void *ptr, struct TraitObject t);

tests/expectations/zst.both.compat.c

@@ -0,0 +1,19 @@
+#include <stdarg.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+typedef struct TraitObject {
+  void *data;
+  void *vtable;
+} TraitObject;
+
+#ifdef __cplusplus
+extern "C" {
+#endif // __cplusplus
+
+void *root(const void *ptr, struct TraitObject t);
+
+#ifdef __cplusplus
+} // extern "C"
+#endif // __cplusplus

tests/expectations/zst.c

@@ -0,0 +1,11 @@
+#include <stdarg.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+typedef struct {
+  void *data;
+  void *vtable;
+} TraitObject;
+
+void *root(const void *ptr, TraitObject t);

tests/expectations/zst.compat.c

@@ -0,0 +1,19 @@
+#include <stdarg.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+typedef struct {
+  void *data;
+  void *vtable;
+} TraitObject;
+
+#ifdef __cplusplus
+extern "C" {
+#endif // __cplusplus
+
+void *root(const void *ptr, TraitObject t);
+
+#ifdef __cplusplus
+} // extern "C"
+#endif // __cplusplus

tests/expectations/zst.cpp

@@ -0,0 +1,16 @@
+#include <cstdarg>
+#include <cstdint>
+#include <cstdlib>
+#include <ostream>
+#include <new>
+
+struct TraitObject {
+  void *data;
+  void *vtable;
+};
+
+extern "C" {
+
+void *root(const void *ptr, TraitObject t);
+
+} // extern "C"

tests/expectations/zst.pyx

@@ -0,0 +1,13 @@
+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 *:
+
+  ctypedef struct TraitObject:
+    void *data;
+    void *vtable;
+
+  void *root(const void *ptr, TraitObject t);

tests/expectations/zst.tag.c

@@ -0,0 +1,11 @@
+#include <stdarg.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+struct TraitObject {
+  void *data;
+  void *vtable;
+};
+
+void *root(const void *ptr, struct TraitObject t);

tests/expectations/zst.tag.compat.c

@@ -0,0 +1,19 @@
+#include <stdarg.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+struct TraitObject {
+  void *data;
+  void *vtable;
+};
+
+#ifdef __cplusplus
+extern "C" {
+#endif // __cplusplus
+
+void *root(const void *ptr, struct TraitObject t);
+
+#ifdef __cplusplus
+} // extern "C"
+#endif // __cplusplus

tests/expectations/zst.tag.pyx

@@ -0,0 +1,13 @@
+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 *:
+
+  cdef struct TraitObject:
+    void *data;
+    void *vtable;
+
+  void *root(const void *ptr, TraitObject t);

tests/rust/zst.rs

@@ -0,0 +1,10 @@
+#[repr(C)]
+pub struct TraitObject {
+    pub data: *mut (),
+    pub vtable: *mut (),
+}
+
+#[no_mangle]
+pub extern "C" fn root(ptr: *const (), t: TraitObject) -> *mut () {
+    std::ptr::null_mut()
+}