make PyDictObject, PyFloatObject opaque under limited API

src/ffi/cpython/dictobject.rs

@@ -3,6 +3,19 @@ use crate::ffi::object::*;
 use crate::ffi::pyport::Py_ssize_t;
 use std::os::raw::c_int;
 
+opaque_struct!(PyDictKeysObject);
+
+#[repr(C)]
+#[derive(Debug)]
+// Not moved because dict.rs uses PyDictObject extensively.
+pub struct PyDictObject {
+    pub ob_base: PyObject,
+    pub ma_used: Py_ssize_t,
+    pub ma_version_tag: u64,
+    pub ma_keys: *mut PyDictKeysObject,
+    pub ma_values: *mut *mut PyObject,
+}
+
 extern "C" {
     // skipped _PyDict_GetItem_KnownHash
     // skipped _PyDict_GetItemIdWithError

src/ffi/dictobject.rs

@@ -107,17 +107,6 @@ extern "C" {
     pub static mut PyDictRevIterItem_Type: PyTypeObject;
 }
 
-#[repr(C)]
-#[derive(Debug)]
-// TODO: move to cpython/dictobject.rs
-// Not moved because dict.rs uses PyDictObject extensively.
-pub struct PyDictObject {
-    pub ob_base: PyObject,
-    pub ma_used: Py_ssize_t,
-    pub ma_version_tag: u64,
-    pub ma_keys: *mut PyDictKeysObject,
-    pub ma_values: *mut *mut PyObject,
-}
-
-// TODO: move to cpython/dictobject.rs
-opaque_struct!(PyDictKeysObject);
+#[cfg(Py_LIMITED_API)]
+// TODO: remove (see https://github.com/PyO3/pyo3/pull/1341#issuecomment-751515985)
+opaque_struct!(PyDictObject);

src/ffi/floatobject.rs

@@ -1,8 +1,11 @@
 use crate::ffi::object::*;
 use std::os::raw::{c_double, c_int};
 
-// TODO: mark non-limited
-// currently used by types/floatob.rs
+#[cfg(Py_LIMITED_API)]
+// TODO: remove (see https://github.com/PyO3/pyo3/pull/1341#issuecomment-751515985)
+opaque_struct!(PyFloatObject);
+
+#[cfg(not(Py_LIMITED_API))]
 #[repr(C)]
 pub struct PyFloatObject {
     pub ob_base: PyObject,