Fix docstrings generated by [pyo3(get, set)]

CHANGELOG.md

@@ -21,6 +21,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 * `PyClass`, `PyClassShell`, `PyObjectLayout`, `PyClassInitializer`. [#683](https://github.com/PyO3/pyo3/pull/683)
 * Implemented `IntoIterator` for `PySet` and `PyFrozenSet`. [#716](https://github.com/PyO3/pyo3/pull/716)
 * `FromPyObject` is now automatically implemented for `T: Clone` pyclasses. [#730](https://github.com/PyO3/pyo3/pull/730)
+* `#[pyo3(get)]` and `#[pyo3(set)]` will now use the Rust doc-comment from the field for the Python property. [#755](https://github.com/PyO3/pyo3/pull/755)
 
 ### Fixed
 

pyo3-derive-backend/src/pyclass.rs

@@ -465,8 +465,8 @@ fn impl_descriptors(
                 .map(|desc| {
                     let name = field.ident.as_ref().unwrap();
 
-                    // FIXME better doc?
-                    let doc = syn::LitStr::new(&name.to_string(), name.span());
+                    let doc = utils::get_doc(&field.attrs, None, true)
+                        .unwrap_or_else(|_| syn::LitStr::new(&name.to_string(), name.span()));
 
                     let field_ty = &field.ty;
                     match *desc {

src/class/methods.rs

@@ -108,6 +108,9 @@ impl PySetterDef {
                 .expect("Method name must not contain NULL byte")
                 .into_raw();
         }
+        if dst.doc.is_null() {
+            dst.doc = self.doc.as_ptr() as *mut libc::c_char;
+        }
         dst.set = Some(self.meth);
     }
 }

tests/test_class_basics.rs

@@ -23,7 +23,19 @@ fn empty_class() {
 ///  Line3
 // this is not doc string
 #[pyclass]
-struct ClassWithDocs {}
+struct ClassWithDocs {
+    /// Property field
+    #[pyo3(get, set)]
+    value: i32,
+
+    /// Read-only property field
+    #[pyo3(get)]
+    readonly: i32,
+
+    /// Write-only property field
+    #[pyo3(set)]
+    writeonly: i32,
+}
 
 #[test]
 fn class_with_docstr() {
@@ -36,6 +48,21 @@ fn class_with_docstr() {
             typeobj,
             "assert typeobj.__doc__ == 'Line1\\nLine2\\n Line3'"
         );
+        py_run!(
+            py,
+            typeobj,
+            "assert typeobj.value.__doc__ == 'Property field'"
+        );
+        py_run!(
+            py,
+            typeobj,
+            "assert typeobj.readonly.__doc__ == 'Read-only property field'"
+        );
+        py_run!(
+            py,
+            typeobj,
+            "assert typeobj.writeonly.__doc__ == 'Write-only property field'"
+        );
     }
 }