Do not store return values in locals so that holders benefit from lif…

…etime extension for temporaries.
PyO3 · May 6, 2023 · a60945f · a60945f
1 parent 0773651
commit a60945f
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Showing 3 changed files with 5 additions and 6 deletions.
diff --git a/newsfragments/3142.fixed.md b/newsfragments/3142.fixed.md
@@ -0,0 +1 @@
+Extend lifetime of holder variables to avoid "temporary value dropped while borrowed" errors when `#[pyfunction]`s take references into `#[pyclass]`es
diff --git a/pyo3-macros-backend/src/method.rs b/pyo3-macros-backend/src/method.rs
@@ -425,9 +425,8 @@ impl<'a> FnSpec<'a> {
 
         let rust_call = |args: Vec<TokenStream>| {
             quote! {
-                let mut ret = function(#self_arg #(#args),*);
-                let owned = _pyo3::impl_::pymethods::OkWrap::wrap(ret, #py);
-                owned.map(|obj| _pyo3::conversion::IntoPyPointer::into_ptr(obj))
+                _pyo3::impl_::pymethods::OkWrap::wrap(function(#self_arg #(#args),*), #py)
+                    .map(|obj| _pyo3::conversion::IntoPyPointer::into_ptr(obj))
                     .map_err(::core::convert::Into::into)
             }
         };

diff --git a/pyo3-macros-backend/src/pymethod.rs b/pyo3-macros-backend/src/pymethod.rs
@@ -456,9 +456,8 @@ fn impl_py_class_attribute(cls: &syn::Type, spec: &FnSpec<'_>) -> syn::Result<Me
         fn #wrapper_ident(py: _pyo3::Python<'_>) -> _pyo3::PyResult<_pyo3::PyObject> {
             let function = #cls::#name; // Shadow the method name to avoid #3017
             #deprecations
-            let mut ret = #fncall;
-            let owned = _pyo3::impl_::pymethods::OkWrap::wrap(ret, py);
-            owned.map_err(::core::convert::Into::into)
+            _pyo3::impl_::pymethods::OkWrap::wrap(#fncall, py)
+                .map_err(::core::convert::Into::into)
         }
     };