Refactor to only raise an error based on isinstance

src/lib.rs

@@ -1,7 +1,4 @@
-#![cfg_attr(
-    feature = "nightly",
-    feature(auto_traits, negative_impls, min_specialization)
-)]
+#![cfg_attr(feature = "nightly", feature(auto_traits, negative_impls))]
 #![cfg_attr(docsrs, feature(doc_cfg, doc_auto_cfg))]
 #![cfg_attr(
     docsrs, // rustdoc:: is not supported on msrv

src/types/sequence.rs

@@ -1,9 +1,8 @@
 // Copyright (c) 2017-present PyO3 Project and Contributors
 use crate::err::{self, PyDowncastError, PyErr, PyResult};
+use crate::exceptions::PyValueError;
 use crate::internal_tricks::get_ssize_index;
-#[cfg(feature = "nightly")]
-use crate::types::PyString;
-use crate::types::{PyAny, PyList, PyTuple};
+use crate::types::{PyAny, PyList, PyString, PyTuple};
 use crate::{ffi, PyNativeType, ToPyObject};
 use crate::{AsPyPointer, IntoPyPointer, Py, Python};
 use crate::{FromPyObject, PyTryFrom};
@@ -266,50 +265,18 @@ fn sequence_slice(seq: &PySequence, start: usize, end: usize) -> &PySequence {
 
 index_impls!(PySequence, "sequence", sequence_len, sequence_slice);
 
-#[cfg(not(feature = "nightly"))]
 impl<'a, T> FromPyObject<'a> for Vec<T>
 where
     T: FromPyObject<'a>,
 {
     fn extract(obj: &'a PyAny) -> PyResult<Self> {
-        extract_sequence(obj)
-    }
-}
-
-#[cfg(feature = "nightly")]
-impl<'a, T> FromPyObject<'a> for Vec<T>
-where
-    T: FromPyObject<'a>,
-{
-    default fn extract(obj: &'a PyAny) -> PyResult<Self> {
-        extract_sequence(obj)
-    }
-}
-
-#[cfg(feature = "nightly")]
-impl<'a> FromPyObject<'a> for Vec<String> {
-    fn extract(obj: &'a PyAny) -> PyResult<Self> {
-        if obj.is_instance_of::<PyString>()? {
-            Ok(vec![FromPyObject::extract(obj)?])
-        } else {
-            extract_sequence(obj)
+        if let Ok(true) = obj.is_instance_of::<PyString>() {
+            return Err(PyValueError::new_err("Can't extract `str` to `Vec`"));
         }
+        extract_sequence(obj)
     }
 }
 
-/*
-#[cfg(feature = "nightly")]
-impl<'a> FromPyObject<'a> for Vec<&'a str>
-{
-    fn extract(obj: &'a PyAny) -> PyResult<Self> {
-        if obj.is_instance_of::<PyString>()? {
-            Ok(vec![FromPyObject::extract(obj)?])
-        } else {
-            extract_sequence(obj)
-        }
-    }
-}*/
-
 fn extract_sequence<'s, T>(obj: &'s PyAny) -> PyResult<Vec<T>>
 where
     T: FromPyObject<'s>,