Fix spans weak ref in doc copy (#7225)

* failing unit test

* ensure that doc.spans refers to the copied doc, not the old

* add type info

spacy/tests/doc/test_doc_api.py

@@ -1,3 +1,5 @@
+import weakref
+
 import pytest
 import numpy
 import logging
@@ -663,3 +665,10 @@ def test_span_groups(en_tokenizer):
     assert doc.spans["hi"].has_overlap
     del doc.spans["hi"]
     assert "hi" not in doc.spans
+
+
+def test_doc_spans_copy(en_tokenizer):
+    doc1 = en_tokenizer("Some text about Colombia and the Czech Republic")
+    assert weakref.ref(doc1) == doc1.spans.doc_ref
+    doc2 = doc1.copy()
+    assert weakref.ref(doc2) == doc2.spans.doc_ref

spacy/tokens/_dict_proxies.py

@@ -33,8 +33,10 @@ class SpanGroups(UserDict):
     def _make_span_group(self, name: str, spans: Iterable["Span"]) -> SpanGroup:
         return SpanGroup(self.doc_ref(), name=name, spans=spans)
 
-    def copy(self) -> "SpanGroups":
-        return SpanGroups(self.doc_ref()).from_bytes(self.to_bytes())
+    def copy(self, doc: "Doc" = None) -> "SpanGroups":
+        if doc is None:
+            doc = self.doc_ref()
+        return SpanGroups(doc).from_bytes(self.to_bytes())
 
     def to_bytes(self) -> bytes:
         # We don't need to serialize this as a dict, because the groups

spacy/tokens/doc.pyx

@@ -1188,7 +1188,7 @@ cdef class Doc:
         other.user_span_hooks = dict(self.user_span_hooks)
         other.length = self.length
         other.max_length = self.max_length
-        other.spans = self.spans.copy()
+        other.spans = self.spans.copy(doc=other)
         buff_size = other.max_length + (PADDING*2)
         assert buff_size > 0
         tokens = <TokenC*>other.mem.alloc(buff_size, sizeof(TokenC))