Add cdef and cpdef support

3 files changed, 45 insertions, 8 deletions

diff --git a/isort/api.py b/isort/api.py
index bf86cd0e..004c5f5b 100644
--- a/isort/api.py
+++ b/isort/api.py
@@ -323,9 +323,11 @@ def sort_imports(
                     output_stream.write(line)
                     indent = ""
 
-                contains_imports = False
                 if next_import_section:
                     cimports = not cimports
+                    contains_imports = True
+                else:
+                    contains_imports = False
                 import_section = next_import_section
                 next_import_section = ""
             else:
diff --git a/isort/output.py b/isort/output.py
index 5f2659f7..cd925c91 100644
--- a/isort/output.py
+++ b/isort/output.py
@@ -1,7 +1,7 @@
 import copy
 import itertools
 from functools import partial
-from typing import Any, Dict, Iterable, List, Optional
+from typing import Any, Dict, Iterable, List, Optional, Tuple
 
 from isort.format import format_simplified
 
@@ -9,6 +9,8 @@ from . import parse, sorting, wrap
 from .comments import add_to_line as with_comments
 from .settings import DEFAULT_CONFIG, Config
 
+STATEMENT_DECLERATIONS: Tuple[str, ...] = ("def ", "cdef ", "cpdef ", "class ", "@", "async def")
+
 
 def sorted_imports(
     parsed: parse.ParsedContent,
@@ -202,12 +204,7 @@ def sorted_imports(
 
         if config.lines_after_imports != -1:
             formatted_output[imports_tail:0] = ["" for line in range(config.lines_after_imports)]
-        elif extension != "pyi" and (
-            next_construct.startswith("def ")
-            or next_construct.startswith("class ")
-            or next_construct.startswith("@")
-            or next_construct.startswith("async def")
-        ):
+        elif extension != "pyi" and next_construct.startswith(STATEMENT_DECLERATIONS):
             formatted_output[imports_tail:0] = ["", ""]
         else:
             formatted_output[imports_tail:0] = [""]
diff --git a/tests/test_isort.py b/tests/test_isort.py
index 11a7079f..0228b414 100644
--- a/tests/test_isort.py
+++ b/tests/test_isort.py
@@ -4627,6 +4627,44 @@ IF CEF_VERSION == 3:
     SortImports(file_contents=test_input).output == expected_output
 
 
+def test_cdef_support():
+    assert (
+        SortImports(
+            file_contents="""
+from cpython.version cimport PY_MAJOR_VERSION
+
+cdef extern from *:
+    ctypedef CefString ConstCefString "const CefString"
+"""
+        ).output
+        == """
+from cpython.version cimport PY_MAJOR_VERSION
+
+
+cdef extern from *:
+    ctypedef CefString ConstCefString "const CefString"
+"""
+    )
+
+    assert (
+        SortImports(
+            file_contents="""
+from cpython.version cimport PY_MAJOR_VERSION
+
+cpdef extern from *:
+    ctypedef CefString ConstCefString "const CefString"
+"""
+        ).output
+        == """
+from cpython.version cimport PY_MAJOR_VERSION
+
+
+cpdef extern from *:
+    ctypedef CefString ConstCefString "const CefString"
+"""
+    )
+
+
 def test_top_level_import_order() -> None:
     test_input = (
         "from rest_framework import throttling, viewsets\n"