fix: Show correct docstring line numbers on Python 3.7

Issue #98: #98

src/griffe/agents/nodes.py

@@ -825,7 +825,15 @@ def get_docstring(
     if isinstance(doc, NodeConstant) and isinstance(doc.value, str):
         return doc.value, doc.lineno, doc.end_lineno  # type: ignore[attr-defined]
     if isinstance(doc, NodeStr):
-        return doc.s, doc.lineno, doc.end_lineno  # type: ignore[attr-defined]
+
+        # TODO: remove once Python 3.7 support is dropped
+        # on Python 3.7, lineno seems to be the ending line of the string
+        # rather than the starting one, so we substract the number of newlines
+        lineno = doc.lineno
+        if sys.version_info < (3, 8):
+            lineno -= doc.s.count("\n")
+
+        return doc.s, lineno, doc.end_lineno  # type: ignore[attr-defined]
     return None, None, None
 
 

tests/test_visitor.py

@@ -227,7 +227,6 @@ def test_parse_complex__all__assignments(statements):
         assert package.exports == {"CONST_INIT", "CONST_A", "CONST_B", "CONST_C"}
 
 
-# issue https://github.com/mkdocstrings/griffe/issues/68
 def test_dont_crash_on_nested_functions_in_init():
     """Assert we don't crash when visiting a nested function in `__init__` methods."""
     with temporary_visited_module(
@@ -239,3 +238,25 @@ def pl(i: int):
         """
     ) as module:
         assert module
+
+
+def test_get_correct_docstring_starting_line_number():
+    """Assert we get the correct line numbers for docstring, even on Python 3.7."""
+    with temporary_visited_module(
+        """
+        '''
+        Module docstring.
+        '''
+        class C:
+            '''
+            Class docstring.
+            '''
+            def method(self):
+                '''
+                Method docstring.
+                '''
+        """
+    ) as module:
+        assert module.docstring.lineno == 2
+        assert module["C"].docstring.lineno == 6
+        assert module["C.method"].docstring.lineno == 10