gh-106727: Make `inspect.getsource` smarter for class for same name definitions (#106815)

1 files changed, 46 insertions, 11 deletions

diff --git a/Lib/inspect.py b/Lib/inspect.py
index 15f94a1..675714d 100644
--- a/Lib/inspect.py
+++ b/Lib/inspect.py
@@ -1034,9 +1034,13 @@ class ClassFoundException(Exception):
 
 class _ClassFinder(ast.NodeVisitor):
 
-    def __init__(self, qualname):
+    def __init__(self, cls, tree, lines, qualname):
         self.stack = []
+        self.cls = cls
+        self.tree = tree
+        self.lines = lines
         self.qualname = qualname
+        self.lineno_found = []
 
     def visit_FunctionDef(self, node):
         self.stack.append(node.name)
@@ -1057,11 +1061,48 @@ class _ClassFinder(ast.NodeVisitor):
                 line_number = node.lineno
 
             # decrement by one since lines starts with indexing by zero
-            line_number -= 1
-            raise ClassFoundException(line_number)
+            self.lineno_found.append((line_number - 1, node.end_lineno))
         self.generic_visit(node)
         self.stack.pop()
 
+    def get_lineno(self):
+        self.visit(self.tree)
+        lineno_found_number = len(self.lineno_found)
+        if lineno_found_number == 0:
+            raise OSError('could not find class definition')
+        elif lineno_found_number == 1:
+            return self.lineno_found[0][0]
+        else:
+            # We have multiple candidates for the class definition.
+            # Now we have to guess.
+
+            # First, let's see if there are any method definitions
+            for member in self.cls.__dict__.values():
+                if isinstance(member, types.FunctionType):
+                    for lineno, end_lineno in self.lineno_found:
+                        if lineno <= member.__code__.co_firstlineno <= end_lineno:
+                            return lineno
+
+            class_strings = [(''.join(self.lines[lineno: end_lineno]), lineno)
+                             for lineno, end_lineno in self.lineno_found]
+
+            # Maybe the class has a docstring and it's unique?
+            if self.cls.__doc__:
+                ret = None
+                for candidate, lineno in class_strings:
+                    if self.cls.__doc__.strip() in candidate:
+                        if ret is None:
+                            ret = lineno
+                        else:
+                            break
+                else:
+                    if ret is not None:
+                        return ret
+
+            # We are out of ideas, just return the last one found, which is
+            # slightly better than previous ones
+            return self.lineno_found[-1][0]
+
 
 def findsource(object):
     """Return the entire source file and starting line number for an object.
@@ -1098,14 +1139,8 @@ def findsource(object):
         qualname = object.__qualname__
         source = ''.join(lines)
         tree = ast.parse(source)
-        class_finder = _ClassFinder(qualname)
-        try:
-            class_finder.visit(tree)
-        except ClassFoundException as e:
-            line_number = e.args[0]
-            return lines, line_number
-        else:
-            raise OSError('could not find class definition')
+        class_finder = _ClassFinder(object, tree, lines, qualname)
+        return lines, class_finder.get_lineno()
 
     if ismethod(object):
         object = object.__func__