gh-81677: basic support for annotations in __text_signature__'s

Lib/inspect.py

@@ -2276,10 +2276,22 @@ def _signature_fromstr(cls, obj, s, skip_bound_arg=True):
 
     def parse_name(node):
         assert isinstance(node, ast.arg)
-        if node.annotation is not None:
-            raise ValueError("Annotations are not currently supported")
         return node.arg
 
+    def parse_annotation(node):
+        assert isinstance(node, (ast.arg, ast.FunctionDef))
+        if isinstance(node, ast.arg):
+            annotation = node.annotation
+        else:
+            annotation = node.returns
+        if annotation:
+            expr = ast.unparse(annotation)
+            try:
+                return eval(expr, sys_module_dict)
+            except NameError:
+                raise ValueError
+        return empty
+
     def wrap_value(s):
         try:
             value = eval(s, module_dict)
@@ -2334,7 +2346,11 @@ def p(name_node, default_node, default=empty):
                 default = ast.literal_eval(default_node)
             except ValueError:
                 raise ValueError("{!r} builtin has invalid signature".format(obj)) from None
-        parameters.append(Parameter(name, kind, default=default, annotation=empty))
+        try:
+            annotation = parse_annotation(name_node)
+        except ValueError:
+            raise ValueError("{!r} builtin has invalid signature".format(obj)) from None
+        parameters.append(Parameter(name, kind, default=default, annotation=annotation))
 
     # non-keyword-only parameters
     total_non_kw_args = len(f.args.posonlyargs) + len(f.args.args)
@@ -2381,7 +2397,12 @@ def p(name_node, default_node, default=empty):
             p = parameters[0].replace(kind=Parameter.POSITIONAL_ONLY)
             parameters[0] = p
 
-    return cls(parameters, return_annotation=cls.empty)
+    try:
+        return_annotation = parse_annotation(f)
+    except ValueError:
+        raise ValueError("{!r} builtin has invalid signature".format(obj)) from None
+
+    return cls(parameters, return_annotation=return_annotation)
 
 
 def _signature_from_builtin(cls, func, skip_bound_arg=True):

Lib/test/test_inspect/test_inspect.py

@@ -4807,6 +4807,33 @@ class MyBufferedReader(BufferedReader):
         sig = inspect.signature(MyBufferedReader)
         self.assertEqual(str(sig), '(raw, buffer_size=8192)')
 
+    def test_annotations_in_text_signature(self):
+        def func(*args, **kwargs):
+            pass
+
+        func.__text_signature__ = '($self, a: int) -> list'
+        sig = inspect.signature(func)
+        self.assertIsNotNone(sig)
+        self.assertEqual(str(sig), '(self, /, a: int) -> list')
+
+        func.__text_signature__ = '($self, a: int | float)'
+        sig = inspect.signature(func)
+        self.assertIsNotNone(sig)
+        self.assertEqual(str(sig), '(self, /, a: int | float)')
+
+        func.__text_signature__ = '($self, a: tuple[int, ...])'
+        sig = inspect.signature(func)
+        self.assertIsNotNone(sig)
+        self.assertEqual(str(sig), '(self, /, a: tuple[int, ...])')
+
+        func.__text_signature__ = '(self, x: spam)'
+        with self.assertRaises(ValueError):
+            inspect.signature(func)
+
+        func.__text_signature__ = '(self, x) -> spam'
+        with self.assertRaises(ValueError):
+            inspect.signature(func)
+
 
 class NTimesUnwrappable:
     def __init__(self, n):

Misc/NEWS.d/next/Library/2023-02-20-07-33-54.gh-issue-81677.bSmaNE.rst

@@ -0,0 +1,2 @@
+Basic support of annotations in :func:`inspect.signature` handling of
+``__text_signature__``.  Patch by Sergey B Kirpichev.

Objects/typeobject.c

@@ -505,8 +505,8 @@ find_signature(const char *name, const char *doc)
     return doc;
 }
 
-#define SIGNATURE_END_MARKER         ")\n--\n\n"
-#define SIGNATURE_END_MARKER_LENGTH  6
+#define SIGNATURE_END_MARKER         "\n--\n\n"
+#define SIGNATURE_END_MARKER_LENGTH  5
 /*
  * skips past the end of the docstring's introspection signature.
  * (assumes doc starts with a valid signature prefix.)
@@ -623,11 +623,12 @@ _PyType_GetTextSignatureFromInternalDoc(const char *name, const char *internal_d
         Py_RETURN_NONE;
     }
 
-    /* back "end" up until it points just past the final ')' */
-    end -= SIGNATURE_END_MARKER_LENGTH - 1;
+    /* back "end" up until it points just to the end marker */
+    end -= SIGNATURE_END_MARKER_LENGTH;
     assert((end - start) >= 2); /* should be "()" at least */
-    assert(end[-1] == ')');
     assert(end[0] == '\n');
+    assert(end[1] == '-');
+    assert(end[2] == '-');
     return PyUnicode_FromStringAndSize(start, end - start);
 }