bpo-44026: Idle - display interpreter's 'did you mean' hints (GH-25912)

A C function accessible by the default exception handler, but not by python code,
finds the existing name closest to the name causing a name or attribute error.  For
such errors, call the default handler after capturing stderr and retrieve its message line.

Co-authored-by: Terry Jan Reedy <tjreedy@udel.edu>

diff --git a/Lib/idlelib/NEWS.txt b/Lib/idlelib/NEWS.txt
index ed1142653d9534224031a92850c9584439dfb009..396820e9117b53d3f634eb0b19f8ebfa41a3183e 100644 (file)
--- a/Lib/idlelib/NEWS.txt
+++ b/Lib/idlelib/NEWS.txt
@@ -4,6 +4,9 @@ Released on 2021-10-04?
 =========================
 
 
+bpo-44026: Include interpreter's typo fix suggestions in message line
+for NameErrors and AttributeErrors.  Patch by E. Paine.
+
 bpo-37903: Add mouse actions to the shell sidebar.  Left click and
 optional drag selects one or more lines of text, as with the
 editor line number sidebar.  Right click after selecting text lines

diff --git a/Lib/idlelib/idle_test/test_run.py b/Lib/idlelib/idle_test/test_run.py
index a31671ee0485fa4e04c305426c0643502bc2cac9..ec4637c5ca617a9eb380d46825ee32c429520edc 100644 (file)
--- a/Lib/idlelib/idle_test/test_run.py
+++ b/Lib/idlelib/idle_test/test_run.py
@@ -1,4 +1,4 @@
-"Test run, coverage 49%."
+"Test run, coverage 54%."
 
 from idlelib import run
 import io
@@ -12,7 +12,7 @@ from idlelib.idle_test.mock_idle import Func
 idlelib.testing = True  # Use {} for executing test user code.
 
 
-class PrintExceptionTest(unittest.TestCase):
+class ExceptionTest(unittest.TestCase):
 
     def test_print_exception_unhashable(self):
         class UnhashableException(Exception):
@@ -28,8 +28,7 @@ class PrintExceptionTest(unittest.TestCase):
                 raise ex1
             except UnhashableException:
                 with captured_stderr() as output:
-                    with mock.patch.object(run,
-                                           'cleanup_traceback') as ct:
+                    with mock.patch.object(run, 'cleanup_traceback') as ct:
                         ct.side_effect = lambda t, e: t
                         run.print_exception()
 
@@ -38,6 +37,46 @@ class PrintExceptionTest(unittest.TestCase):
         self.assertIn('UnhashableException: ex2', tb[3])
         self.assertIn('UnhashableException: ex1', tb[10])
 
+    data = (('1/0', ZeroDivisionError, "division by zero\n"),
+            ('abc', NameError, "name 'abc' is not defined. "
+                               "Did you mean: 'abs'?\n"),
+            ('int.reel', AttributeError,
+                 "type object 'int' has no attribute 'reel'. "
+                 "Did you mean: 'real'?\n"),
+            )
+
+    def test_get_message(self):
+        for code, exc, msg in self.data:
+            with self.subTest(code=code):
+                try:
+                    eval(compile(code, '', 'eval'))
+                except exc:
+                    typ, val, tb = sys.exc_info()
+                    actual = run.get_message_lines(typ, val, tb)[0]
+                    expect = f'{exc.__name__}: {msg}'
+                    self.assertEqual(actual, expect)
+
+    @mock.patch.object(run, 'cleanup_traceback',
+                       new_callable=lambda: (lambda t, e: None))
+    def test_get_multiple_message(self, mock):
+        d = self.data
+        data2 = ((d[0], d[1]), (d[1], d[2]), (d[2], d[0]))
+        subtests = 0
+        for (code1, exc1, msg1), (code2, exc2, msg2) in data2:
+            with self.subTest(codes=(code1,code2)):
+                try:
+                    eval(compile(code1, '', 'eval'))
+                except exc1:
+                    try:
+                        eval(compile(code2, '', 'eval'))
+                    except exc2:
+                        with captured_stderr() as output:
+                            run.print_exception()
+                        actual = output.getvalue()
+                        self.assertIn(msg1, actual)
+                        self.assertIn(msg2, actual)
+                        subtests += 1
+        self.assertEqual(subtests, len(data2))  # All subtests ran?
 
 # StdioFile tests.
 

diff --git a/Lib/idlelib/run.py b/Lib/idlelib/run.py
index 07e9a2bf9ceeae1d356e404c58c2247cd43a688f..3836727691229e3e81ef4bc3db666ec76e2efb90 100644 (file)
--- a/Lib/idlelib/run.py
+++ b/Lib/idlelib/run.py
@@ -4,6 +4,7 @@ Simplified, pyshell.ModifiedInterpreter spawns a subprocess with
 f'''{sys.executable} -c "__import__('idlelib.run').run.main()"'''
 '.run' is needed because __import__ returns idlelib, not idlelib.run.
 """
+import contextlib
 import functools
 import io
 import linecache
@@ -211,6 +212,19 @@ def show_socket_error(err, address):
             parent=root)
     root.destroy()
 
+
+def get_message_lines(typ, exc, tb):
+    "Return line composing the exception message."
+    if typ in (AttributeError, NameError):
+        # 3.10+ hints are not directly accessible from python (#44026).
+        err = io.StringIO()
+        with contextlib.redirect_stderr(err):
+            sys.__excepthook__(typ, exc, tb)
+        return [err.getvalue().split("\n")[-2] + "\n"]
+    else:
+        return traceback.format_exception_only(typ, exc)
+
+
 def print_exception():
     import linecache
     linecache.checkcache()
@@ -241,7 +255,7 @@ def print_exception():
                        "debugger_r.py", "bdb.py")
             cleanup_traceback(tbe, exclude)
             traceback.print_list(tbe, file=efile)
-        lines = traceback.format_exception_only(typ, exc)
+        lines = get_message_lines(typ, exc, tb)
         for line in lines:
             print(line, end='', file=efile)
 

diff --git a/Misc/NEWS.d/next/IDLE/2021-05-05-09-45-24.bpo-44026.m2Z0zR.rst b/Misc/NEWS.d/next/IDLE/2021-05-05-09-45-24.bpo-44026.m2Z0zR.rst
new file mode 100644 (file)
index 0000000..bc4b680
--- /dev/null
+++ b/Misc/NEWS.d/next/IDLE/2021-05-05-09-45-24.bpo-44026.m2Z0zR.rst
@@ -0,0 +1,2 @@
+Include interpreter's typo fix suggestions in message line for
+NameErrors and AttributeErrors.  Patch by E. Paine.