Notes added to "SyntaxError" (and subclasses) are not displayed

[Delgan]

Bug report

Bug description:

Hi.

I noticed that using add_note() with an error of type SyntaxError (or its derived such as IndentationError and TabError) produces a traceback without the expected notes.

Here is a minimal reproducible example:

try:
    exec("a = 7 *")
except SyntaxError as e:
    e.add_note("Note")
    raise

Or alternatively:

e = SyntaxError("invalid syntax", ("<string>", 1, 8, "a = 7 *\n", 1, 8))
e.add_note("Note")
raise e

The output of these examples is:

Traceback (most recent call last):
  File "/home/delgan/test.py", line 2, in <module>
    exec("a = 7 *")
  File "<string>", line 1
    a = 7 *
           ^
SyntaxError: invalid syntax

The expected "Note" is missing.

Since neither PEP 678 nor the documentation mention that SyntaxError is not fully compatible with notes, I assume that this is probably a bug.

CPython versions tested on:

3.11, 3.12

Operating systems tested on:

Linux

Linked PRs

• gh-109179: Fix traceback display for SyntaxErrors with notes #109197
• [3.12] gh-109179: Fix traceback display for SyntaxErrors with notes (#109197) #109280
• [3.11] gh-109179: Fix traceback display for SyntaxErrors with notes (#109197) #109283

[terryjreedy]

Test code above works with IndexError, for instance. The .__notes__ attribute is added but not used.
@iritkatriel You added this and its doc.

[iritkatriel]

Thanks, this is a bug. SyntaxError is handled differently and it drops the notes. Fixed in #109197.