Foo.__int__() must return an int, not NoneTypeFoo.__float__() must return a float, not NoneTypeFoo.__bytes__() must return a bytes, not NoneTypeFoo.__complex__() must return a complex, not NoneTypeFoo.__bool__() must return a bool, not NoneTypeFoo.__str__() must return a str, not NoneType

but we still have a lot of other places where wrong type errors have inconsistent messages. should they be updated too?

Issue:Inconsistent error messages when returning the wrong type for the type-conversion magic methods #130821

Add type information to wrong type error messages

a513ee8

donBarbos requested a review frommarkshannon as acode owner

March 4, 2025 14:25

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Mar 4, 2025

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Mar 4, 2025

Inconsistent error messages when returning the wrong type for the type-conversion magic methods#130821

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Use %T to format type names

4d792e4

jstasiak reviewed

Mar 8, 2025

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Drive-by comment: does it make sense to have tests for these changes?

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donBarbos commentedApr 10, 2025

Drive-by comment: does it make sense to have tests for these changes?

it seems that we don't check the text of error messages if we don't want to check the error type itself

Fix error message for methods return type

d976676

donBarbos requested a review fromericsnowcurrently as acode owner

April 28, 2025 01:45

donBarbos added3 commits

April 28, 2025 05:50

Revert "Fix error message for methods return type"

d811b4c

This reverts commitd976676.

Use new message template

70d57c2

Merge branch 'main' into issue-130821

b6f75e4

skirpichev reviewed

Apr 28, 2025

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Improve message and fix test

390f941

donBarbos requested a review fromJelleZijlstra as acode owner

April 28, 2025 13:07

skirpichev self-requested a review

April 28, 2025 13:19

donBarbos added4 commits

April 28, 2025 18:17

Fix more methods

d2e54e6

Escape parentheses in regex pattern to fix test match

0ac8a1c

Fix message for coroutine test

59bca2d

Add News entry

51a6c79

JelleZijlstra reviewed

Apr 28, 2025

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I think many of the changes in wording are not clear improvements.

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Objects/abstract.c

		@@ -1421,17 +1423,17 @@ _PyNumber_Index(PyObject *item)

		if (!PyLong_Check(result)) {
		PyErr_Format(PyExc_TypeError,
		"__index__ returned non-int (type %.200s)",

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I don't see much reason to change this error message either.

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donBarbosApr 29, 2025•
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I changed it to the more common way as you recommended elsewhere:__method__() must return an int, not ...
and added type info before method name, like for other methods

Objects/abstract.c

		@@ -2435,10 +2436,8 @@ method_output_as_list(PyObject o, PyObject meth)
		PyThreadState *tstate = _PyThreadState_GET();
		if (_PyErr_ExceptionMatches(tstate, PyExc_TypeError)) {
		_PyErr_Format(tstate, PyExc_TypeError,
		"%.200s.%U() returned a non-iterable (type %.200s)",