Description

serhiy-storchaka

opened on Mar 10, 2026

Issue body actions

Since Struct.__init__() first saves the format in s_format, then sets s_code used to pack/unpack, after calling it with invalid format argument it leaves the Struct object in inconsistent state -- format returns the new (invalid) format, while packing/unpacking use old format (if it was set). This happens only when call it explicitly, which will be deprecated (see #143715). If simply call Struct() with invalid argument, you will not get a broken object, you will get an error.

Linked PRs

• gh-145743: Fix inconsistency after calling Struct.__init__() with invalid format #145744
• [3.14] gh-145743: Fix inconsistency after calling Struct.__init__() with invalid format (GH-145744) #145763
• [3.13] gh-145743: Fix inconsistency after calling Struct.__init__() with invalid format (GH-145744) #145764

Activity

1. serhiy-storchaka

   added a commit that references this issue on Mar 10, 2026

   pythongh-145743: Fix inconsistancy after calling Struct.__init__() wi…

   7336aaa
2. StanFromIreland

   added

   type-bugAn unexpected behavior, bug, or errorAn unexpected behavior, bug, or error

   extension-modulesC modules in the Modules dirC modules in the Modules dir

   on Mar 10, 2026
3. serhiy-storchaka

   added a commit that references this issue on Mar 10, 2026

   gh-145743: Fix inconsistency after calling Struct.__init__() with inv…

   3f33bf8
4. miss-islington

   added 2 commits that reference this issue on Mar 10, 2026

   pythongh-145743: Fix inconsistency after calling Struct.__init__() wi…

   6ab0473

   pythongh-145743: Fix inconsistency after calling Struct.__init__() wi…

   c9ade5e
5. serhiy-storchaka

   closed this as completedon Mar 10, 2026
6. serhiy-storchaka

   added 2 commits that reference this issue on Mar 10, 2026

   [3.13] gh-145743: Fix inconsistency after calling Struct.__init__() w…

   b5082d8

   [3.14] gh-145743: Fix inconsistency after calling Struct.__init__() w…

   7e38926
7. ljfp

   added a commit that references this issue on Apr 25, 2026

   pythongh-145743: Fix inconsistency after calling Struct.__init__() wi…

   1c1c04c
8. serhiy-storchaka

   added this to Struct, memoryview and array issues 🏗️on Jul 13, 2026
9. github-project-automation

   moved this to Todo in Struct, memoryview and array issues 🏗️on Jul 13, 2026
10. github-project-automation

    moved this from Todo to Done in Struct, memoryview and array issues 🏗️on Jul 13, 2026

Issue actions