Scripting: undo after mesh.separate causes crash #106248

New Issue

Open

opened 2023-03-29 00:35:33 +02:00 by Scurest · 8 comments

Scurest commented

2023-03-29 00:35:33 +02:00

Contributor

System Information
Operating system: Linux

Blender Version
Latest tested: blender-3.5.0-beta+v35.f23e3c7f04f3-linux.x86_64-release
Earliest tested: blender-3.1.2-linux-x64

Short description of error
Trying to undo bpy.ops.mesh.separate(type='MATERIAL') in a script crashes Blender.

Exact steps for others to reproduce the error

Create a cube and two materials. Go to edit mode and assign some faces to both materials. Go back to object mode.

Open the Text Editor and run this script

import bpy
bpy.ops.ed.undo_push( message = "temp" )
bpy.ops.mesh.separate( type = 'MATERIAL' )
bpy.ops.ed.undo()

Crash (segmentation fault).

Somewhat mysteriously if I save just before running the script, close Blender, then reopen the .blend and then run the script, I get non-determinstic results (sometimes the undo does nothing, sometimes the white part is gone). The only consistent way I found to get a crash was to create the cube from scratch every time. So no .blend is attached to this issue.

**System Information** Operating system: Linux **Blender Version** Latest tested: blender-3.5.0-beta+v35.f23e3c7f04f3-linux.x86_64-release Earliest tested: blender-3.1.2-linux-x64 **Short description of error** Trying to undo `bpy.ops.mesh.separate(type='MATERIAL')` in a script crashes Blender. **Exact steps for others to reproduce the error** 1. Create a cube and two materials. Go to edit mode and assign some faces to both materials. Go back to object mode. ![A cube with white and red materials](/attachments/8054c887-97b8-4a42-a26d-7a7064ec1335) 2. Open the Text Editor and run this script ```py import bpy bpy.ops.ed.undo_push( message = "temp" ) bpy.ops.mesh.separate( type = 'MATERIAL' ) bpy.ops.ed.undo() ``` 3. Crash (segmentation fault). Somewhat mysteriously if I save just before running the script, close Blender, then reopen the .blend and then run the script, I get non-determinstic results (sometimes the undo does nothing, sometimes the white part is gone). The only consistent way I found to get a crash was to create the cube from scratch every time. So no .blend is attached to this issue.

WhiteRedCube.png

21 KiB

Scurest added the

labels 2023-03-29 00:35:34 +02:00

Iliya Katushenock added the

label 2023-03-29 03:32:09 +02:00

Pratik Borhade commented

2023-03-29 07:31:25 +02:00

Member

Can confirm

Can confirm

Pratik Borhade added

and removed

labels 2023-03-29 07:32:16 +02:00

Philipp Oeser added the

label 2023-06-06 10:32:15 +02:00

Philipp Oeser commented

2024-02-19 09:43:40 +01:00

Member

@mont29 : does this crash sound like High priority to you?

@mont29 : does this crash sound like High priority to you?

Bastien Montagne commented

2024-02-19 09:55:25 +01:00

Owner

Please always attach a blendfile, this makes reproducing way simpler and faster.

Also, the issue here is getting out of Editmode, then running the script.

Please always attach a blendfile, this makes reproducing way simpler and faster. Also, the issue here is getting out of Editmode, then running the script. [106248.blend](/attachments/29766a5a-f35b-41b2-ac7d-95a7c3b13734)

106248.blend

121 KiB

Philipp Oeser commented

2024-02-19 10:09:38 +01:00

Member

Please always attach a blendfile, this makes reproducing way simpler and faster.

This was mentioned here

Somewhat mysteriously if I save just before running the script, close Blender, then reopen the .blend and then run the script, I get non-determinstic results (sometimes the undo does nothing, sometimes the white part is gone). The only consistent way I found to get a crash was to create the cube from scratch every time. So no .blend is attached to this issue.

Also, the issue here is getting out of Editmode, then running the script.

Sorry if I dont get this right: what does this mean? This is then still wrong, see the comment above (non-determinstic results)

> Please always attach a blendfile, this makes reproducing way simpler and faster. This was mentioned here >Somewhat mysteriously if I save just before running the script, close Blender, then reopen the .blend and then run the script, I get non-determinstic results (sometimes the undo does nothing, sometimes the white part is gone). The only consistent way I found to get a crash was to create the cube from scratch every time. So no .blend is attached to this issue. > Also, the issue here is getting out of Editmode, then running the script. Sorry if I dont get this right: what does this mean? This is then still wrong, see the comment above (non-determinstic results)

Bastien Montagne commented

2024-02-19 10:26:49 +01:00

Owner

It is not wrong, open that blendfile, go in/out of Edit mode, run the script, crash

It is not wrong, open that blendfile, go in/out of Edit mode, run the script, crash

Philipp Oeser commented

2024-02-19 10:50:04 +01:00

Member

It is not wrong, open that blendfile, go in/out of Edit mode, run the script, crash

Ah, OK, sorry for my confusion

> It is not wrong, open that blendfile, go in/out of Edit mode, run the script, crash Ah, OK, sorry for my confusion

Bastien Montagne commented

2024-02-19 15:33:25 +01:00

Owner

@scurest I would consider this case as unsupported tbh.

Thing is, running the script from the text editor is already running an operator, so all the operator calls you are doing here are done as sub-level calls of the main operator.

The WindowManager handles undo automatically for operators, ensuring that undo steps are only created after executing top-level operators, and none of their potential operators sub-calls inside the top-level one.

So calling things like bpy.ops.ed.undo_push and bpy.ops.ed.undo here is enforcing undo stack operations in a context which does not support them.

In general, usage of bpy.ops.ed.undo related operators should be very carefully weighted, these should almost never be needed in a normal usage case.

@scurest I would consider this case as unsupported tbh. Thing is, running the script from the text editor is already running an operator, so all the operator calls you are doing here are done as sub-level calls of the main operator. The WindowManager handles undo automatically for operators, ensuring that undo steps are only created after executing top-level operators, and none of their potential operators sub-calls inside the top-level one. So calling things like `bpy.ops.ed.undo_push` and `bpy.ops.ed.undo` here is enforcing undo stack operations in a context which does not support them. In general, usage of `bpy.ops.ed.undo` related operators should be very carefully weighted, these should almost never be needed in a normal usage case.

Scurest commented

2024-02-19 21:58:19 +01:00

Author

Contributor

Okay. Can it produce an error instead of crashing?

Okay. Can it produce an error instead of crashing?

Sign in to join this conversation.

No Label

Animation & Rigging

Asset Browser Project Overview

Automated Testing

Blender Asset Bundle

Dependency Graph

Development Management

EEVEE & Viewport

Images & Movies

Motion Tracking

Nodes & Physics

Pipeline, Assets & IO

Platforms, Builds & Tests

Render & Cycles

Render Pipeline

Sculpt, Paint & Texture

Video Sequencer

Virtual Reality

Blender 2.8 Project

Milestone 1: Basic, Local Asset Browser

Good First Issue

Animation & Rigging

Development Management

EEVEE & Viewport

Nodes & Physics

Pipeline, Assets & IO

Platforms, Builds & Tests

Render & Cycles

Sculpt, Paint & Texture

Needs Info from Developers

Needs Information from User

No Milestone

No project

No Assignees

4 Participants

Notifications

Due Date

The due date is invalid or out of range. Please use the format 'yyyy-mm-dd'.

No due date set.

Dependencies

No dependencies set.

Reference: blender/blender#106248

No description provided.