Godot crashes on script editor autocomplete

[BlendyDev]

Tested versions

Found in Godot Engine v4.4.1.stable.arch_linux - https://godotengine.org

• not reproducible in 4.3 stable
• reproducible in 4.4 stable

System information

Godot v4.4.1.stable unknown - Arch Linux #1 SMP PREEMPT_DYNAMIC Tue, 29 Jul 2025 15:05:00 +0000 on X11 - X11 display driver, Multi-window, 1 monitor - OpenGL 3 (Compatibility) - NVIDIA GeForce RTX 3070 (nvidia; 575.64.05) - 11th Gen Intel(R) Core(TM) i7-11700KF @ 3.60GHz (16 threads)

Issue description

Script editor causes a godot crash when autocomplete is used incorrectly

animation_player.

ERROR: FATAL: Index p_index = 41 is out of bounds (size() = 35).
   at: get (./core/templates/cowdata.h:219)

================================================================
handle_crash: Program crashed with signal 4
Engine version: Godot Engine v4.4.1.stable.arch_linux
Dumping the backtrace. Please include this when reporting the bug to the project developer.
[1] /usr/lib/libc.so.6(+0x3e540) [0x7fe0e774e540] (??:0)
[2] /usr/bin/godot(+0x3d04720) [0x55804eb7b720] (??:?)
[3] /usr/bin/godot(+0x3d077ad) [0x55804eb7e7ad] (??:?)
[4] /usr/bin/godot(+0x3ca8fe1) [0x55804eb1ffe1] (??:?)
[5] /usr/bin/godot(+0x3caaed8) [0x55804eb21ed8] (??:?)
[6] /usr/bin/godot(+0x3cd0b42) [0x55804eb47b42] (??:?)
[7] /usr/bin/godot(+0xeb853b) [0x55804bd2f53b] (??:?)
[8] /usr/bin/godot(+0xf03bfd) [0x55804bd7abfd] (??:?)
[9] /usr/bin/godot(+0x609f404) [0x558050f16404] (??:?)
[10] /usr/bin/godot(+0x60a0c22) [0x558050f17c22] (??:?)
[11] /usr/bin/godot(+0xf07e7f) [0x55804bd7ee7f] (??:?)
[12] /usr/bin/godot(+0xe1f7dc) [0x55804bc967dc] (??:?)
[13] /usr/lib/libc.so.6(+0x27675) [0x7fe0e7737675] (??:0)
[14] /usr/lib/libc.so.6(__libc_start_main+0x89) [0x7fe0e7737729] (??:0)
[15] /usr/bin/godot(+0xe48255) [0x55804bcbf255] (??:?)

Steps to reproduce

• Create a script for a Node2D
• Somewhere in code write transform. to activate autocomplete
• Before autocomplete menu finishes loading (but not immediatly) shift down arrow to select until next line, and wait until autocomplete menu shows up
• Click enter to accept any of the suggestions

Minimal reproduction project (MRP)

mrp.zip
(use on transform.)

[AThousandShips]

Sounds like it could be the same as:

• Using auto completion triggers the Vulkan render driver initialization exception #109193

[Calinou]

I can confirm this on 4.5.rc 2dd26a0 (Linux, KDE X11):

ERROR: FATAL: Index p_index = 27 is out of bounds (size() = 6).
   at: get (./core/templates/cowdata.h:187)

================================================================
handle_crash: Program crashed with signal 4
Engine version: Godot Engine v4.5.rc.custom_build (2dd26a027a99633231184616d4dd287bbdd1c0a3)
Dumping the backtrace. Please include this when reporting the bug on: https://github.com/godotengine/godot/issues
[1] /lib64/libc.so.6(+0x1a070) [0x7f9ab933a070] (??:0)
[2] gde() [0x7e06892] (/home/hugo/Documents/Git/godotengine/godot/core/templates/cowdata.h:187 (discriminator 13))
[3] gde() [0x7df0646] (/home/hugo/Documents/Git/godotengine/godot/core/string/string_name.h:182)
[4] gde() [0x7ecee70] (/home/hugo/Documents/Git/godotengine/godot/scene/gui/control.cpp:1866)
[5] gde() [0x7d0f3d0] (/home/hugo/Documents/Git/godotengine/godot/scene/main/viewport.cpp:2284)
[6] gde() [0x7d16f42] (/home/hugo/Documents/Git/godotengine/godot/scene/main/viewport.cpp:3454 (discriminator 2))
[7] gde() [0x7d44af0] (/home/hugo/Documents/Git/godotengine/godot/scene/main/window.cpp:1834)
[8] gde() [0x7dcf780] (/home/hugo/Documents/Git/godotengine/godot/core/variant/binder_common.h:223 (discriminator 6))
[9] gde() [0x7dc0a48] (/home/hugo/Documents/Git/godotengine/godot/core/variant/binder_common.h:338)
[10] gde() [0x7dac270] (/home/hugo/Documents/Git/godotengine/godot/core/object/callable_method_pointer.h:107)
[11] gde() [0xadd96d3] (/home/hugo/Documents/Git/godotengine/godot/core/variant/callable.cpp:57)
[12] gde() [0x3d30afd] (/home/hugo/Documents/Git/godotengine/godot/core/variant/variant.h:944)
[13] gde() [0x3d128f0] (/home/hugo/Documents/Git/godotengine/godot/core/variant/variant.h:870)
[14] gde() [0x3d12602] (/home/hugo/Documents/Git/godotengine/godot/platform/linuxbsd/x11/display_server_x11.cpp:4459)
[15] gde() [0xad48708] (/home/hugo/Documents/Git/godotengine/godot/core/input/input.cpp:979)
[16] gde() [0xad49b5d] (/home/hugo/Documents/Git/godotengine/godot/core/input/input.cpp:1262)
[17] gde() [0x3d18c43] (/home/hugo/Documents/Git/godotengine/godot/core/templates/local_vector.h:402)
[18] gde() [0x3ce3790] (/home/hugo/Documents/Git/godotengine/godot/platform/linuxbsd/os_linuxbsd.cpp:985)
[19] gde() [0x3cd7831] (/home/hugo/Documents/Git/godotengine/godot/platform/linuxbsd/godot_linuxbsd.cpp:85)
[20] /lib64/libc.so.6(+0x3575) [0x7f9ab9323575] (??:0)
[21] /lib64/libc.so.6(__libc_start_main+0x88) [0x7f9ab9323628] (??:0)
[22] gde() [0x3cd7625] (??:?)
-- END OF C++ BACKTRACE --
================================================================

Video of the crash occurring:

autocomplete_crash.mp4

Note that you shouldn't hold Shift when pressing Enter.

I would probably fix this by discarding the autocompletion box when using Shift + arrow keys, just like in VS Code. This should happen in all directions (up/down/left/right). This was indeed the behavior in 4.3, prior to the regression.

Edit: I've tried to bisect the regression (it's between 4.4.dev6 and 4.4.dev7), but results were inconclusive, even though I could reproduce the crash multiple times in commits where it did happen. For me, the bisect pointed to dc5f1b7, but checking out that commit doesn't result in a crash.

[Mostafa808]

I took a look at this issue.
So, in this function CodeEdit::confirm_code_completion, the autocompletion is applied at cursors by default.
In selection case, these cursors point to the end of selections in which becomes empty lines after replacement.
I think modifying these cursors to point to the start of selections when it detects a selection case would solve this issue.