Crash on interface scale adjustment

[lexcyn]

Steps to reproduce

Build Telegram from source (in this case I am building the ARM64 version in Windows)
Go into Settings
Adjust default interface scale

Expected behaviour

Scale should change and ask you to restart the client

Actual behaviour

Telegram crashes with the following error

Attached log.txt
log.txt

Operating system

Windows 11 24H2 (ARM64)

Version of Telegram Desktop

5.4.6

Installation source

Other (unofficial) source

Crash ID

No response

Logs

No response

[lexcyn]

Note that the last working version is 5.4.4.

[ilya-fedin]

log.txt won't really help here... You got a breakpoint so you need Visual Studio's debugger to find where that variable resides at.

[lexcyn]

log.txt won't really help here... You got a breakpoint so you need Visual Studio's debugger to find where that variable resides at.

Seems like an issue with QT 6.8 in qdrawhelper.cpp, specifically the ARM NEON instructions:

#elif defined(__ARM_NEON__)
        const int16x8_t colorMask = vdupq_n_s16(0x00ff);
        const int16x8_t invColorMask = vmvnq_s16(colorMask);
        const int16x8_t v_256 = vdupq_n_s16(256);
        const int16x8_t v_disty = vdupq_n_s16(disty4);
        const int16x8_t v_disty_ = vshlq_n_s16(v_disty, 4);
        int32x4_t v_fdx = vdupq_n_s32(fdx*4);

        int32x4_t v_fx = vmovq_n_s32(fx);
        v_fx = vsetq_lane_s32(fx + fdx, v_fx, 1);
        v_fx = vsetq_lane_s32(fx + fdx * 2, v_fx, 2);
        v_fx = vsetq_lane_s32(fx + fdx * 3, v_fx, 3);

        const int32x4_t v_ffff_mask = vdupq_n_s32(0x0000ffff);
        const int32x4_t v_fx_r = vdupq_n_s32(0x0800);

        while (b < boundedEnd - 3) {
            uint32x4x2_t v_top, v_bot;

            int x1 = (fx >> 16);
            fx += fdx;
            v_top = vld2q_lane_u32(s1 + x1, v_top, 0); < this is the break point
            v_bot = vld2q_lane_u32(s2 + x1, v_bot, 0);

[john-preston]

@lexcyn Good thing we don't have an official native ARM build =)

[lexcyn]

@lexcyn Good thing we don't have an official native ARM build =)

True, but I'm trying my best to see an ARM build happen :) Since the issue falls on QT I will close this bug and report it on the QT bug tracker. Too bad though, with QT 6.7.2 it was working (currently running 5.4.4 arm build with no issues)

Created https://bugreports.qt.io/browse/QTBUG-128667

[ilya-fedin]

I wonder if anyone would spot that before Qt's final release if tdesktop hasn't updated to the beta version (this happens not always)