Incorrect rendering on Midway Seattle when building with buildtools 7.0

[davidmorom]

MAME version

0.256

System information

Windows 10, 22H2, 64 bits, Es-es
Intel Core i7 12700KF
32 GB DDR5
Nvidia 1650 GTX

INI configuration details

Default configuration

Emulated system/software

Midway Seattle (seattle.cpp)

Incorrect behaviour

When building MAME 0.256 on Windows with buildtools 7.0 (GCC 11.2.0), Midway Seattle games renders incorrectly some textures. Is very noticeable in the game Carnevil, in the flying joker head at the begining of each level, as in the following image:

Expected behaviour

With buildtools 6.0 (GCC 10.2.0), or updating the build environment with Pacman (GCC 13), the rendering is correct:

With the 0.256 binaries publicly available at "www.mamedev.org/release.html" the rendering is also correct. I don't know which version of buildtools, GCC, and operating system is used for that build.

This is a problem because it also affects other MAME forks, like ARCADE64, that are built on Windows with latest buildtools.

Steps to reproduce

1. Download and extract buildtools 7.0.
2. Download and extract MAME 0.256 source code.
3. Build the binaries with a simple "make", without touching anything else.
4. Run the game Carnevil and start a level.

Additional details

No response

[cuavas]

If you can isolate undefined behaviour in the MAME code, report it. Otherwise I’m going to assume it’s a compiler bug. Releases are currently built with GCC 10.3.