How to enable C++17 (std::variant) in TouchGFX Simulator

[josonYe]

Title: How to enable C++17 (std::variant) in TouchGFX Simulator?

Hello everyone,

I'm working on a TouchGFX project in STM32CubeIDE and trying to use C++17 features in the simulator, specifically `std::variant`. However, when I compile the simulator code, I get the following error:

In file included from gui/include/gui/model/Model.hpp:5:0, from generated/gui_generated/include/gui_generated/common/FrontendApplicationBase.hpp:8, from gui/include/gui/common/FrontendApplication.hpp:4, from generated/gui_generated/include/gui_generated/containers/ItemContainerLevel3Base.hpp:7, from gui/include/gui/containers/ItemContainerLevel3.hpp:4, from gui/src/containers/ItemContainerLevel3.cpp:1: gui/include/gui/common/CommonDefinitions.hpp:257:26: error: 'variant' in namespace 'std' does not name a template type using DataVariant = std::variant<int, float, double, std::string, ConfigData>; ^~~~~~~

It seems that the TouchGFX simulator environment is not compiling with `-std=c++17`. I've tried editing the Makefile in `simulator/gcc/Makefile` and adding `-std=c++17` to `cpp_compiler_options`, but it still fails with the same error.

How can I properly configure TouchGFX (and its built-in MinGW toolchain, if necessary) so that the simulator uses C++17? Is there a specific place to override the default compiler flags? Also, do I need to update the MinGW version that ships with TouchGFX to fully support C++17 features like `std::variant`?

Any advice or steps you can share would be greatly appreciated. Thanks in advance!

[josonYe · Accepted solution]

In the \TouchGFX\config\gcc\app.mk file, I modified the content as follows:

# Relative location of the TouchGFX framework from root of application
touchgfx_path := ../Middlewares/ST/touchgfx

# Location of the TouchGFX Environment
touchgfx_env := ../../../../../../../ProgramFiles/STMicroelectronics/TouchGFX/4.24.1/env
# Optional additional compiler flags
user_cflags := -DUSE_BPP=16 -std=c++17

After adding -std=c++17, the build was successful.