Gcc-arm-none-eabi is the gcc compiler toolchain for arm outside of a hosted environment. This means that it compiles bare metal code: code running without an already existing OS. ‘Normal’ gcc uses libraries from the system where its installed, so if you compile a hello world links to and uses the standard library. Gcc-arm would mean that the compiler is a cross compiler: its installed on your system but it compiles for arm. On an arm processor could run a full fledged linux environment so a gcc-arm-aarch64-linux or something like that would compile a program on your pc for that arm system running linux. Now there are meriads of arm systems not running linux which needs code to be compiled for as well. This is the place for the none-eabi variant: it does not use any system library and uses a standard interface for calling functions and other stuff. So in other words this is just the bare metal cross compiler for arm systems. And who makes these? Anyone who wants to. Gcc is an open source project and anyone could compile the toolchain. With compiling you can ‘select’ your version: do you want to build a linux-on-riscv compiler running on your pc? Definitely possible! The linux distro repos contain a couple of standard versions of gcc of which arm-none-eabi is one

Hello @lotou, · To determine the version of the toolchain used with your CubeIDE, navigate to the directory:  · C:\ST\STM32CubeIDE_1.18.0\STM32CubeIDE\plugins\com.st.stm32cube.ide.mcu.externaltools.gnu-tools-for-stm32.13.3.rel1.win32_1.0.0.202411081344\tools\bin  · Note: adjust the identifiers according to your system. · Open the command prompt and execute the command: ./arm-none-eabi-gcc --version. · This will display the GCC compiler version. You can then download it directly from ARM's website · For example: ARM GNU Toolchain. · Regarding cyclomatic complexity, it measures the number of linear paths, branching points, and loops in your code. Higher complexity increases the likelihood of crashes in your application. By incorporating cyclomatic complexity checks into your build pipeline, you can periodically ensure your solution hasn't regressed into a more failure-prone version. But you should keep in mind that it is not a performance metric of your code. · To know more about the usage of cyclomatic complexity in CubeIDE, refer to UM2609 for CubeIDE, specifically section 4.1 Cyclomatic Complexity. · Please mark my answer as best by clicking on the “Accept as solution" button if it fully answered your question. This will help other users find this solution faster.​

Here is an excellent doc.

Tool chains have a loose name convention like arch [-vendor] [-os] - eabi

 arch -    refers to target architecture (which in our case is ARM)
 vendor -  refers to toolchain supplier
 os -      refers to the target operating system
 eabi -    refers to Embedded Application Binary Interface

some illustrations as follows :

• arm-none-eabi - This tool chain targets for ARM architecture, has no vendor, does not target an operating system and complies with the ARM EABI.
• arm-none-linux-gnueabi - This toolchain targets the ARM architecture, has no vendor, creates binaries that run on the Linux operating system, and uses the GNU EABI. It is used to target ARM-based Linux systems.