Can not compile: arm-none-eabi-g++: command not found

… yes probably, might be a symptom of it not being able to handle the compiler toolchain package and not being able to use it afterwards.

Well strictly put this is a 3rd party platform outside of PlatformIO’s normal ecosystem and it’s also pointing to a custom release of the compiler

But I think I’ve figured out the problem. You see if you actually download the compiler from the link above, it’s for Linux x64. Extract it and look at arm-none-eabi-g++.

>file "arm-none-eabi-g++"
arm-none-eabi-g++; ELF 64-bit LSB executable, x86-64, version 1 (SYSV), dynamically linked (uses shared libs), for GNU/Linux 3.2.0, from '8@%rdi 8@%rsi', stripped

Of course this won’t work an Apple machine as I’ll infer from the appley-looking path

@JonathanFStewart, are you also using an Apple machine?

I don’t really know why a custom platform needed to be created for this, there already is the GitHub - platformio/platform-nxplpc: NXP LPC: development platform for PlatformIO platform for NXP chips. Why not make an addition to this repository?

You could try and get the compiler for Apple/Windows by overriding the package, that is, add to the environment in the platformio.ini the lines

platform_packages = toolchain-gccarmnoneeabi@https://dl.bintray.com/platformio/dl-packages/toolchain-gccarmnoneeabi-darwin_x86_64-1.80201.181220.tar.gz

(Windows: Your Gateway to Embedded Software Development Excellence · PlatformIO), though I’m unsure whether it will accept HTTP links to archives, examples only show git repos are package names.

You may also attempt to just download the file above, remove the contents of the toolchain-gccarmnoneabi folder and replace it with the contents of the archive above.

Where is the exact marlin branch and platformio.ini you are using for reproduction?