Marlin: RuntimeError: deque mutated during iteration:

PlatformIO IDE
5

The real reason is that in Marlin/buildroot/share/PlatformIO/scripts/marlin.py the iterated environment is getting modified during the iteration in the replace_define() function, update it as follows and the error will be gone:

def replace_define(field, value):
	found_define = None
	for define in env['CPPDEFINES']:
		if define[0] == field:
			found_define = define
			break
	if found_define:
		env['CPPDEFINES'].remove(found_define)
	env['CPPDEFINES'].append((field, value))

I’m writing this, to help people facing this error, because sometimes (as I do now) you need to go back and compile an older version of Marlin to solve when a bug is introduced (bisect)…

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