I've asked a variant of this before, but as there doesn't appear to be an existing mechanism to create a Subsystem which can either download from a url OR be setup from a system path, is there an approach I should take on this. Two mutually exclusive subsystems? New Subsystem type?

In general, there is no prebuilt mechanism for subsystems to be loaded via system path. You have to use stuff from

system_binaries.py

. You also can still subclass

ExternalTool

but choose to not use the apprporiate

Get

in your rule What this means is that you can use the same subsystem and then figure out based on the options whether to load the binary via

system_binaries.py

vs

Get(ExternalTool)

👍 My plan was some sort of default to system, with a URL escape hatch Actually, it's even more nuanced, because one could theoretically use an ARM compiler and x86 compiler in the same project, but I feel like multiple compilers is a "later" thing at the moment

BinaryPath

is only intended for system-level stuff, absolute paths

Okay, I was hoping to use that with the optional ExternalTool/System Binary - to keep my toolchain model the same. I use the fingerprint in an environment to check if the toolchain changes from run to run

but reminder

BinaryPath

is solely an abstraction for DRY. What really matters are the underlying engine mechanisms. All that the engine (and REAPI) cares about is your argv0 is either: • absolute path , or • relative path to a file from

input_digest

Yep, I've replaced it with a string - but feels very... stringy...... 🤷