unix: support command line arguments

[aykevl]

This has been a long requested feature.

fixes #456 and #541

example usage:

package main

import "os"

func main() {
	println("num args:", len(os.Args))
	for _, arg := range os.Args {
		println("arg:", arg)
	}
}

$ tinygo build -o args ./args.go
$ ./args hello world
num args: 3
arg: ./args
arg: hello
arg: world

[bgould]

This is an exciting new feature, and looks good to me. Do you think that we should have any tests for this functionality?

[deadprogram]

Agreed with @bgould this is very exciting! Also agree that some test coverage would be a very good idea.

[deadprogram]

@aykevl can you please both handle the merge conflict, and also consider adding a unit test? Thank you.

[deadprogram]

Reminder to @aykevl to please resolve and merge conflict, and consider adding unit test. Thanks.

[aykevl]

I have gotten it working, but somehow this change causes a segmentation fault when I run the stdlib test. The issue seems to be in the interp package where somehow an unaligned memory location is loaded from.

I plan to finish this PR after #1430 is finished and merged, as that PR should avoid this issue (hopefully).

That said, this PR is now rebased to fix the conflicts and has a test (which is indeed a good idea). I made the test in such a way that it should be easy to add environment variables in the future, which I assume will come up soon enough.

[arp242]

I was looking at this yesterday – as I'm kind of waiting on it – and it segfaults when you try to import the os package; this doesn't just happen from the tests, it also happens when you run a program compiled with this change. I couldn't really figure out the cause though 😅

[aykevl]

Yeah I haven't found the root cause yet. It seems to be related to the interp package and/or the way globals are packed into one giant global to make them scannable by the GC, and it might just be a LLVM compiler bug even. Either I can look for that, or maybe just give up on that and work on the new interp package instead (which should sidestep this problem entirely).

[jfcg]

would be great to have os.Args, really fundamental stuff. i want to try on some tools with tinygo.
thanks..

[hanabi1224]

Looking forward to having this!

[aykevl]

Closed in favor of #1812.

[aykevl]

Now actually closing.