generic sendable error

[EEVV]

https://playground.ponylang.io/?gist=cabc4cf1bc725250d8a688af896da229

class A[T: (T #send & T)]

it is one liner: I tried to have a generic sendable type, messing around with how I should actually do it and ended up with segmentation fault.

0.33.2 [release]
compiled with: llvm 9.0.1 -- cc (GCC) 9.2.0
Defaults: pic=true

Building builtin -> /usr/lib/pony/0.33.2/packages/builtin
Building . -> /home/eevv/offgit/reserver
Building debug -> /usr/lib/pony/0.33.2/packages/debug
Building collections -> /usr/lib/pony/0.33.2/packages/collections
Building ponytest -> /usr/lib/pony/0.33.2/packages/ponytest
Building time -> /usr/lib/pony/0.33.2/packages/time
Building random -> /usr/lib/pony/0.33.2/packages/random
Building net -> /usr/lib/pony/0.33.2/packages/net
Building files -> /usr/lib/pony/0.33.2/packages/files
Building buffered -> /usr/lib/pony/0.33.2/packages/buffered
Building term -> /usr/lib/pony/0.33.2/packages/term
Building promises -> /usr/lib/pony/0.33.2/packages/promises
Building strings -> /usr/lib/pony/0.33.2/packages/strings
Building signals -> /usr/lib/pony/0.33.2/packages/signals
Building capsicum -> /usr/lib/pony/0.33.2/packages/capsicum
Segmentation fault

[teggotic]

I'm a new to compiler architecture. Despite this, I tried to investigate this issue and got to this state.
With this diff

I get 100% tests passed and no seg fault here.
This is the output here

I don't mean in any way that my solution is OK. This is just what I've got to, playing around this issue

The issue is about the TK_TYPEPARAMREF. When we use T in our example then it's parsed as TK_TYPEPARAMREF instead of TK_NOMINAL. In such a case

cap_from_constraint(typeparam_constraint(type));

typeparam_constraint returns parent of the TK_TYPEPARAMREF and it starts recursively process itself. Here we get the seg fault

[SeanTAllen]

@jemc thoughts?

[SeanTAllen]

@EEVV thanks for opening this. I've pinged @jemc who knows this part of the compiler much better than me.

[jemc]

@teggotic's fix looks like the correct one. Nice work!

[SeanTAllen]

@teggotic do you want to open a PR for this?

[teggotic]

@teggotic do you want to open a PR for this?

Sure