Compiler segfaults with async spaghetti

[pmwhite]

Sorry for the unhelpful title - I'm not really sure what the cause of this segfault is, but here is a small-ish piece of code that will produce it. Feel free to edit the title if you know what the more root issue is. If you have a guess, I can also try to make a smaller program that reproduces the error. If this works in the latest master, then feel free to close; the segfault is in 0.5.0. EDIT: Just tested with master. The program still segfaults

const std = @import("std");

var global: ?u32 = null;

fn getResult() ?u32 {
    if (global == null) {
        suspend {
            frames.append(@frame()) catch unreachable;
        }
    }
    return global;
}

fn return_result(a: ?u32) void {
    global = a;
    for (frames.toSlice()) |frame| {
        resume frame;
    }
}

fn handleEvent(x: bool) void {
    if (x) {
        var result = await (async getResult());
        std.debug.warn("result is {}\n", result);
    } else {
        return_result(10);
    }
}

var frames: std.ArrayList(anyframe) = undefined;
fn amain() void {
    const events = [_]bool{ true, true, true, false };
    for (events) |event| {
        _ = async handleEvent(event);
    }
}

pub fn main() void {
    frames = std.ArrayList(anyframe).init(std.heap.direct_allocator);

    _ = async amain();
}

I wrote this while trying to produce a smaller version of some other code that was acting unexpectedly. The flow of this code matches the structure of my application - the eventHandler may suspend until the user does some action that resumes it.

[pmwhite]

I assume this is probably the same segfault, but here is a much simpler program.

fn getResult() u32 {
    suspend;
    return 5;
}

fn handleEvent() void {
    _ = await (async getResult());
}

pub fn main() void {
    _ = async handleEvent();
}

[pmwhite]

Splitting up the await and async lines is a workaround, which makes this so simple that I imagine it has to be a duplicate issue, but I couldn't find one like it.

var f = async getResult();
_ = await f;

[schmee]

Just tried it and it still segfaults as of f40b6b8.

[charles-l]

I can't reproduce the issue for the smaller example as of 0.10.0-dev.2413+ee1a95b55 (after replacing suspend; with suspend {} to make it compile)