runtime panic is missing message and stack trace

[awaitlink]

Was playing around with https://playground.zigtools.org and noticed that:

const std = @import("std");

const Silly = struct {
    a: u64,

    pub fn init(a: u32) Silly {
        return .{ .a = a * a };
    }
};

pub fn main() !void {
    const silly = Silly.init(7777777);

    std.log.info("{}", .{silly.a});
}

outputs:

RuntimeError: Unreachable code should not be executed (evaluating 'e.exports._start()')

On the other hand, on godbolt the output is more expected:

Program returned: 139
Program stderr
thread 1 panic: integer overflow
/app/example.zig:7:26: 0x11d87bd in init (example.zig)
        return .{ .a = a * a };
                         ^
/app/example.zig:12:29: 0x11d7231 in main (example.zig)
    const silly = Silly.init(7777777);
                            ^
/cefs/88/88fde13df29428d00d960468_consolidated/compilers_zig_new_naming_0.16.0/lib/std/start.zig:698:59: 0x11d783c in callMain (std.zig)
    if (fn_info.params.len == 0) return wrapMain(root.main());
                                                          ^
/cefs/88/88fde13df29428d00d960468_consolidated/compilers_zig_new_naming_0.16.0/lib/std/start.zig:190:5: 0x11d7211 in _start (std.zig)
    asm volatile (switch (native_arch) {
    ^
Program terminated with signal: SIGSEGV

I'm wondering if this is a bug in Zig's experimental WASM support (and should be reported there) or a problem with the playground?

P.S. Also, for the record, what is the version of Zig that runs on the playground? I see it hardcoded as 0.17.0 (hence builtin.zig_version_string says as much) but I'm not sure which specific development revision it is.

[Techatrix]

The playground currently lacks any special handling for when the zig code panics at runtime. It should be fairly doable to at least show the "integer overflow" message but the stack trace below it is currently blocked on missing debug info from Zig's self hosted wasm backend.

Also, for the record, what is the version of Zig that runs on the playground?

It's 0.16.0 with a tiny patch on top. See the build.zig.zon. The version string was unintentionally set to 0.17.0 which I just fixed in a9f1f3e.