Crash using `extern` builtin in stage2 | Zig Programming Language | Page 1

I'm upgrading a library I'm working on to use the stage2 compiler and I've encountered a crash that seems to be related to the @extern builtin function. In my library I construct library and function names using comptime string interpolation, and then load a dynamic library and call a C function using those names. This appears to compile correctly, but crashes at runtime. I constructed a basic example to see if I could replicate the behavior:

test2.zig

const std = @import("std");

pub fn main() void {
    const func = @extern(*const fn (i32, i32) i32, .{
        .name = "plus",
        .library_name = "add",
        .linkage = .Strong,
        .is_thread_local = false,
    });

    const three = func(1, 2);
    std.debug.assert(three == 3);
}

with the C shared library add.c

int plus(int a, int b) {
    return a + b;
}

I compile the shared library with zig cc -c add.c and zig cc -shared -o libadd.so add.o and then compile the zig program with zig build-exe test.zig -L. -ladd. This appears to build correctly, but crashes at runtime with a seg fault.

Segmentation fault at address 0x0
???:?:?: 0x0 in ??? (???)
/home/adam/zig-linux-x86_64-0.10.0/lib/std/start.zig:596:22: 0x20de34 in posixCallMainAndExit (test2)
            root.main();
                     ^
/home/adam/zig-linux-x86_64-0.10.0/lib/std/start.zig:368:5: 0x20d920 in _start (test2)
    @call(.{ .modifier = .never_inline }, posixCallMainAndExit, .{});
    ^
Aborted (core dumped)

My original, more complicated, code worked fine in stage1, and I'm not 100% sure this simple example is reproducing the exact same issue, but it certainly doesn't work. Am I missing something in this example, is there a difference in the usage of @extern between stage1 and self-hosted, or is this a self-hosted bug?

#Crash using `extern` builtin in stage2