`std.MultiArrayList` errors with a tuple that containing void

[youdie323323]

Zig Version

0.15.1

Steps to Reproduce and Observed Behavior

test {
    const gpa = testing.allocator;

    var list: std.MultiArrayList(struct { void }) = .empty;
    defer list.deinit(gpa);

    list.append(gpa, .{{}}) catch unreachable;
}

const std = @import("std");
const testing = std.testing;

Testing this code causes the build error:

*\zig\x86_64-windows-0.15.1\lib\std\multi_array_list.zig:625:26: error: extern struct fields cannot be marked comptime
            break :entry @Type(.{ .@"struct" = .{
                         ^~~~~
referenced by:
    dbHelper: *\zig\x86_64-windows-0.15.1\lib\std\multi_array_list.zig:634:71
    comptime: *\zig\x86_64-windows-0.15.1\lib\std\multi_array_list.zig:643:22
    test_1: *\zig\x86_64-windows-0.15.1\lib\std\multi_array_list.zig:21:12

Expected Behavior

MultiArrayList must works with a tuple that containing void.

[andrewrk]

Thanks for taking the time to file an issue. However, this is working as designed - it's not intended to support tuples. Furthermore, I find the compile error acceptable and do not see a need to explicitly check for "is tuple" and emit an explicit @compileError.

Recommended alternative: don't use tuples.

[xdBronch]

fwiw this specific case will actually be solved by #25462 if it's merged