infinite_loop

const std = @import("std");

const A = struct {
    val: i64,
    a_val: ?*A,

    pub fn format(self: A, comptime fmt: []const u8, opt: std.fmt.FormatOptions, writer: anytype) !void {
        if (self.a_val) |a| {
            try writer.print("{} {}", .{ a.*, self.val }); // infinite loop issue
        }
    }
};

pub fn main() !void {
    const a = A{ .val = 10, .a_val = null };

    const str = try std.fmt.allocPrint(std.testing.allocator, "{}", .{a});
}