const std = @import("std"); const Foo = union { float: f32, int: u32, }; pub fn main() void { var f = Foo{ .int = 42 }; f = Foo{ .float = undefined }; bar(&f); std.debug.print("value: {}\n", .{f.float}); } fn bar(f: *Foo) void { f.float = 12.34; } // exe=succeed