Composing a string during run time

Help
,
1

I tried composing a string during comptime. The string is dependent on a type given. Currently i m trying somthing like this:

            const size: usize = str: {
                comptime {
                    var length: usize = calculateLength();
                    break :str length;
                }
            };
            comptime var string: [size]u8 = undefined;
            const actual_length = len: {
                comptime {
                    @memset(string[0..], 0);
                    var string_builder: StringBuilder = .{ .buffer = string[0..] };
                    _ = string_builder.addSlice(create).addSlice(table_name).addSlice("(").addSlice(create_2);
                    buildStringFields(&string_builder, .{ .include_id = false, .include_type = true });
                    _ = string_builder.addSlice(")");
                    break :len string_builder.position;
                }
            };
            @compileLog(string);
            someFunction(string[0..actual_length);

The compileLog gives me the correct result. But the compiler gives an error if im using the variable:

src/root.zig:135:36: error: runtime value contains reference to comptime var
           someFunction(string[0..actual_length]);

Is it even possible to compose a string like this (or differntly)?
Thanks in advance

2

var’s cannot be used across the comptime-runtime boundary. Just make a const copy, that will be able to be used at runtime.

3

Thanks for your answer. Do you know how exactly? Adding the following results in the same error:

const result: [size]u8 = undefined;
@memcpy(@constCast(result[0..string.len]), string);