Function write 

pub fn write(
    text: &Text,
    data: &Data,
    aliases: &[Alias],
    target: &TargetInfo,
    output: Output,
) -> Result<Vec<u8>, Error>

One text section and the variables beside it, as a relocatable object in the target’s format.

Errors

Error::Format for a machine or a platform this does not write, and Error::Refused for anything the writer underneath objected to, which would be a bug here. An alias whose target this file does not define is refused the same way, since the front end is what reports that as a program’s mistake and one reaching here means it did not. So is anything the target’s format has no way to write, which for COFF is a thread-local variable, a reference through a table the platform does not have, a record of where a patcher’s room is and a section the startup code is expected to gather. See Error.