Getting C-compatible structs in Go with and for cgo

This just makes the beauty of Rust so much more clear. Compatible C structs without going through this headache. It also points out another reason why Go is not a "systems" language.

From the article:

> (By the way, I do mean 'Sysinfo' here, not 'Cpu_sysinfo'. Cgo is smart enough to take that sort of commonly seen prefix off of struct field names. I don't know what its algorithm is for doing this, but it's at least useful.)

Anyone know why cgo does this? This seems like an anti-feature to me – if I want fields with prefixes that are different from the C ones, at least make that a knob (and preferably one that isn't turned on by default).

It is still useless for me if you have struct with 'packed' attribute ie: http://lxr.free-electrons.com/source/fs/btrfs/ctree.h#L220

  // +build ignore
  package tmp
  /*
  #include <btrfs/ctree.h>
  */
  import "C"
  // 220 struct btrfs_disk_key {
  // 221         __le64 objectid;
  // 222         u8 type;
  // 223         __le64 offset;
  // 224 } __attribute__ ((__packed__));
  type BtrfsDiskKey C.struct_btrfs_disk_key

Output:

  $ go tool cgo -godefs test.go 
  // Created by cgo -godefs - DO NOT EDIT
  // cgo -godefs test.go
  package tmp
  type BtrfsDiskKey struct {
	Objectid	uint64
	Type		uint8
	Pad_cgo_0	[8]byte
  }

After all the experiments I created my own helper[1], which helps map C structure(even packed) to Go structure using reflect package.

[1] https://github.com/plar/btrfs/blob/master/ioctl/mappings.go

I wish Go made more of an effort to be more easily C compatible instead of trying to continue breaking away from C.