Cgo's most interesting translation is for functions.  If xxx is a C
function, then cgo rewrites C.xxx into a new function _C_xxx that
calls the C xxx in a standard pthread.  The new function translates
its arguments, calls xxx, and translates the return value.

Translation of parameters and the return value follows the type
translation above except that arrays passed as parameters translate

			// This was an extension in the old C version of 'go tool addr2line'
			// and is probably not used by anyone, but recognize the syntax.
			// We don't have an implementation.
			fmt.Fprintf(stdout, "!reverse translation not implemented\n")
			continue
		}
		pc, _ := strconv.ParseUint(strings.TrimPrefix(p, "0x"), 16, 64)
		file, line, fn := tab.PCToLine(pc)
		name := "?"
		if fn != nil {
			name = fn.Name
		} else {

distinguish functions from global variables.) Cgo reads the constant
values from the __cgodebug_* from the object file's data segment.

At this point cgo knows the meaning of each C.xxx well enough to start
the translation process.

Translating Go

Given the input Go files x.go and y.go, cgo generates these source
files:

	x.cgo1.go       # for gc (cmd/compile)
	y.cgo1.go       # for gc
	_cgo_gotypes.go # for gc

			t.Go = c.complex64
		case 16:
			t.Go = c.complex128
		}
		if t.Align = t.Size / 2; t.Align >= c.ptrSize {
			t.Align = c.ptrSize
		}

	case *dwarf.FuncType:
		// No attempt at translation: would enable calls
		// directly between worlds, but we need to moderate those.
		t.Go = c.uintptr
		t.Align = c.ptrSize

	case *dwarf.IntType:
		if dt.BitSize > 0 {