Observation:
pi@raspberrypi:~/src/tmp.tmp $ go version
go version go1.15.1 linux/arm
pi@raspberrypi:~/src/tmp.tmp $ cat main.go
package main
/*
struct s {
long long i;
} x;
size_t align() {
return _Alignof(struct s);
}
*/
import "C"
import (
"fmt"
"unsafe"
)
type S struct {
i int64
}
func main() {
fmt.Printf(" C alignof struct s: %v\n", C.align())
fmt.Printf("Go alignof struct s: %v\n",
unsafe.Alignof(C.struct_s{}))
fmt.Printf("Go alignof S: %v\n", unsafe.Alignof(S{}))
}
pi@raspberrypi:~/src/tmp.tmp $ go run main.go
C alignof struct s: 8
Go alignof struct s: 4
Go alignof S: 4
pi@raspberrypi:~/src/tmp.tmp $ uname -a
Linux raspberrypi 4.19.66-v7+ #1253 SMP Thu Aug 15 11:49:46 BST 2019 armv7l
GNU/Linux
pi@raspberrypi:~/src/tmp.tmp $
My code relies on all the numbers being the same, ie. that Go will report
the same as C for both C.struct_s{} and S{}.
AFAICT Go and C agree on struct layout on linux/{amd64,386} perfectly in
all cases I've tested (thousands probably).
Is this a bug or are my expectations ill founded?
Thanks in advance for any insights.
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