github.com/huandu/go@v0.0.0-20151114150818-04e615e41150/misc/cgo/test/issue7560.go (about)

     1  // Copyright 2014 The Go Authors.  All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package cgotest
     6  
     7  /*
     8  #include <stdint.h>
     9  
    10  typedef struct {
    11  	char x;
    12  	long y;
    13  } __attribute__((__packed__)) misaligned;
    14  
    15  int
    16  offset7560(void)
    17  {
    18  	return (uintptr_t)&((misaligned*)0)->y;
    19  }
    20  */
    21  import "C"
    22  
    23  import (
    24  	"reflect"
    25  	"testing"
    26  )
    27  
    28  func test7560(t *testing.T) {
    29  	// some mingw don't implement __packed__ correctly.
    30  	if C.offset7560() != 1 {
    31  		t.Skip("C compiler did not pack struct")
    32  	}
    33  
    34  	// C.misaligned should have x but then a padding field to get to the end of the struct.
    35  	// There should not be a field named 'y'.
    36  	var v C.misaligned
    37  	rt := reflect.TypeOf(&v).Elem()
    38  	if rt.NumField() != 2 || rt.Field(0).Name != "x" || rt.Field(1).Name != "_" {
    39  		t.Errorf("unexpected fields in C.misaligned:\n")
    40  		for i := 0; i < rt.NumField(); i++ {
    41  			t.Logf("%+v\n", rt.Field(i))
    42  		}
    43  	}
    44  }