/* $NetBSD: d_alignof.c,v 1.12 2023/07/07 19:45:22 rillig Exp $ */
# 3 "d_alignof.c"
/*
https://gcc.gnu.org/onlinedocs/gcc/Alignment.html */
/* lint1-extra-flags: -X 351 */
unsigned long
leading_and_trailing_alignof_type(void)
{
return __alignof__(short);
}
unsigned long
leading_alignof_type(void)
{
return __alignof(short);
}
unsigned long
plain_alignof_type(void)
{
/* The plain word 'alignof' is not recognized by GCC. */
/* expect+2: error: function 'alignof' implicitly declared to return int [215] */
/* expect+1: error: syntax error 'short' [249] */
return alignof(short);
}
/* expect-1: warning: function 'plain_alignof_type' falls off bottom without returning value [217] */
unsigned long
leading_and_trailing_alignof_expr(void)
{
return __alignof__ 3;
}
unsigned long
leading_alignof_expr(void)
{
return __alignof 3;
}
unsigned long
plain_alignof_expr(void)
{
/* The plain word 'alignof' is not recognized by GCC. */
/* expect+2: error: 'alignof' undefined [99] */
/* expect+1: error: syntax error '3' [249] */
return alignof 3;
}
/* expect-1: warning: function 'plain_alignof_expr' falls off bottom without returning value [217] */
/*
* As with 'sizeof', the keyword '__alignof__' doesn't require parentheses
* when followed by an expression. This allows for the seemingly strange
* '->' after the parentheses, which in fact is perfectly fine.
*
* The NetBSD style guide says "We parenthesize sizeof expressions", even
* though it is misleading in edge cases like this. The GCC manual says that
* '__alignof__' and 'sizeof' are syntactically the same, therefore the same
* reasoning applies to '__alignof__'.
*/
unsigned long
alignof_pointer_to_member(void)
{
struct s {
unsigned long member;
} var = { 0 }, *ptr = &var;
return __alignof__(ptr)->member + ptr->member;
}
void
alignof_variants(void)
{
/* expect+1: error: negative array dimension (-4) [20] */
typedef int array_int[-(int)__alignof(int[3])];
/* expect+1: error: negative array dimension (-8) [20] */
typedef int array_double[-(int)__alignof(double[3])];
/* expect+1: error: cannot take size/alignment of function type 'function(int) returning int' [144] */
typedef int func[-(int)__alignof(int(int))];
struct int_double {
int i;
double d;
};
/* expect+1: error: negative array dimension (-8) [20] */
typedef int struct_int_double[-(int)__alignof(struct int_double)];
struct chars {
char name[20];
};
/* expect+1: error: negative array dimension (-1) [20] */
typedef int struct_chars[-(int)__alignof(struct chars)];
/* expect+1: warning: struct 'incomplete_struct' never defined [233] */
struct incomplete_struct;
/* expect+1: error: cannot take size/alignment of incomplete type [143] */
typedef int incomplete_struct[-(int)__alignof(struct incomplete_struct)];
/* expect+1: warning: union 'incomplete_union' never defined [234] */
union incomplete_union;
/* expect+1: error: cannot take size/alignment of incomplete type [143] */
typedef int incomplete_union[-(int)__alignof(union incomplete_union)];
/* expect+1: warning: enum 'incomplete_enum' never defined [235] */
enum incomplete_enum;
/* expect+1: error: cannot take size/alignment of incomplete type [143] */
typedef int incomplete_enum[-(int)__alignof(enum incomplete_enum)];
/* expect+1: error: cannot take size/alignment of incomplete type [143] */
typedef int incomplete_array[-(int)__alignof(int[])];
struct bit_fields {
_Bool bit_field:1;
};
/*
* FIXME: This is not an attempt to initialize the typedef, it's the
* initialization of a nested expression.
*/
/* expect+2: error: cannot initialize typedef '00000000_tmp' [25] */
/* expect+1: error: cannot take size/alignment of bit-field [145] */
typedef int bit_field_1[-(int)__alignof((struct bit_fields){0}.bit_field)];
struct bit_fields bit_fields;
/* expect+1: error: cannot take size/alignment of bit-field [145] */
typedef int bit_field_2[-(int)__alignof(bit_fields.bit_field)];
/* expect+1: error: cannot take size/alignment of void [146] */
typedef int plain_void[-(int)__alignof(void)];
}
