/* $NetBSD: expr_cast.c,v 1.7 2025/04/12 15:49:49 rillig Exp $ */
# 3 "expr_cast.c"
/*
* Tests for value conversion using a cast-expression.
*
* K&R C does not mention any restrictions on the target type.
* C90 requires both the source type and the target type to be scalar.
*
* GCC allows casting to a struct type but there is no documentation about
* it at
https://gcc.gnu.org/onlinedocs/gcc/C-Extensions.html. See
* c-typeck.c, function build_c_cast, RECORD_OR_UNION_TYPE_P.
*/
/* lint1-flags: -Sw -X 351 */
struct S {
int member;
};
struct S
cast(void)
{
struct S {
double incompatible;
} local = {
0.0
};
/* expect+2: error: invalid cast from 'struct S' to 'struct S' [147] */
/* expect+1: error: function 'cast' expects to return value [214] */
return (struct S)local;
}
/*
*
https://gnats.netbsd.org/22119
*
* Before 2021-02-28, lint crashed in cast() since the target type of the
* cast is NULL.
*/
void
cast_from_error(void)
{
void (*f1)(void);
/* expect+1: error: 'p' undefined [99] */
f1 = (void (*)(void))p;
/* expect+2: error: function returns invalid type 'function(void) returning pointer to void' [15] */
/* expect+1: error: invalid cast from 'int' to 'function() returning pointer to function(void) returning pointer to void' [147] */
f1 = (void *()(void))p; /* crash before 2021-02-28 */
}
/*
* Pointer casts had been valid lvalues in GCC before 4.0.
*
*
https://gcc.gnu.org/onlinedocs/gcc-3.4.6/gcc/Lvalues.html#Lvalues
*
* C99 6.5.4 "Cast operators" footnote 85 says "A cast does not yield an
* lvalue".
*/
void take_ptr(const void *);
void *
lvalue_cast(void *p)
{
struct str {
int member;
};
/* expect+2: error: a cast does not yield an lvalue [163] */
/* expect+1: error: left operand of '=' must be lvalue [114] */
((struct str *)p) = 0;
/* expect+2: error: a cast does not yield an lvalue [163] */
/* expect+1: error: operand of '&' must be lvalue [114] */
take_ptr(&(const void *)p);
return p;
}
