103_unions.c File Reference

Unit test for passing and returning unions by value. More...

#include "common/double_tap.h"
#include "types.h"
#include <infix/infix.h>
#include <math.h>
#include <string.h>

Include dependency graph for 103_unions.c:

Macros
#define	DBLTAP_IMPLEMENTATION

Functions
int	process_number_union_as_int (Number num)
	A C function that interprets a passed-in Number union as an integer.
float	process_number_union_as_float (Number num)
	A C function that interprets a passed-in Number union as a float.
Number	return_number_union (int selector)
	A C function that returns a Number union by value.
	if (!ok(status==INFIX_SUCCESS, "infix_type for Number union created successfully"))
	subtest ("Passing union as argument")
	subtest ("Returning union by value")
	infix_arena_destroy (arena)

Variables
	TEST
infix_arena_t *	arena = infix_arena_create(4096)
infix_struct_member *	members
infix_type *	union_type = nullptr
infix_status	status = infix_type_create_union(arena, &union_type, members, 2)

Detailed Description

Unit test for passing and returning unions by value.

This test verifies that infix correctly handles C unions in FFI calls. A union is a special type of aggregate, and its handling by the ABI often follows the same rules as structs of the same size and alignment.

This test uses a simple Number union containing an int and a float. It verifies that:

1. The infix_type for the union is created with the correct size (the size of the largest member) and alignment (the alignment of the most-aligned member).
2. When the union is passed as an argument, its raw byte representation is correctly transmitted, allowing the callee to interpret it as either an int or a float.
3. When a union is returned by value, its raw bytes are correctly received by the caller.

This test is important for validating the aggregate classification logic for a type that is less common than structs but still a core part of the C language.

Macro Definition Documentation

DBLTAP_IMPLEMENTATION

#define DBLTAP_IMPLEMENTATION

Function Documentation

if()

if

(

!

okstatus==INFIX_SUCCESS, "infix_type for Number union created successfully"

)

infix_arena_destroy()

infix_arena_destroy

(

arena

)

process_number_union_as_float()

float process_number_union_as_float

(

Number

num

)

A C function that interprets a passed-in Number union as a float.

process_number_union_as_int()

int process_number_union_as_int

(

Number

num

)

A C function that interprets a passed-in Number union as an integer.

return_number_union()

Number return_number_union

(

int

selector

)

A C function that returns a Number union by value.

subtest() [1/2]

subtest

(

"Passing union as argument"

)

subtest() [2/2]

subtest

(

"Returning union by value"

)

Variable Documentation

arena

infix_arena_t* arena = infix_arena_create(4096)

members

members[1]

Initial value:

=
        infix_arena_alloc(arena, sizeof(infix_struct_member) * 2, _Alignof(infix_struct_member))

status

infix_status status = infix_type_create_union(arena, &union_type, members, 2)

TEST

TEST

Initial value:

{
    plan(3)

union_type

infix_type* union_type = nullptr