imaami/compile-time-whitespace.c

## compile-time-whitespace.c
#include <stddef.h>
#include <stdio.h>

#define options(X)                                       \
	X('h', "help",      "",     "print this help")   \
	X('s', "segfault",  "",     "commit sudoku")     \
	X('d', "directory", "DIR",  "touch a directory") \
	X('u', "uid-of",    "NAME", "print a user ID")

#ifdef __clang__
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wc++-compat"
#pragma clang diagnostic ignored "-Wc++98-compat"
#pragma clang diagnostic ignored "-Wgnu-empty-initializer"
#pragma clang diagnostic ignored "-Wpre-c2x-compat"
#pragma clang diagnostic ignored "-Wunknown-attributes"
#endif // __clang__

[[gnu::optimize("Os")]] static void usage(char const *argv0);

int main([[maybe_unused]] int argc, char **argv)
{
	usage(argv[0]);
}

#define ws0()  " "
#define ws1()  "  "
#define ws2()  "    "
#define ws3()  "        "
#define ws4()  "                "
#define ws5()  "                                "
#define ws6()  "                                                                "
#define ws7()  ws6()  ws6()
#define ws8()  ws7()  ws7()
#define ws9()  ws8()  ws8()
#define ws10() ws9()  ws9()
#define ws11() ws10() ws10()

#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wpedantic"
struct bit_off  { };
#pragma GCC diagnostic pop

struct bit0_on  { const char a[1U <<  0U]; };
struct bit1_on  { const char a[1U <<  1U]; };
struct bit2_on  { const char a[1U <<  2U]; };
struct bit3_on  { const char a[1U <<  3U]; };
struct bit4_on  { const char a[1U <<  4U]; };
struct bit5_on  { const char a[1U <<  5U]; };
struct bit6_on  { const char a[1U <<  6U]; };
struct bit7_on  { const char a[1U <<  7U]; };
struct bit8_on  { const char a[1U <<  8U]; };
struct bit9_on  { const char a[1U <<  9U]; };
struct bit10_on { const char a[1U << 10U]; };
struct bit11_on { const char a[1U << 11U]; };

#define bit_(b, n, v) _Generic(&(char[1U + ((n) & (1U << (size_t)b))]){0} \
	, char(*)[1U + (1U << (size_t)b)]: (const struct bit##b##_on){v}  \
	, char(*)[1U]: (const struct bit_off){})

#define bit(b, n)      bit_(b, n, {ws##b()})
#define bit_type(b, n) typeof(bit_(b, n, 0))

#define ws_type(n) struct {               \
	bit_type( 0, n) b0; bit_type( 1, n) b1; \
	bit_type( 2, n) b2; bit_type( 3, n) b3; \
	bit_type( 4, n) b4; bit_type( 5, n) b5; \
	bit_type( 6, n) b6; bit_type( 7, n) b7; \
	bit_type( 8, n) b8; bit_type( 9, n) b9; \
	bit_type(10, n) ba; bit_type(11, n) bb; }

#define ws_init(n) {                                  \
	bit(0, n), bit(1, n), bit( 2, n), bit( 3, n), \
	bit(4, n), bit(5, n), bit( 6, n), bit( 7, n), \
	bit(8, n), bit(9, n), bit(10, n), bit(11, n), }

#define dog(x,y) x##y
#define cat(x,y) dog(x, y)
#define sym(x)   cat(x##_,__COUNTER__)
#define c_str(x) char sym(m)[sizeof x]

#define mkarr(chr, str, arg, ...) c_str(str " " arg " ");
typedef char str_arg_max[sizeof(union {options(mkarr)})];
#undef mkarr
#define str_arg_align(x) (sizeof(str_arg_max) - sizeof x)

#define space(x)      ws_type(str_arg_align(x)) sym(m)
#define space_init(x) ws_init(str_arg_align(x))

#define line_vars(chr, str, arg, help)   \
	const c_str("  -");              \
	const c_str(", --" str " " arg); \
	const space(str " " arg);        \
	const c_str(help);

#define line_init(chr, str, arg, help) \
	{ ' ', ' ', '-', chr },        \
	", --" str " " arg " ",        \
	space_init(str " " arg),       \
	help "\n",

#define help_text(x) ((const union { \
	const struct {               \
		x(line_vars)         \
		const char nul[1];   \
	};                           \
	const char str[1U + sizeof ( \
		struct {             \
			x(line_vars) \
		}                    \
	)];                          \
}){{                                 \
	x(line_init) ""              \
}}.str)

static void usage(char const *argv0)
{
	(void)printf("Usage: %s [OPTIONS]\n\nOptions:\n%s",
	             argv0, help_text(options));
}

#ifdef __clang__
#pragma clang diagnostic pop
#endif // __clang__
	#include <stddef.h>
	#include <stdio.h>

	#define options(X) \
	X('h', "help", "", "print this help") \
	X('s', "segfault", "", "commit sudoku") \
	X('d', "directory", "DIR", "touch a directory") \
	X('u', "uid-of", "NAME", "print a user ID")

	#ifdef __clang__
	#pragma clang diagnostic push
	#pragma clang diagnostic ignored "-Wc++-compat"
	#pragma clang diagnostic ignored "-Wc++98-compat"
	#pragma clang diagnostic ignored "-Wgnu-empty-initializer"
	#pragma clang diagnostic ignored "-Wpre-c2x-compat"
	#pragma clang diagnostic ignored "-Wunknown-attributes"
	#endif // __clang__

	[[gnu::optimize("Os")]] static void usage(char const *argv0);

	int main([[maybe_unused]] int argc, char **argv)
	{
	usage(argv[0]);
	}

	#define ws0() " "
	#define ws1() " "
	#define ws2() " "
	#define ws3() " "
	#define ws4() " "
	#define ws5() " "
	#define ws6() " "
	#define ws7() ws6() ws6()
	#define ws8() ws7() ws7()
	#define ws9() ws8() ws8()
	#define ws10() ws9() ws9()
	#define ws11() ws10() ws10()

	#pragma GCC diagnostic push
	#pragma GCC diagnostic ignored "-Wpedantic"
	struct bit_off { };
	#pragma GCC diagnostic pop

	struct bit0_on { const char a[1U << 0U]; };
	struct bit1_on { const char a[1U << 1U]; };
	struct bit2_on { const char a[1U << 2U]; };
	struct bit3_on { const char a[1U << 3U]; };
	struct bit4_on { const char a[1U << 4U]; };
	struct bit5_on { const char a[1U << 5U]; };
	struct bit6_on { const char a[1U << 6U]; };
	struct bit7_on { const char a[1U << 7U]; };
	struct bit8_on { const char a[1U << 8U]; };
	struct bit9_on { const char a[1U << 9U]; };
	struct bit10_on { const char a[1U << 10U]; };
	struct bit11_on { const char a[1U << 11U]; };

	#define bit_(b, n, v) _Generic(&(char[1U + ((n) & (1U << (size_t)b))]){0} \
	, char(*)[1U + (1U << (size_t)b)]: (const struct bit##b##_on){v} \
	, char(*)[1U]: (const struct bit_off){})

	#define bit(b, n) bit_(b, n, {ws##b()})
	#define bit_type(b, n) typeof(bit_(b, n, 0))

	#define ws_type(n) struct { \
	bit_type( 0, n) b0; bit_type( 1, n) b1; \
	bit_type( 2, n) b2; bit_type( 3, n) b3; \
	bit_type( 4, n) b4; bit_type( 5, n) b5; \
	bit_type( 6, n) b6; bit_type( 7, n) b7; \
	bit_type( 8, n) b8; bit_type( 9, n) b9; \
	bit_type(10, n) ba; bit_type(11, n) bb; }

	#define ws_init(n) { \
	bit(0, n), bit(1, n), bit( 2, n), bit( 3, n), \
	bit(4, n), bit(5, n), bit( 6, n), bit( 7, n), \
	bit(8, n), bit(9, n), bit(10, n), bit(11, n), }

	#define dog(x,y) x##y
	#define cat(x,y) dog(x, y)
	#define sym(x) cat(x##_,__COUNTER__)
	#define c_str(x) char sym(m)[sizeof x]

	#define mkarr(chr, str, arg, ...) c_str(str " " arg " ");
	typedef char str_arg_max[sizeof(union {options(mkarr)})];
	#undef mkarr
	#define str_arg_align(x) (sizeof(str_arg_max) - sizeof x)

	#define space(x) ws_type(str_arg_align(x)) sym(m)
	#define space_init(x) ws_init(str_arg_align(x))

	#define line_vars(chr, str, arg, help) \
	const c_str(" -"); \
	const c_str(", --" str " " arg); \
	const space(str " " arg); \
	const c_str(help);

	#define line_init(chr, str, arg, help) \
	{ ' ', ' ', '-', chr }, \
	", --" str " " arg " ", \
	space_init(str " " arg), \
	help "\n",

	#define help_text(x) ((const union { \
	const struct { \
	x(line_vars) \
	const char nul[1]; \
	}; \
	const char str[1U + sizeof ( \
	struct { \
	x(line_vars) \
	} \
	)]; \
	}){{ \
	x(line_init) "" \
	}}.str)

	static void usage(char const *argv0)
	{
	(void)printf("Usage: %s [OPTIONS]\n\nOptions:\n%s",
	argv0, help_text(options));
	}

	#ifdef __clang__
	#pragma clang diagnostic pop
	#endif // __clang__