[tz] strftime %s

[Guy Harris]

On Jan 23, 2024, at 4:55 AM, Clive D.W. Feather via tz <tz at iana.org> wrote:
> 
> Paul Eggert via tz said:
> 
>> and (if they exist) the intN_t and
>> uintN_t types. In the C standard the intN_t and uintN_t types are optional;
>> POSIX requires them only for N equal to 8, 16, and 32.
> 
> C requires them for N equal to 8, 16, 32, and 64 if the implementation has
> a type with the required properties. So they would be required on things
> like x86 and ARM architectures.

At least as I read 5.2.4.2.1 "Sizes of integer types <limits.h>":

	The values given below shall be replaced by constant expressions suitable for use in #if preprocessing directives. Moreover, except for CHAR_BIT and MB_LEN_MAX, the following shall be replaced by expressions that have the same type as would an expression that is an object of the corresponding type converted according to the integer promotions. Their implementation-defined values shall be equal or greater in magnitude (absolute value) to those shown, with the same sign.

		...

	— minimum value for an object of type long long int
		LLONG_MIN	-9223372036854775807 // −(2^63−1)

	— maximum value for an object of type long long int
		LLONG_MAX	+9223372036854775807 // 2^63−1

	— maximum value for an object of type unsigned long long int
		ULLONG_MAX	18446744073709551615 // 2^64−1

and 6.2.5 "Types" in C11:

		...

	There are five standard signed integer types, designated as signed char, short int, int, long int, and long long int. (These and other types may be designated in several additional ways, as described in 6.7.2.) There may also be implementation-defined extended signed integer types.) The standard and extended signed integer types are collectively called signed integer types.

		...

	For each of the signed integer types, there is a corresponding (but different) unsigned integer type (designated with the keyword unsigned) that uses the same amount of storage (including sign information) and has the same alignment requirements. The type _Bool and the unsigned integer types that correspond to the standard signed integer types are the standard unsigned integer types. The unsigned integer types that correspond to the extended signed integer types are the extended unsigned integer types. The standard and extended unsigned integer types are collectively called unsigned integer types.)

that C11 requires the existence of long long int data types that support, at minimum, 64-bit integral values, *even if the machine's "word size" is smaller*, so even 32-bit x86 (IA-32) and 32-bit ARM (A32/T32) need to support 64-bit integral values - and the same applies to PowerPC/Power ISA, SPARCv{7,8,9}, 32-bit and 64-bit RISC-V, and z/Architecture (and any now-dead ISAs that existed in 2011).

As for the intN_t/uintN_t types, as I read 7.20.1.1 "Exact-width integer types":

	These types are optional. However, if an implementation provides integer types with widths of 8, 16, 32, or 64 bits, no padding bits, and (for the signed types) that have a two’s complement representation, it shall define the corresponding typedef names.

C for the Univac/Unisys 36-bit systems and the Burroughs/Unisys 48+3-tag-bits systems need not provide the intN_t/uintN_t types, although power-of-2 word-size two's complement machines would.

And as I read 7.20.1.2 "Minimum-width integer types":

	The following types are required:

		int_least8_t		uint_least8_t
		int_least16_t		uint_least16_t
		int_least32_t		uint_least32_t
		int_least64_t		uint_least64_t

all of them would have to provide those types, even if, for example, the least64_t type are 72-bit or 96-bit-with-two-3-bit-tags-for-each-48-bits on the Unisys machines.