Portability macros

Compiler-portability shims and small utility macros used throughout rlib. More...

Files
file	rmacros.h
	Compiler-portability macros and small utility macros.

Macros
#define	R_GNUC_PREREQ(x, y)   0
	TRUE if compiling with GCC x.y or newer (0 elsewhere).

Symbol visibility
#define	R_API_EXPORT
#define	R_API_IMPORT
#define	R_API_HIDDEN
#define	R_API   R_API_IMPORT
	Public-API decoration: resolves to R_API_EXPORT while building rlib and R_API_IMPORT for consumers.

Common constants
#define	NULL   ((void*) 0)
	Null pointer constant (defined only if absent).
#define	FALSE   (0)
	Boolean false (0).
#define	TRUE   (!FALSE)
	Boolean true (!FALSE).

Arithmetic helpers
Argument-evaluating macros (no type checking) — beware passing expressions with side effects.
#define	MAX(a, b)   (((a) > (b)) ? (a) : (b))
	Larger of a and b.
#define	MIN(a, b)   (((a) < (b)) ? (a) : (b))
	Smaller of a and b.
#define	ABS(a)   (((a) < 0) ? -(a) : (a))
	Absolute value of a.
#define	CLAMP(x, l, h)   (((x) > (h)) ? (h) : (((x) < (l)) ? (l) : (x)))
	Clamp x to the inclusive range [l, h].
#define	R_N_ELEMENTS(a)   (sizeof (a) / sizeof ((a)[0]))
	Number of elements in a fixed-size array a.

Token manipulation
#define	R_STRINGIFY_ARG(str)   #str
	Stringify str without macro expansion.
#define	R_STRINGIFY(str)   R_STRINGIFY_ARG (str)
	Stringify str after macro expansion.
#define	R_PASTE_ARGS(a1, a2)   a1 ## a2
	Token-paste a1 and a2 without macro expansion.
#define	R_PASTE(a1, a2)   R_PASTE_ARGS (a1, a2)
	Token-paste a1 and a2 after macro expansion.
#define	R_STRLOC   __FILE__ ":" R_STRINGIFY (__LINE__)
	Source location string "file:line".
#define	R_STRFUNC   ((const char*) ("???"))
	Current function name as a string (compiler-specific spelling).

Declaration and statement wrappers
#define	R_BEGIN_DECLS
	Open an extern "C" block under C++ (no-op in C).
#define	R_END_DECLS
#define	R_STMT_START   do
	Start a brace-free multi-statement macro body; pair with R_STMT_END.
#define	R_STMT_END   while (0)
	End an R_STMT_START body (suppresses MSVC C4127 on the while(0)).

Initializers and branch hints
#define	R_LIKELY(expr)   (expr)
	Hint that expr is likely true (branch-prediction).
#define	R_UNLIKELY(expr)   (expr)

Section, function, and variable attributes
Each resolves to the GCC/Clang attribute, the MSVC equivalent, or nothing on toolchains that lack it.
#define	R_ATTR_WARN_UNUSED_RESULT
	Warn if a function's return value is ignored.
#define	R_ATTR_NORETURN
	Mark a function as never returning.
#define	R_ATTR_WEAK
#define	R_ATTR_ALIGN(a)
#define	R_ATTR_FALLTHROUGH   ((void)0)
	Mark an intentional switch fall-through.
#define	R_ATTR_NULL_TERMINATED
	Mark a variadic function as requiring a NULL sentinel.
#define	R_ATTR_UNUSED
#define	R_ATTR_CONST
#define	R_ATTR_PURE
#define	R_ATTR_MALLOC
#define	R_ATTR_FORMAT_ARG(arg_idx)
#define	R_ATTR_PRINTF(fmt_idx, arg_idx)
#define	R_ATTR_SCANF(fmt_idx, arg_idx)
#define	R_ATTR_RESTRICT
	Pointer-aliasing hint (restrict) in the compiler's spelling.

Feature-test fallbacks
Define the Clang feature-test builtins as 0 on compilers that lack them.
#define	__has_feature(x)   0
#define	__has_builtin(x)   0
#define	__has_extension   __has_feature
#define	R_ATTR_ALLOC_SIZE_ARG(x)
#define	R_ATTR_ALLOC_SIZE_ARGS(x, y)

Detailed Description

Compiler-portability shims and small utility macros used throughout rlib.

Everything here resolves to a compiler-specific spelling (GCC / Clang attributes, MSVC __declspec, or an empty fallback) so the rest of the codebase can use one name regardless of toolchain: symbol-visibility decoration (R_API), function / variable attributes (the R_ATTR_* family), branch hints, constructors, and the usual MIN / MAX / stringify helpers.