X-Git-Url: https://git.distorted.org.uk/~mdw/sod/blobdiff_plain/2b2252cc8d730004a1c95f227a0024a28b65087c..8c2c58ae77fe3afce6ac4d027e9e47157a535961:/lib/sod.h

diff --git a/lib/sod.h b/lib/sod.h
index 360afa8..943ed4b 100644
--- a/lib/sod.h
+++ b/lib/sod.h
@@ -34,6 +34,16 @@
 
 /*----- Preliminary utilities ---------------------------------------------*/
 
+/* Various hacks for checking compiler versions. */
+#define SOD__GCC_P(maj, min)						\
+	(__GNUC__ > (maj) || (__GNUC__ == (maj) && __GNUC_MINOR__ >= (min)))
+
+#ifdef __GNUC__
+#  define SOD__EXTENSION __extension__
+#else
+#  define SOD__EXTENSION
+#endif
+
 /* --- @SOD__HAVE_VARARGS_MACROS@ --- *
  *
  * Use:		Defined if the compiler supports C99-style variadic macros.
@@ -49,7 +59,7 @@
 
 #  define SOD__HAVE_VARARGS_MACROS
 
-#elif __GNUC__ >= 3
+#elif SOD__GCC_P(3, 0)
    /* We're using GCC, which is trying to deny it but we don't believe it.
     * Unfortunately there's a fly in the ointment: if `-pedantic' -- or,
     * worse, `-pedantic-errors' -- is set, then GCC will warn about these
@@ -77,6 +87,26 @@
 /* We're going to want to make use of this ourselves. */
 SOD__VARARGS_MACROS_PREAMBLE
 
+/* --- @SOD__ALIGNOF@ --- *
+ *
+ * Arguments:	@type@ = a C type name, consisting of declaration specifiers
+ *			and `*[QUALIFIERS]' declarator operators
+ *
+ * Returns:	A sufficient alignment for objects of the given @type@, as a
+ *		@size_t@.
+ */
+
+#if __STDC_VERSION__ >= 201112
+#  define SOD__ALIGNOF(type) _Alignof(type)
+#elif SOD__GCC_P(4, 7)
+#  define SOD__ALIGNOF(type) __extension__ _Alignof(type)
+#elif defined(__GNUC__)
+#  define SOD__ALIGNOF(type) __alignof__(type)
+#else
+#  define SOD__ALIGNOF(type)						\
+offsetof(struct { char sod__x; type sod__y; }, sod__y)
+#endif
+
 /* --- @SOD__CAR@ --- *
  *
  * Arguments:	@...@ = a nonempty list of arguments