X-Git-Url: https://git.distorted.org.uk/~mdw/mLib/blobdiff_plain/5b078c11a05739c5869a6fff858019a7c520ca83..3832000d8a0d417dbfda0ca2d26bc7d66f7f4741:/utils/macros.h

diff --git a/utils/macros.h b/utils/macros.h
index 41f2d67..b960475 100644
--- a/utils/macros.h
+++ b/utils/macros.h
@@ -32,7 +32,7 @@
   extern "C" {
 #endif
 
-/*----- Macros provided ---------------------------------------------------*/
+/*----- Miscellaneous utility macros --------------------------------------*/
 
 #define N(v) (sizeof(v)/sizeof(*v))
 
@@ -42,6 +42,140 @@
 #define MLIB__GLUE(x, y) x##y
 #define GLUE(x, y) MLIB__GLUE(x, y)
 
+/*----- Compiler diagnostics ----------------------------------------------*/
+
+/* --- Compiler-specific definitions --- */
+
+#if defined(__GNUC__)
+
+#  define GCC_VERSION_P(maj, min)					\
+	(__GNUC__ > (maj) || (__GNUC__ == (maj) && __GNUC_MINOR__ >= (min)))
+
+#  if GCC_VERSION_P(2, 5)
+#    define NORETURN __attribute__((noreturn))
+#    define PRINTF_LIKE(fix, aix) __attribute__((format(printf, fix, aix)))
+#    define SCANF_LIKE(fix, aix) __attribute__((format(scanf, fix, aix)))
+#    define IGNORABLE __attribute__((unused))
+#  endif
+
+#  if GCC_VERSION_P(4, 5)
+#    define DEPRECATED(msg) __attribute__((deprecated(msg)))
+#  elif GCC_VERSION_P(3, 1)
+#    define DEPRECATED(msg) __attribute__((deprecated))
+#  endif
+
+#  if GCC_VERSION_P(4, 0)
+#    define EXECL_LIKE(ntrail) __attribute__((sentinel(ntrail)))
+#  endif
+
+#  if GCC_VERSION_P(4, 6)
+
+     /* --- Diagnostic suppression in GCC: a tale of woe --- *
+      *
+      * This is extremely unpleasant, largely as a result of bugs in the GCC
+      * preprocessor's handling of @_Pragma@.  The fundamental problem is
+      * that it's the preprocessor, and not the compiler proper, which
+      * detects @_Pragma@, emitting @#pragma@ lines into its output; and it
+      * does it during macro expansion, even if the macro is being expanded
+      * during argument collection.  Since arguments are expanded before
+      * replacing the macro's invocation with its body, a pragma in an
+      * argument will be emitted %%\emph{before}%% any pragmata in the body,
+      * even if they appear before the argument in the body -- and even if
+      * the argument doesn't actually appear anywhere at all in the body.
+      *
+      * Another, rather less significant, problem is that @_Pragma@'s
+      * argument is a single string literal, recognized in translation phase
+      * 4, before string-literal concatenation in phase 6, so we must build
+      * pragma bodies as token lists and then stringify them.
+      *
+      * As a result, we need some subterfuge here.  The @MLIB__PRAGMA_HACK@
+      * macro issues a @_Pragma@ on its argument token list, which it
+      * stringifies; this deals with the second problem.  The first is
+      * trickier: we must delay expansion of @MLIB__PRAGMA_HACK@ from the
+      * argument collection phase to the body rescanning phase, and we do
+      * this by splitting the invocations between @GCC_WARNING@ macro calls:
+      * the name is left hanging from the previous call (or from
+      * @MLIB__MUFFLE_WARNINGS@, in the first case) and the body is supplied
+      * by @GCC_WARNING@, which also supplies the next @MLIB__PRAGMA_HACK@.
+      * The remaining problem is to make sure we can dispose of the final
+      * trailing @MLIB__PRAGMA_HACK@ harmlessly, which we do by introducing
+      * an extra argument @emitp@, which may be either @t@ or @nil@; this
+      * dispatches to an appropriate helper macro by means of token-pasting.
+      *
+      * I'm so sorry.
+      */
+
+#    define MLIB__PRAGMA_HACK_t(x) _Pragma(#x)
+#    define MLIB__PRAGMA_HACK_nil(x)
+#    define MLIB__PRAGMA_HACK(emitp, x) MLIB__PRAGMA_HACK_##emitp(x)
+#    define MLIB__MUFFLE_WARNINGS(warns, body)				\
+	_Pragma("GCC diagnostic push") MLIB__PRAGMA_HACK		\
+	warns								\
+	(nil, nil)							\
+	body								\
+	_Pragma("GCC diagnostic pop")
+#    define GCC_WARNING(warn)						\
+	(t, GCC diagnostic ignored warn) MLIB__PRAGMA_HACK
+#    define MUFFLE_WARNINGS_DECL(warns, body)				\
+	MLIB__MUFFLE_WARNINGS(warns, body)
+#    define MUFFLE_WARNINGS_EXPR(warns, body)				\
+	__extension__ ({ MLIB__MUFFLE_WARNINGS(warns, (body);) })
+#    define MUFFLE_WARNINGS_STMT(warns, body)				\
+	do { MLIB__MUFFLE_WARNINGS(warns, body) } while (0)
+#  endif
+
+#endif
+
+/* --- Fallback definitions, mostly trivial --- */
+
+#ifndef GCC_VERSION_P
+#  define GCC_VERSION_P(maj, min) 0
+#endif
+
+#ifndef DEPRECATED
+#  define DEPRECATED(msg)
+#endif
+
+#ifndef EXECL_LIKE
+#  define EXECL_LIKE(ntrail)
+#endif
+
+#ifndef DISCARD
+#  define DISCARD(x) do if (x); while (0)
+#endif
+
+#ifndef IGNORE
+#  define IGNORE(x) ((void)(x))
+#endif
+
+#ifndef MUFFLE_WARNINGS_DECL
+#  define MUFFLE_WARNINGS_DECL(warns, body) body
+#endif
+
+#ifndef MUFFLE_WARNINGS_EXPR
+#  define MUFFLE_WARNINGS_EXPR(warns, body) (body)
+#endif
+
+#ifndef MUFFLE_WARNINGS_STMT
+#  define MUFFLE_WARNINGS_STMT(warns, body) do { body } while (0)
+#endif
+
+#ifndef PRINTF_LIKE
+#  define PRINF_LIKE(fmtix, argix)
+#endif
+
+#ifndef SCANF_LIKE
+#  define SCANF_LIKE(fmtix, argix)
+#endif
+
+#ifndef IGNORABLE
+#  define IGNORABLE
+#endif
+
+#ifndef GCC_WARNING
+#  define GCC_WARNING(warn)
+#endif
+
 /*----- That's all, folks -------------------------------------------------*/
 
 #ifdef __cplusplus