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authorGuy Harris <guy@alum.mit.edu>2017-10-26 11:19:13 -0700
committerGuy Harris <guy@alum.mit.edu>2017-10-26 18:19:49 +0000
commitfb160e53c8a9423ff78688bc9ef1ad5e1ec1edb1 (patch)
tree77b47aeca41f04640d331c9ef7290c59907ee81d
parentb7f7bee8cf6ecb04a4dec86b80ce2065d4192da7 (diff)
Use more than just "does it claim to be GCC?" to test for attributes.
Not all versions of GCC or Clang have the returns_nonnull function attribute, so use the same technique used in current master branch libpcap - use __has_attribute() if it's available, otherwise use compiler version tests. This also lets us use WS_NORETURN on some non-GCC compilers. Change-Id: I6ca4a81797ebfca9f743e16f83839c49d303da81 Reviewed-on: https://code.wireshark.org/review/24083 Reviewed-by: Guy Harris <guy@alum.mit.edu>
-rw-r--r--ws_attributes.h140
1 files changed, 135 insertions, 5 deletions
diff --git a/ws_attributes.h b/ws_attributes.h
index 488a9fabab..44a3c195cc 100644
--- a/ws_attributes.h
+++ b/ws_attributes.h
@@ -35,6 +35,119 @@ extern "C" {
* XXX - similar hints for other compilers?
*/
+/*
+ * This was introduced by Clang:
+ *
+ * http://clang.llvm.org/docs/LanguageExtensions.html#has-attribute
+ *
+ * in some version (which version?); it has been picked up by GCC 5.0.
+ */
+#ifndef __has_attribute
+ /*
+ * It's a macro, so you can check whether it's defined to check
+ * whether it's supported.
+ *
+ * If it's not, define it to always return 0, so that we move on to
+ * the fallback checks.
+ */
+ #define __has_attribute(x) 0
+#endif
+
+/*
+ * Note that the C90 spec's "6.8.1 Conditional inclusion" and the
+ * C99 spec's and C11 spec's "6.10.1 Conditional inclusion" say:
+ *
+ * Prior to evaluation, macro invocations in the list of preprocessing
+ * tokens that will become the controlling constant expression are
+ * replaced (except for those macro names modified by the defined unary
+ * operator), just as in normal text. If the token "defined" is
+ * generated as a result of this replacement process or use of the
+ * "defined" unary operator does not match one of the two specified
+ * forms prior to macro replacement, the behavior is undefined.
+ *
+ * so you shouldn't use defined() in a #define that's used in #if or
+ * #elif. Some versions of Clang, for example, will warn about this.
+ *
+ * Instead, we check whether the pre-defined macros for particular
+ * compilers are defined and, if not, define the "is this version XXX
+ * or a later version of this compiler" macros as 0.
+ */
+
+/*
+ * Check whether this is GCC major.minor or a later release, or some
+ * compiler that claims to be "just like GCC" of that version or a
+ * later release.
+ */
+
+#if !defined(__GNUC__)
+ #define WS_IS_AT_LEAST_GNUC_VERSION(major, minor) 0
+#else
+ #define WS_IS_AT_LEAST_GNUC_VERSION(major, minor) \
+ (__GNUC__ > (major) || \
+ (__GNUC__ == (major) && __GNUC_MINOR__ >= (minor)))
+#endif
+
+/*
+ * Check whether this is Sun C/SunPro C/Oracle Studio major.minor
+ * or a later release.
+ *
+ * The version number in __SUNPRO_C is encoded in hex BCD, with the
+ * uppermost hex digit being the major version number, the next
+ * one or two hex digits being the minor version number, and
+ * the last digit being the patch version.
+ *
+ * It represents the *compiler* version, not the product version;
+ * see
+ *
+ * https://sourceforge.net/p/predef/wiki/Compilers/
+ *
+ * for a partial mapping, which we assume continues for later
+ * 12.x product releases.
+ */
+
+#if !defined(__SUNPRO_C)
+ #define WS_IS_AT_LEAST_SUNC_VERSION(major,minor) 0
+#else
+ #define WS_SUNPRO_VERSION_TO_BCD(major, minor) \
+ (((minor) >= 10) ? \
+ (((major) << 12) | (((minor)/10) << 8) | (((minor)%10) << 4)) : \
+ (((major) << 8) | ((minor) << 4)))
+ #define WS_IS_AT_LEAST_SUNC_VERSION(major,minor) \
+ (__SUNPRO_C >= WS_SUNPRO_VERSION_TO_BCD((major), (minor)))
+#endif
+
+/*
+ * Check whether this is IBM XL C major.minor or a later release.
+ *
+ * The version number in __xlC__ has the major version in the
+ * upper 8 bits and the minor version in the lower 8 bits.
+ */
+
+#if !defined(__xlC__)
+ #define WS_IS_AT_LEAST_XL_C_VERSION(major,minor) 0
+#else
+ #define WS_IS_AT_LEAST_XL_C_VERSION(major, minor) \
+ (__xlC__ >= (((major) << 8) | (minor)))
+#endif
+
+/*
+ * Check whether this is HP aC++/HP C major.minor or a later release.
+ *
+ * The version number in __HP_aCC is encoded in zero-padded decimal BCD,
+ * with the "A." stripped off, the uppermost two decimal digits being
+ * the major version number, the next two decimal digits being the minor
+ * version number, and the last two decimal digits being the patch version.
+ * (Strip off the A., remove the . between the major and minor version
+ * number, and add two digits of patch.)
+ */
+
+#if !defined(__HP_aCC)
+ #define WS_IS_AT_LEAST_HP_C_VERSION(major,minor) 0
+#else
+ #define WS_IS_AT_LEAST_HP_C_VERSION(major,minor) \
+ (__HP_aCC >= ((major)*10000 + (minor)*100))
+#endif
+
#if defined(__GNUC__)
/* This includes clang */
#define _U_ __attribute__((unused))
@@ -42,19 +155,36 @@ extern "C" {
#define _U_
#endif
-/* Hint to the compiler that a function never returns */
-#if defined(__GNUC__)
- /* This includes clang */
+/*
+ * WS_NORETURN, before a function declaration, means "this function
+ * never returns". (It must go before the function declaration, e.g.
+ * "extern WS_NORETURN func(...)" rather than after the function
+ * declaration, as the MSVC version has to go before the declaration.)
+ */
+#if __has_attribute(noreturn) \
+ || WS_IS_AT_LEAST_GNUC_VERSION(2,5) \
+ || WS_IS_AT_LEAST_SUNC_VERSION(5,9) \
+ || WS_IS_AT_LEAST_XL_C_VERSION(10,1) \
+ || WS_IS_AT_LEAST_HP_C_VERSION(6,10)
+ /*
+ * Compiler with support for __attribute__((noreturn)), or GCC 2.5 and
+ * later, or Solaris Studio 12 (Sun C 5.9) and later, or IBM XL C 10.1
+ * and later (do any earlier versions of XL C support this?), or
+ * HP aCC A.06.10 and later.
+ */
#define WS_NORETURN __attribute__((noreturn))
#elif defined(_MSC_VER)
+ /*
+ * MSVC.
+ */
#define WS_NORETURN __declspec(noreturn)
#else
#define WS_NORETURN
#endif
/* Hint to the compiler that the function returns a non-null value */
-#if defined(__GNUC__)
- /* This includes clang */
+#if __has_attribute(returns_nonnull) \
+ || WS_IS_AT_LEAST_GNUC_VERSION(4,9)
#define WS_RETNONNULL __attribute__((returns_nonnull))
#else
#define WS_RETNONNULL