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authorGuy Harris <guy@alum.mit.edu>2018-01-21 17:57:20 -0800
committerGuy Harris <guy@alum.mit.edu>2018-01-21 17:57:20 -0800
commit45fc519a2ac35af5805204418c370136aa0db1f7 (patch)
tree4fb15d49aabe44730e7e042ee1a658de7040faa6 /compiler-tests.h
parentc29177f65837dfa7bc18daf7df872069811ab91e (diff)
downloadtcpdump-45fc519a2ac35af5805204418c370136aa0db1f7.tar.gz
Don't test for __attribute__ in the configure script.
Instead, use compiler test macros to check whether *particular* attributes are supported, and set various #defines appropriately, in header files. Rename the UNALIGNED structure attribute to ND_UNALIGNED, and ask whether we still need it.
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+/* -*- Mode: c; tab-width: 8; indent-tabs-mode: 1; c-basic-offset: 8; -*- */
+/*
+ * Copyright (c) 1993, 1994, 1995, 1996, 1997
+ * The Regents of the University of California. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ * 3. All advertising materials mentioning features or use of this software
+ * must display the following acknowledgement:
+ * This product includes software developed by the Computer Systems
+ * Engineering Group at Lawrence Berkeley Laboratory.
+ * 4. Neither the name of the University nor of the Laboratory may be used
+ * to endorse or promote products derived from this software without
+ * specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#ifndef nd_compiler_tests_h
+#define nd_compiler_tests_h
+
+/*
+ * 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 ND_IS_AT_LEAST_GNUC_VERSION(major, minor) 0
+#else
+#define ND_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 ND_IS_AT_LEAST_SUNC_VERSION(major,minor) 0
+#else
+#define ND_SUNPRO_VERSION_TO_BCD(major, minor) \
+ (((minor) >= 10) ? \
+ (((major) << 12) | (((minor)/10) << 8) | (((minor)%10) << 4)) : \
+ (((major) << 8) | ((minor) << 4)))
+#define ND_IS_AT_LEAST_SUNC_VERSION(major,minor) \
+ (__SUNPRO_C >= ND_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 ND_IS_AT_LEAST_XL_C_VERSION(major,minor) 0
+#else
+#define ND_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 ND_IS_AT_LEAST_HP_C_VERSION(major,minor) 0
+#else
+#define ND_IS_AT_LEAST_HP_C_VERSION(major,minor) \
+ (__HP_aCC >= ((major)*10000 + (minor)*100))
+#endif
+
+#endif /* nd_funcattrs_h */