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diff --git a/include/ws_compiler_tests.h b/include/ws_compiler_tests.h
new file mode 100644
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--- /dev/null
+++ b/include/ws_compiler_tests.h
@@ -0,0 +1,152 @@
+/* ws_compiler_tests.h
+ *
+ * Wireshark - Network traffic analyzer
+ * By Gerald Combs <gerald@wireshark.org>
+ * Copyright 1998 Gerald Combs
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#ifndef __WS_COMPILER_TESTS_H__
+#define __WS_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 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 if the compiler is GCC and not a compiler from another
+ * vendor that also defines __GNUC__ (claiming support for GNU C dialect).
+ * Unfortunately there is no way to test this directly so we need
+ * to exclude other known compilers that claim such support (hacky).
+ */
+#if defined(__GNUC__) && \
+        !defined(__clang__) && \
+        !defined(__INTEL_COMPILER) && \
+        !defined(__INTEL_LLVM_COMPILER)
+  #define WS_GCC_VERSION \
+        (__GNUC__ * 10000 + __GNUC_MINOR__ * 100 + __GNUC_PATCHLEVEL)
+#endif
+
+/*
+ * Check whether this is Clang major.minor or a later release.
+ */
+
+#if !defined(__clang__)
+  #define WS_IS_AT_LEAST_CLANG_VERSION(major, minor) 0
+#else
+  #define WS_IS_AT_LEAST_CLANG_VERSION(major, minor) \
+	(__clang_major__ > (major) || \
+	 (__clang_major__ == (major) && __clang_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
+
+#endif /* __WS_COMPILER_TESTS_H__ */