Handle older OSes without DLT_PRISM_HEADER/DLT_AIRONET_HEADER/DLT_PPI.

[libpcap] / pcap / compiler-tests.h

diff --git a/pcap/compiler-tests.h b/pcap/compiler-tests.h
index 552941ca2c90cd77f5555f5bc774f2cb720ac645..ea5962c7bf5e6849521167db95274ec81f06576b 100644 (file)
--- a/pcap/compiler-tests.h
+++ b/pcap/compiler-tests.h
@@ -35,7 +35,6 @@
 #ifndef lib_pcap_compiler_tests_h
 #define lib_pcap_compiler_tests_h
 
-
 /*
  * This was introduced by Clang:
  *
@@ -54,6 +53,26 @@
   #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
@@ -68,6 +87,18 @@
         (__GNUC__ == (major) && __GNUC_MINOR__ >= (minor)))
 #endif
 
+/*
+ * Check whether this is Clang major.minor or a later release.
+ */
+
+#if !defined(__clang__)
+#define PCAP_IS_AT_LEAST_CLANG_VERSION(major, minor) 0
+#else
+#define PCAP_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.
@@ -129,4 +160,4 @@
        (__HP_aCC >= ((major)*10000 + (minor)*100))
 #endif
 
-#endif /* lib_pcap_funcattrs_h */
+#endif /* lib_pcap_compiler_tests_h */