Test PCAP_IS_AT_LEAST_CLANG_VERSION(2,8) before testing _MSC_VER.

As Gisle Vanem notes, "...using clang-cl on Windows to compile with (a
MSVC-compatible compiler driver), this includes _MSC_VER as
a built-in. Hence the above blocks should be swapped..."

This fixes issue #1101.

(cherry picked from commit 49c94a759ccfebf157d549954b5254ecc39ee53d)

1 files changed, 58 insertions, 55 deletions

diff --git a/diag-control.h b/diag-control.h
index d1622aa6..28624306 100644
--- a/diag-control.h
+++ b/diag-control.h
@@ -86,44 +86,7 @@
 /*
  * Suppress Flex, narrowing, and deprecation warnings.
  */
-#if defined(_MSC_VER)
-  /*
-   * This is Microsoft Visual Studio; we can use __pragma(warning(disable:XXXX))
-   * and __pragma(warning(push/pop)).
-   *
-   * Suppress signed-vs-unsigned comparison, narrowing, and unreachable
-   * code warnings.
-   */
-  #define DIAG_OFF_FLEX \
-    __pragma(warning(push)) \
-    __pragma(warning(disable:4127)) \
-    __pragma(warning(disable:4242)) \
-    __pragma(warning(disable:4244)) \
-    __pragma(warning(disable:4702))
-  #define DIAG_ON_FLEX \
-    __pragma(warning(pop))
-
-  /*
-   * Suppress narrowing warnings.
-   */
-  #define DIAG_OFF_NARROWING \
-    __pragma(warning(push)) \
-    __pragma(warning(disable:4242)) \
-    __pragma(warning(disable:4311))
-  #define DIAG_ON_NARROWING \
-    __pragma(warning(pop))
-
-  /*
-   * Suppress deprecation warnings.
-   */
-  #define DIAG_OFF_DEPRECATION \
-    __pragma(warning(push)) \
-    __pragma(warning(disable:4996))
-  #define DIAG_ON_DEPRECATION \
-    __pragma(warning(pop))
-  #define DIAG_OFF_FORMAT_TRUNCATION
-  #define DIAG_ON_FORMAT_TRUNCATION
-#elif PCAP_IS_AT_LEAST_CLANG_VERSION(2,8)
+#if PCAP_IS_AT_LEAST_CLANG_VERSION(2,8)
   /*
    * This is Clang 2.8 or later; we can use "clang diagnostic
    * ignored -Wxxx" and "clang diagnostic push/pop".
@@ -132,6 +95,9 @@
    * at least according to the GCC 7.3 documentation.  Apparently, Flex
    * generates code that upsets at least some versions of Clang's
    * -Wdocumentation.
+   *
+   * (This could be clang-cl, which defines _MSC_VER, so test this
+   * before testing _MSC_VER.)
    */
   #define DIAG_OFF_FLEX \
     PCAP_DO_PRAGMA(clang diagnostic push) \
@@ -164,6 +130,43 @@
     PCAP_DO_PRAGMA(clang diagnostic pop)
   #define DIAG_OFF_FORMAT_TRUNCATION
   #define DIAG_ON_FORMAT_TRUNCATION
+#elif defined(_MSC_VER)
+  /*
+   * This is Microsoft Visual Studio; we can use __pragma(warning(disable:XXXX))
+   * and __pragma(warning(push/pop)).
+   *
+   * Suppress signed-vs-unsigned comparison, narrowing, and unreachable
+   * code warnings.
+   */
+  #define DIAG_OFF_FLEX \
+    __pragma(warning(push)) \
+    __pragma(warning(disable:4127)) \
+    __pragma(warning(disable:4242)) \
+    __pragma(warning(disable:4244)) \
+    __pragma(warning(disable:4702))
+  #define DIAG_ON_FLEX \
+    __pragma(warning(pop))
+
+  /*
+   * Suppress narrowing warnings.
+   */
+  #define DIAG_OFF_NARROWING \
+    __pragma(warning(push)) \
+    __pragma(warning(disable:4242)) \
+    __pragma(warning(disable:4311))
+  #define DIAG_ON_NARROWING \
+    __pragma(warning(pop))
+
+  /*
+   * Suppress deprecation warnings.
+   */
+  #define DIAG_OFF_DEPRECATION \
+    __pragma(warning(push)) \
+    __pragma(warning(disable:4996))
+  #define DIAG_ON_DEPRECATION \
+    __pragma(warning(pop))
+  #define DIAG_OFF_FORMAT_TRUNCATION
+  #define DIAG_ON_FORMAT_TRUNCATION
 #elif PCAP_IS_AT_LEAST_GNUC_VERSION(4,6)
   /*
    * This is GCC 4.6 or later, or a compiler claiming to be that.
@@ -241,21 +244,21 @@
    * In addition, the generated code may have functions with unreachable
    * code, so suppress warnings about those.
    */
-  #if defined(_MSC_VER)
+  #if PCAP_IS_AT_LEAST_CLANG_VERSION(2,8)
     /*
-     * This is Microsoft Visual Studio; we can use
-     * __pragma(warning(disable:XXXX)).
+     * This is Clang 2.8 or later (including clang-cl, so test this
+     * before _MSC_VER); we can use "clang diagnostic ignored -Wxxx".
      */
     #define DIAG_OFF_BISON_BYACC \
-      __pragma(warning(disable:4702))
-  #elif PCAP_IS_AT_LEAST_CLANG_VERSION(2,8)
+      PCAP_DO_PRAGMA(clang diagnostic ignored "-Wshadow") \
+      PCAP_DO_PRAGMA(clang diagnostic ignored "-Wunreachable-code")
+  #elif defined(_MSC_VER)
     /*
-     * This is Clang 2.8 or later; we can use "clang diagnostic
-     * ignored -Wxxx".
+     * This is Microsoft Visual Studio; we can use
+     * __pragma(warning(disable:XXXX)).
      */
     #define DIAG_OFF_BISON_BYACC \
-      PCAP_DO_PRAGMA(clang diagnostic ignored "-Wshadow") \
-      PCAP_DO_PRAGMA(clang diagnostic ignored "-Wunreachable-code")
+      __pragma(warning(disable:4702))
   #elif PCAP_IS_AT_LEAST_GNUC_VERSION(4,6)
     /*
      * This is GCC 4.6 or later, or a compiler claiming to be that.
@@ -279,7 +282,14 @@
    * The generated code may have functions with unreachable code and
    * switches with only a default case, so suppress warnings about those.
    */
-  #if defined(_MSC_VER)
+  #if PCAP_IS_AT_LEAST_CLANG_VERSION(2,8)
+    /*
+     * This is Clang 2.8 or later (including clang-cl, so test this
+     * before _MSC_VER); we can use "clang diagnostic ignored -Wxxx".
+     */
+    #define DIAG_OFF_BISON_BYACC \
+      PCAP_DO_PRAGMA(clang diagnostic ignored "-Wunreachable-code")
+  #elif defined(_MSC_VER)
     /*
      * This is Microsoft Visual Studio; we can use
      * __pragma(warning(disable:XXXX)).
@@ -292,13 +302,6 @@
       __pragma(warning(disable:4242)) \
       __pragma(warning(disable:4244)) \
       __pragma(warning(disable:4702))
-  #elif PCAP_IS_AT_LEAST_CLANG_VERSION(2,8)
-    /*
-     * This is Clang 2.8 or later; we can use "clang diagnostic
-     * ignored -Wxxx".
-     */
-    #define DIAG_OFF_BISON_BYACC \
-      PCAP_DO_PRAGMA(clang diagnostic ignored "-Wunreachable-code")
   #elif PCAP_IS_AT_LEAST_GNUC_VERSION(4,6)
     /*
      * This is GCC 4.6 or later, or a compiler claiming to be that.