Allow self configured definition of _WRS_VXWORKS_MAJOR

This conditions the use of system headers to fetch a
_WRS_VXWORKS_MAJOR macro on the non definition of that
macro. This allows builds where a specific value is
predefined, e.g. with a self spec, useful in environments
where the system headers don't actually define that macro
(e.g. vxworks 5 or 653).

In addition, _WRS_VXWORKS_MINOR is only provided by the
system headers when really meaningful, e.g. from 6.4 to 6.9.

We just pick a conservative default to 0 for all the cases
where it is not exposed by the system headers or otherwise.

2020-10-15  Olivier Hainque  <hainque@adacore.com>

gcc/
	* config/vxworks/_vxworks-versions.h: Only include
	version.h if _WRS_VXWORKS_MAJOR is not defined.
	Provide a default _WRS_VXWORKS_MINOR (0).

diff --git a/gcc/config/vxworks/_vxworks-versions.h b/gcc/config/vxworks/_vxworks-versions.h
index 0aaf547..15e8bfe 100644 (file)
--- a/gcc/config/vxworks/_vxworks-versions.h
+++ b/gcc/config/vxworks/_vxworks-versions.h
@@ -22,17 +22,29 @@ see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
 #ifndef _VXWORKS_VERSIONS_H
 #define _VXWORKS_VERSIONS_H  1
 
-/* All we need is access to the bare _WRS_VXWORKS_MAJOR/MINOR macros
-   exposed by version.h.  Cheat a bit to make sure we don't drag additional
-   header files, which can easily cause #include ordering nightmares.  */
+/* All we need is access to the bare _WRS_VXWORKS_MAJOR/MINOR macros,
+   exposed by version.h or already provided somehow (e.g. with a self
+   spec for some reason).  When resorting to system headers, cheat a
+   bit to make sure we don't drag additional header files, which can
+   easily cause #include ordering nightmares.  */
 
+#if !defined(_WRS_VXWORKS_MAJOR)
 #pragma push_macro("_WRS_KERNEL")
 #undef _WRS_KERNEL
 #include <version.h>
 #pragma pop_macro("_WRS_KERNEL")
+#endif
+
+/* A lot depends on the MAJOR so we really need to make sure we have
+   that.  MINOR is less critical and many environments don't actually
+   define it unless it is really meaningful (e.g. 6.4 through 6.9).  */
 
 #if !defined(_WRS_VXWORKS_MAJOR)
-#error "VxWorks version macros needed but not defined"
+#error "_WRS_VXWORKS_MAJOR undefined"
+#endif
+
+#if !defined(_WRS_VXWORKS_MINOR)
+#define _WRS_VXWORKS_MINOR 0
 #endif
 
 #define _VXWORKS_MAJOR_GT(MAJOR) (_WRS_VXWORKS_MAJOR > (MAJOR))