Retrieve HWLOC API version from hwloc.h header

The FindLIBHWLOC.cmake module previously used the config.h header
to retrieve the HWLOC library version. This header was not always
present depending on how the library was distributed. To address
this issue, we now rely on the HWLOC API version retrieved from
hwloc.h, the main HWLOC library header.

Author: kswiecicki

cmake/FindLIBHWLOC.cmake

@@ -15,24 +15,25 @@ get_filename_component(LIBHWLOC_INCLUDE_DIR ${LIBHWLOC_HEADER} DIRECTORY)
 set(LIBHWLOC_INCLUDE_DIRS ${LIBHWLOC_INCLUDE_DIR})
 
 if(LIBHWLOC_INCLUDE_DIR)
-    if(EXISTS "${LIBHWLOC_INCLUDE_DIR}/hwloc/autogen/config.h")
-        file(
-            STRINGS "${LIBHWLOC_INCLUDE_DIR}/hwloc/autogen/config.h"
-            LIBHWLOC_VERSION
-            REGEX
-                "#define[ \t]HWLOC_VERSION[ \t]\"([0-9]+.[0-9]+.[0-9]+(rc[0-9])?)(-git)?\""
-        )
-        string(
-            REGEX
-            REPLACE
-                "#define[ \t]HWLOC_VERSION[ \t]\"([0-9]+.[0-9]+.[0-9]+(rc[0-9])?)(-git)?\""
-                "\\1"
-                LIBHWLOC_VERSION
-                "${LIBHWLOC_VERSION}")
+    if(EXISTS "${LIBHWLOC_INCLUDE_DIR}/hwloc.h")
+        file(STRINGS "${LIBHWLOC_INCLUDE_DIR}/hwloc.h" LIBHWLOC_API_VERSION
+             REGEX "#define[ \t]HWLOC_API_VERSION[ \t]0x[0-9]+")
+        string(REGEX
+               REPLACE "#define[ \t]HWLOC_API_VERSION[ \t](0x[0-9]+)" "\\1"
+                       LIBHWLOC_API_VERSION "${LIBHWLOC_API_VERSION}")
+
+        math(EXPR LIBHWLOC_API_PATCH "(${LIBHWLOC_API_VERSION} & 0xFF)")
+        math(EXPR LIBHWLOC_API_MINOR "(${LIBHWLOC_API_VERSION} & 0xFF00) >> 8")
+        math(EXPR LIBHWLOC_API_MAJOR
+             "(${LIBHWLOC_API_VERSION} & 0xFF0000) >> 16")
+
+        set(LIBHWLOC_API_VERSION
+            "${LIBHWLOC_API_MAJOR}.${LIBHWLOC_API_MINOR}.${LIBHWLOC_API_PATCH}")
+
     else()
         message(
             WARNING
-                "LIBHWLOC_INCLUDE_DIR found, but header with version info is missing"
+                "LIBHWLOC_INCLUDE_DIR found, but header with API version info is missing"
         )
     endif()
 endif()
@@ -48,18 +49,19 @@ if(LIBHWLOC_LIBRARY)
     message(STATUS "    LIBHWLOC_LIBRARIES = ${LIBHWLOC_LIBRARIES}")
     message(STATUS "    LIBHWLOC_INCLUDE_DIRS = ${LIBHWLOC_INCLUDE_DIRS}")
     message(STATUS "    LIBHWLOC_LIBRARY_DIRS = ${LIBHWLOC_LIBRARY_DIRS}")
-    message(STATUS "    LIBHWLOC_VERSION = ${LIBHWLOC_VERSION}")
+    message(STATUS "    LIBHWLOC_API_VERSION = ${LIBHWLOC_API_VERSION}")
     if(WINDOWS)
         message(STATUS "    LIBHWLOC_DLL_DIRS = ${LIBHWLOC_DLL_DIRS}")
     endif()
 
     if(LIBHWLOC_FIND_VERSION)
-        if(NOT LIBHWLOC_VERSION)
+        if(NOT LIBHWLOC_API_VERSION)
             message(FATAL_ERROR "Failed to retrieve libhwloc version")
-        elseif(NOT LIBHWLOC_VERSION VERSION_GREATER_EQUAL LIBHWLOC_FIND_VERSION)
+        elseif(NOT LIBHWLOC_API_VERSION VERSION_GREATER_EQUAL
+               LIBHWLOC_FIND_VERSION)
             message(
                 FATAL_ERROR
-                    "    Required version: ${LIBHWLOC_FIND_VERSION}, found ${LIBHWLOC_VERSION}"
+                    "    Required version: ${LIBHWLOC_FIND_VERSION}, found ${LIBHWLOC_API_VERSION}"
             )
         endif()
     endif()