Merge pull request #1412 from KrisThielemans/GHA_MacOSxcode

[GHA] remove explicit setting of xcode version

.github/workflows/build-test.yml

@@ -162,9 +162,6 @@ jobs:
             CXX=${CXX}-${{ matrix.compiler_version }}            
           fi
           if test 'XX${{ matrix.os }}' = 'XXmacOS-latest'; then
-            # need to force XCode version for the moment due to a linker bug
-            # see https://github.com/UCL/STIR/issues/1103
-            echo DEVELOPER_DIR="/Applications/Xcode_14.1.app/Contents/Developer" >> $GITHUB_ENV
             if test 'XX${{ matrix.compiler }}' = 'XXclang'; then
               brew install llvm@${{ matrix.compiler_version }}
               if test XX${HOMEBREW_PREFIX} = XX; then

documentation/release_6.1.htm

@@ -70,6 +70,11 @@ <h3>Bug fixes</h3>
   <li>The Relative Difference Prior gave incorrect results, probably since switching to C++-14 in version 6.0, although we are not sure.
     See <a href=https://github.com/UCL/STIR/pull/1410>PR #1410</a> and associated <a href=https://github.com/UCL/STIR/pull/1409>issue #1409</a>.
   </li>
+  <li>
+      Our checks for determining system byte-order were out-of-date and in particular did not work on MacOS 14 on ARM.
+      We now use CMake's <code>CMAKE_CXX_BYTE_ORDER</code> (available since CMake 3.20).
+      See <a href=https://github.com/UCL/STIR/pull/1412>PR #1412</a>.
+  </li>
 </ul>
 
 <h3>Known problems</h3>

src/CMakeLists.txt

@@ -192,6 +192,18 @@ else()
     set(STIR_USE_BOOST_SHARED_PTR ON)
 endif()
 
+# Byte order
+if (CMAKE_VERSION VERSION_GREATER_EQUAL 3.20)
+    # Use CMake to find byte order of target system.
+    # We create some variables that are then used in config.h.in
+    if (CMAKE_CXX_BYTE_ORDER STREQUAL "BIG_ENDIAN")
+        set(BIG_ENDIAN_BYTE_ORDER_FROM_CMAKE TRUE)
+        message(STATUS "CMake detected a big_endian system")
+    elseif (CMAKE_CXX_BYTE_ORDER STREQUAL "LITTLE_ENDIAN")
+        set(LITTLE_ENDIAN_BYTE_ORDER_FROM_CMAKE TRUE)
+        message(STATUS "CMake detected a little_endian system")
+    endif()
+endif()
 
 #### Create stir/config.h
 

src/cmake/STIRConfig.h.in

@@ -52,6 +52,10 @@ namespace stir {
 
 #include "boost/config.hpp"
 
+// 2 variables set via CMake
+#cmakedefine BIG_ENDIAN_BYTE_ORDER_FROM_CMAKE
+#cmakedefine LITTLE_ENDIAN_BYTE_ORDER_FROM_CMAKE
+
 #cmakedefine HAVE_ECAT
 #ifdef HAVE_ECAT
 #define HAVE_LLN_MATRIX

src/include/stir/ByteOrderDefine.h

@@ -23,10 +23,14 @@
 START_NAMESPACE_STIR
 
 // currently checked by asserts()
-#if !defined(__alpha) && (!defined(_WIN32) || defined(_M_PPC) || defined(_M_MPPC)) && !defined(__i386__) && !defined(__i486__)   \
-        && !defined(__i586__) && !defined(__i686__) && !defined(__i786__) && !defined(__i886__) && !defined(__k6__)              \
-        && !defined(__athlon__) && !defined(__x86_64__) && !defined(__k6__)                                                      \
-    || (defined(__MSL__) && !defined(__LITTLE_ENDIAN))
+// partially from https://stackoverflow.com/a/27054190
+#if defined(BIG_ENDIAN_BYTE_ORDER_FROM_CMAKE)         /* variable set via CMake in stir/config.h */                              \
+    || (!defined(LITTLE_ENDIAN_BYTE_ORDER_FROM_CMAKE) /* variable set via CMake in stir/config.h */                              \
+        && ((!defined(__alpha) && (!defined(_WIN32) || defined(_M_PPC) || defined(_M_MPPC)) && !defined(__i386__)                \
+                 && !defined(__i486__) && !defined(__i586__) && !defined(__i686__) && !defined(__i786__) && !defined(__i886__)   \
+                 && !defined(__k6__) && !defined(__athlon__) && !defined(__x86_64__) && !defined(__k6__))                         \
+             || (defined(__MSL__) && !defined(__LITTLE_ENDIAN)) || (defined(__BYTE_ORDER) && __BYTE_ORDER == __BIG_ENDIAN)       \
+             || (defined(__BYTE_ORDER__) && (__BYTE_ORDER__ == __ORDER_BIG_ENDIAN__) /* gcc */) || defined(__BIG_ENDIAN__)))
 #  define STIRIsNativeByteOrderBigEndian 1
 #  define STIRIsNativeByteOrderLittleEndian 0
 #else