From aa95b70f6da1852f136e36954814be0fa4b02fa2 Mon Sep 17 00:00:00 2001
From: Sean <sean@rogue-research.com>
Date: Mon, 8 Feb 2021 15:16:41 -0500
Subject: Remove prohibition against building Universal Binaries on macOS
 (#318)

Fixes github issue #311.
---
 config/cmake/H5pubconf.h.in                |  3 ---
 config/cmake_ext_mod/ConfigureChecks.cmake | 15 ---------------
 release_docs/RELEASE.txt                   |  7 +++++++
 3 files changed, 7 insertions(+), 18 deletions(-)

diff --git a/config/cmake/H5pubconf.h.in b/config/cmake/H5pubconf.h.in
index a4d07fc..1256cf8 100644
--- a/config/cmake/H5pubconf.h.in
+++ b/config/cmake/H5pubconf.h.in
@@ -26,9 +26,6 @@
 /* Define if using a Windows compiler (i.e. Visual Studio) */
 #cmakedefine H5_HAVE_VISUAL_STUDIO @H5_HAVE_VISUAL_STUDIO@
 
-/* Define if building universal (internal helper macro) */
-#cmakedefine H5_AC_APPLE_UNIVERSAL_BUILD @H5_AC_APPLE_UNIVERSAL_BUILD@
-
 /* Define if C++ compiler recognizes offsetof */
 #cmakedefine H5_CXX_HAVE_OFFSETOF @CXX_HAVE_OFFSETOF@
 
diff --git a/config/cmake_ext_mod/ConfigureChecks.cmake b/config/cmake_ext_mod/ConfigureChecks.cmake
index 5fa6ca1..3722a0c 100644
--- a/config/cmake_ext_mod/ConfigureChecks.cmake
+++ b/config/cmake_ext_mod/ConfigureChecks.cmake
@@ -22,21 +22,6 @@ include (CheckVariableExists)
 include (TestBigEndian)
 include (CheckStructHasMember)
 
-#-----------------------------------------------------------------------------
-# APPLE/Darwin setup
-#-----------------------------------------------------------------------------
-if (APPLE)
-  list (LENGTH CMAKE_OSX_ARCHITECTURES ARCH_LENGTH)
-  if (ARCH_LENGTH GREATER 1)
-    set (CMAKE_OSX_ARCHITECTURES "" CACHE STRING "" FORCE)
-    message (FATAL_ERROR "Building Universal Binaries on OS X is NOT supported by the HDF5 project. This is"
-    "due to technical reasons. The best approach would be build each architecture in separate directories"
-    "and use the 'lipo' tool to combine them into a single executable or library. The 'CMAKE_OSX_ARCHITECTURES'"
-    "variable has been set to a blank value which will build the default architecture for this system.")
-  endif ()
-  set (${HDF_PREFIX}_AC_APPLE_UNIVERSAL_BUILD 0)
-endif ()
-
 # Check for Darwin (not just Apple - we also want to catch OpenDarwin)
 if (${CMAKE_SYSTEM_NAME} MATCHES "Darwin")
     set (${HDF_PREFIX}_HAVE_DARWIN 1)
diff --git a/release_docs/RELEASE.txt b/release_docs/RELEASE.txt
index 91eaaec..1d7e6da 100644
--- a/release_docs/RELEASE.txt
+++ b/release_docs/RELEASE.txt
@@ -48,6 +48,13 @@ New Features
 
     Configuration:
     -------------
+    - On macOS, Universal Binaries can now be built, allowing native execution on
+      both Intel and Apple Silicon (ARM) based Macs.
+
+      To do so, set CMAKE_OSX_ARCHITECTURES="x86_64;arm64"
+
+      (SAM - 2021/02/07, https://github.com/HDFGroup/hdf5/issues/311)
+
     - CMake option to build the HDF filter plugins project as an external project
 
         The HDF filter plugins project is a collection of registered compression
-- 
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