CMake Module for deriving the target architecture

This is needed for packaging and other decisions at configuration time

cmake/DetermineTargetArchitecture.cmake

@@ -0,0 +1,47 @@
+# - Determines the target architecture of the compilation
+#
+# This function checks the architecture that will be built by the compiler
+# and sets a variable to the architecture
+#
+#  determine_target_architecture(<OUTPUT_VAR>)
+#
+# - Example
+#
+# include(DetermineTargetArchitecture)
+# determine_target_architecture(PROJECT_NAME_ARCHITECTURE)
+
+if(__determine_target_architecture)
+  return()
+endif()
+set(__determine_target_architecture INCLUDED)
+
+function(determine_target_architecture FLAG)
+  if (MSVC)
+    if("${MSVC_C_ARCHITECTURE_ID}" STREQUAL "X86")
+      set(ARCH "i686")
+    elseif("${MSVC_C_ARCHITECTURE_ID}" STREQUAL "x64")
+      set(ARCH "x86_64")
+    elseif("${MSVC_C_ARCHITECTURE_ID}" STREQUAL "ARM")
+      set(ARCH "arm")
+    else()
+      message(FATAL_ERROR "Failed to determine the MSVC target architecture: ${MSVC_C_ARCHITECTURE_ID}")
+    endif()
+  else()
+    execute_process(
+      COMMAND ${CMAKE_C_COMPILER} -dumpmachine
+      RESULT_VARIABLE RESULT
+      OUTPUT_VARIABLE ARCH
+      ERROR_QUIET
+    )
+    if (RESULT)
+      message(FATAL_ERROR "Failed to determine target architecture triplet: ${RESULT}")
+    endif()
+    string(REGEX MATCH "([^-]+).*" ARCH_MATCH ${ARCH})
+    if (NOT CMAKE_MATCH_1 OR NOT ARCH_MATCH)
+      message(FATAL_ERROR "Failed to match the target architecture triplet: ${ARCH}")
+    endif()
+    set(ARCH ${CMAKE_MATCH_1})
+  endif()
+  message(STATUS "Target architecture - ${ARCH}")
+  set(FLAG ${ARCH} PARENT_SCOPE)
+endfunction()