From 7115ef469d20bf4a3aba3dcfbb38629bcc57ac5b Mon Sep 17 00:00:00 2001
From: pastdue <30942300+past-due@users.noreply.github.com>
Date: Thu, 28 Jan 2021 22:38:32 -0500
Subject: vcpkg_configure_make: Support macOS cross-compile (#15659)

* vcpkg_configure_make: Support macOS cross-compile

* Move compiler flags logic to get_cmake_vars

* Better match the arch behavior of config.guess

* Apply suggestions from code review

Co-authored-by: Billy O'Neal <bion@microsoft.com>

Co-authored-by: Billy O'Neal <bion@microsoft.com>
---
 scripts/cmake/vcpkg_configure_make.cmake | 43 ++++++++++++++++++++++++++++++--
 1 file changed, 41 insertions(+), 2 deletions(-)

(limited to 'scripts/cmake')

diff --git a/scripts/cmake/vcpkg_configure_make.cmake b/scripts/cmake/vcpkg_configure_make.cmake
index 122281f42..c30de38bd 100644
--- a/scripts/cmake/vcpkg_configure_make.cmake
+++ b/scripts/cmake/vcpkg_configure_make.cmake
@@ -139,6 +139,26 @@ macro(_vcpkg_determine_autotools_target_cpu out_var)
     endif()
 endmacro()
 
+macro(_vcpkg_determine_autotools_host_arch_mac out_var)
+    set(${out_var} "${VCPKG_DETECTED_CMAKE_HOST_SYSTEM_PROCESSOR}")
+endmacro()
+
+macro(_vcpkg_determine_autotools_target_arch_mac out_var)
+    list(LENGTH VCPKG_OSX_ARCHITECTURES _num_osx_archs)
+    if(_num_osx_archs GREATER_EQUAL 2)
+        set(${out_var} "universal")
+    else()
+        # Better match the arch behavior of config.guess
+        # See: https://git.savannah.gnu.org/gitweb/?p=config.git;a=blob_plain;f=config.guess;hb=HEAD
+        if(VCPKG_OSX_ARCHITECTURES MATCHES "^(ARM|arm)64$")
+            set(${out_var} "aarch64")
+        else()
+            set(${out_var} "${VCPKG_OSX_ARCHITECTURES}")
+        endif()
+    endif()
+    unset(_num_osx_archs)
+endmacro()
+
 macro(_vcpkg_backup_env_variable envvar)
     if(DEFINED ENV{${envvar}})
         set(${envvar}_BACKUP "$ENV{${envvar}}")
@@ -407,6 +427,25 @@ function(vcpkg_configure_make)
         set(prefix_var "\${prefix}")
     endif()
 
+    # macOS - cross-compiling support
+    if(VCPKG_TARGET_IS_OSX)
+        if (_csc_AUTOCONFIG AND NOT _csc_BUILD_TRIPLET OR _csc_DETERMINE_BUILD_TRIPLET)
+            _vcpkg_determine_autotools_host_arch_mac(BUILD_ARCH) # machine you are building on => --build=
+            _vcpkg_determine_autotools_target_arch_mac(TARGET_ARCH)
+            # --build: the machine you are building on
+            # --host: the machine you are building for
+            # --target: the machine that CC will produce binaries for
+            # https://stackoverflow.com/questions/21990021/how-to-determine-host-value-for-configure-when-using-cross-compiler
+            # Only for ports using autotools so we can assume that they follow the common conventions for build/target/host
+            set(_csc_BUILD_TRIPLET "--build=${BUILD_ARCH}-apple-darwin")
+            if(NOT "${TARGET_ARCH}" STREQUAL "${BUILD_ARCH}") # we don't need to specify the additional flags if we build natively.
+
+                list(APPEND _csc_BUILD_TRIPLET "--host=${TARGET_ARCH}-apple-darwin") # (Host activates crosscompilation; The name given here is just the prefix of the host tools for the target)
+            endif()
+            debug_message("Using make triplet: ${_csc_BUILD_TRIPLET}")
+        endif()
+    endif()
+
     # Cleanup previous build dirs
     file(REMOVE_RECURSE "${CURRENT_BUILDTREES_DIR}/${TARGET_TRIPLET}-rel"
                         "${CURRENT_BUILDTREES_DIR}/${TARGET_TRIPLET}-dbg"
@@ -671,8 +710,8 @@ function(vcpkg_configure_make)
         if (CMAKE_HOST_WIN32)
             set(command ${base_cmd} -c "${CONFIGURE_ENV} ./${RELATIVE_BUILD_PATH}/configure ${_csc_BUILD_TRIPLET} ${_csc_OPTIONS} ${_csc_OPTIONS_${_buildtype}}")
         else()
-            find_program(BASH bash REQUIRED)
-            set(command "${BASH}" "./${RELATIVE_BUILD_PATH}/configure" ${_csc_BUILD_TRIPLET} ${_csc_OPTIONS} ${_csc_OPTIONS_${_buildtype}})
+            find_program(BASH bash REQUIRED)
+            set(command "${BASH}" "./${RELATIVE_BUILD_PATH}/configure" ${_csc_BUILD_TRIPLET} ${_csc_OPTIONS} ${_csc_OPTIONS_${_buildtype}})
         endif()
         if(_csc_ADD_BIN_TO_PATH)
             set(PATH_BACKUP $ENV{PATH})
-- 
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