From 6dff2c38c809f57b23062d6433be1584c362a21a Mon Sep 17 00:00:00 2001
From: wheremyfoodat <44909372+wheremyfoodat@users.noreply.github.com>
Date: Wed, 27 Sep 2023 19:51:06 +0300
Subject: [PATCH] Properly detect architecture for Qt

---
 CMakeLists.txt                            |  2 --
 third_party/CMakeModules/install_qt.cmake | 31 +++++++++++++++++++++++
 2 files changed, 31 insertions(+), 2 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 7f882b91..89565045 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -65,8 +65,6 @@ if(ENABLE_DISCORD_RPC AND NOT ANDROID)
 endif()
 
 if (ENABLE_QT_GUI)
-    set(ARCHITECTURE "x86_64")
-
     if (NOT USE_SYSTEM_QT)
         # Shout-out to whoever made this
         include(third_party/CMakeModules/install_qt.cmake)
diff --git a/third_party/CMakeModules/install_qt.cmake b/third_party/CMakeModules/install_qt.cmake
index 95f53b81..93cd3fe4 100644
--- a/third_party/CMakeModules/install_qt.cmake
+++ b/third_party/CMakeModules/install_qt.cmake
@@ -4,6 +4,22 @@
 # Params:
 #   target: Qt dependency to install. Specify a version number to download Qt, or "tools_(name)" for a specific build tool.
 function(download_qt target)
+    # Detect architecture to find which Qt version to fetch
+    if (CMAKE_OSX_ARCHITECTURES)
+        set(ARCHITECTURE "${CMAKE_OSX_ARCHITECTURES}")
+    elseif (MSVC)
+        detect_architecture("_M_AMD64" x86_64)
+        detect_architecture("_M_IX86" x86)
+        detect_architecture("_M_ARM" arm)
+        detect_architecture("_M_ARM64" arm64)
+    else()
+        detect_architecture("__x86_64__" x86_64)
+        detect_architecture("__i386__" x86)
+        detect_architecture("__arm__" arm)
+        detect_architecture("__aarch64__" arm64)
+    endif()
+    message(STATUS "Qt Downloader: Detected target architecture: ${ARCHITECTURE}")
+
     if (target MATCHES "tools_.*")
         set(DOWNLOAD_QT_TOOL ON)
     else()
@@ -101,4 +117,19 @@ endfunction()
 
 function(get_external_prefix lib_name prefix_var)
     set(${prefix_var} "${CMAKE_BINARY_DIR}/externals/${lib_name}" PARENT_SCOPE)
+endfunction()
+
+function(detect_architecture symbol arch)
+    include(CheckSymbolExists)
+    if (NOT DEFINED ARCHITECTURE)
+        set(CMAKE_REQUIRED_QUIET 1)
+        check_symbol_exists("${symbol}" "" ARCHITECTURE_${arch})
+        unset(CMAKE_REQUIRED_QUIET)
+
+        # The output variable needs to be unique across invocations otherwise
+        # CMake's crazy scope rules will keep it defined
+        if (ARCHITECTURE_${arch})
+            set(ARCHITECTURE "${arch}" PARENT_SCOPE)
+        endif()
+    endif()
 endfunction()
\ No newline at end of file