Detect architecture from the compiler instead of the host

CMakeLists.txt

@@ -1,4 +1,4 @@
-cmake_minimum_required(VERSION 3.18)
+cmake_minimum_required(VERSION 3.25)
 
 list(APPEND CMAKE_MODULE_PATH ${CMAKE_SOURCE_DIR}/cmake)
 include(identity)

cmake/utils/arch.cmake

@@ -4,20 +4,17 @@ set(DETECT_ARCH_C ${CMAKE_BINARY_DIR}/detect_arch.c)
 
 file(WRITE ${DETECT_ARCH_C}
 "#include \"${SOURCE_DIR}/qcommon/q_platform.h\"
-#include <stdio.h>
-int main()
-{
-    puts(ARCH_STRING);
-    return 0;
-}
+#pragma message(\"@\" ARCH_STRING \"@\")
+int main(void) { return 0; }
 ")
 
-try_run(RUN_EXITCODE COMPILE_SUCCESS
-    ${CMAKE_BINARY_DIR} ${DETECT_ARCH_C}
-    RUN_OUTPUT_VARIABLE ARCH)
+try_compile(COMPILE_SUCCESS
+    SOURCES ${DETECT_ARCH_C}
+    OUTPUT_VARIABLE COMPILE_OUTPUT)
 
-string(STRIP ${ARCH} ARCH)
+string(REGEX MATCH "^[^\@]+@([a-zA-Z0-9_]+)@.*$" HAVE_MATCH ${COMPILE_OUTPUT})
+set(ARCH ${CMAKE_MATCH_1})
 
-if(NOT COMPILE_SUCCESS OR RUN_EXITCODE OR NOT ARCH)
+if(NOT COMPILE_SUCCESS OR RUN_EXITCODE OR NOT HAVE_MATCH OR NOT ARCH)
     message(FATAL_ERROR "Architecture detection failed")
 endif()