fix: fix the gcc-15 msys2 problem inside meson

Author: Totto16

src/helper/message_box.hpp

@@ -13,8 +13,7 @@
 
 namespace helper {
 
-#if defined(WIN32) || defined(_WIN32) || defined(__WIN32__) || defined(__NT__) || defined(__MINGW32__) \
-        || defined(__MINGW64__)
+#if defined(WIN32) || defined(_WIN32) || defined(__WIN32__) || defined(__NT__) 
     // "WinUser.h" defines "#define MessageBox  MessageBoxA"
     // which breaks this valid code, I love windows xD.
 #ifdef MessageBox

tools/options/meson.build

@@ -23,10 +23,26 @@ graphics_lib = {
     'deps': [],
 }
 
+c = meson.get_compiler('c')
+
+# Detect if compiling in an MSYS2-based MinGW/Clang environment
+host_is_msys2 = host_machine.system() == 'windows' and c.get_argument_syntax() == 'gcc'
+
+## since gcc-15 msys2 doesn't define "_WIN32" if it is a bug or intentional, but it is needed by a few things, e.g. spdlog
+if host_is_msys2
+    add_global_arguments(
+        '-D_WIN32',
+        language: 'c',
+    )
+    add_global_arguments(
+        '-D_WIN32',
+        language: 'cpp',
+    )
+endif
+
 # check if running in CI, than we only support certain versions, this helps in checking if the Ci installs the correct tool version in e.g. msys2
 if get_option('run_in_ci')
 
-    c = meson.get_compiler('c')
 
     system_name = host_machine.system()
 
@@ -35,8 +51,6 @@ if get_option('run_in_ci')
 
     endif
 
-    # Detect if compiling in an MSYS2-based MinGW/Clang environment
-    host_is_msys2 = host_machine.system() == 'windows' and c.get_argument_syntax() == 'gcc'
     if host_is_msys2
         system_name = 'msys2'
     endif