Meson: Add check for Qt version

See RM #881

Signed-off-by: Marko Lindqvist <cazfi74@gmail.com>

meson.build

@@ -901,13 +901,16 @@ if qtver == 'qt5'
   add_global_arguments('-DQT_DISABLE_DEPRECATED_BEFORE=0x050f00', language : 'cpp')
   priv_conf_data.set('FC_QT5_MODE', 1)
   qt_opts = []
+  qt_minver='0x050f00'
 elif qtver == 'qt6x'
   add_global_arguments('-DQT_DISABLE_DEPRECATED_BEFORE=0x060600', language : 'cpp')
   priv_conf_data.set('FC_QT6X_MODE', 1)
   qt_opts = 'cpp_std=c++17'
+  qt_minver='0x060600'
 else
   add_global_arguments('-DQT_DISABLE_DEPRECATED_BEFORE=0x060000', language : 'cpp')
   qt_opts = 'cpp_std=c++17'
+  qt_minver='0x060000'
 endif
 
 if get_option('audio') != 'none'
@@ -3559,11 +3562,34 @@ else
   qt_dep = dependency('Qt5', modules: ['Core', 'Gui', 'Widgets'], required: false)
 endif
 
+if qt_dep.found() and cxx_build
+  if cxx_compiler.compiles(
+'''#include <QtCore>
+int main()
+{
+#if QT_VERSION < ''' + qt_minver + '''
+  fail
+#endif
+  return 0;
+}
+''',
+    name: 'qt minver',
+    dependencies: qt_dep)
+    qtfine = true
+  else
+    qtfine = false
+  endif
+else
+  qtfine = false
+endif
+
 if get_option('clients').contains('qt')
 
-if not qt_dep.found()
-  if qtver == 'qt6' or qtver == 'qt6x'
+if not qtfine
+  if qtver == 'qt6'
     error('Qt6 >= 6.0 required for qt-client in Qt6 mode, but not found')
+  elif qtver == 'qt6x'
+    error('Qt6 >= 6.6 required for qt-client in Qt6x mode, but not found')
   else
     error('Qt5 >= 5.15 required for qt-client in Qt5 mode, but not found')
   endif
@@ -4259,9 +4285,11 @@ endif
 
 if get_option('fcmp').contains('qt')
 
-if not qt_dep.found()
-  if qtver == 'qt6' or qtver == 'qt6x'
+if not qtfine
+  if qtver == 'qt6'
     error('Qt6 >= 6.0 required for qt-modpack-installer in Qt6 mode, but not found')
+  elif qtver == 'qt6x'
+    error('Qt6 >= 6.6 required for qt-modpack-installer in Qt6x mode, but not found')
   else
     error('Qt5 >= 5.15 required for qt-modpack-installer in Qt5 mode, but not found')
   endif
@@ -4346,9 +4374,11 @@ endif
 
 if get_option('tools').contains('ruledit')
 
-if not qt_dep.found()
-  if qtver == 'qt6' or qtver == 'qt6x'
+if not qtfine
+  if qtver == 'qt6'
     error('Qt6 >= 6.0 required for ruledit in Qt6 mode, but not found')
+  elif qtver == 'qt6x'
+    error('Qt6 >= 6.6 required for ruledit in Qt6x mode, but not found')
   else
     error('Qt5 >= 5.15 required for ruledit in Qt5 mode, but not found')
   endif