use_mingw=true does nothing for compiling godot-cpp bindings, even though g++/Mingw in PATH

compile.log

PS C:\Users\razzl\Development\Godot\gdnative_cpp_example\godot-cpp> scons platform=windows generate_bindings=yes -j4 use_mingw=yes
scons: Reading SConscript files ...
scons: done reading SConscript files.
scons: Building targets ...
cl /Fosrc\core\AABB.obj /c src\core\AABB.cpp /TP /nologo /EHsc /D_DEBUG /MDd /I. /Igodot_headers /Iinclude /Iinclude\gen /Iinclude\core
AABB.cpp
cl /Fosrc\core\Array.obj /c src\core\Array.cpp /TP /nologo /EHsc /D_DEBUG /MDd /I. /Igodot_headers /Iinclude /Iinclude\gen /Iinclude\core
cl /Fosrc\core\Basis.obj /c src\core\Basis.cpp /TP /nologo /EHsc /D_DEBUG /MDd /I. /Igodot_headers /Iinclude /Iinclude\gen /Iinclude\core
cl /Fosrc\core\Color.obj /c src\core\Color.cpp /TP /nologo /EHsc /D_DEBUG /MDd /I. /Igodot_headers /Iinclude /Iinclude\gen /Iinclude\core
Array.cpp
Basis.cpp
Color.cpp
cl /Fosrc\core\Dictionary.obj /c src\core\Dictionary.cpp /TP /nologo /EHsc /D_DEBUG /MDd /I. /Igodot_headers /Iinclude /Iinclude\gen /Iinclude\core
Dictionary.cpp
cl /Fosrc\core\GodotGlobal.obj /c src\core\GodotGlobal.cpp /TP /nologo /EHsc /D_DEBUG /MDd /I. /Igodot_headers /Iinclude /Iinclude\gen /Iinclude\core
cl /Fosrc\core\NodePath.obj /c src\core\NodePath.cpp /TP /nologo /EHsc /D_DEBUG /MDd /I. /Igodot_headers /Iinclude /Iinclude\gen /Iinclude\core
GodotGlobal.cpp
NodePath.cpp
cl /Fosrc\core\Plane.obj /c src\core\Plane.cpp /TP /nologo /EHsc /D_DEBUG /MDd /I. /Igodot_headers /Iinclude /Iinclude\gen /Iinclude\core
cl /Fosrc\core\PoolArrays.obj /c src\core\PoolArrays.cpp /TP /nologo /EHsc /D_DEBUG /MDd /I. /Igodot_headers /Iinclude /Iinclude\gen /Iinclude\core
cl /Fosrc\core\Quat.obj /c src\core\Quat.cpp /TP /nologo /EHsc /D_DEBUG /MDd /I. /Igodot_headers /Iinclude /Iinclude\gen /Iinclude\core
Plane.cpp
cl /Fosrc\core\Rect2.obj /c src\core\Rect2.cpp /TP /nologo /EHsc /D_DEBUG /MDd /I. /Igodot_headers /Iinclude /Iinclude\gen /Iinclude\core
PoolArrays.cpp
Quat.cpp
Rect2.cpp
cl /Fosrc\core\RID.obj /c src\core\RID.cpp /TP /nologo /EHsc /D_DEBUG /MDd /I. /Igodot_headers /Iinclude /Iinclude\gen /Iinclude\core
RID.cpp
cl /Fosrc\core\String.obj /c src\core\String.cpp /TP /nologo /EHsc /D_DEBUG /MDd /I. /Igodot_headers /Iinclude /Iinclude\gen /Iinclude\core
cl /Fosrc\core\TagDB.obj /c src\core\TagDB.cpp /TP /nologo /EHsc /D_DEBUG /MDd /I. /Igodot_headers /Iinclude /Iinclude\gen /Iinclude\core
String.cpp
cl /Fosrc\core\Transform.obj /c src\core\Transform.cpp /TP /nologo /EHsc /D_DEBUG /MDd /I. /Igodot_headers /Iinclude /Iinclude\gen /Iinclude\core
Transform.cpp
TagDB.cpp
cl /Fosrc\core\Transform2D.obj /c src\core\Transform2D.cpp /TP /nologo /EHsc /D_DEBUG /MDd /I. /Igodot_headers /Iinclude /Iinclude\gen /Iinclude\core
Transform2D.cpp
cl /Fosrc\core\Variant.obj /c src\core\Variant.cpp /TP /nologo /EHsc /D_DEBUG /MDd /I. /Igodot_headers /Iinclude /Iinclude\gen /Iinclude\core
src\core\String.cpp(102): error C2440: 'return': cannot convert from 'const wchar_t' to 'wchar_t &'
Variant.cpp
src\core\String.cpp(102): note: Conversion loses qualifiers
scons: *** [src\core\String.obj] Error 2
scons: *** [src\core\Variant.obj] Build interrupted.
scons: Build interrupted.
scons: building terminated because of errors.
scons: writing .sconsign file.
Terminate batch job (Y/N)?
^C
PS C:\Users\razzl\Development\Godot\gdnative_cpp_example\godot-cpp>
PS C:\Users\razzl\Development\Godot\gdnative_cpp_example\godot-cpp> g++
g++.exe: fatal error: no input files
compilation terminated.