Missing references - Windows 10 - MinGW 5.1

[niasie]

Hey guys,
so I recently upgraded from Windows 7 to Windows 10 and basically, everything SFML related just broke. Today I set up MinGW 5.1 SJLJ and built SFML 2.3.1 statically in debug mode with it - no problems whatsoever. After that, I tried to compile the standard SFML example and the first step went fine:

g++ -c testProject.cpp  -DSFML_STATIC -ID:\Programme\SFML-2.3.1-GCC5.1-S-D\include -o testProject.o

However, the second step miserably failed:

g++ testProject.o -o  testProject.exe -LD:\Programme\SFML-2.3.1-GCC5.1-S-D\lib -lsfml-graphics-s-d -lsfml-window-s-d -lsfml-system-s-d

This is the output:

(click to show/hide)

D:\Programme\SFML-2.3.1-GCC5.1-S-D\lib/libsfml-graphics-s-d.a(RenderTarget.cpp.obj): In function `sf::RenderTarget::clear(sf::Color const&)':
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/RenderTarget.cpp:97: undefined reference to `glClearColor'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/RenderTarget.cpp:98: undefined reference to `glClear'
D:\Programme\SFML-2.3.1-GCC5.1-S-D\lib/libsfml-graphics-s-d.a(RenderTarget.cpp.obj): In function `sf::RenderTarget::draw(sf::Vertex const*, unsigned long long, sf::PrimitiveType, sf::RenderStates const&)':
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/RenderTarget.cpp:267: undefined reference to `glVertexPointer'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/RenderTarget.cpp:268: undefined reference to `glColorPointer'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/RenderTarget.cpp:269: undefined reference to `glTexCoordPointer'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/RenderTarget.cpp:278: undefined reference to `glDrawArrays'
D:\Programme\SFML-2.3.1-GCC5.1-S-D\lib/libsfml-graphics-s-d.a(RenderTarget.cpp.obj): In function `sf::RenderTarget::pushGLStates()':
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/RenderTarget.cpp:297: undefined reference to `glGetError'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/RenderTarget.cpp:307: undefined reference to `glPushClientAttrib'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/RenderTarget.cpp:308: undefined reference to `glPushAttrib'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/RenderTarget.cpp:310: undefined reference to `glMatrixMode'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/RenderTarget.cpp:311: undefined reference to `glPushMatrix'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/RenderTarget.cpp:312: undefined reference to `glMatrixMode'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/RenderTarget.cpp:313: undefined reference to `glPushMatrix'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/RenderTarget.cpp:314: undefined reference to `glMatrixMode'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/RenderTarget.cpp:315: undefined reference to `glPushMatrix'
D:\Programme\SFML-2.3.1-GCC5.1-S-D\lib/libsfml-graphics-s-d.a(RenderTarget.cpp.obj): In function `sf::RenderTarget::popGLStates()':
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/RenderTarget.cpp:327: undefined reference to `glMatrixMode'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/RenderTarget.cpp:328: undefined reference to `glPopMatrix'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/RenderTarget.cpp:329: undefined reference to `glMatrixMode'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/RenderTarget.cpp:330: undefined reference to `glPopMatrix'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/RenderTarget.cpp:331: undefined reference to `glMatrixMode'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/RenderTarget.cpp:332: undefined reference to `glPopMatrix'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/RenderTarget.cpp:334: undefined reference to `glPopClientAttrib'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/RenderTarget.cpp:335: undefined reference to `glPopAttrib'
D:\Programme\SFML-2.3.1-GCC5.1-S-D\lib/libsfml-graphics-s-d.a(RenderTarget.cpp.obj): In function `sf::RenderTarget::resetGLStates()':
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/RenderTarget.cpp:360: undefined reference to `glDisable'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/RenderTarget.cpp:361: undefined reference to `glDisable'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/RenderTarget.cpp:362: undefined reference to `glDisable'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/RenderTarget.cpp:363: undefined reference to `glDisable'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/RenderTarget.cpp:364: undefined reference to `glEnable'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/RenderTarget.cpp:365: undefined reference to `glEnable'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/RenderTarget.cpp:366: undefined reference to `glMatrixMode'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/RenderTarget.cpp:367: undefined reference to `glEnableClientState'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/RenderTarget.cpp:368: undefined reference to `glEnableClientState'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/RenderTarget.cpp:369: undefined reference to `glEnableClientState'
D:\Programme\SFML-2.3.1-GCC5.1-S-D\lib/libsfml-graphics-s-d.a(RenderTarget.cpp.obj): In function `sf::RenderTarget::applyCurrentView()':
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/RenderTarget.cpp:405: undefined reference to `glViewport'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/RenderTarget.cpp:408: undefined reference to `glMatrixMode'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/RenderTarget.cpp:409: undefined reference to `glLoadMatrixf'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/RenderTarget.cpp:412: undefined reference to `glMatrixMode'
D:\Programme\SFML-2.3.1-GCC5.1-S-D\lib/libsfml-graphics-s-d.a(RenderTarget.cpp.obj): In function `sf::RenderTarget::applyBlendMode(sf::BlendMode const&)':
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/RenderTarget.cpp:430: undefined reference to `glBlendFunc'
D:\Programme\SFML-2.3.1-GCC5.1-S-D\lib/libsfml-graphics-s-d.a(RenderTarget.cpp.obj): In function `sf::RenderTarget::applyTransform(sf::Transform const&)':
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/RenderTarget.cpp:471: undefined reference to `glLoadMatrixf'
D:\Programme\SFML-2.3.1-GCC5.1-S-D\lib/libsfml-graphics-s-d.a(RenderWindow.cpp.obj): In function `sf::RenderWindow::capture() const':
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/RenderWindow.cpp:92: undefined reference to `glReadPixels'
D:\Programme\SFML-2.3.1-GCC5.1-S-D\lib/libsfml-graphics-s-d.a(Shader.cpp.obj): In function `checkMaxTextureUnits':
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/Shader.cpp:62: undefined reference to `glGetIntegerv'
D:\Programme\SFML-2.3.1-GCC5.1-S-D\lib/libsfml-graphics-s-d.a(Shader.cpp.obj): In function `sf::Shader::compile(char const*, char const*)':
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/Shader.cpp:613: undefined reference to `glFlush'
D:\Programme\SFML-2.3.1-GCC5.1-S-D\lib/libsfml-graphics-s-d.a(Texture.cpp.obj): In function `checkMaximumTextureSize':
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/Texture.cpp:64: undefined reference to `glGetIntegerv'
D:\Programme\SFML-2.3.1-GCC5.1-S-D\lib/libsfml-graphics-s-d.a(Texture.cpp.obj): In function `sf::Texture::~Texture()':
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/Texture.cpp:110: undefined reference to `glDeleteTextures'
D:\Programme\SFML-2.3.1-GCC5.1-S-D\lib/libsfml-graphics-s-d.a(Texture.cpp.obj): In function `sf::Texture::create(unsigned int, unsigned int)':
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/Texture.cpp:151: undefined reference to `glGenTextures'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/Texture.cpp:178: undefined reference to `glBindTexture'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/Texture.cpp:179: undefined reference to `glTexImage2D'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/Texture.cpp:180: undefined reference to `glTexParameteri'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/Texture.cpp:181: undefined reference to `glTexParameteri'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/Texture.cpp:182: undefined reference to `glTexParameteri'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/Texture.cpp:183: undefined reference to `glTexParameteri'
D:\Programme\SFML-2.3.1-GCC5.1-S-D\lib/libsfml-graphics-s-d.a(Texture.cpp.obj): In function `sf::Texture::loadFromImage(sf::Image const&, sf::Rect<int> const&)':
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/Texture.cpp:232: undefined reference to `glFlush'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/Texture.cpp:260: undefined reference to `glBindTexture'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/Texture.cpp:263: undefined reference to `glTexSubImage2D'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/Texture.cpp:269: undefined reference to `glFlush'
D:\Programme\SFML-2.3.1-GCC5.1-S-D\lib/libsfml-graphics-s-d.a(Texture.cpp.obj): In function `sf::Texture::copyToImage() const':
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/Texture.cpp:327: undefined reference to `glBindTexture'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/Texture.cpp:328: undefined reference to `glGetTexImage'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/Texture.cpp:336: undefined reference to `glBindTexture'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/Texture.cpp:337: undefined reference to `glGetTexImage'
D:\Programme\SFML-2.3.1-GCC5.1-S-D\lib/libsfml-graphics-s-d.a(Texture.cpp.obj): In function `sf::Texture::update(unsigned char const*, unsigned int, unsigned int, unsigned int, unsigned int)':
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/Texture.cpp:392: undefined reference to `glBindTexture'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/Texture.cpp:393: undefined reference to `glTexSubImage2D'
D:\Programme\SFML-2.3.1-GCC5.1-S-D\lib/libsfml-graphics-s-d.a(Texture.cpp.obj): In function `sf::Texture::update(sf::Window const&, unsigned int, unsigned int)':
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/Texture.cpp:434: undefined reference to `glBindTexture'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/Texture.cpp:435: undefined reference to `glCopyTexSubImage2D'
D:\Programme\SFML-2.3.1-GCC5.1-S-D\lib/libsfml-graphics-s-d.a(Texture.cpp.obj): In function `sf::Texture::setSmooth(bool)':
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/Texture.cpp:456: undefined reference to `glBindTexture'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/Texture.cpp:457: undefined reference to `glTexParameteri'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/Texture.cpp:458: undefined reference to `glTexParameteri'
D:\Programme\SFML-2.3.1-GCC5.1-S-D\lib/libsfml-graphics-s-d.a(Texture.cpp.obj): In function `sf::Texture::setRepeated(bool)':
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/Texture.cpp:501: undefined reference to `glBindTexture'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/Texture.cpp:502: undefined reference to `glTexParameteri'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/Texture.cpp:503: undefined reference to `glTexParameteri'
D:\Programme\SFML-2.3.1-GCC5.1-S-D\lib/libsfml-graphics-s-d.a(Texture.cpp.obj): In function `sf::Texture::bind(sf::Texture const*, sf::Texture::CoordinateType)':
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/Texture.cpp:524: undefined reference to `glBindTexture'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/Texture.cpp:550: undefined reference to `glMatrixMode'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/Texture.cpp:551: undefined reference to `glLoadMatrixf'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/Texture.cpp:554: undefined reference to `glMatrixMode'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/Texture.cpp:560: undefined reference to `glBindTexture'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/Texture.cpp:563: undefined reference to `glMatrixMode'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/Texture.cpp:564: undefined reference to `glLoadIdentity'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/Texture.cpp:567: undefined reference to `glMatrixMode'
D:\Programme\SFML-2.3.1-GCC5.1-S-D\lib/libsfml-graphics-s-d.a(TextureSaver.cpp.obj): In function `sf::priv::TextureSaver::TextureSaver()':
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/TextureSaver.cpp:38: undefined reference to `glGetIntegerv'
D:\Programme\SFML-2.3.1-GCC5.1-S-D\lib/libsfml-graphics-s-d.a(TextureSaver.cpp.obj): In function `sf::priv::TextureSaver::~TextureSaver()':
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/TextureSaver.cpp:45: undefined reference to `glBindTexture'
D:\Programme\SFML-2.3.1-GCC5.1-S-D\lib/libsfml-graphics-s-d.a(GLLoader.cpp.obj): In function `sfogl_LoadFunctions':
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/GLLoader.cpp:443: undefined reference to `glGetString'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/GLLoader.cpp:456: undefined reference to `glGetIntegerv'
D:\Programme\SFML-2.3.1-GCC5.1-S-D\lib/libsfml-graphics-s-d.a(GLLoader.cpp.obj): In function `GetGLVersion':
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/GLLoader.cpp:518: undefined reference to `glGetIntegerv'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/GLLoader.cpp:519: undefined reference to `glGetIntegerv'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/GLLoader.cpp:522: undefined reference to `glGetError'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/GLLoader.cpp:525: undefined reference to `glGetString'
D:\Programme\SFML-2.3.1-GCC5.1-S-D\lib/libsfml-graphics-s-d.a(GLCheck.cpp.obj): In function `sf::priv::glCheckError(char const*, unsigned int)':
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/GLCheck.cpp:40: undefined reference to `glGetError'
D:\Programme\SFML-2.3.1-GCC5.1-S-D\lib/libsfml-graphics-s-d.a(ImageLoader.cpp.obj): In function `sf::priv::ImageLoader::writeJpg(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, std::vector<unsigned char, std::allocator<unsigned char> > const&, unsigned int, unsigned int)':
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/ImageLoader.cpp:278: undefined reference to `jpeg_std_error'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/ImageLoader.cpp:281: undefined reference to `jpeg_CreateCompress'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/ImageLoader.cpp:286: undefined reference to `jpeg_stdio_dest'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/ImageLoader.cpp:287: undefined reference to `jpeg_set_defaults'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/ImageLoader.cpp:288: undefined reference to `jpeg_set_quality'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/ImageLoader.cpp:301: undefined reference to `jpeg_start_compress'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/ImageLoader.cpp:307: undefined reference to `jpeg_write_scanlines'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/ImageLoader.cpp:311: undefined reference to `jpeg_finish_compress'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Graphics/ImageLoader.cpp:312: undefined reference to `jpeg_destroy_compress'
D:\Programme\SFML-2.3.1-GCC5.1-S-D\lib/libsfml-window-s-d.a(GlContext.cpp.obj): In function `sf::priv::GlContext::initialize()':
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Window/GlContext.cpp:378: undefined reference to `__imp_glGetIntegerv'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Window/GlContext.cpp:379: undefined reference to `__imp_glGetIntegerv'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Window/GlContext.cpp:381: undefined reference to `__imp_glGetError'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Window/GlContext.cpp:389: undefined reference to `__imp_glGetString'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Window/GlContext.cpp:426: undefined reference to `__imp_glGetIntegerv'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Window/GlContext.cpp:440: undefined reference to `__imp_glGetIntegerv'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Window/GlContext.cpp:458: undefined reference to `__imp_glGetIntegerv'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Window/GlContext.cpp:467: undefined reference to `__imp_glEnable'
D:\Programme\SFML-2.3.1-GCC5.1-S-D\lib/libsfml-window-s-d.a(GlContext.cpp.obj): In function `sf::priv::GlContext::checkSettings(sf::ContextSettings const&)':
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Window/GlContext.cpp:477: undefined reference to `__imp_glGetString'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Window/GlContext.cpp:478: undefined reference to `__imp_glGetString'
D:\Programme\SFML-2.3.1-GCC5.1-S-D\lib/libsfml-window-s-d.a(WglContext.cpp.obj): In function `sf::priv::WglContext::~WglContext()':
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Window/Win32/WglContext.cpp:137: undefined reference to `__imp_wglGetCurrentContext'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Window/Win32/WglContext.cpp:138: undefined reference to `__imp_wglMakeCurrent'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Window/Win32/WglContext.cpp:139: undefined reference to `__imp_wglDeleteContext'
D:\Programme\SFML-2.3.1-GCC5.1-S-D\lib/libsfml-window-s-d.a(WglContext.cpp.obj): In function `sf::priv::WglContext::getFunction(char const*)':
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Window/Win32/WglContext.cpp:155: undefined reference to `__imp_wglGetProcAddress'
D:\Programme\SFML-2.3.1-GCC5.1-S-D\lib/libsfml-window-s-d.a(WglContext.cpp.obj): In function `sf::priv::WglContext::makeCurrent()':
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Window/Win32/WglContext.cpp:181: undefined reference to `__imp_wglMakeCurrent'
D:\Programme\SFML-2.3.1-GCC5.1-S-D\lib/libsfml-window-s-d.a(WglContext.cpp.obj): In function `sf::priv::WglContext::display()':
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Window/Win32/WglContext.cpp:189: undefined reference to `__imp_SwapBuffers'
D:\Programme\SFML-2.3.1-GCC5.1-S-D\lib/libsfml-window-s-d.a(WglContext.cpp.obj): In function `sf::priv::WglContext::selectBestPixelFormat(HDC__*, unsigned int, sf::ContextSettings const&)':
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Window/Win32/WglContext.cpp:313: undefined reference to `__imp_ChoosePixelFormat'
D:\Programme\SFML-2.3.1-GCC5.1-S-D\lib/libsfml-window-s-d.a(WglContext.cpp.obj): In function `sf::priv::WglContext::createContext(sf::priv::WglContext*, unsigned int, sf::ContextSettings const&)':
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Window/Win32/WglContext.cpp:344: undefined reference to `__imp_DescribePixelFormat'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Window/Win32/WglContext.cpp:391: undefined reference to `__imp_SetPixelFormat'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Window/Win32/WglContext.cpp:480: undefined reference to `__imp_wglCreateContext'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Window/Win32/WglContext.cpp:494: undefined reference to `__imp_wglShareLists'
D:\Programme\SFML-2.3.1-GCC5.1-S-D\lib/libsfml-window-s-d.a(WindowImplWin32.cpp.obj): In function `sf::priv::WindowImplWin32::WindowImplWin32(sf::VideoMode, sf::String const&, unsigned int, sf::ContextSettings const&)':
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Window/Win32/WindowImplWin32.cpp:170: undefined reference to `__imp_GetDeviceCaps'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Window/Win32/WindowImplWin32.cpp:171: undefined reference to `__imp_GetDeviceCaps'
D:\Programme\SFML-2.3.1-GCC5.1-S-D\lib/libsfml-window-s-d.a(JoystickImpl.cpp.obj): In function `sf::priv::JoystickImpl::initialize()':
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Window/Win32/JoystickImpl.cpp:161: undefined reference to `__imp_joyGetPosEx'
D:\Programme\SFML-2.3.1-GCC5.1-S-D\lib/libsfml-window-s-d.a(JoystickImpl.cpp.obj): In function `sf::priv::JoystickImpl::isConnected(unsigned int)':
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Window/Win32/JoystickImpl.cpp:191: undefined reference to `__imp_joyGetPosEx'
D:\Programme\SFML-2.3.1-GCC5.1-S-D\lib/libsfml-window-s-d.a(JoystickImpl.cpp.obj): In function `sf::priv::JoystickImpl::open(unsigned int)':
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Window/Win32/JoystickImpl.cpp:208: undefined reference to `__imp_joyGetDevCapsW'
D:\Programme\SFML-2.3.1-GCC5.1-S-D\lib/libsfml-window-s-d.a(JoystickImpl.cpp.obj): In function `sf::priv::JoystickImpl::update()':
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/Window/Win32/JoystickImpl.cpp:266: undefined reference to `__imp_joyGetPosEx'
D:\Programme\SFML-2.3.1-GCC5.1-S-D\lib/libsfml-system-s-d.a(SleepImpl.cpp.obj): In function `sf::priv::sleepImpl(sf::Time)':
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/System/Win32/SleepImpl.cpp:41: undefined reference to `__imp_timeGetDevCaps'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/System/Win32/SleepImpl.cpp:44: undefined reference to `__imp_timeBeginPeriod'
D:/Benutzer/Siegenni/SFML Build/SFML Source/SFML-2.3.1/src/SFML/System/Win32/SleepImpl.cpp:50: undefined reference to `__imp_timeEndPeriod'
collect2.exe: error: ld returned 1 exit status
 

The vast majority of the errors are related to OpenGL references missing, as you can tell by the names, but at the end a few other ones, including Joystick and JPEG problems, occur. As I built SFML statically, they should be included with the .a files in the lib folder, shouldn't they? Also, for some reason g++.exe crashes when I build SFML projects from Eclipse, but it's fine from the command line. Weird.
Would be great, if someone had a bit of advice for me. 

Niall

[eXpl0it3r]

Well reading the tutorial or the FAQ on static linking might turn out to be enlightening.

[niasie]

Ohh... this is actually my first time using 2.3, so I didn't realise you will now have to link the dependencies aswell. Thanks for the help! I however still have a question, and this might be dumb, sorry: The FAQ states that the extlibs folder includes all dependencies for Windows, but I can't seem to find winmm, for example. When I try to compile with:

g++ -o  testProject.exe -LD:\Programme\SFML-2.3.1-GCC5.1-S-D\lib -lsfml-graphics-s-d -lopengl32 -lfreetype -ljpeg -lsfml-window-s-d -lwinmm -lgdi32 -lsfml-system-s-d

I get this error:

D:/Programme/mingw-w64/x86_64-5.1.0-posix-sjlj-rt_v4-rev0/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/5.1.0/../../../../x86_64-w64-mingw32/lib/../lib/libmingw32.a(lib64_libmingw32_a-crt0_c.o):crt0_c.c:(.text.startup+0x25): undefined reference to `WinMain'
collect2.exe: error: ld returned 1 exit status

This could either indicate that I did something wrong, or that the information in the FAQ is actually wrong and you have to get some of the dependencies yourself. I'm betting on assumption one

Niall

[eXpl0it3r]

System libraries such as winmm or gdi32 are not included in SFML because they come either with your OS or your toolchain.

As for the error, did you set thd subsystem to window instead of console (flag -mwindow), if so you'll need to link against sfml-main.

[niasie]

Okay, wow, this was a REALLY dumb mistake on my side: I forgot to specify the input object file at the second step. Anyways, thank you for your help eXpl0it3r, everything is now working fine. I'll also try to remember to read the changelog of new versions of SFML before blindlessly installing them
Have a nice day!