Account for __EMSCRIPTEN_major__ etc. not being implicit on 3.1.23+.

It would all be much simpler if the <emscripten/version.h> header wasn't
added just a few versions ago.

src/Magnum/DebugTools/BufferData.cpp

@@ -24,6 +24,17 @@
     DEALINGS IN THE SOFTWARE.
 */
 
+/* The __EMSCRIPTEN_major__ etc macros used to be passed implicitly, version
+   3.1.4 moved them to a version header and version 3.1.23 dropped the
+   backwards compatibility. To work consistently on all versions, including the
+   header only if the version macros aren't present.
+   https://github.com/emscripten-core/emscripten/commit/f99af02045357d3d8b12e63793cef36dfde4530a
+   https://github.com/emscripten-core/emscripten/commit/f76ddc702e4956aeedb658c49790cc352f892e4c */
+#include <Corrade/configure.h>
+#if defined(CORRADE_TARGET_EMSCRIPTEN) && !defined(__EMSCRIPTEN_major__)
+#include <emscripten/version.h>
+#endif
+
 /* Don't compile this file on Emscripten < 2.0.17. Because it's easier to do
    that here than through CMake. */
 #if !defined(__EMSCRIPTEN_major__) || __EMSCRIPTEN_major__*10000 + __EMSCRIPTEN_minor__*100 + __EMSCRIPTEN_tiny__ >= 20017

src/Magnum/DebugTools/BufferData.h

@@ -39,6 +39,16 @@
 #include "Magnum/GL/OpenGL.h"
 #include "Magnum/DebugTools/visibility.h"
 
+/* The __EMSCRIPTEN_major__ etc macros used to be passed implicitly, version
+   3.1.4 moved them to a version header and version 3.1.23 dropped the
+   backwards compatibility. To work consistently on all versions, including the
+   header only if the version macros aren't present.
+   https://github.com/emscripten-core/emscripten/commit/f99af02045357d3d8b12e63793cef36dfde4530a
+   https://github.com/emscripten-core/emscripten/commit/f76ddc702e4956aeedb658c49790cc352f892e4c */
+#if defined(CORRADE_TARGET_EMSCRIPTEN) && !defined(__EMSCRIPTEN_major__)
+#include <emscripten/version.h>
+#endif
+
 #ifdef MAGNUM_BUILD_DEPRECATED
 #include <Corrade/Containers/Array.h>
 #include <Corrade/Utility/Macros.h>

src/Magnum/GL/Buffer.h

@@ -41,6 +41,16 @@
 #include "Magnum/GL/AbstractObject.h"
 #include "Magnum/GL/GL.h"
 
+/* The __EMSCRIPTEN_major__ etc macros used to be passed implicitly, version
+   3.1.4 moved them to a version header and version 3.1.23 dropped the
+   backwards compatibility. To work consistently on all versions, including the
+   header only if the version macros aren't present.
+   https://github.com/emscripten-core/emscripten/commit/f99af02045357d3d8b12e63793cef36dfde4530a
+   https://github.com/emscripten-core/emscripten/commit/f76ddc702e4956aeedb658c49790cc352f892e4c */
+#if defined(CORRADE_TARGET_EMSCRIPTEN) && !defined(__EMSCRIPTEN_major__)
+#include <emscripten/version.h>
+#endif
+
 #ifdef MAGNUM_BUILD_DEPRECATED
 /* For label() / setLabel(), which used to be a std::string. Not ideal for the
    return type, but at least something. */

src/Magnum/GL/Implementation/BufferState.h

@@ -28,6 +28,16 @@
 
 #include "Magnum/GL/Buffer.h"
 
+/* The __EMSCRIPTEN_major__ etc macros used to be passed implicitly, version
+   3.1.4 moved them to a version header and version 3.1.23 dropped the
+   backwards compatibility. To work consistently on all versions, including the
+   header only if the version macros aren't present.
+   https://github.com/emscripten-core/emscripten/commit/f99af02045357d3d8b12e63793cef36dfde4530a
+   https://github.com/emscripten-core/emscripten/commit/f76ddc702e4956aeedb658c49790cc352f892e4c */
+#if defined(CORRADE_TARGET_EMSCRIPTEN) && !defined(__EMSCRIPTEN_major__)
+#include <emscripten/version.h>
+#endif
+
 namespace Magnum { namespace GL { namespace Implementation {
 
 struct BufferState {

src/Magnum/GL/Implementation/MeshState.cpp

@@ -33,6 +33,16 @@
 
 #include "State.h"
 
+/* The __EMSCRIPTEN_major__ etc macros used to be passed implicitly, version
+   3.1.4 moved them to a version header and version 3.1.23 dropped the
+   backwards compatibility. To work consistently on all versions, including the
+   header only if the version macros aren't present.
+   https://github.com/emscripten-core/emscripten/commit/f99af02045357d3d8b12e63793cef36dfde4530a
+   https://github.com/emscripten-core/emscripten/commit/f76ddc702e4956aeedb658c49790cc352f892e4c */
+#if defined(CORRADE_TARGET_EMSCRIPTEN) && !defined(__EMSCRIPTEN_major__)
+#include <emscripten/version.h>
+#endif
+
 namespace Magnum { namespace GL { namespace Implementation {
 
 using namespace Containers::Literals;

src/Magnum/GL/Implementation/driverSpecific.cpp

@@ -31,6 +31,11 @@
 #include "Magnum/Math/Range.h"
 
 #if defined(MAGNUM_TARGET_WEBGL) && defined(CORRADE_TARGET_EMSCRIPTEN)
+/* Including any Emscripten header should also make __EMSCRIPTEN_major__ etc
+   macros available, independently of whether they're passed implicitly (before
+   version 3.1.23) or taken from a version header (after version 3.1.4).
+   https://github.com/emscripten-core/emscripten/commit/f99af02045357d3d8b12e63793cef36dfde4530a
+   https://github.com/emscripten-core/emscripten/commit/f76ddc702e4956aeedb658c49790cc352f892e4c */
 #include <emscripten/emscripten.h>
 #include <emscripten/html5.h>
 #endif

src/Magnum/GL/Mesh.h

@@ -38,6 +38,16 @@
 #include "Magnum/GL/Buffer.h"
 #include "Magnum/GL/GL.h"
 
+/* The __EMSCRIPTEN_major__ etc macros used to be passed implicitly, version
+   3.1.4 moved them to a version header and version 3.1.23 dropped the
+   backwards compatibility. To work consistently on all versions, including the
+   header only if the version macros aren't present.
+   https://github.com/emscripten-core/emscripten/commit/f99af02045357d3d8b12e63793cef36dfde4530a
+   https://github.com/emscripten-core/emscripten/commit/f76ddc702e4956aeedb658c49790cc352f892e4c */
+#if defined(CORRADE_TARGET_EMSCRIPTEN) && !defined(__EMSCRIPTEN_major__)
+#include <emscripten/version.h>
+#endif
+
 #ifdef MAGNUM_BUILD_DEPRECATED
 /* For label() / setLabel(), which used to be a std::string. Not ideal for the
    return type, but at least something. */

src/Magnum/Platform/Test/EmscriptenApplicationTest.cpp

@@ -33,6 +33,16 @@
 #include "Magnum/GL/Mesh.h"
 #include "Magnum/Math/Color.h"
 
+/* The __EMSCRIPTEN_major__ etc macros used to be passed implicitly, version
+   3.1.4 moved them to a version header and version 3.1.23 dropped the
+   backwards compatibility. To work consistently on all versions, including the
+   header only if the version macros aren't present.
+   https://github.com/emscripten-core/emscripten/commit/f99af02045357d3d8b12e63793cef36dfde4530a
+   https://github.com/emscripten-core/emscripten/commit/f76ddc702e4956aeedb658c49790cc352f892e4c */
+#if defined(CORRADE_TARGET_EMSCRIPTEN) && !defined(__EMSCRIPTEN_major__)
+#include <emscripten/version.h>
+#endif
+
 namespace Magnum { namespace Platform { namespace Test {
 
 using namespace Containers::Literals;

src/Magnum/Platform/WindowlessEglApplication.cpp

@@ -39,6 +39,16 @@
 
 #include "Implementation/Egl.h"
 
+/* The __EMSCRIPTEN_major__ etc macros used to be passed implicitly, version
+   3.1.4 moved them to a version header and version 3.1.23 dropped the
+   backwards compatibility. To work consistently on all versions, including the
+   header only if the version macros aren't present.
+   https://github.com/emscripten-core/emscripten/commit/f99af02045357d3d8b12e63793cef36dfde4530a
+   https://github.com/emscripten-core/emscripten/commit/f76ddc702e4956aeedb658c49790cc352f892e4c */
+#if defined(CORRADE_TARGET_EMSCRIPTEN) && !defined(__EMSCRIPTEN_major__)
+#include <emscripten/version.h>
+#endif
+
 /* ANGLE's EGL on Windows needs an actual window */
 /** @todo investigate if this is still needed */
 #ifdef CORRADE_TARGET_WINDOWS

src/Magnum/Platform/gl-info.cpp

@@ -72,6 +72,16 @@
 #error no windowless application available on this platform
 #endif
 
+/* The __EMSCRIPTEN_major__ etc macros used to be passed implicitly, version
+   3.1.4 moved them to a version header and version 3.1.23 dropped the
+   backwards compatibility. To work consistently on all versions, including the
+   header only if the version macros aren't present.
+   https://github.com/emscripten-core/emscripten/commit/f99af02045357d3d8b12e63793cef36dfde4530a
+   https://github.com/emscripten-core/emscripten/commit/f76ddc702e4956aeedb658c49790cc352f892e4c */
+#if defined(CORRADE_TARGET_EMSCRIPTEN) && !defined(__EMSCRIPTEN_major__)
+#include <emscripten/version.h>
+#endif
+
 namespace Magnum {
 
 /** @page magnum-gl-info Magnum GL Info