No need to use class/struct keyword in friend declarations.

src/Magnum/AbstractFramebuffer.h

@@ -177,7 +177,7 @@ If @extension{ARB,robustness} is available, @ref read() operations are
 protected from buffer overflow.
 */
 class MAGNUM_EXPORT AbstractFramebuffer {
-    friend struct Implementation::FramebufferState;
+    friend Implementation::FramebufferState;
 
     public:
         /** @todo `GL_IMPLEMENTATION_COLOR_READ_FORMAT`, `GL_IMPLEMENTATION_COLOR_READ_TYPE`, seems to be depending on currently bound FB (aargh) (@extension{ARB,ES2_compatibility}). */

src/Magnum/AbstractObject.h

@@ -44,7 +44,7 @@ namespace Implementation { struct DebugState; }
 @brief Base for all OpenGL objects
 */
 class MAGNUM_EXPORT AbstractObject {
-    friend struct Implementation::DebugState;
+    friend Implementation::DebugState;
 
     public:
         /**

src/Magnum/AbstractQuery.h

@@ -47,7 +47,7 @@ more information.
 @todo `QUERY_COUNTER_BITS` (not sure since when this is supported)
 */
 class MAGNUM_EXPORT AbstractQuery: public AbstractObject {
-    friend struct Implementation::QueryState;
+    friend Implementation::QueryState;
 
     public:
         /** @brief Copying is not allowed */

src/Magnum/AbstractResourceLoader.h

@@ -101,7 +101,7 @@ Resource<Mesh> myMesh = manager->get<Mesh>("my-mesh");
     buffers), should that be allowed?
 */
 template<class T> class AbstractResourceLoader {
-    friend class Implementation::ResourceManagerData<T>;
+    friend Implementation::ResourceManagerData<T>;
 
     public:
         explicit AbstractResourceLoader(): manager(nullptr), _requestedCount(0), _loadedCount(0), _notFoundCount(0) {}

src/Magnum/AbstractShaderProgram.h

@@ -392,10 +392,10 @@ comes in handy.
 @todo `GL_NUM_{PROGRAM,SHADER}_BINARY_FORMATS` + `GL_{PROGRAM,SHADER}_BINARY_FORMATS` (vector), (@extension{ARB,ES2_compatibility})
  */
 class MAGNUM_EXPORT AbstractShaderProgram: public AbstractObject {
-    friend class Mesh;
+    friend Mesh;
-    friend class MeshView;
+    friend MeshView;
-    friend class TransformFeedback;
+    friend TransformFeedback;
-    friend struct Implementation::ShaderProgramState;
+    friend Implementation::ShaderProgramState;
 
     public:
         #ifndef MAGNUM_TARGET_GLES2

src/Magnum/AbstractTexture.h

@@ -133,8 +133,8 @@ functions do nothing.
 @todo Query for immutable levels (@extension{ARB,ES3_compatibility})
 */
 class MAGNUM_EXPORT AbstractTexture: public AbstractObject {
-    friend struct Implementation::TextureState;
+    friend Implementation::TextureState;
-    friend class CubeMapTexture;
+    friend CubeMapTexture;
 
     public:
         #ifdef MAGNUM_BUILD_DEPRECATED

src/Magnum/Buffer.h

@@ -209,7 +209,7 @@ by OpenGL in order to preserve the data. If running on OpenGL ES or extension
 functions do nothing.
  */
 class MAGNUM_EXPORT Buffer: public AbstractObject {
-    friend struct Implementation::BufferState;
+    friend Implementation::BufferState;
 
     public:
         /**

src/Magnum/BufferTexture.h

@@ -200,7 +200,7 @@ and respective function documentation for more information.
 @requires_gl Texture buffers are not available in OpenGL ES.
 */
 class MAGNUM_EXPORT BufferTexture: public AbstractTexture {
-    friend struct Implementation::TextureState;
+    friend Implementation::TextureState;
 
     public:
         /**

src/Magnum/Context.h

@@ -56,7 +56,7 @@ See also @ref Extensions namespace, which contain compile-time information
 about OpenGL extensions.
 */
 class MAGNUM_EXPORT Extension {
-    friend class Context;
+    friend Context;
 
     public:
         /** @brief All extensions for given OpenGL version */
@@ -94,7 +94,7 @@ using @ref Platform::Context subclass, see @ref platform documentation for more
 information.
 */
 class MAGNUM_EXPORT Context {
-    friend class Platform::Context;
+    friend Platform::Context;
 
     public:
         /**

src/Magnum/CubeMapTexture.h

@@ -80,7 +80,7 @@ which intersects one of the six sides of the cube map. See
     @ref MultisampleTexture
 */
 class MAGNUM_EXPORT CubeMapTexture: public AbstractTexture {
-    friend struct Implementation::TextureState;
+    friend Implementation::TextureState;
 
     public:
         /** @brief Cube map coordinate */

src/Magnum/DebugMessage.h

@@ -71,7 +71,7 @@ With default callback the messages will be printed on standard output:
         Hello from OpenGL command stream!
 */
 class MAGNUM_EXPORT DebugMessage {
-    friend struct Implementation::DebugState;
+    friend Implementation::DebugState;
 
     public:
         /**

src/Magnum/DefaultFramebuffer.h

@@ -81,7 +81,7 @@ use DSA to avoid unnecessary calls to @fn_gl{BindFramebuffer}. See their
 respective documentation for more information.
 */
 class MAGNUM_EXPORT DefaultFramebuffer: public AbstractFramebuffer {
-    friend class Context;
+    friend Context;
 
     public:
         /**

src/Magnum/Framebuffer.h

@@ -105,7 +105,7 @@ information.
 @todo `MAX_COLOR_ATTACHMENTS`
 */
 class MAGNUM_EXPORT Framebuffer: public AbstractFramebuffer, public AbstractObject {
-    friend struct Implementation::FramebufferState;
+    friend Implementation::FramebufferState;
 
     public:
         /**
@@ -116,7 +116,7 @@ class MAGNUM_EXPORT Framebuffer: public AbstractFramebuffer, public AbstractObje
          *      @ref attachCubeMapTexture(), @ref attachTexture3D()
          */
         class ColorAttachment {
-            friend class Framebuffer;
+            friend Framebuffer;
 
             public:
                 /**

src/Magnum/Mesh.h

@@ -336,8 +336,8 @@ drawing commands are used on desktop OpenGL and OpenGL ES 3.0. See also
 @ref draw() for more information.
  */
 class MAGNUM_EXPORT Mesh: public AbstractObject {
-    friend class MeshView;
+    friend MeshView;
-    friend struct Implementation::MeshState;
+    friend Implementation::MeshState;
 
     public:
         #ifdef MAGNUM_BUILD_DEPRECATED

src/Magnum/MeshView.h

@@ -57,7 +57,7 @@ You must ensure that the original mesh remains available for whole view
 lifetime.
 */
 class MAGNUM_EXPORT MeshView {
-    friend struct Implementation::MeshState;
+    friend Implementation::MeshState;
 
     public:
         /**

src/Magnum/Platform/AbstractXApplication.h

@@ -334,7 +334,7 @@ CORRADE_ENUMSET_OPERATORS(AbstractXApplication::InputEvent::Buttons)
 @see @ref keyPressEvent(), @ref keyReleaseEvent()
 */
 class AbstractXApplication::KeyEvent: public AbstractXApplication::InputEvent {
-    friend class AbstractXApplication;
+    friend AbstractXApplication;
 
     public:
         /**
@@ -434,7 +434,7 @@ class AbstractXApplication::KeyEvent: public AbstractXApplication::InputEvent {
 @see @ref MouseMoveEvent, @ref mousePressEvent(), @ref mouseReleaseEvent()
 */
 class AbstractXApplication::MouseEvent: public AbstractXApplication::InputEvent {
-    friend class AbstractXApplication;
+    friend AbstractXApplication;
 
     public:
         /**
@@ -469,7 +469,7 @@ class AbstractXApplication::MouseEvent: public AbstractXApplication::InputEvent
 @see @ref MouseEvent, @ref mouseMoveEvent()
 */
 class AbstractXApplication::MouseMoveEvent: public AbstractXApplication::InputEvent {
-    friend class AbstractXApplication;
+    friend AbstractXApplication;
 
     public:
         /** @brief Position */

src/Magnum/Platform/AndroidApplication.h

@@ -418,7 +418,7 @@ class AndroidApplication::InputEvent {
 @see @ref MouseMoveEvent, @ref mousePressEvent(), @ref mouseReleaseEvent()
 */
 class AndroidApplication::MouseEvent: public InputEvent {
-    friend class AndroidApplication;
+    friend AndroidApplication;
 
     public:
         /**
@@ -490,7 +490,7 @@ class AndroidApplication::MouseEvent: public InputEvent {
 @see @ref MouseEvent, @ref mouseMoveEvent()
 */
 class AndroidApplication::MouseMoveEvent: public InputEvent {
-    friend class AndroidApplication;
+    friend AndroidApplication;
 
     public:
         /**

src/Magnum/Platform/GlutApplication.h

@@ -424,7 +424,7 @@ class GlutApplication::InputEvent {
 @see @ref keyPressEvent()
 */
 class GlutApplication::KeyEvent: public GlutApplication::InputEvent {
-    friend class GlutApplication;
+    friend GlutApplication;
 
     public:
         /**
@@ -523,7 +523,7 @@ class GlutApplication::KeyEvent: public GlutApplication::InputEvent {
 @see @ref MouseMoveEvent, @ref mousePressEvent(), @ref mouseReleaseEvent()
 */
 class GlutApplication::MouseEvent: public GlutApplication::InputEvent {
-    friend class GlutApplication;
+    friend GlutApplication;
 
     public:
         /**
@@ -558,7 +558,7 @@ class GlutApplication::MouseEvent: public GlutApplication::InputEvent {
 @see @ref MouseEvent, @ref mouseMoveEvent()
 */
 class GlutApplication::MouseMoveEvent: public GlutApplication::InputEvent {
-    friend class GlutApplication;
+    friend GlutApplication;
 
     public:
         /**

src/Magnum/Platform/NaClApplication.h

@@ -557,7 +557,7 @@ See also @ref InputEvent for more information.
 @see @ref keyPressEvent(), @ref keyReleaseEvent()
 */
 class NaClApplication::KeyEvent: public NaClApplication::InputEvent {
-    friend class NaClApplication;
+    friend NaClApplication;
 
     public:
         /**
@@ -652,7 +652,7 @@ See also @ref InputEvent for more information.
 @see @ref MouseMoveEvent, @ref mousePressEvent(), @ref mouseReleaseEvent()
 */
 class NaClApplication::MouseEvent: public NaClApplication::InputEvent {
-    friend class NaClApplication;
+    friend NaClApplication;
 
     public:
         /**
@@ -694,7 +694,7 @@ See also @ref InputEvent for more information.
 @see @ref MouseEvent, @ref mouseMoveEvent()
 */
 class NaClApplication::MouseMoveEvent: public NaClApplication::InputEvent {
-    friend class NaClApplication;
+    friend NaClApplication;
 
     public:
         /** @brief Position */

src/Magnum/Platform/Screen.h

@@ -67,9 +67,9 @@ The following specialization are explicitly compiled into each particular
 -   @ref XEglApplication "BasicScreen<XEglApplication>"
 */
 template<class Application> class BasicScreen: private Containers::LinkedListItem<BasicScreen<Application>, BasicScreenedApplication<Application>> {
-    friend class Containers::LinkedListItem<BasicScreen<Application>, BasicScreenedApplication<Application>>;
+    friend Containers::LinkedListItem<BasicScreen<Application>, BasicScreenedApplication<Application>>;
-    friend class Containers::LinkedList<BasicScreen<Application>>;
+    friend Containers::LinkedList<BasicScreen<Application>>;
-    friend class BasicScreenedApplication<Application>;
+    friend BasicScreenedApplication<Application>;
 
     public:
         #ifdef DOXYGEN_GENERATING_OUTPUT

src/Magnum/Platform/ScreenedApplication.h

@@ -89,9 +89,9 @@ The following specialization are explicitly compiled into each particular
 -   @ref XEglApplication "BasicScreenedApplication<XEglApplication>"
 */
 template<class Application> class BasicScreenedApplication: public Application, private Containers::LinkedList<BasicScreen<Application>> {
-    friend class Containers::LinkedList<BasicScreen<Application>>;
+    friend Containers::LinkedList<BasicScreen<Application>>;
-    friend class Containers::LinkedListItem<BasicScreen<Application>, BasicScreenedApplication<Application>>;
+    friend Containers::LinkedListItem<BasicScreen<Application>, BasicScreenedApplication<Application>>;
-    friend class BasicScreen<Application>;
+    friend BasicScreen<Application>;
 
     public:
         /**

src/Magnum/Platform/Sdl2Application.h

@@ -692,7 +692,7 @@ class Sdl2Application::InputEvent {
 @see @ref keyPressEvent(), @ref keyReleaseEvent()
 */
 class Sdl2Application::KeyEvent: public Sdl2Application::InputEvent {
-    friend class Sdl2Application;
+    friend Sdl2Application;
 
     public:
         /**
@@ -792,7 +792,7 @@ class Sdl2Application::KeyEvent: public Sdl2Application::InputEvent {
 @see @ref MouseMoveEvent, @ref mousePressEvent(), @ref mouseReleaseEvent()
 */
 class Sdl2Application::MouseEvent: public Sdl2Application::InputEvent {
-    friend class Sdl2Application;
+    friend Sdl2Application;
 
     public:
         /**
@@ -836,7 +836,7 @@ class Sdl2Application::MouseEvent: public Sdl2Application::InputEvent {
 @see @ref MouseEvent, @ref mouseMoveEvent()
 */
 class Sdl2Application::MouseMoveEvent: public Sdl2Application::InputEvent {
-    friend class Sdl2Application;
+    friend Sdl2Application;
 
     public:
         /**

src/Magnum/Renderbuffer.h

@@ -60,7 +60,7 @@ information.
 @requires_gl30 Extension @extension{ARB,framebuffer_object}
 */
 class MAGNUM_EXPORT Renderbuffer: public AbstractObject {
-    friend struct Implementation::FramebufferState;
+    friend Implementation::FramebufferState;
 
     public:
         /**

src/Magnum/Renderer.h

@@ -48,8 +48,8 @@ namespace Implementation { struct RendererState; }
 @todo `GL_MAX_CLIP_DISTANCES`...
 */
 class MAGNUM_EXPORT Renderer {
-    friend class Context;
+    friend Context;
-    friend struct Implementation::RendererState;
+    friend Implementation::RendererState;
 
     public:
         Renderer() = delete;

src/Magnum/Resource.h

@@ -116,7 +116,7 @@ template<class T, class U = T>
 template<class T, class U>
 #endif
 class Resource {
-    friend class Implementation::ResourceManagerData<T>;
+    friend Implementation::ResourceManagerData<T>;
 
     public:
         /**

src/Magnum/ResourceManager.h

@@ -96,7 +96,7 @@ namespace Implementation {
 
 template<class T> class ResourceManagerData {
     template<class, class> friend class Magnum::Resource;
-    friend class AbstractResourceLoader<T>;
+    friend AbstractResourceLoader<T>;
 
     public:
         ResourceManagerData(const ResourceManagerData<T>&) = delete;

src/Magnum/SceneGraph/AbstractFeature.h

@@ -169,9 +169,9 @@ template<UnsignedInt dimensions, class T> class AbstractFeature
     : private Containers::LinkedListItem<AbstractFeature<dimensions, T>, AbstractObject<dimensions, T>>
     #endif
 {
-    friend class Containers::LinkedList<AbstractFeature<dimensions, T>>;
+    friend Containers::LinkedList<AbstractFeature<dimensions, T>>;
-    friend class Containers::LinkedListItem<AbstractFeature<dimensions, T>, AbstractObject<dimensions, T>>;
+    friend Containers::LinkedListItem<AbstractFeature<dimensions, T>, AbstractObject<dimensions, T>>;
-    template<class Transformation> friend class Object;
+    template<class> friend class Object;
 
     public:
         /**

src/Magnum/SceneGraph/AbstractGroupedFeature.h

@@ -68,7 +68,7 @@ errors. See also @ref compilation-speedup-hpp for more information.
     @ref AbstractGroupedFeature3D, @ref FeatureGroup
 */
 template<UnsignedInt dimensions, class Derived, class T> class AbstractGroupedFeature: public AbstractFeature<dimensions, T> {
-    friend class FeatureGroup<dimensions, Derived, T>;
+    friend FeatureGroup<dimensions, Derived, T>;
 
     public:
         /**

src/Magnum/SceneGraph/AbstractObject.h

@@ -76,9 +76,9 @@ template<UnsignedInt dimensions, class T> class AbstractObject
     : private Containers::LinkedList<AbstractFeature<dimensions, T>>
     #endif
 {
-    friend class Containers::LinkedList<AbstractFeature<dimensions, T>>;
+    friend Containers::LinkedList<AbstractFeature<dimensions, T>>;
-    friend class Containers::LinkedListItem<AbstractFeature<dimensions, T>, AbstractObject<dimensions, T>>;
+    friend Containers::LinkedListItem<AbstractFeature<dimensions, T>, AbstractObject<dimensions, T>>;
-    friend class AbstractFeature<dimensions, T>;
+    friend AbstractFeature<dimensions, T>;
 
     public:
         /** @brief Matrix type */

src/Magnum/SceneGraph/Animable.h

@@ -142,7 +142,7 @@ errors. See also @ref compilation-speedup-hpp for more information.
     @ref Animable2D, @ref Animable3D, @ref AnimableGroup
 */
 template<UnsignedInt dimensions, class T> class Animable: public AbstractGroupedFeature<dimensions, Animable<dimensions, T>, T> {
-    friend class AnimableGroup<dimensions, T>;
+    friend AnimableGroup<dimensions, T>;
 
     public:
         /**

src/Magnum/SceneGraph/AnimableGroup.h

@@ -42,7 +42,7 @@ See @ref Animable for more information.
     @ref AnimableGroup2D, @ref AnimableGroup3D
 */
 template<UnsignedInt dimensions, class T> class AnimableGroup: public FeatureGroup<dimensions, Animable<dimensions, T>, T> {
-    friend class Animable<dimensions, T>;
+    friend Animable<dimensions, T>;
 
     public:
         /**

src/Magnum/SceneGraph/FeatureGroup.h

@@ -62,7 +62,7 @@ See @ref AbstractGroupedFeature for more information.
     @ref FeatureGroup2D, @ref FeatureGroup3D
 */
 template<UnsignedInt dimensions, class Feature, class T> class FeatureGroup: public AbstractFeatureGroup<dimensions, T> {
-    friend class AbstractGroupedFeature<dimensions, Feature, T>;
+    friend AbstractGroupedFeature<dimensions, Feature, T>;
 
     public:
         explicit FeatureGroup() = default;

src/Magnum/SceneGraph/Object.h

@@ -102,8 +102,8 @@ template<class Transformation> class Object: public AbstractObject<Transformatio
     , private Containers::LinkedList<Object<Transformation>>, private Containers::LinkedListItem<Object<Transformation>, Object<Transformation>>
     #endif
 {
-    friend class Containers::LinkedList<Object<Transformation>>;
+    friend Containers::LinkedList<Object<Transformation>>;
-    friend class Containers::LinkedListItem<Object<Transformation>, Object<Transformation>>;
+    friend Containers::LinkedListItem<Object<Transformation>, Object<Transformation>>;
 
     public:
         /** @brief Matrix type */

src/Magnum/Shapes/Composition.h

@@ -67,7 +67,7 @@ Result of logical operations on shapes. See @ref shapes for brief introduction.
 template<UnsignedInt dimensions> class MAGNUM_SHAPES_EXPORT Composition {
     friend Implementation::AbstractShape<dimensions>& Implementation::getAbstractShape<>(Composition<dimensions>&, std::size_t);
     friend const Implementation::AbstractShape<dimensions>& Implementation::getAbstractShape<>(const Composition<dimensions>&, std::size_t);
-    friend struct Implementation::ShapeHelper<Composition<dimensions>>;
+    friend Implementation::ShapeHelper<Composition<dimensions>>;
 
     public:
         enum: UnsignedInt {

src/Magnum/Shapes/Shape.h

@@ -67,7 +67,7 @@ Shapes::AbstractShape3D* firstCollision = shapes.firstCollision(shape);
     @ref DebugTools::ShapeRenderer
 */
 template<class T> class Shape: public AbstractShape<T::Dimensions> {
-    friend struct Implementation::ShapeHelper<T>;
+    friend Implementation::ShapeHelper<T>;
 
     public:
         /**

src/Magnum/Shapes/ShapeGroup.h

@@ -44,7 +44,7 @@ See @ref Shape for more information. See @ref shapes for brief introduction.
 @see @ref scenegraph, @ref ShapeGroup2D, @ref ShapeGroup3D
 */
 template<UnsignedInt dimensions> class MAGNUM_SHAPES_EXPORT ShapeGroup: public SceneGraph::FeatureGroup<dimensions, AbstractShape<dimensions>, Float> {
-    friend class AbstractShape<dimensions>;
+    friend AbstractShape<dimensions>;
 
     public:
         /**

src/Magnum/TransformFeedback.h

@@ -61,7 +61,7 @@ documentation for more information.
 @todo @extension{AMD,transform_feedback3_lines_triangles}?
 */
 class MAGNUM_EXPORT TransformFeedback: public AbstractObject {
-    friend struct Implementation::TransformFeedbackState;
+    friend Implementation::TransformFeedbackState;
 
     public:
         /**