WebGL requires GL_FRAMEBUFFER_UNSUPPORTED for identical FBO attachments.

src/libANGLE/Framebuffer.cpp

@@ -1125,8 +1125,19 @@ GLenum Framebuffer::checkStatusImpl(const Context *context)
         return GL_FRAMEBUFFER_INCOMPLETE_MULTISAMPLE;
     }
 
+    // The WebGL conformance tests implicitly define that all framebuffer
+    // attachments must be unique. For example, the same level of a texture can
+    // not be attached to two different color attachments.
+    if (state.getExtensions().webglCompatibility)
+    {
+        if (!mState.colorAttachmentsAreUniqueImages())
+        {
+            return GL_FRAMEBUFFER_UNSUPPORTED;
+        }
+    }
+
     syncState(context);
-    if (!mImpl->checkStatus())
+    if (!mImpl->checkStatus(context))
     {
         return GL_FRAMEBUFFER_UNSUPPORTED;
     }

src/libANGLE/renderer/FramebufferImpl.h

@@ -78,7 +78,7 @@ class FramebufferImpl : angle::NonCopyable
                            GLbitfield mask,
                            GLenum filter) = 0;
 
-    virtual bool checkStatus() const = 0;
+    virtual bool checkStatus(const gl::Context *context) const = 0;
 
     virtual void syncState(const gl::Context *context,
                            const gl::Framebuffer::DirtyBits &dirtyBits) = 0;

src/libANGLE/renderer/FramebufferImpl_mock.h

@@ -48,7 +48,7 @@ class MockFramebufferImpl : public rx::FramebufferImpl
                            GLbitfield,
                            GLenum));
 
-    MOCK_CONST_METHOD0(checkStatus, bool());
+    MOCK_CONST_METHOD1(checkStatus, bool(const gl::Context *));
 
     MOCK_METHOD2(syncState, void(const gl::Context *, const gl::Framebuffer::DirtyBits &));
 
@@ -60,7 +60,7 @@ inline ::testing::NiceMock<MockFramebufferImpl> *MakeFramebufferMock()
     ::testing::NiceMock<MockFramebufferImpl> *framebufferImpl =
         new ::testing::NiceMock<MockFramebufferImpl>();
     // TODO(jmadill): add ON_CALLS for other returning methods
-    ON_CALL(*framebufferImpl, checkStatus()).WillByDefault(::testing::Return(true));
+    ON_CALL(*framebufferImpl, checkStatus(testing::_)).WillByDefault(::testing::Return(true));
 
     // We must mock the destructor since NiceMock doesn't work for destructors.
     EXPECT_CALL(*framebufferImpl, destructor()).Times(1).RetiresOnSaturation();

src/libANGLE/renderer/d3d/FramebufferD3D.cpp

@@ -285,7 +285,7 @@ gl::Error FramebufferD3D::blit(const gl::Context *context,
     return gl::NoError();
 }
 
-bool FramebufferD3D::checkStatus() const
+bool FramebufferD3D::checkStatus(const gl::Context *context) const
 {
     // if we have both a depth and stencil buffer, they must refer to the same object
     // since we only support packed_depth_stencil and not separate depth and stencil
@@ -295,10 +295,15 @@ bool FramebufferD3D::checkStatus() const
         return false;
     }
 
-    // D3D11 does not allow for overlapping RenderTargetViews
-    if (!mState.colorAttachmentsAreUniqueImages())
+    // D3D11 does not allow for overlapping RenderTargetViews.
+    // If WebGL compatibility is enabled, this has already been checked at a higher level.
+    ASSERT(!context->getExtensions().webglCompatibility || mState.colorAttachmentsAreUniqueImages());
+    if (!context->getExtensions().webglCompatibility)
     {
-        return false;
+        if (!mState.colorAttachmentsAreUniqueImages())
+        {
+            return false;
+        }
     }
 
     // D3D requires all render targets to have the same dimensions.

src/libANGLE/renderer/d3d/FramebufferD3D.h

@@ -92,7 +92,7 @@ class FramebufferD3D : public FramebufferImpl
                    GLbitfield mask,
                    GLenum filter) override;
 
-    bool checkStatus() const override;
+    bool checkStatus(const gl::Context *context) const override;
 
     void syncState(const gl::Context *context,
                    const gl::Framebuffer::DirtyBits &dirtyBits) override;

src/libANGLE/renderer/gl/FramebufferGL.cpp

@@ -594,7 +594,7 @@ gl::Error FramebufferGL::getSamplePosition(size_t index, GLfloat *xy) const
     return gl::NoError();
 }
 
-bool FramebufferGL::checkStatus() const
+bool FramebufferGL::checkStatus(const gl::Context *context) const
 {
     mStateManager->bindFramebuffer(GL_FRAMEBUFFER, mFramebufferID);
     GLenum status = mFunctions->checkFramebufferStatus(GL_FRAMEBUFFER);

src/libANGLE/renderer/gl/FramebufferGL.h

@@ -87,7 +87,7 @@ class FramebufferGL : public FramebufferImpl
 
     gl::Error getSamplePosition(size_t index, GLfloat *xy) const override;
 
-    bool checkStatus() const override;
+    bool checkStatus(const gl::Context *context) const override;
 
     void syncState(const gl::Context *context,
                    const gl::Framebuffer::DirtyBits &dirtyBits) override;

src/libANGLE/renderer/null/FramebufferNULL.cpp

@@ -179,7 +179,7 @@ gl::Error FramebufferNULL::blit(const gl::Context *context,
     return gl::NoError();
 }
 
-bool FramebufferNULL::checkStatus() const
+bool FramebufferNULL::checkStatus(const gl::Context *context) const
 {
     return true;
 }

src/libANGLE/renderer/null/FramebufferNULL.h

@@ -63,7 +63,7 @@ class FramebufferNULL : public FramebufferImpl
                    GLbitfield mask,
                    GLenum filter) override;
 
-    bool checkStatus() const override;
+    bool checkStatus(const gl::Context *context) const override;
 
     void syncState(const gl::Context *context,
                    const gl::Framebuffer::DirtyBits &dirtyBits) override;

src/libANGLE/renderer/vulkan/FramebufferVk.cpp

@@ -346,7 +346,7 @@ gl::Error FramebufferVk::blit(const gl::Context *context,
     return gl::InternalError();
 }
 
-bool FramebufferVk::checkStatus() const
+bool FramebufferVk::checkStatus(const gl::Context *context) const
 {
     UNIMPLEMENTED();
     return bool();

src/libANGLE/renderer/vulkan/FramebufferVk.h

@@ -76,7 +76,7 @@ class FramebufferVk : public FramebufferImpl, public ResourceVk
                    GLbitfield mask,
                    GLenum filter) override;
 
-    bool checkStatus() const override;
+    bool checkStatus(const gl::Context *context) const override;
 
     void syncState(const gl::Context *context,
                    const gl::Framebuffer::DirtyBits &dirtyBits) override;