Project names should match their location
If you need to compare models that:
Due to Bug 354801, we cannot properly support models that are located in Eclipse projects which identifier is distinct from their containing folder, case included. For example, if you have a project named EcoreModels, it must be contained in a folder named EcoreModels. Any other name, even if changing only the case, such as ecoreModels, will cause issues when comparing fragmented models (or any model which references another).
Note that this only applies to comparisons launched from within Eclipse, which would trigger the opening of the EMF Compare user interface.
Symptoms vary, but they often include a NullPointerException somewhere in EMFSynchronizationModel such as :
Caused by: java.lang.NullPointerException at org.eclipse.emf.compare.ide.ui.logical.RevisionedURIConverter.<init>(RevisionedURIConverter.java:108) at org.eclipse.emf.compare.ide.ui.logical.EMFSynchronizationModel.resolveTraversal(EMFSynchronizationModel.java:464) at org.eclipse.emf.compare.ide.ui.logical.EMFSynchronizationModel.createSynchronizationModel(EMFSynchronizationModel.java:165) at org.eclipse.emf.compare.ide.ui.internal.structuremergeviewer.EMFCompareStructureMergeViewer.compareInputChanged(EMFCompareStructureMergeViewer.java:258)
The models should be imported within the workspace
Trying to compare models that are not present in the current Eclipse workspace from either the Git repositories perspective, or from the Git Staging view.
Note that this only applies to comparisons launched from within Eclipse, which would trigger the opening of the EMF Compare user interface.
Symptoms are mostly the same here as they would be with the limitation mentionned above regarding project names, and they usually include the same NullPointerException:
Caused by: java.lang.NullPointerException at org.eclipse.emf.compare.ide.ui.logical.RevisionedURIConverter.<init>(RevisionedURIConverter.java:108) at org.eclipse.emf.compare.ide.ui.logical.EMFSynchronizationModel.resolveTraversal(EMFSynchronizationModel.java:464) at org.eclipse.emf.compare.ide.ui.logical.EMFSynchronizationModel.createSynchronizationModel(EMFSynchronizationModel.java:165) at org.eclipse.emf.compare.ide.ui.internal.structuremergeviewer.EMFCompareStructureMergeViewer.compareInputChanged(EMFCompareStructureMergeViewer.java:258)