fix: Show incomplete indicator only if completion list is not empty

Author: FlorianKroiss

org.eclipse.lsp4e.test/src/org/eclipse/lsp4e/test/completion/IncompleteCompletionTest.java

@@ -675,4 +675,21 @@ public void testIncompleteIndication() throws CoreException {
 		assertEquals("FirstClass", proposalsWithIncompleteProposal[0].getDisplayString());
 		assertEquals("➕ Continue typing for more proposals...", proposalsWithIncompleteProposal[1].getDisplayString());
 	}
+	
+	@Test
+	public void testIncompleteIndicationWithEmptyList() throws CoreException {
+		MockLanguageServer.INSTANCE.setCompletionList(new CompletionList(true, List.of()));
+
+		IFile testFile = TestUtils.createUniqueTestFile(project, "");
+		ITextViewer viewer = TestUtils.openTextViewer(testFile);
+
+		// without incomplete indication
+		ICompletionProposal[] proposals = contentAssistProcessor.computeCompletionProposals(viewer, 0);
+		assertEquals(0, proposals.length);
+
+		// with incomplete indication
+		final var incompleIndicatingProcessor = new LSContentAssistProcessor(true, true);
+		ICompletionProposal[] proposalsWithIncompleteProposal = incompleIndicatingProcessor.computeCompletionProposals(viewer, 0);
+		assertEquals(0, proposalsWithIncompleteProposal.length);
+	}
 }

org.eclipse.lsp4e/src/org/eclipse/lsp4e/operations/completion/LSContentAssistProcessor.java

@@ -189,7 +189,10 @@ public ICompletionProposal[] computeCompletionProposals(ITextViewer viewer, int
 		}
 		completeProposals.sort(proposalComparator);
 		final ICompletionProposal incompleteProposal = createIncompleteProposal(offset, anyIncomplete.get());
-		if (incompleteProposal != null) {
+		if (incompleteProposal != null && !completeProposals.isEmpty()) {
+			// Only add the incompleteProposal if the list is not empty.
+			// Otherwise we might get a completion popup which contains only the incompleteProposal.
+
 			@SuppressWarnings("unchecked")
 			final var incompleteProposals = (List<ICompletionProposal>) (List<?>) completeProposals;
 			incompleteProposals.add(incompleteProposal);