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fix: fall back to next LS when formatting returns no edits #1433

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Merged
sebthom merged 1 commit into from
Dec 1, 2025
Merged

fix: fall back to next LS when formatting returns no edits #1433

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2 changes: 1 addition & 1 deletion org.eclipse.lsp4e.test/META-INF/MANIFEST.MF
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Original file line number Diff line number Diff line change
Expand Up @@ -2,7 +2,7 @@ Manifest-Version: 1.0
Bundle-ManifestVersion: 2
Bundle-Name: Tests for language server bundle (Incubation)
Bundle-SymbolicName: org.eclipse.lsp4e.test;singleton:=true
Bundle-Version: 0.16.3.qualifier
Bundle-Version: 0.16.4.qualifier
Fragment-Host: org.eclipse.lsp4e
Bundle-Vendor: Eclipse LSP4E
Bundle-RequiredExecutionEnvironment: JavaSE-21
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2 changes: 1 addition & 1 deletion org.eclipse.lsp4e.test/pom.xml
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Expand Up @@ -8,7 +8,7 @@
</parent>
<artifactId>org.eclipse.lsp4e.test</artifactId>
<packaging>eclipse-test-plugin</packaging>
<version>0.16.3-SNAPSHOT</version>
<version>0.16.4-SNAPSHOT</version>

<properties>
<os-jvm-flags /> <!-- for the default case -->
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39 changes: 30 additions & 9 deletions org.eclipse.lsp4e.test/src/org/eclipse/lsp4e/test/format/FormatTest.java
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Expand Up @@ -21,6 +21,7 @@
import java.util.ArrayList;
import java.util.Collections;
import java.util.ConcurrentModificationException;
import java.util.List;
import java.util.Optional;
import java.util.concurrent.ExecutionException;

Expand Down Expand Up @@ -57,6 +58,29 @@ public void testFormattingInvalidDocument() throws Exception {
assertTrue(edits.isEmpty());
}

/**
* Verifies that when the language server reports no formatting edits
* (empty edit list), {@link LSPFormatter} returns an empty Optional
* and leaves the document content unchanged.
*/
@Test
public void testFormattingEmptyEditsYieldEmptyOptional() throws Exception {
MockLanguageServer.INSTANCE.setFormattingTextEdits(Collections.emptyList());

IFile file = TestUtils.createUniqueTestFile(project, "Formatting Other Text");
IEditorPart editor = TestUtils.openEditor(file);
ITextViewer viewer = LSPEclipseUtils.getTextViewer(editor);

final var formatter = new LSPFormatter();
ISelection selection = viewer.getSelectionProvider().getSelection();

Optional<VersionedEdits> edits = formatter.requestFormatting(viewer.getDocument(), (ITextSelection) selection).get();
assertTrue(edits.isEmpty());
assertEquals("Formatting Other Text", viewer.getDocument().get());

TestUtils.closeEditor(editor, false);
}

@Test
public void testFormattingNoChanges() throws Exception {
MockLanguageServer.INSTANCE.setFormattingTextEdits(Collections.emptyList());
Expand All @@ -69,14 +93,10 @@ public void testFormattingNoChanges() throws Exception {
ISelection selection = viewer.getSelectionProvider().getSelection();

Optional<VersionedEdits> edits = formatter.requestFormatting(viewer.getDocument(), (ITextSelection) selection).get();
assertTrue(edits.isPresent());
editor.getSite().getShell().getDisplay().syncExec(() -> {
try {
edits.get().apply();
} catch (ConcurrentModificationException | BadLocationException e) {
fail(e.getMessage());
}
});

// No formatting edits produced -> no VersionedEdits returned
assertTrue(edits.isEmpty());

final var textEditor = (ITextEditor) editor;
textEditor.getDocumentProvider().getDocument(textEditor.getEditorInput());
assertEquals("Formatting Other Text", viewer.getDocument().get());
Expand Down Expand Up @@ -243,7 +263,8 @@ public void testSelectiveFormattingWithIncapableServer() throws Exception {
@Test
public void testOutdatedFormatting()
throws CoreException, InterruptedException, ExecutionException, BadLocationException {
MockLanguageServer.INSTANCE.setFormattingTextEdits(Collections.emptyList());
// Use a non-empty edit list so that a VersionedEdits is produced
MockLanguageServer.INSTANCE.setFormattingTextEdits(List.of(new TextEdit(new Range(new Position(0, 0), new Position(0, 0)), "X")));

IFile file = TestUtils.createUniqueTestFile(project, "Formatting Other Text");
IEditorPart editor = TestUtils.openEditor(file);
Expand Down
2 changes: 1 addition & 1 deletion org.eclipse.lsp4e/META-INF/MANIFEST.MF
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Original file line number Diff line number Diff line change
Expand Up @@ -2,7 +2,7 @@ Manifest-Version: 1.0
Bundle-ManifestVersion: 2
Bundle-Name: Language Server Protocol client for Eclipse IDE (Incubation)
Bundle-SymbolicName: org.eclipse.lsp4e;singleton:=true
Bundle-Version: 0.19.2.qualifier
Bundle-Version: 0.19.3.qualifier
Bundle-RequiredExecutionEnvironment: JavaSE-21
Require-Bundle: org.eclipse.core.runtime;bundle-version="3.12.0",
org.eclipse.equinox.common;bundle-version="3.8.0",
Expand Down
2 changes: 1 addition & 1 deletion org.eclipse.lsp4e/pom.xml
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Original file line number Diff line number Diff line change
Expand Up @@ -10,7 +10,7 @@
</parent>
<artifactId>org.eclipse.lsp4e</artifactId>
<packaging>eclipse-plugin</packaging>
<version>0.19.2-SNAPSHOT</version>
<version>0.19.3-SNAPSHOT</version>

<build>
<plugins>
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22 changes: 13 additions & 9 deletions org.eclipse.lsp4e/src/org/eclipse/lsp4e/operations/format/LSPFormatter.java
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Original file line number Diff line number Diff line change
Expand Up @@ -14,9 +14,11 @@
package org.eclipse.lsp4e.operations.format;

import java.net.URI;
import java.util.List;
import java.util.Optional;
import java.util.concurrent.CompletableFuture;

import org.eclipse.jdt.annotation.Nullable;
import org.eclipse.jface.preference.IPreferenceStore;
import org.eclipse.jface.text.BadLocationException;
import org.eclipse.jface.text.IDocument;
Expand All @@ -31,6 +33,7 @@
import org.eclipse.lsp4j.FormattingOptions;
import org.eclipse.lsp4j.ServerCapabilities;
import org.eclipse.lsp4j.TextDocumentIdentifier;
import org.eclipse.lsp4j.TextEdit;
import org.eclipse.ui.editors.text.EditorsUI;
import org.eclipse.ui.texteditor.AbstractDecoratedTextEditorPreferenceConstants;

Expand All @@ -49,20 +52,21 @@ public CompletableFuture<Optional<VersionedEdits>> requestFormatting(IDocument d

DocumentFormattingParams params = getFullFormatParams(formatOptions, docId);

// TODO: Could refine this algorithm: at present this grabs the first non-null response but the most functional
// implementation (if a text selection is present) would try all the servers in turn to see if they supported
// range formatting, falling back to a full format if unavailable
// **NOTE:** We let LanguageServers.computeFirst() see the *raw* edit lists so that servers which
// advertise formatting but return no edits (empty list) are treated as "no result" and formatting
// can fall through to the next server (e.g. Vue LS after TS LS on .vue files).
long modificationStamp = DocumentUtil.getDocumentModificationStamp(document);
return executor.computeFirst((w, ls) -> w.getServerCapabilitiesAsync().thenCompose(capabilities -> {
if (isDocumentRangeFormattingSupported(capabilities) && (textSelection.getLength() > 0 || !isDocumentFormattingSupported(capabilities))) {
return ls.getTextDocumentService().rangeFormatting(rangeParams)
.thenApply(edits -> new VersionedEdits(modificationStamp, edits, document));
return (CompletableFuture<@Nullable List<? extends TextEdit>>) ls.getTextDocumentService()
.rangeFormatting(rangeParams);
} else if (isDocumentFormattingSupported(capabilities)) {
return ls.getTextDocumentService().formatting(params)
.thenApply(edits -> new VersionedEdits(modificationStamp, edits, document));
return (CompletableFuture<@Nullable List<? extends TextEdit>>) ls.getTextDocumentService()
.formatting(params);
}
return CompletableFuture.<VersionedEdits>completedFuture(null);
}));
return CompletableFuture.completedFuture(null);
})).thenApply(
optionalEdits -> optionalEdits.map(edits -> new VersionedEdits(modificationStamp, edits, document)));
}

public static DocumentFormattingParams getFullFormatParams(FormattingOptions formatOptions,
Expand Down
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