Improvement to getCustomOptions to prevent premature loading of element info (eclipse-jdt#4779)

Signed-off-by: Rob Stryker <rob@oxbeef.net>

Author: robstryker

org.eclipse.jdt.core.tests.model/src/org/eclipse/jdt/core/tests/model/CompilationUnitTests.java

@@ -36,9 +36,11 @@
 import org.eclipse.jdt.core.dom.ASTParser;
 import org.eclipse.jdt.core.dom.rewrite.ImportRewrite;
 import org.eclipse.jdt.core.formatter.DefaultCodeFormatterConstants;
+import org.eclipse.jdt.internal.compiler.env.IElementInfo;
 import org.eclipse.jdt.internal.compiler.impl.CompilerOptions;
 import org.eclipse.jdt.internal.core.Buffer;
 import org.eclipse.jdt.internal.core.CompilationUnit;
+import org.eclipse.jdt.internal.core.JavaModelManager;
 import org.eclipse.jdt.internal.core.util.Util;
 import org.eclipse.text.edits.ReplaceEdit;
 import org.eclipse.text.edits.TextEdit;
@@ -2882,4 +2884,52 @@ public void java15SwitchExpr(int x){
 	assertTrue(methodStatements.size() == 1);
 	assertTrue("Should have at least 1 problem", problems.length > 0);
 }
+
+/**
+ * Test that calling getOptions(true) on a closed ICompilationUnit does NOT
+ * cause the element info to be loaded (i.e., does not trigger parsing/opening).
+ *
+ * Regression test for https://github.com/eclipse-jdt/eclipse.jdt.core/pull/4779
+ *
+ * Before the fix, getCustomOptions() unconditionally called
+ * getCompilationUnitElementInfo(), which triggered openWhenClosed() ->
+ * buildStructure() -> parse, even when no setOptions() had ever been called
+ * on the CU.  After the fix it uses JavaModelManager.getInfo(this) which
+ * returns null without opening when the element is not yet cached.
+ */
+public void testGetOptionsDoesNotLoadElementInfo() throws CoreException {
+    // Use a CU that is definitely not open (force-close it first).
+    ICompilationUnit cu2 = getCompilationUnit("P", "src", "p", "X.java");
+    cu2.close(); // ensure info is evicted from the model cache
+
+    // Precondition: info must be null before we call getOptions.
+    IElementInfo infoBefore = JavaModelManager.getJavaModelManager().getInfo(cu2);
+    assertNull("Precondition failed: element info should be null before getOptions()", infoBefore);
+
+    // Call the API under test.
+    cu2.getOptions(true);
+
+    // The fix: info must STILL be null — getOptions must not have opened the CU.
+    IElementInfo infoAfter = JavaModelManager.getJavaModelManager().getInfo(cu2);
+    assertNull(
+        "getOptions(true) should not load the IElementInfo when setOptions() " +
+        "has never been called on this CU",
+        infoAfter);
+}
+
+public void testGetOptionsReturnsCustomOptionsWhenSet() throws CoreException {
+    ICompilationUnit cu2 = getCompilationUnit("P", "src", "p", "X.java");
+    ICompilationUnit wc = null;
+    try {
+        wc = cu2.getWorkingCopy(null);
+        Map<String, String> opts = new HashMap<>();
+        opts.put(JavaCore.COMPILER_SOURCE, "11");
+        wc.setOptions(opts);
+
+        Map<String, String> result = wc.getOptions(false);
+        assertEquals("11", result.get(JavaCore.COMPILER_SOURCE));
+    } finally {
+        if (wc != null) wc.discardWorkingCopy();
+    }
+}
 }

org.eclipse.jdt.core/model/org/eclipse/jdt/internal/core/CompilationUnit.java

@@ -1579,23 +1579,26 @@ public void setOptions(Map<String, String> newOptions) {
 @Override
 public Map<String, String> getCustomOptions() {
 	if (this.owner != null) {
-		try {
-			Map<String, String> customOptions = this.getCompilationUnitElementInfo().getCustomOptions();
-			IJavaProject parentProject = getJavaProject();
-			Map<String, String> parentOptions = parentProject == null ? JavaCore.getOptions() : parentProject.getOptions(true);
-			if (JavaCore.ENABLED.equals(parentOptions.get(JavaCore.COMPILER_PB_ENABLE_PREVIEW_FEATURES)) &&
-				CompilerOptions.versionToJdkLevel(parentOptions.getOrDefault(JavaCore.COMPILER_SOURCE, JavaCore.latestSupportedJavaVersion())) < ClassFileConstants.getLatestJDKLevel()) {
-				// Disable preview features for older Java releases as it causes the compiler to fail later
-				if (customOptions != null) {
-					customOptions.put(JavaCore.COMPILER_PB_ENABLE_PREVIEW_FEATURES, JavaCore.DISABLED);
-				} else {
-					customOptions = Map.of(JavaCore.COMPILER_PB_ENABLE_PREVIEW_FEATURES, JavaCore.DISABLED);
-				}
+		Map<String, String> customOptions = null;
+		JavaModelManager manager = JavaModelManager.getJavaModelManager();
+		IElementInfo info = manager.getInfo(this);
+		// If the info has not been loaded, then nobody has called setOptions() yet.
+		// So no need to load the IElementInfo, which may also parse the cu.
+		if (info != null)
+			customOptions = ((CompilationUnitElementInfo)info).getCustomOptions();
+
+		IJavaProject parentProject = getJavaProject();
+		Map<String, String> parentOptions = parentProject == null ? JavaCore.getOptions() : parentProject.getOptions(true);
+		if (JavaCore.ENABLED.equals(parentOptions.get(JavaCore.COMPILER_PB_ENABLE_PREVIEW_FEATURES)) &&
+			CompilerOptions.versionToJdkLevel(parentOptions.getOrDefault(JavaCore.COMPILER_SOURCE, JavaCore.latestSupportedJavaVersion())) < ClassFileConstants.getLatestJDKLevel()) {
+			// Disable preview features for older Java releases as it causes the compiler to fail later
+			if (customOptions != null) {
+				customOptions.put(JavaCore.COMPILER_PB_ENABLE_PREVIEW_FEATURES, JavaCore.DISABLED);
+			} else {
+				customOptions = Map.of(JavaCore.COMPILER_PB_ENABLE_PREVIEW_FEATURES, JavaCore.DISABLED);
 			}
-			return customOptions == null ? Collections.emptyMap() : customOptions;
-		} catch (JavaModelException e) {
-			// do nothing
 		}
+		return customOptions == null ? Collections.emptyMap() : customOptions;
 	}
 
 	return Collections.emptyMap();