ASTParser should use CompilationUnit options.

Instead of parent project one, as the CompilationUnit may override some
options.

org.eclipse.jdt.core/dom/org/eclipse/jdt/core/dom/ASTParser.java

@@ -602,7 +602,9 @@ public void setSource(char[] source) {
 	 *
 	 * <p>This method automatically sets the project (and compiler
 	 * options) based on the given compilation unit, in a manner
-	 * equivalent to {@link #setProject(IJavaProject) setProject(source.getJavaProject())}.</p>
+	 * equivalent to {@link #setProject(IJavaProject) setProject(source.getJavaProject())}
+	 * and the custom compiler options supported by the compilation unit through
+	 * {@link ICompilationUnit#getCustomOptions() getCustomOptions()}.</p>
 	 *
 	 * <p>This source is not used when the AST is built using
 	 * {@link #createASTs(ICompilationUnit[], String[], ASTRequestor, IProgressMonitor)}.</p>
@@ -612,6 +614,9 @@ public void setSource(char[] source) {
 	 */
 	public void setSource(ICompilationUnit source) {
 		setSource((ITypeRoot)source);
+		if (source != null) {
+			setCompilerOptions(source.getOptions(true));
+		}
 	}
 
 	/**

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

@@ -1453,11 +1453,13 @@ public void setOptions(Map<String, String> newOptions) {
 
 @Override
 public Map<String, String> getCustomOptions() {
-	try {
-		Map<String, String> customOptions = this.getCompilationUnitElementInfo().getCustomOptions();
-		return customOptions == null ? Collections.emptyMap() : customOptions;
-	} catch (JavaModelException e) {
-		// do nothing
+	if (this.owner != null) {
+		try {
+			Map<String, String> customOptions = this.getCompilationUnitElementInfo().getCustomOptions();
+			return customOptions == null ? Collections.emptyMap() : customOptions;
+		} catch (JavaModelException e) {
+			// do nothing
+		}
 	}
 
 	return Collections.emptyMap();