Try to mitigate evaluation problems with old project settings

If there are some projects lurking in the workspace that somehow use
unsupported Java compiler versions, evaluation could find the type from
such a project and try to use the project options for snippet
evaluation. Let simply disregard such option values and use first
supported Java version for evaluation.

Fixes #668

Author: iloveeclipse

org.eclipse.jdt.debug/eval/org/eclipse/jdt/internal/debug/eval/ast/engine/EvaluationSourceGenerator.java

@@ -14,7 +14,15 @@
  *******************************************************************************/
 package org.eclipse.jdt.internal.debug.eval.ast.engine;
 
+import static org.eclipse.jdt.core.JavaCore.COMPILER_CODEGEN_TARGET_PLATFORM;
+import static org.eclipse.jdt.core.JavaCore.COMPILER_COMPLIANCE;
+import static org.eclipse.jdt.core.JavaCore.COMPILER_RELEASE;
+import static org.eclipse.jdt.core.JavaCore.COMPILER_SOURCE;
+import static org.eclipse.jdt.core.JavaCore.DISABLED;
+
+import java.util.HashMap;
 import java.util.Map;
+import java.util.SortedSet;
 
 import org.eclipse.core.runtime.CoreException;
 import org.eclipse.core.runtime.IStatus;
@@ -183,7 +191,9 @@ private boolean needsReturn(String codeSnippet){
 		if ( codeSnippet.length() == 0) {
 			return false;
 		}
-		IScanner scanner = ToolFactory.createScanner(false, false, false, fJavaProject.getOption(JavaCore.COMPILER_SOURCE, true), fJavaProject.getOption(JavaCore.COMPILER_COMPLIANCE, true), true);
+		String sourceLevel = toSupportedVersion(fJavaProject.getOption(COMPILER_SOURCE, true));
+		String complianceLevel = toSupportedVersion(fJavaProject.getOption(COMPILER_COMPLIANCE, true));
+		IScanner scanner = ToolFactory.createScanner(false, false, false, sourceLevel, complianceLevel, true);
 		scanner.setSource(codeSnippet.toCharArray());
 		int token;
 		try {
@@ -314,7 +324,7 @@ private void createEvaluationSourceFromSource(String source, IType type,
 		ASTParser parser = ASTParser.newParser(AST.getJLSLatest());
 		parser.setSource(source.toCharArray());
 		Map<String, String> options = getCompilerOptions(project);
-		String sourceLevel = project.getOption(JavaCore.COMPILER_SOURCE, true);
+		String sourceLevel = toSupportedVersion(project.getOption(COMPILER_SOURCE, true));
 		parser.setCompilerOptions(options);
 		CompilationUnit unit = (CompilationUnit) parser.createAST(null);
 		SourceBasedSourceGenerator visitor = new SourceBasedSourceGenerator(
@@ -342,25 +352,76 @@ private void createEvaluationSourceFromSource(String source, IType type,
 	/**
 	 * Returns the compiler options used for compiling the expression.
 	 * <p>
-	 * Turns all errors and warnings into ignore and disables task tags. The customizable set of compiler options only contains additional Eclipse
-	 * options. The standard JDK compiler options can't be changed anyway.
+	 * Turns all errors and warnings into ignore and disables task tags.
+	 * The customizable set of compiler options only contains additional Eclipse
+	 * options. The standard JDK compiler options will be changed only if they
+	 * are not supported anymore but required by compiler.
 	 *
 	 * @param project
 	 *            the IJavaProject
 	 * @return compiler options
 	 */
 	public static Map<String, String> getCompilerOptions(IJavaProject project) {
-		Map<String, String> options = project.getOptions(true);
+		Map<String, String> options = new HashMap<>(project.getOptions(true));
 		for (String key : options.keySet()) {
 			String value = options.get(key);
 			if (JavaCore.ERROR.equals(value) || JavaCore.WARNING.equals(value) || JavaCore.INFO.equals(value)) {
 				options.put(key, JavaCore.IGNORE);
 			}
 		}
 		options.put(JavaCore.COMPILER_TASK_TAGS, ""); //$NON-NLS-1$
+
+		toSupportedVersion(options, COMPILER_COMPLIANCE);
+		toSupportedVersion(options, COMPILER_CODEGEN_TARGET_PLATFORM);
+		toSupportedVersion(options, COMPILER_SOURCE);
+		toSupportedVersion(options, COMPILER_RELEASE);
 		return options;
 	}
 
+	/**
+	 * Updates given options for a given key
+	 *
+	 * @param value
+	 *            one of the four "JLS versions" constants
+	 *            <ul>
+	 *            <li>{@link JavaCore#COMPILER_COMPLIANCE}
+	 *            <li>{@link JavaCore#COMPILER_CODEGEN_TARGET_PLATFORM}
+	 *            <li>{@link JavaCore#COMPILER_SOURCE}
+	 *            <li>{@link JavaCore#COMPILER_RELEASE}
+	 *            </ul>
+	 * @return given value if supported by compiler or first compiler supported value
+	 * @see JavaCore#getAllJavaSourceVersionsSupportedByCompiler()
+	 */
+	private static String toSupportedVersion(Map<String, String> options, String key) {
+		SortedSet<String> supported = JavaCore.getAllJavaSourceVersionsSupportedByCompiler();
+		String value = options.get(key);
+		if (value != null && !supported.contains(value) && !DISABLED.equals(value)) {
+			value = supported.first();
+			options.put(key, value);
+		}
+		return value;
+	}
+
+	/**
+	 * @param value
+	 *            one of the four "JLS versions" constants
+	 *            <ul>
+	 *            <li>{@link JavaCore#COMPILER_COMPLIANCE}
+	 *            <li>{@link JavaCore#COMPILER_CODEGEN_TARGET_PLATFORM}
+	 *            <li>{@link JavaCore#COMPILER_SOURCE}
+	 *            <li>{@link JavaCore#COMPILER_RELEASE}
+	 *            </ul>
+	 * @return given value if supported by compiler or first compiler supported value
+	 * @see JavaCore#getAllJavaSourceVersionsSupportedByCompiler()
+	 */
+	private static String toSupportedVersion(String value) {
+		SortedSet<String> supported = JavaCore.getAllJavaSourceVersionsSupportedByCompiler();
+		if (value != null && !supported.contains(value) && !DISABLED.equals(value)) {
+			value = supported.first();
+		}
+		return value;
+	}
+
 	private void createEvaluationSourceFromJDIObject(
 			BinaryBasedSourceGenerator objectToEvaluationSourceMapper) {
 
@@ -379,7 +440,7 @@ private void createEvaluationSourceFromJDIObject(
 	private BinaryBasedSourceGenerator getInstanceSourceMapper(
 			JDIReferenceType referenceType, boolean isInStaticMethod,
 			IJavaProject project) {
-		String sourceLevel = project.getOption(JavaCore.COMPILER_SOURCE, true);
+		String sourceLevel = toSupportedVersion(project.getOption(COMPILER_SOURCE, true));
 		BinaryBasedSourceGenerator objectToEvaluationSourceMapper = new BinaryBasedSourceGenerator(
 				fLocalVariableTypeNames, fLocalVariableNames, isInStaticMethod,
 				sourceLevel);