// AspectJ
/*******************************************************************************
 * Copyright (c) 2012, 2018 IBM Corporation and others.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *     Jesper S Moller - Contributions for
 *							bug 382701 - [1.8][compiler] Implement semantic analysis of Lambda expressions & Reference expression
 *							bug 382721 - [1.8][compiler] Effectively final variables needs special treatment
 *							Bug 416885 - [1.8][compiler]IncompatibleClassChange error (edit)
 *     Stephan Herrmann - Contribution for
 *							bug 401030 - [1.8][null] Null analysis support for lambda methods.
 *							Bug 392099 - [1.8][compiler][null] Apply null annotation on types for null analysis
 *							Bug 392238 - [1.8][compiler][null] Detect semantically invalid null type annotations
 *							Bug 400874 - [1.8][compiler] Inference infrastructure should evolve to meet JLS8 18.x (Part G of JSR335 spec)
 *							Bug 423504 - [1.8] Implement "18.5.3 Functional Interface Parameterization Inference"
 *							Bug 425142 - [1.8][compiler] NPE in ConstraintTypeFormula.reduceSubType
 *							Bug 425153 - [1.8] Having wildcard allows incompatible types in a lambda expression
 *							Bug 424205 - [1.8] Cannot infer type for diamond type with lambda on method invocation
 *							Bug 425798 - [1.8][compiler] Another NPE in ConstraintTypeFormula.reduceSubType
 *							Bug 425156 - [1.8] Lambda as an argument is flagged with incompatible error
 *							Bug 424403 - [1.8][compiler] Generic method call with method reference argument fails to resolve properly.
 *							Bug 426563 - [1.8] AIOOBE when method with error invoked with lambda expression as argument
 *							Bug 420525 - [1.8] [compiler] Incorrect error "The type Integer does not define sum(Object, Object) that is applicable here"
 *							Bug 427438 - [1.8][compiler] NPE at org.aspectj.org.eclipse.jdt.internal.compiler.ast.ConditionalExpression.generateCode(ConditionalExpression.java:280)
 *							Bug 428294 - [1.8][compiler] Type mismatch: cannot convert from List<Object> to Collection<Object[]>
 *							Bug 428786 - [1.8][compiler] Inference needs to compute the "ground target type" when reducing a lambda compatibility constraint
 *							Bug 428980 - [1.8][null] simple expression as lambda body doesn't leverage null annotation on argument
 *							Bug 429430 - [1.8] Lambdas and method reference infer wrong exception type with generics (RuntimeException instead of IOException)
 *							Bug 432110 - [1.8][compiler] nested lambda type incorrectly inferred vs javac
 *							Bug 438458 - [1.8][null] clean up handling of null type annotations wrt type variables
 *							Bug 441693 - [1.8][null] Bogus warning for type argument annotated with @NonNull
 *							Bug 452788 - [1.8][compiler] Type not correctly inferred in lambda expression
 *							Bug 453483 - [compiler][null][loop] Improve null analysis for loops
 *							Bug 455723 - Nonnull argument not correctly inferred in loop
 *							Bug 463728 - [1.8][compiler][inference] Ternary operator in lambda derives wrong type
 *     Andy Clement (GoPivotal, Inc) aclement@gopivotal.com - Contributions for
 *                          Bug 405104 - [1.8][compiler][codegen] Implement support for serializeable lambdas
 *******************************************************************************/
package org.aspectj.org.eclipse.jdt.internal.compiler.ast;

import static org.aspectj.org.eclipse.jdt.internal.compiler.ast.ExpressionContext.INVOCATION_CONTEXT;

import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.LinkedHashSet;
import java.util.Map;
import java.util.Set;

import org.aspectj.org.eclipse.jdt.core.compiler.CategorizedProblem;
import org.aspectj.org.eclipse.jdt.core.compiler.CharOperation;
import org.aspectj.org.eclipse.jdt.core.compiler.IProblem;
import org.aspectj.org.eclipse.jdt.internal.compiler.ASTVisitor;
import org.aspectj.org.eclipse.jdt.internal.compiler.ClassFile;
import org.aspectj.org.eclipse.jdt.internal.compiler.CompilationResult;
import org.aspectj.org.eclipse.jdt.internal.compiler.IErrorHandlingPolicy;
import org.aspectj.org.eclipse.jdt.internal.compiler.classfmt.ClassFileConstants;
import org.aspectj.org.eclipse.jdt.internal.compiler.codegen.CodeStream;
import org.aspectj.org.eclipse.jdt.internal.compiler.env.ICompilationUnit;
import org.aspectj.org.eclipse.jdt.internal.compiler.flow.ExceptionHandlingFlowContext;
import org.aspectj.org.eclipse.jdt.internal.compiler.flow.ExceptionInferenceFlowContext;
import org.aspectj.org.eclipse.jdt.internal.compiler.flow.FlowContext;
import org.aspectj.org.eclipse.jdt.internal.compiler.flow.FlowInfo;
import org.aspectj.org.eclipse.jdt.internal.compiler.flow.UnconditionalFlowInfo;
import org.aspectj.org.eclipse.jdt.internal.compiler.impl.CompilerOptions;
import org.aspectj.org.eclipse.jdt.internal.compiler.impl.Constant;
import org.aspectj.org.eclipse.jdt.internal.compiler.impl.ReferenceContext;
import org.aspectj.org.eclipse.jdt.internal.compiler.lookup.AnnotationBinding;
import org.aspectj.org.eclipse.jdt.internal.compiler.lookup.Binding;
import org.aspectj.org.eclipse.jdt.internal.compiler.lookup.BlockScope;
import org.aspectj.org.eclipse.jdt.internal.compiler.lookup.ClassScope;
import org.aspectj.org.eclipse.jdt.internal.compiler.lookup.ExtraCompilerModifiers;
import org.aspectj.org.eclipse.jdt.internal.compiler.lookup.InferenceContext18;
import org.aspectj.org.eclipse.jdt.internal.compiler.lookup.IntersectionTypeBinding18;
import org.aspectj.org.eclipse.jdt.internal.compiler.lookup.LocalTypeBinding;
import org.aspectj.org.eclipse.jdt.internal.compiler.lookup.LocalVariableBinding;
import org.aspectj.org.eclipse.jdt.internal.compiler.lookup.LookupEnvironment;
import org.aspectj.org.eclipse.jdt.internal.compiler.lookup.MethodBinding;
import org.aspectj.org.eclipse.jdt.internal.compiler.lookup.MethodScope;
import org.aspectj.org.eclipse.jdt.internal.compiler.lookup.ParameterizedTypeBinding;
import org.aspectj.org.eclipse.jdt.internal.compiler.lookup.PolyTypeBinding;
import org.aspectj.org.eclipse.jdt.internal.compiler.lookup.ProblemMethodBinding;
import org.aspectj.org.eclipse.jdt.internal.compiler.lookup.ProblemReasons;
import org.aspectj.org.eclipse.jdt.internal.compiler.lookup.ReferenceBinding;
import org.aspectj.org.eclipse.jdt.internal.compiler.lookup.Scope;
import org.aspectj.org.eclipse.jdt.internal.compiler.lookup.SourceTypeBinding;
import org.aspectj.org.eclipse.jdt.internal.compiler.lookup.Substitution;
import org.aspectj.org.eclipse.jdt.internal.compiler.lookup.Substitution.NullSubstitution;
import org.aspectj.org.eclipse.jdt.internal.compiler.lookup.SyntheticArgumentBinding;
import org.aspectj.org.eclipse.jdt.internal.compiler.lookup.SyntheticMethodBinding;
import org.aspectj.org.eclipse.jdt.internal.compiler.lookup.TagBits;
import org.aspectj.org.eclipse.jdt.internal.compiler.lookup.TypeBinding;
import org.aspectj.org.eclipse.jdt.internal.compiler.lookup.TypeConstants;
import org.aspectj.org.eclipse.jdt.internal.compiler.lookup.TypeIds;
import org.aspectj.org.eclipse.jdt.internal.compiler.lookup.VariableBinding;
import org.aspectj.org.eclipse.jdt.internal.compiler.lookup.WildcardBinding;
import org.aspectj.org.eclipse.jdt.internal.compiler.lookup.Scope.Substitutor;
import org.aspectj.org.eclipse.jdt.internal.compiler.parser.Parser;
import org.aspectj.org.eclipse.jdt.internal.compiler.problem.AbortCompilation;
import org.aspectj.org.eclipse.jdt.internal.compiler.problem.AbortCompilationUnit;
import org.aspectj.org.eclipse.jdt.internal.compiler.problem.AbortMethod;
import org.aspectj.org.eclipse.jdt.internal.compiler.problem.AbortType;
import org.aspectj.org.eclipse.jdt.internal.compiler.problem.ProblemSeverities;

@SuppressWarnings({"rawtypes", "unchecked"})
public class LambdaExpression extends FunctionalExpression implements IPolyExpression, ReferenceContext, ProblemSeverities {
	public Argument [] arguments;
	private TypeBinding [] argumentTypes;
	public int arrowPosition;
	public Statement body;
	public boolean hasParentheses;
	public MethodScope scope;
	boolean voidCompatible = true;
	boolean valueCompatible = false;
	boolean returnsValue;
	private boolean requiresGenericSignature;
	boolean returnsVoid;
	public LambdaExpression original = this;
	public SyntheticArgumentBinding[] outerLocalVariables = NO_SYNTHETIC_ARGUMENTS;
	private int outerLocalVariablesSlotSize = 0;
	private boolean assistNode = false;
	private boolean hasIgnoredMandatoryErrors = false;
	private ReferenceBinding classType;
	private Set thrownExceptions;
	public char[] text;  // source representation of the lambda.
	private static final SyntheticArgumentBinding [] NO_SYNTHETIC_ARGUMENTS = new SyntheticArgumentBinding[0];
	private static final Block NO_BODY = new Block(0);
	private HashMap<TypeBinding, LambdaExpression> copiesPerTargetType;
	protected Expression [] resultExpressions = NO_EXPRESSIONS;
	public InferenceContext18 inferenceContext; // when performing tentative resolve keep a back reference to the driving context
	private Map<Integer/*sourceStart*/, LocalTypeBinding> localTypes; // support look-up of a local type from this lambda copy

	
	public LambdaExpression(CompilationResult compilationResult, boolean assistNode, boolean requiresGenericSignature) {
		super(compilationResult);
		this.assistNode = assistNode;
		this.requiresGenericSignature = requiresGenericSignature;
		setArguments(NO_ARGUMENTS);
		setBody(NO_BODY);
	}

	public LambdaExpression(CompilationResult compilationResult, boolean assistNode) {
		this(compilationResult, assistNode, false);
	}

	public void setArguments(Argument [] arguments) {
		this.arguments = arguments != null ? arguments : ASTNode.NO_ARGUMENTS;
		this.argumentTypes = new TypeBinding[arguments != null ? arguments.length : 0];
	}
	
	public Argument [] arguments() {
		return this.arguments;
	}

	public TypeBinding[] argumentTypes() {
		return this.argumentTypes;
	}

	public void setBody(Statement body) {
		this.body = body == null ? NO_BODY : body;
	}
	
	public Statement body() {
		return this.body;
	}

	public Expression[] resultExpressions() {
		return this.resultExpressions;
	}

	public void setArrowPosition(int arrowPosition) {
		this.arrowPosition = arrowPosition;
	}
	
	public int arrowPosition() {
		return this.arrowPosition;
	}
	
	protected FunctionalExpression original() {
		return this.original;
	}
	
	@Override
	public void generateCode(BlockScope currentScope, CodeStream codeStream, boolean valueRequired) {
		if (this.shouldCaptureInstance) {
			this.binding.modifiers &= ~ClassFileConstants.AccStatic;
		} else {
			this.binding.modifiers |= ClassFileConstants.AccStatic;
		}
		SourceTypeBinding sourceType = currentScope.enclosingSourceType();
		boolean firstSpill = !(this.binding instanceof SyntheticMethodBinding);
		this.binding = sourceType.addSyntheticMethod(this);
		int pc = codeStream.position;
		StringBuffer signature = new StringBuffer();
		signature.append('(');
		if (this.shouldCaptureInstance) {
			codeStream.aload_0();
			signature.append(sourceType.signature());
		}
		for (int i = 0, length = this.outerLocalVariables == null ? 0 : this.outerLocalVariables.length; i < length; i++) {
			SyntheticArgumentBinding syntheticArgument = this.outerLocalVariables[i];
			if (this.shouldCaptureInstance && firstSpill) { // finally block handling results in extra spills, avoid side effect.
				syntheticArgument.resolvedPosition++;
			}
			signature.append(syntheticArgument.type.signature());
			LocalVariableBinding capturedOuterLocal = syntheticArgument.actualOuterLocalVariable;
			VariableBinding[] path = currentScope.getEmulationPath(capturedOuterLocal);
			codeStream.generateOuterAccess(path, this, capturedOuterLocal, currentScope);
		}
		signature.append(')');
		if (this.expectedType instanceof IntersectionTypeBinding18) {
			signature.append(((IntersectionTypeBinding18)this.expectedType).getSAMType(currentScope).signature());
		} else {
			signature.append(this.expectedType.signature());
		}
		int invokeDynamicNumber = codeStream.classFile.recordBootstrapMethod(this);
		codeStream.invokeDynamic(invokeDynamicNumber, (this.shouldCaptureInstance ? 1 : 0) + this.outerLocalVariablesSlotSize, 1, this.descriptor.selector, signature.toString().toCharArray());
		if (!valueRequired)
			codeStream.pop();
		codeStream.recordPositionsFrom(pc, this.sourceStart);		
	}

	@Override
	public boolean kosherDescriptor(Scope currentScope, MethodBinding sam, boolean shouldChatter) {
		if (sam.typeVariables != Binding.NO_TYPE_VARIABLES) {
			if (shouldChatter)
				currentScope.problemReporter().lambdaExpressionCannotImplementGenericMethod(this, sam);
			return false;
		}
		return super.kosherDescriptor(currentScope, sam, shouldChatter);
	}
	
	/* This code is arranged so that we can continue with as much analysis as possible while avoiding 
	 * mine fields that would result in a slew of spurious messages. This method is a merger of:
	 * @see org.aspectj.org.eclipse.jdt.internal.compiler.lookup.MethodScope.createMethod(AbstractMethodDeclaration)
	 * @see org.aspectj.org.eclipse.jdt.internal.compiler.lookup.SourceTypeBinding.resolveTypesFor(MethodBinding)
	 * @see org.aspectj.org.eclipse.jdt.internal.compiler.ast.AbstractMethodDeclaration.resolve(ClassScope)
	 */
	@Override
	public TypeBinding resolveType(BlockScope blockScope, boolean skipKosherCheck) {
		
		boolean argumentsTypeElided = argumentsTypeElided();
		boolean argumentsTypeVar = argumentsTypeVar(blockScope);
		int argumentsLength = this.arguments == null ? 0 : this.arguments.length;
		
		if (this.constant != Constant.NotAConstant) {
			this.constant = Constant.NotAConstant;
			this.enclosingScope = blockScope;
			if (this.original == this)
				this.ordinal = recordFunctionalType(blockScope);
			
			if (!argumentsTypeElided && !argumentsTypeVar) {
				for (int i = 0; i < argumentsLength; i++)
					this.argumentTypes[i] = this.arguments[i].type.resolveType(blockScope, true /* check bounds*/);
			}
			if (this.expectedType == null && this.expressionContext == INVOCATION_CONTEXT) {
				return new PolyTypeBinding(this);
			} 
		}
		
		MethodScope methodScope = blockScope.methodScope();
		this.scope = new MethodScope(blockScope, this, methodScope.isStatic, methodScope.lastVisibleFieldID);
		this.scope.isConstructorCall = methodScope.isConstructorCall;

		super.resolveType(blockScope, skipKosherCheck); // compute & capture interface function descriptor.
		
		final boolean haveDescriptor = this.descriptor != null;
		
		if (!skipKosherCheck && (!haveDescriptor || this.descriptor.typeVariables != Binding.NO_TYPE_VARIABLES)) // already complained in kosher*
			return this.resolvedType = null;
		
		// AspectJ extension - start
		int modifiers = 0;
		if (methodScope.parent != null && methodScope.parent.isInterTypeScope()) {
			modifiers = ClassFileConstants.AccPublic | ClassFileConstants.AccSynthetic | ExtraCompilerModifiers.AccUnresolved;
		} else {
			modifiers = ClassFileConstants.AccPrivate | ClassFileConstants.AccSynthetic | ExtraCompilerModifiers.AccUnresolved;
		}
		this.binding = new MethodBinding(modifiers,
		// was
		// this.binding = new MethodBinding(ClassFileConstants.AccPrivate | ClassFileConstants.AccSynthetic | ExtraCompilerModifiers.AccUnresolved,
		// AspectJ extension - end
		
							CharOperation.concat(TypeConstants.ANONYMOUS_METHOD, Integer.toString(this.ordinal).toCharArray()), // will be fixed up later.
							haveDescriptor ? this.descriptor.returnType : TypeBinding.VOID, 
							Binding.NO_PARAMETERS, // for now. 
							haveDescriptor ? this.descriptor.thrownExceptions : Binding.NO_EXCEPTIONS, 
							blockScope.enclosingSourceType());
		this.binding.typeVariables = Binding.NO_TYPE_VARIABLES;
		
		boolean argumentsHaveErrors = false;
		if (haveDescriptor) {
			int parametersLength = this.descriptor.parameters.length;
			if (parametersLength != argumentsLength) {
            	this.scope.problemReporter().lambdaSignatureMismatched(this);
            	if (argumentsTypeElided || argumentsTypeVar || this.original != this) // no interest in continuing to error check copy.
            		return this.resolvedType = null; // FUBAR, bail out ...
            	else {
            		this.resolvedType = null; // continue to type check.
            		argumentsHaveErrors = true;
            	}
            }
		}
		
		TypeBinding[] newParameters = new TypeBinding[argumentsLength];

		AnnotationBinding [][] parameterAnnotations = null;
		for (int i = 0; i < argumentsLength; i++) {
			Argument argument = this.arguments[i];
			if (argument.isVarArgs()) {
				if (i == argumentsLength - 1) {
					this.binding.modifiers |= ClassFileConstants.AccVarargs;
				} else {
					this.scope.problemReporter().illegalVarargInLambda(argument);
					argumentsHaveErrors = true;
				}
			}
			
			TypeBinding argumentType;
			final TypeBinding expectedParameterType = haveDescriptor && i < this.descriptor.parameters.length ? this.descriptor.parameters[i] : null;
			argumentType = (argumentsTypeElided || argumentsTypeVar) ? expectedParameterType : this.argumentTypes[i];
			if (argumentType == null) {
				argumentsHaveErrors = true;
			} else if (argumentType == TypeBinding.VOID) {
				this.scope.problemReporter().argumentTypeCannotBeVoid(this, argument);
				argumentsHaveErrors = true;
			} else {
				if (!argumentType.isValidBinding()) {
					this.binding.tagBits |= TagBits.HasUnresolvedArguments;
				}
				if ((argumentType.tagBits & TagBits.HasMissingType) != 0) {
					this.binding.tagBits |= TagBits.HasMissingType;
				}
			}
		}
		if (!argumentsTypeElided && !argumentsTypeVar && !argumentsHaveErrors) {
			ReferenceBinding groundType = null;
			ReferenceBinding expectedSAMType = null;
			if (this.expectedType instanceof IntersectionTypeBinding18)
				expectedSAMType = (ReferenceBinding) ((IntersectionTypeBinding18) this.expectedType).getSAMType(blockScope); 
			else if (this.expectedType instanceof ReferenceBinding)
				expectedSAMType = (ReferenceBinding) this.expectedType;
			if (expectedSAMType != null)
				groundType = findGroundTargetType(blockScope, this.expectedType, expectedSAMType, argumentsTypeElided);
			
			if (groundType != null) {
				this.descriptor = groundType.getSingleAbstractMethod(blockScope, true);
				if (!this.descriptor.isValidBinding()) {
					reportSamProblem(blockScope, this.descriptor);
				} else {
					if (groundType != expectedSAMType) { //$IDENTITY-COMPARISON$
						if (!groundType.isCompatibleWith(expectedSAMType, this.scope)) { // the ground has shifted, are we still on firm grounds ? 
							blockScope.problemReporter().typeMismatchError(groundType, this.expectedType, this, null); // report deliberately against block scope so as not to blame the lambda.
							return null;
						}
					}
					this.resolvedType = groundType;
				}
			} else {
				this.binding = new ProblemMethodBinding(TypeConstants.ANONYMOUS_METHOD, null, ProblemReasons.NotAWellFormedParameterizedType);
				reportSamProblem(blockScope, this.binding);
				return this.resolvedType = null;
			}
		}
		boolean parametersHaveErrors = false;
		boolean genericSignatureNeeded = this.requiresGenericSignature || blockScope.compilerOptions().generateGenericSignatureForLambdaExpressions;
		TypeBinding[] expectedParameterTypes = new TypeBinding[argumentsLength];
		for (int i = 0; i < argumentsLength; i++) {
			Argument argument = this.arguments[i];
			TypeBinding argumentType;
			final TypeBinding expectedParameterType = haveDescriptor && i < this.descriptor.parameters.length ? this.descriptor.parameters[i] : null;
			argumentType = (argumentsTypeElided || argumentsTypeVar) ? expectedParameterType : this.argumentTypes[i];
			expectedParameterTypes[i] = expectedParameterType;
			if (argumentType != null && argumentType != TypeBinding.VOID) {
				if (haveDescriptor && expectedParameterType != null && argumentType.isValidBinding() && TypeBinding.notEquals(argumentType, expectedParameterType)) {
					if (expectedParameterType.isProperType(true)) {
						if (!isOnlyWildcardMismatch(expectedParameterType, argumentType)) {
							this.scope.problemReporter().lambdaParameterTypeMismatched(argument, argument.type, expectedParameterType);
							parametersHaveErrors = true; // continue to type check, but don't signal success
						}
					}
				}
				if (genericSignatureNeeded) {
					TypeBinding leafType = argumentType.leafComponentType();
					if (leafType instanceof ReferenceBinding && (((ReferenceBinding) leafType).modifiers & ExtraCompilerModifiers.AccGenericSignature) != 0)
						this.binding.modifiers |= ExtraCompilerModifiers.AccGenericSignature;
				}
				newParameters[i] = argument.bind(this.scope, argumentType, false);				
				if (argument.annotations != null) {
					this.binding.tagBits |= TagBits.HasParameterAnnotations;
					if (parameterAnnotations == null) {
						parameterAnnotations = new AnnotationBinding[argumentsLength][];
						for (int j = 0; j < i; j++) {
							parameterAnnotations[j] = Binding.NO_ANNOTATIONS;
						}
					}
					parameterAnnotations[i] = argument.binding.getAnnotations();
				} else if (parameterAnnotations != null) {
					parameterAnnotations[i] = Binding.NO_ANNOTATIONS;
				}
			}
		}
		if (argumentsTypeVar) {
			for (int i = 0; i < argumentsLength; ++i) {
				this.arguments[i].type.resolvedType = expectedParameterTypes[i];
			}
		}
		// only assign parameters if no problems are found
		if (!argumentsHaveErrors) {
			this.binding.parameters = newParameters;
			if (parameterAnnotations != null)
				this.binding.setParameterAnnotations(parameterAnnotations);
		}
	
		if (!argumentsTypeElided && !argumentsTypeVar && !argumentsHaveErrors && this.binding.isVarargs()) {
			if (!this.binding.parameters[this.binding.parameters.length - 1].isReifiable()) {
				this.scope.problemReporter().possibleHeapPollutionFromVararg(this.arguments[this.arguments.length - 1]);
			}
		}

		ReferenceBinding [] exceptions = this.binding.thrownExceptions;
		int exceptionsLength = exceptions.length;
		for (int i = 0; i < exceptionsLength; i++) {
			ReferenceBinding exception = exceptions[i];
			if ((exception.tagBits & TagBits.HasMissingType) != 0) {
				this.binding.tagBits |= TagBits.HasMissingType;
			}
			if (genericSignatureNeeded)
				this.binding.modifiers |= (exception.modifiers & ExtraCompilerModifiers.AccGenericSignature);
		}
		
		TypeBinding returnType = this.binding.returnType;
		if (returnType != null) {
			if ((returnType.tagBits & TagBits.HasMissingType) != 0) {
				this.binding.tagBits |= TagBits.HasMissingType;
			}
			if (genericSignatureNeeded) {
				TypeBinding leafType = returnType.leafComponentType();
				if (leafType instanceof ReferenceBinding && (((ReferenceBinding) leafType).modifiers & ExtraCompilerModifiers.AccGenericSignature) != 0)
					this.binding.modifiers |= ExtraCompilerModifiers.AccGenericSignature;
			}
		} // TODO (stephan): else? (can that happen?)

		if (haveDescriptor && !argumentsHaveErrors && blockScope.compilerOptions().isAnnotationBasedNullAnalysisEnabled) {
			if (!argumentsTypeElided && !argumentsTypeVar) {
				AbstractMethodDeclaration.createArgumentBindings(this.arguments, this.binding, this.scope); // includes validation
				// no application of null-ness default, hence also no warning regarding redundant null annotation
				mergeParameterNullAnnotations(blockScope);
			}
			this.binding.tagBits |= (this.descriptor.tagBits & TagBits.AnnotationNullMASK);
		}

		this.binding.modifiers &= ~ExtraCompilerModifiers.AccUnresolved;
		
		if (this.body instanceof Expression) {
			Expression expression = (Expression) this.body;
			new ReturnStatement(expression, expression.sourceStart, expression.sourceEnd, true).resolve(this.scope); // :-) ;-)
			if (expression.resolvedType == TypeBinding.VOID && !expression.statementExpression())
				this.scope.problemReporter().invalidExpressionAsStatement(expression);
		} else {
			this.body.resolve(this.scope);
			/* At this point, shape analysis is complete for ((see returnsExpression(...))
		       - a lambda with an expression body,
			   - a lambda with a block body in which we saw a return statement naked or otherwise.
		    */
			if (!this.returnsVoid && !this.returnsValue)
				this.valueCompatible = this.body.doesNotCompleteNormally();
		}
		if ((this.binding.tagBits & TagBits.HasMissingType) != 0) {
			this.scope.problemReporter().missingTypeInLambda(this, this.binding);
		}
		if (this.shouldCaptureInstance && this.scope.isConstructorCall) {
			this.scope.problemReporter().fieldsOrThisBeforeConstructorInvocation(this);
		}
		// beyond this point ensure that all local type bindings are their final binding:
		updateLocalTypes();
		return (argumentsHaveErrors|parametersHaveErrors) ? null : this.resolvedType;
	}

	// check if the given types are parameterized types and if their type arguments
	// differ only in a wildcard
	// ? and ? extends Object
	private boolean isOnlyWildcardMismatch(TypeBinding expected, TypeBinding argument) {
		boolean onlyWildcardMismatch = false;
		if (expected.isParameterizedType() && argument.isParameterizedType()) {
			TypeBinding[] expectedArgs = ((ParameterizedTypeBinding)expected).typeArguments();
			TypeBinding[] args = ((ParameterizedTypeBinding)argument).typeArguments();
			for (int j = 0; j < args.length; j++) {
				if (TypeBinding.notEquals(expectedArgs[j], args[j])) {
					if (expectedArgs[j].isWildcard() && args[j].isUnboundWildcard()) {
						WildcardBinding wc = (WildcardBinding)expectedArgs[j];
						TypeBinding bound = wc.allBounds();
						if (bound != null && wc.boundKind == Wildcard.EXTENDS && bound.id == TypeIds.T_JavaLangObject)
							onlyWildcardMismatch = true;
					} else {
						onlyWildcardMismatch = false;
						break;
					}
				}
			}
		}
		return onlyWildcardMismatch;
	}
	private ReferenceBinding findGroundTargetType(BlockScope blockScope, TypeBinding targetType, TypeBinding expectedSAMType, boolean argumentTypesElided) {
		
		if (expectedSAMType instanceof IntersectionTypeBinding18)
			expectedSAMType = ((IntersectionTypeBinding18) expectedSAMType).getSAMType(blockScope); 
		
		if (expectedSAMType instanceof ReferenceBinding && expectedSAMType.isValidBinding()) {
			ParameterizedTypeBinding withWildCards = InferenceContext18.parameterizedWithWildcard(expectedSAMType);
			if (withWildCards != null) {
				if (!argumentTypesElided) {
					InferenceContext18 freshInferenceContext = new InferenceContext18(blockScope);
					try {
						return freshInferenceContext.inferFunctionalInterfaceParameterization(this, blockScope, withWildCards);
					} finally {
						freshInferenceContext.cleanUp();
					}
				} else {
					return findGroundTargetTypeForElidedLambda(blockScope, withWildCards);
				}
			}
			if (targetType instanceof ReferenceBinding)
				return (ReferenceBinding) targetType;
		}
		return null;
	}

	public ReferenceBinding findGroundTargetTypeForElidedLambda(BlockScope blockScope, ParameterizedTypeBinding withWildCards) {
		// non-wildcard parameterization (9.8) of the target type
		TypeBinding[] types = withWildCards.getNonWildcardParameterization(blockScope);
		if (types == null)
			return null;
		ReferenceBinding genericType = withWildCards.genericType();
		return blockScope.environment().createParameterizedType(genericType, types, withWildCards.enclosingType());
	}

	@Override
	public boolean argumentsTypeElided() {
		return this.arguments.length > 0 && this.arguments[0].hasElidedType();
	}

	private boolean argumentsTypeVar(BlockScope blockScope) {
		if (blockScope.compilerOptions().complianceLevel < ClassFileConstants.getComplianceLevelForJavaVersion(ClassFileConstants.MAJOR_VERSION_11)) return false;
		boolean retval = false, isVar = false, mixReported = false;
		Argument[] args =  this.arguments;
		for (int i = 0, l = args.length; i < l; ++i) {
			Argument arg = args[i];
			TypeReference type = arg.type;
			if (type == null) continue;
			boolean prev = isVar;
			retval |= isVar = type.isTypeNameVar(blockScope);
			if (i > 0 && prev != isVar && !mixReported) { // report only once per list
				blockScope.problemReporter().varCannotBeMixedWithNonVarParams(isVar ? arg : args[i - 1]);
				mixReported = true;
			}
			if (isVar && (type.dimensions() > 0 || type.extraDimensions() > 0)) {
				blockScope.problemReporter().varLocalCannotBeArray(arg);
			}
		}
		return retval;
	}

	private void analyzeExceptions() {
		ExceptionHandlingFlowContext ehfc;
		CompilerOptions compilerOptions = this.scope.compilerOptions();
		boolean oldAnalyseResources = compilerOptions.analyseResourceLeaks;
		compilerOptions.analyseResourceLeaks = false;
		try {
			this.body.analyseCode(this.scope, 
									 ehfc = new ExceptionInferenceFlowContext(null, this, Binding.NO_EXCEPTIONS, null, this.scope, FlowInfo.DEAD_END), 
									 UnconditionalFlowInfo.fakeInitializedFlowInfo(this.scope.outerMostMethodScope().analysisIndex, this.scope.referenceType().maxFieldCount));
			this.thrownExceptions = ehfc.extendedExceptions == null ? Collections.emptySet() : new HashSet<TypeBinding>(ehfc.extendedExceptions);
		} catch (Exception e) {
			// drop silently.
		} finally {
			compilerOptions.analyseResourceLeaks = oldAnalyseResources;
		}
	}
	@Override
	public FlowInfo analyseCode(BlockScope currentScope, FlowContext flowContext, final FlowInfo flowInfo) {
		
		if (this.ignoreFurtherInvestigation) 
			return flowInfo;
		
		FlowInfo lambdaInfo = flowInfo.copy(); // what happens in vegas, stays in vegas ...
		ExceptionHandlingFlowContext methodContext =
				new ExceptionHandlingFlowContext(
						flowContext,
						this,
						this.binding.thrownExceptions,
						flowContext.getInitializationContext(),
						this.scope,
						FlowInfo.DEAD_END);

		// nullity and mark as assigned
		MethodBinding methodWithParameterDeclaration = argumentsTypeElided() ? this.descriptor : this.binding;
		AbstractMethodDeclaration.analyseArguments(currentScope.environment(), lambdaInfo, this.arguments, methodWithParameterDeclaration);

		if (this.arguments != null) {
			for (int i = 0, count = this.arguments.length; i < count; i++) {
				this.bits |= (this.arguments[i].bits & ASTNode.HasTypeAnnotations);
			}
		}
		
		lambdaInfo = this.body.analyseCode(this.scope, methodContext, lambdaInfo);
		
		// check for missing returning path for block body's ...
		if (this.body instanceof Block) {
			TypeBinding returnTypeBinding = expectedResultType();
			if ((returnTypeBinding == TypeBinding.VOID)) {
				if ((lambdaInfo.tagBits & FlowInfo.UNREACHABLE_OR_DEAD) == 0 || ((Block) this.body).statements == null) {
					this.bits |= ASTNode.NeedFreeReturn;
				}
			} else {
				if (lambdaInfo != FlowInfo.DEAD_END) {
					this.scope.problemReporter().shouldReturn(returnTypeBinding, this);
				}
			}
		} else { // Expression
			if (currentScope.compilerOptions().isAnnotationBasedNullAnalysisEnabled 
					&& lambdaInfo.reachMode() == FlowInfo.REACHABLE)
			{
				Expression expression = (Expression)this.body;
				checkAgainstNullAnnotation(flowContext, expression, flowInfo, expression.nullStatus(lambdaInfo, flowContext));
			}
		}
		return flowInfo;
	}

	// cf. AbstractMethodDeclaration.validateNullAnnotations()
	// pre: !argumentTypeElided()
	void validateNullAnnotations() {
		// null annotations on parameters?
		if (this.binding != null) {
			int length = this.binding.parameters.length;
			for (int i=0; i<length; i++) {
				if (!this.scope.validateNullAnnotation(this.binding.returnType.tagBits, this.arguments[i].type, this.arguments[i].annotations))
					this.binding.returnType = this.binding.returnType.withoutToplevelNullAnnotation();
			}
		}
	}

	// pre: !argumentTypeElided()
	// try to merge null annotations from descriptor into binding, complaining about any incompatibilities found
	private void mergeParameterNullAnnotations(BlockScope currentScope) {
		LookupEnvironment env = currentScope.environment();
		TypeBinding[] ourParameters = this.binding.parameters;
		TypeBinding[] descParameters = this.descriptor.parameters;
		int len = Math.min(ourParameters.length, descParameters.length);
		for (int i = 0; i < len; i++) {
			long ourTagBits = ourParameters[i].tagBits & TagBits.AnnotationNullMASK;
			long descTagBits = descParameters[i].tagBits & TagBits.AnnotationNullMASK;
			if (ourTagBits == 0L) {
				if (descTagBits != 0L && !ourParameters[i].isBaseType()) {
					AnnotationBinding [] annotations = descParameters[i].getTypeAnnotations();
					for (int j = 0, length = annotations.length; j < length; j++) {
						AnnotationBinding annotation = annotations[j];
						if (annotation != null && annotation.getAnnotationType().hasNullBit(TypeIds.BitNonNullAnnotation|TypeIds.BitNullableAnnotation)) {
							ourParameters[i] = env.createAnnotatedType(ourParameters[i], new AnnotationBinding [] { annotation });
						}
					}
				}
			} else if (ourTagBits != descTagBits) {
				if (ourTagBits == TagBits.AnnotationNonNull) { // requested @NonNull not provided
					char[][] inheritedAnnotationName = null;
					if (descTagBits == TagBits.AnnotationNullable)
						inheritedAnnotationName = env.getNullableAnnotationName();
					currentScope.problemReporter().illegalRedefinitionToNonNullParameter(this.arguments[i], this.descriptor.declaringClass, inheritedAnnotationName);
				}
			}			
		}
	}

	// simplified version of ReturnStatement.checkAgainstNullAnnotation()
	void checkAgainstNullAnnotation(FlowContext flowContext, Expression expression, FlowInfo flowInfo, int nullStatus) {
		if (nullStatus != FlowInfo.NON_NULL) {
			// if we can't prove non-null check against declared null-ness of the descriptor method:
			// Note that this.binding never has a return type declaration, always inherit null-ness from the descriptor
			if ((this.descriptor.returnType.tagBits & TagBits.AnnotationNonNull) != 0) {
				flowContext.recordNullityMismatch(this.scope, expression, expression.resolvedType, this.descriptor.returnType, flowInfo, nullStatus, null);
			}
		}
	}

	@Override
	public boolean isPertinentToApplicability(final TypeBinding targetType, final MethodBinding method) {

		class NotPertientToApplicability extends RuntimeException {
			private static final long serialVersionUID = 1L;
		}
		class ResultsAnalyser extends ASTVisitor {
			@Override
			public boolean visit(TypeDeclaration type, BlockScope skope) {
				return false;
			}
			@Override
			public boolean visit(TypeDeclaration type, ClassScope skope) {
				return false;
			}
			@Override
			public boolean visit(LambdaExpression type, BlockScope skope) {
				return false;
			}
		    @Override
			public boolean visit(ReturnStatement returnStatement, BlockScope skope) {
		    	if (returnStatement.expression != null) {
					if (!returnStatement.expression.isPertinentToApplicability(targetType, method))
						throw new NotPertientToApplicability();
		    	}
		    	return false;
		    }
		}

		if (targetType == null) // assumed to signal another primary error
			return true;
		
		if (argumentsTypeElided())
			return false;
		
		if (!super.isPertinentToApplicability(targetType, method))
			return false;
		
		if (this.body instanceof Expression) {
			if (!((Expression) this.body).isPertinentToApplicability(targetType, method))
				return false;
		} else {
			Expression [] returnExpressions = this.resultExpressions;
			if (returnExpressions != NO_EXPRESSIONS) {
				for (int i = 0, length = returnExpressions.length; i < length; i++) {
					if (!returnExpressions[i].isPertinentToApplicability(targetType, method))
						return false;
				}
			} else {
				// return expressions not yet discovered by resolveType(), so traverse no looking just for one that's not pertinent
				try {
					this.body.traverse(new ResultsAnalyser(), this.scope);
				} catch (NotPertientToApplicability npta) {
					return false;
				}
			}
		}
		
		return true;
	}
	
	public boolean isVoidCompatible() {
		return this.voidCompatible;
	}

	public boolean isValueCompatible() {
		return this.valueCompatible;
	}
	
	@Override
	public StringBuffer printExpression(int tab, StringBuffer output) {
		return printExpression(tab, output, false);
	}

	public StringBuffer printExpression(int tab, StringBuffer output, boolean makeShort) {
		int parenthesesCount = (this.bits & ASTNode.ParenthesizedMASK) >> ASTNode.ParenthesizedSHIFT;
		String suffix = ""; //$NON-NLS-1$
		for(int i = 0; i < parenthesesCount; i++) {
			output.append('(');
			suffix += ')';
		}
		output.append('(');
		if (this.arguments != null) {
			for (int i = 0; i < this.arguments.length; i++) {
				if (i > 0) output.append(", "); //$NON-NLS-1$
				this.arguments[i].print(0, output);
			}
		}
		output.append(") -> " ); //$NON-NLS-1$
		if (makeShort) {
			output.append("{}"); //$NON-NLS-1$
		} else {
			if (this.body != null)
				this.body.print(this.body instanceof Block ? tab : 0, output);
			else
				output.append("<@incubator>"); //$NON-NLS-1$
		}
		return output.append(suffix);
	}

	public TypeBinding expectedResultType() {
		return this.descriptor != null && this.descriptor.isValidBinding() ? this.descriptor.returnType : null;
	}
	
	@Override
	public void traverse(ASTVisitor visitor, BlockScope blockScope) {

			if (visitor.visit(this, blockScope)) {
				if (this.arguments != null) {
					int argumentsLength = this.arguments.length;
					for (int i = 0; i < argumentsLength; i++)
						this.arguments[i].traverse(visitor, this.scope);
				}

				if (this.body != null) {
					this.body.traverse(visitor, this.scope);
				}
			}
			visitor.endVisit(this, blockScope);
	}
	
	public MethodScope getScope() {
		return this.scope;
	}
	
	private boolean enclosingScopesHaveErrors() {
		Scope skope = this.enclosingScope;
		while (skope != null) {
			ReferenceContext context = skope.referenceContext();
			if (context != null && context.hasErrors())
				return true;
			skope = skope.parent;
		}
		return false;
	}
		
	private void analyzeShape() { // Simple minded analysis for code assist & potential compatibility.
		class ShapeComputer extends ASTVisitor {
			@Override
			public boolean visit(TypeDeclaration type, BlockScope skope) {
				return false;
			}
			@Override
			public boolean visit(TypeDeclaration type, ClassScope skope) {
				return false;
			}
			@Override
			public boolean visit(LambdaExpression type, BlockScope skope) {
				return false;
			}
		    @Override
			public boolean visit(ReturnStatement returnStatement, BlockScope skope) {
		    	if (returnStatement.expression != null) {
		    		LambdaExpression.this.valueCompatible = true;
		    		LambdaExpression.this.voidCompatible = false;
		    		LambdaExpression.this.returnsValue = true;
		    	} else {
		    		LambdaExpression.this.voidCompatible = true;
		    		LambdaExpression.this.valueCompatible = false;
		    		LambdaExpression.this.returnsVoid = true;
		    	}
		    	return false;
		    }
		}
		if (this.body instanceof Expression) {
			// When completion is still in progress, it is not possible to ask if the expression constitutes a statement expression. See https://bugs.eclipse.org/bugs/show_bug.cgi?id=435219
			this.voidCompatible = this.assistNode ? true : ((Expression) this.body).statementExpression();
			this.valueCompatible = true; // expression could be of type void - we can't determine that as we are working with unresolved expressions, for potential compatibility it is OK.
		} else {
			// For code assist, we need to be a bit tolerant/fuzzy here: the code is being written "just now", if we are too pedantic, selection/completion will break;
			if (this.assistNode) {
				this.voidCompatible = true;
				this.valueCompatible = true;
			}
			this.body.traverse(new ShapeComputer(), null);
			if (!this.returnsValue && !this.returnsVoid)
				this.valueCompatible = this.body.doesNotCompleteNormally();
		}
	}
	
	@Override
	public boolean isPotentiallyCompatibleWith(TypeBinding targetType, Scope skope) {
		/* We get here only when the lambda is NOT pertinent to applicability and that too only for type elided lambdas. */
		
		/* 15.12.2.1: A lambda expression (§15.27) is potentially compatible with a functional interface type (§9.8) if all of the following are true:
		       – The arity of the target type's function type is the same as the arity of the lambda expression.
		       – If the target type's function type has a void return, then the lambda body is either a statement expression (§14.8) or a void-compatible block (§15.27.2).
		       – If the target type's function type has a (non-void) return type, then the lambda body is either an expression or a value-compatible block (§15.27.2).
		*/
		if (!super.isPertinentToApplicability(targetType, null))
			return true;
		
		final MethodBinding sam = targetType.getSingleAbstractMethod(skope, true);
		if (sam == null || !sam.isValidBinding())
			return false;
		
		if (sam.parameters.length != this.arguments.length)
			return false;
		
		analyzeShape();
		if (sam.returnType.id == TypeIds.T_void) {
			if (!this.voidCompatible)
				return false;
		} else {
			if (!this.valueCompatible)
				return false;
		}
		return true;
	}
	
	@Override
	public boolean isCompatibleWith(TypeBinding targetType, final Scope skope) {
		
		if (!super.isPertinentToApplicability(targetType, null))
			return true;
		
		LambdaExpression copy = null;
		try {
			copy = cachedResolvedCopy(targetType, argumentsTypeElided(), false, null); // if argument types are elided, we don't care for result expressions against *this* target, any valid target is OK.
		} catch (CopyFailureException cfe) {
			if (this.assistNode)
				return true; // can't type check result expressions, just say yes.
			return !isPertinentToApplicability(targetType, null); // don't expect to hit this ever.
		}
		if (copy == null)
			return false;
		
		// copy here is potentially compatible with the target type and has its shape fully computed: i.e value/void compatibility is determined and result expressions have been gathered.
		targetType = findGroundTargetType(this.enclosingScope, targetType, targetType, argumentsTypeElided());
		MethodBinding sam = targetType.getSingleAbstractMethod(this.enclosingScope, true);
		if (sam == null || sam.problemId() == ProblemReasons.NoSuchSingleAbstractMethod) {
			return false;
		}
		if (sam.returnType.id == TypeIds.T_void) {
			if (!copy.voidCompatible)
				return false;
		} else {
			if (!copy.valueCompatible)
				return false;
		}

		if (!isPertinentToApplicability(targetType, null))
			return true;

		// catch up on one check deferred via skipKosherCheck=true (only if pertinent for applicability)
		if (!kosherDescriptor(this.enclosingScope, sam, false))
			return false;

		Expression [] returnExpressions = copy.resultExpressions;
		for (int i = 0, length = returnExpressions.length; i < length; i++) {
			if (sam.returnType.isProperType(true) // inference variables can reach here during nested inference
					&& this.enclosingScope.parameterCompatibilityLevel(returnExpressions[i].resolvedType, sam.returnType) == Scope.NOT_COMPATIBLE) {
				if (!returnExpressions[i].isConstantValueOfTypeAssignableToType(returnExpressions[i].resolvedType, sam.returnType))
					if (sam.returnType.id != TypeIds.T_void || this.body instanceof Block)
						return false;
			}
		}
		return true;
	}
	
	class CopyFailureException extends RuntimeException {
		private static final long serialVersionUID = 1L;
	}

	private LambdaExpression cachedResolvedCopy(TypeBinding targetType, boolean anyTargetOk, boolean requireExceptionAnalysis, InferenceContext18 context) {

		targetType = findGroundTargetType(this.enclosingScope, targetType, targetType, argumentsTypeElided());
		if (targetType == null)
			return null;
		
		MethodBinding sam = targetType.getSingleAbstractMethod(this.enclosingScope, true);
		if (sam == null || !sam.isValidBinding())
			return null;
		
		if (sam.parameters.length != this.arguments.length)
			return null;
		
		LambdaExpression copy = null;
		if (this.copiesPerTargetType != null) {
			copy = this.copiesPerTargetType.get(targetType);
			if (copy == null) {
				if (anyTargetOk && this.copiesPerTargetType.values().size() > 0)
					copy = this.copiesPerTargetType.values().iterator().next();
			}
		}
		IErrorHandlingPolicy oldPolicy = this.enclosingScope.problemReporter().switchErrorHandlingPolicy(silentErrorHandlingPolicy);
		try {
			if (copy == null) {
				copy = copy();
				if (copy == null)
					throw new CopyFailureException();

				copy.setExpressionContext(this.expressionContext);
				copy.setExpectedType(targetType);
				copy.inferenceContext = context;
				TypeBinding type = copy.resolveType(this.enclosingScope, true);
				if (type == null || !type.isValidBinding())
					return null;

				if (this.copiesPerTargetType == null)
					this.copiesPerTargetType = new HashMap<TypeBinding, LambdaExpression>();
				this.copiesPerTargetType.put(targetType, copy);
			}
			if (!requireExceptionAnalysis)
				return copy;
			if (copy.thrownExceptions == null)
				if (!copy.hasIgnoredMandatoryErrors && !enclosingScopesHaveErrors())
					copy.analyzeExceptions();
			return copy;
		} finally {
			this.enclosingScope.problemReporter().switchErrorHandlingPolicy(oldPolicy);
		}
	}
	
	/**
	 * Get a resolved copy of this lambda for use by type inference, as to avoid spilling any premature
	 * type results into the original lambda.
	 * 
	 * @param targetType the target functional type against which inference is attempted, must be a non-null valid functional type 
	 * @return a resolved copy of 'this' or null if significant errors where encountered
	 */
	@Override
	public LambdaExpression resolveExpressionExpecting(TypeBinding targetType, Scope skope, InferenceContext18 context) {
		LambdaExpression copy = null;
		try {
			copy = cachedResolvedCopy(targetType, false, true, context);
		} catch (CopyFailureException cfe) {
			return null;
		}
		return copy;
	}

	@Override
	public boolean sIsMoreSpecific(TypeBinding s, TypeBinding t, Scope skope) {
		
		// 15.12.2.5 
		
		if (super.sIsMoreSpecific(s, t, skope))
			return true;
		
		if (argumentsTypeElided() || t.findSuperTypeOriginatingFrom(s) != null)
			return false;
		TypeBinding sPrime = s; // uncaptured
		s = s.capture(this.enclosingScope, this.sourceStart, this.sourceEnd);
		MethodBinding sSam = s.getSingleAbstractMethod(this.enclosingScope, true);
		if (sSam == null || !sSam.isValidBinding())
			return false;
		MethodBinding tSam = t.getSingleAbstractMethod(this.enclosingScope, true);
		if (tSam == null || !tSam.isValidBinding())
			return true; // See ORT8.test450415a for a case that slips through isCompatibleWith.
		MethodBinding adapted = tSam.computeSubstitutedMethod(sSam, skope.environment());
		if (adapted == null) // not same type params
			return false;
		MethodBinding sSamPrime = sPrime.getSingleAbstractMethod(this.enclosingScope, true);
		TypeBinding[] ps = adapted.parameters; // parameters of S adapted to type parameters of T
		// parameters of S (without capture), adapted to type params of T
		MethodBinding prime = tSam.computeSubstitutedMethod(sSamPrime, skope.environment());
		TypeBinding[] pPrimes = prime.parameters;
		TypeBinding[] qs = tSam.parameters;
		for (int i = 0; i < ps.length; i++) {
			if (!qs[i].isCompatibleWith(ps[i]) || TypeBinding.notEquals(qs[i], pPrimes[i]))
				return false;
		}
		TypeBinding r1 = adapted.returnType; // return type of S adapted to type parameters of T
		TypeBinding r2 = tSam.returnType;
		
		if (r2.id == TypeIds.T_void)
			return true;
		
		if (r1.id == TypeIds.T_void)
			return false;
		
		// r1 <: r2
		if (r1.isCompatibleWith(r2, skope))
			return true;
		
		LambdaExpression copy;
		try {
			copy = cachedResolvedCopy(s, true /* any resolved copy is good */, false, null); // we expect a cached copy - otherwise control won't reach here.
		} catch (CopyFailureException cfe) {
			if (this.assistNode)
				return false;
			throw cfe;
		}
		Expression [] returnExpressions = copy.resultExpressions;
		int returnExpressionsLength = returnExpressions == null ? 0 : returnExpressions.length;
		if (returnExpressionsLength > 0) {
			int i;
			// r1 is a primitive type, r2 is a reference type, and each result expression is a standalone expression (15.2) of a primitive type
			if (r1.isBaseType() && !r2.isBaseType()) {
				for (i = 0; i < returnExpressionsLength; i++) {
					if (returnExpressions[i].isPolyExpression() || !returnExpressions[i].resolvedType.isBaseType())
						break;
				}
				if (i == returnExpressionsLength)
					return true;
			}
			if (!r1.isBaseType() && r2.isBaseType()) {
				for (i = 0; i < returnExpressionsLength; i++) {
					if (returnExpressions[i].resolvedType.isBaseType())
						break;
				}
				if (i == returnExpressionsLength)
					return true;
			}
			if (r1.isFunctionalInterface(this.enclosingScope) && r2.isFunctionalInterface(this.enclosingScope)) {
				for (i = 0; i < returnExpressionsLength; i++) {
					Expression resultExpression = returnExpressions[i];
					if (!resultExpression.sIsMoreSpecific(r1, r2, skope))
						break;
				}
				if (i == returnExpressionsLength)
					return true;
			}	
		}
		return false;
	}

	LambdaExpression copy() {
		final Parser parser = new Parser(this.enclosingScope.problemReporter(), false);
		final ICompilationUnit compilationUnit = this.compilationResult.getCompilationUnit();
		char[] source = compilationUnit != null ? compilationUnit.getContents() : this.text;
		LambdaExpression copy =  (LambdaExpression) parser.parseLambdaExpression(source, compilationUnit != null ? this.sourceStart : 0, this.sourceEnd - this.sourceStart + 1, 
										this.enclosingScope.referenceCompilationUnit(), false /* record line separators */);

		if (copy != null) { // ==> syntax errors == null
			copy.original = this;
			copy.assistNode = this.assistNode;
			copy.enclosingScope = this.enclosingScope;
		}
		return copy;
	}

	public void returnsExpression(Expression expression, TypeBinding resultType) {
		if (this.original == this) // Not in overload resolution context. result expressions not relevant.
			return;
		if (this.body instanceof Expression) {
			this.valueCompatible = resultType != null && resultType.id == TypeIds.T_void ? false : true;
			this.voidCompatible = this.assistNode ? true : ((Expression) this.body).statementExpression(); // while code is still being written and completed, we can't ask if it is a statement
			this.resultExpressions = new Expression[] { expression };
			return;
		}
		if (expression != null) {
			this.returnsValue = true;
			this.voidCompatible = false;
			this.valueCompatible = !this.returnsVoid;
			Expression [] returnExpressions = this.resultExpressions;
			int resultsLength = returnExpressions.length;
			System.arraycopy(returnExpressions, 0, returnExpressions = new Expression[resultsLength + 1], 0, resultsLength);
			returnExpressions[resultsLength] = expression;
			this.resultExpressions = returnExpressions;
		} else {
			this.returnsVoid = true;
			this.valueCompatible = false;
			this.voidCompatible = !this.returnsValue;
		}
	}
	
	@Override
	public CompilationResult compilationResult() {
		return this.compilationResult;
	}

	@Override
	public void abort(int abortLevel, CategorizedProblem problem) {
	
		switch (abortLevel) {
			case AbortCompilation :
				throw new AbortCompilation(this.compilationResult, problem);
			case AbortCompilationUnit :
				throw new AbortCompilationUnit(this.compilationResult, problem);
			case AbortType :
				throw new AbortType(this.compilationResult, problem);
			default :
				throw new AbortMethod(this.compilationResult, problem);
		}
	}

	@Override
	public CompilationUnitDeclaration getCompilationUnitDeclaration() {
		return this.enclosingScope == null ? null : this.enclosingScope.compilationUnitScope().referenceContext;
	}

	@Override
	public boolean hasErrors() {
		return this.ignoreFurtherInvestigation;
	}

	@Override
	public void tagAsHavingErrors() {
		this.ignoreFurtherInvestigation = true;
		Scope parent = this.enclosingScope.parent;
		while (parent != null) {
			switch(parent.kind) {
				case Scope.CLASS_SCOPE:
				case Scope.METHOD_SCOPE:
					ReferenceContext parentAST = parent.referenceContext();
					if (parentAST != this) {
						parentAST.tagAsHavingErrors();
						return;
					}
					//$FALL-THROUGH$
				default:
					parent = parent.parent;
					break;
			}
		}
	}
	
	@Override
	public void tagAsHavingIgnoredMandatoryErrors(int problemId) {
		switch (problemId) {
			// 15.27.3 requires exception throw related errors to not influence congruence. Other errors should. Also don't abort shape analysis.
			case IProblem.UnhandledExceptionOnAutoClose:
			case IProblem.UnhandledExceptionInDefaultConstructor:
			case IProblem.UnhandledException:
				return;
			/* The following structural problems can occur only because of target type imposition. Filter, so we can distinguish inherent errors 
			   in explicit lambdas. This is to help decide whether to proceed with data/control flow analysis to discover shape. In case of inherent
			   errors, we will not call analyze code as it is not prepared to analyze broken programs.
			*/
			case IProblem.VoidMethodReturnsValue:
			case IProblem.ShouldReturnValueHintMissingDefault:
			case IProblem.ShouldReturnValue:
			case IProblem.ReturnTypeMismatch:
			case IProblem.IncompatibleLambdaParameterType:
			case IProblem.lambdaParameterTypeMismatched:
			case IProblem.lambdaSignatureMismatched:
			case IProblem.LambdaDescriptorMentionsUnmentionable:
			case IProblem.TargetTypeNotAFunctionalInterface:
			case IProblem.illFormedParameterizationOfFunctionalInterface:
			case IProblem.NoGenericLambda:
				return;
			default: 
				this.hasIgnoredMandatoryErrors = true;
				MethodScope enclosingLambdaScope = this.scope == null ? null : this.scope.enclosingLambdaScope();
				while (enclosingLambdaScope != null) {
					LambdaExpression enclosingLambda = (LambdaExpression) enclosingLambdaScope.referenceContext;
					enclosingLambda.hasIgnoredMandatoryErrors = true;
					enclosingLambdaScope = enclosingLambdaScope.enclosingLambdaScope();
				}
				return;
		}
	}
	
	public Set<TypeBinding> getThrownExceptions() {
		if (this.thrownExceptions == null)
			return Collections.emptySet();
		return this.thrownExceptions;
	}

	public void generateCode(ClassScope classScope, ClassFile classFile) {
		int problemResetPC = 0;
		classFile.codeStream.wideMode = false;
		boolean restart = false;
		do {
			try {
				problemResetPC = classFile.contentsOffset;
				this.generateCode(classFile);
				restart = false;
			} catch (AbortMethod e) {
				// Restart code generation if possible ...
				if (e.compilationResult == CodeStream.RESTART_IN_WIDE_MODE) {
					// a branch target required a goto_w, restart code generation in wide mode.
					classFile.contentsOffset = problemResetPC;
					classFile.methodCount--;
					classFile.codeStream.resetInWideMode(); // request wide mode
					restart = true;
				} else if (e.compilationResult == CodeStream.RESTART_CODE_GEN_FOR_UNUSED_LOCALS_MODE) {
					classFile.contentsOffset = problemResetPC;
					classFile.methodCount--;
					classFile.codeStream.resetForCodeGenUnusedLocals();
					restart = true;
				} else {
					throw new AbortType(this.compilationResult, e.problem);
				}
			}
		} while (restart);
	}
	
	public void generateCode(ClassFile classFile) {
		classFile.generateMethodInfoHeader(this.binding);
		int methodAttributeOffset = classFile.contentsOffset;
		int attributeNumber = classFile.generateMethodInfoAttributes(this.binding);
		int codeAttributeOffset = classFile.contentsOffset;
		classFile.generateCodeAttributeHeader();
		CodeStream codeStream = classFile.codeStream;
		codeStream.reset(this, classFile);
		// initialize local positions
		this.scope.computeLocalVariablePositions(this.outerLocalVariablesSlotSize + (this.binding.isStatic() ? 0 : 1), codeStream);
		if (this.outerLocalVariables != null) {
			for (int i = 0, max = this.outerLocalVariables.length; i < max; i++) {
				LocalVariableBinding argBinding;
				codeStream.addVisibleLocalVariable(argBinding = this.outerLocalVariables[i]);
				codeStream.record(argBinding);
				argBinding.recordInitializationStartPC(0);
			}
		}
		// arguments initialization for local variable debug attributes
		if (this.arguments != null) {
			for (int i = 0, max = this.arguments.length; i < max; i++) {
				LocalVariableBinding argBinding;
				codeStream.addVisibleLocalVariable(argBinding = this.arguments[i].binding);
				argBinding.recordInitializationStartPC(0);
			}
		}
		if (this.body instanceof Block) {
			this.body.generateCode(this.scope, codeStream);
			if ((this.bits & ASTNode.NeedFreeReturn) != 0) {
				codeStream.return_();
			}
		} else {
			Expression expression = (Expression) this.body;
			expression.generateCode(this.scope, codeStream, true);
			if (this.binding.returnType == TypeBinding.VOID) {
				codeStream.return_();
			} else {
				codeStream.generateReturnBytecode(expression);
			}
		}
		// local variable attributes
		codeStream.exitUserScope(this.scope);
		codeStream.recordPositionsFrom(0, this.sourceEnd); // WAS declarationSourceEnd.
		try {
			classFile.completeCodeAttribute(codeAttributeOffset);
		} catch(NegativeArraySizeException e) {
			throw new AbortMethod(this.scope.referenceCompilationUnit().compilationResult, null);
		}
		attributeNumber++;

		classFile.completeMethodInfo(this.binding, methodAttributeOffset, attributeNumber);
	}
	
	public void addSyntheticArgument(LocalVariableBinding actualOuterLocalVariable) {
		
		if (this.original != this || this.binding == null) 
			return; // Do not bother tracking outer locals for clones created during overload resolution.
		
		SyntheticArgumentBinding syntheticLocal = null;
		int newSlot = this.outerLocalVariables.length;
		for (int i = 0; i < newSlot; i++) {
			if (this.outerLocalVariables[i].actualOuterLocalVariable == actualOuterLocalVariable)
				return;
		}
		System.arraycopy(this.outerLocalVariables, 0, this.outerLocalVariables = new SyntheticArgumentBinding[newSlot + 1], 0, newSlot);
		this.outerLocalVariables[newSlot] = syntheticLocal = new SyntheticArgumentBinding(actualOuterLocalVariable);
		syntheticLocal.resolvedPosition = this.outerLocalVariablesSlotSize; // may need adjusting later if we need to generate an instance method for the lambda.
		syntheticLocal.declaringScope = this.scope;
		int parameterCount = this.binding.parameters.length;
		TypeBinding [] newParameters = new TypeBinding[parameterCount + 1];
		newParameters[newSlot] = actualOuterLocalVariable.type;
		for (int i = 0, j = 0; i < parameterCount; i++, j++) {
			if (i == newSlot) j++;
			newParameters[j] = this.binding.parameters[i];
		}
		this.binding.parameters = newParameters;
		switch (syntheticLocal.type.id) {
			case TypeIds.T_long :
			case TypeIds.T_double :
				this.outerLocalVariablesSlotSize  += 2;
				break;
			default :
				this.outerLocalVariablesSlotSize++;
				break;
		}		
	}

	public SyntheticArgumentBinding getSyntheticArgument(LocalVariableBinding actualOuterLocalVariable) {
		for (int i = 0, length = this.outerLocalVariables == null ? 0 : this.outerLocalVariables.length; i < length; i++)
			if (this.outerLocalVariables[i].actualOuterLocalVariable == actualOuterLocalVariable)
				return this.outerLocalVariables[i];
		return null;
	}

	// Return the actual method binding devoid of synthetics. 
	@Override
	public MethodBinding getMethodBinding() {
		if (this.actualMethodBinding == null) {
			if (this.binding != null) {
				// Get rid of the synthetic arguments added via addSyntheticArgument()
				TypeBinding[] newParams = null;
				if (this.binding instanceof SyntheticMethodBinding && this.outerLocalVariables.length > 0) {
					newParams = new TypeBinding[this.binding.parameters.length - this.outerLocalVariables.length];
					System.arraycopy(this.binding.parameters, this.outerLocalVariables.length, newParams, 0, newParams.length);
				} else {
					newParams = this.binding.parameters;
				}
				this.actualMethodBinding = new MethodBinding(this.binding.modifiers, this.binding.selector,
						this.binding.returnType, newParams, this.binding.thrownExceptions, this.binding.declaringClass);
				this.actualMethodBinding.tagBits = this.binding.tagBits;
			} else {
				this.actualMethodBinding = new ProblemMethodBinding(CharOperation.NO_CHAR, null, ProblemReasons.NoSuchSingleAbstractMethod);
			}
		}
		return this.actualMethodBinding;
	}

	@Override
	public int diagnosticsSourceEnd() {
		return this.body instanceof Block ? this.arrowPosition : this.sourceEnd;
	}

	public TypeBinding[] getMarkerInterfaces() {
		if (this.expectedType instanceof IntersectionTypeBinding18) {
			Set markerBindings = new LinkedHashSet();
			IntersectionTypeBinding18 intersectionType = (IntersectionTypeBinding18)this.expectedType;
			TypeBinding[] intersectionTypes = intersectionType.intersectingTypes;
			TypeBinding samType = intersectionType.getSAMType(this.enclosingScope);
			for (int i = 0,max = intersectionTypes.length; i < max; i++) {
				TypeBinding typeBinding = intersectionTypes[i];
				if (!typeBinding.isInterface()							// only interfaces
					|| TypeBinding.equalsEquals(samType, typeBinding)	// except for the samType itself
					|| typeBinding.id == TypeIds.T_JavaIoSerializable)	// but Serializable is captured as a bitflag
				{
					continue;
				}
				markerBindings.add(typeBinding);
			}
			if (markerBindings.size() > 0) {
				return (TypeBinding[])markerBindings.toArray(new TypeBinding[markerBindings.size()]);
			}
		}
		return null;
	}

	public ReferenceBinding getTypeBinding() {
	
		if (this.classType != null || this.resolvedType == null)
			return null;
		
		class LambdaTypeBinding extends ReferenceBinding {
			@Override
			public MethodBinding[] methods() {
				return new MethodBinding [] { getMethodBinding() };
			}
			@Override
			public char[] sourceName() {
				return TypeConstants.LAMBDA_TYPE;
			}
			@Override
			public ReferenceBinding superclass() {
				return LambdaExpression.this.scope.getJavaLangObject();
			}
			@Override
			public ReferenceBinding[] superInterfaces() {
				return new ReferenceBinding[] { (ReferenceBinding) LambdaExpression.this.resolvedType };
			}
			@Override
			public char[] computeUniqueKey() {
				return LambdaExpression.this.descriptor.declaringClass.computeUniqueKey();
			}
			@Override
			public String toString() {
				StringBuffer output = new StringBuffer("()->{} implements "); //$NON-NLS-1$
				output.append(LambdaExpression.this.descriptor.declaringClass.sourceName());
				output.append('.');
				output.append(LambdaExpression.this.descriptor.toString());
				return output.toString();
			}
		}
		return this.classType = new LambdaTypeBinding();
	}

	public void addLocalType(LocalTypeBinding localTypeBinding) {
		if (this.localTypes == null)
			this.localTypes = new HashMap<>();
		this.localTypes.put(localTypeBinding.sourceStart, localTypeBinding);
	}

	/**
	 * During inference, several copies of a lambda may be created.
	 * If a lambda body contains a local type declaration, one binding may be created
	 * within each of the lambda copies. Once inference finished, we need to map all
	 * such local type bindings to the instance from the correct lambda copy.
	 * <p>
	 * When a local type binding occurs as a field of another type binding (e.g.,
	 * type argument), the local type will be replaced in-place, assuming that the
	 * previous binding should never escape the context of resolving this lambda.
	 * </p>
	 */
	class LocalTypeSubstitutor extends Substitutor {
		Map<Integer,LocalTypeBinding> localTypes2;
		
		public LocalTypeSubstitutor(Map<Integer, LocalTypeBinding> localTypes) {
			this.localTypes2 = localTypes;
		}

		@Override
		public TypeBinding substitute(Substitution substitution, TypeBinding originalType) {
			if (originalType.isLocalType()) {
				LocalTypeBinding orgLocal = (LocalTypeBinding) originalType;
				MethodScope lambdaScope2 = orgLocal.scope.enclosingLambdaScope();
				if (lambdaScope2 != null) {
					if (((LambdaExpression) lambdaScope2.referenceContext).sourceStart == LambdaExpression.this.sourceStart) {
						// local type within this lambda needs replacement: 
						TypeBinding substType = this.localTypes2.get(orgLocal.sourceStart);
						if (substType != null) {
							orgLocal.transferConstantPoolNameTo(substType);
							return substType;
						}
					}
				}
				return originalType;
			}
			return super.substitute(substitution, originalType);
		}
	}

	private void updateLocalTypes() {
		if (this.descriptor == null || this.localTypes == null)
			return;
		LocalTypeSubstitutor substor = new LocalTypeSubstitutor(this.localTypes);
		NullSubstitution subst = new NullSubstitution(this.scope.environment());
		updateLocalTypesInMethod(this.binding, substor, subst);
		updateLocalTypesInMethod(this.descriptor, substor, subst);
		this.resolvedType = substor.substitute(subst, this.resolvedType);
		this.expectedType = substor.substitute(subst, this.expectedType);
	}

	/**
	 * Perform substitution with a {@link LocalTypeSubstitutor} on all types mentioned in the given method binding.
	 */
	void updateLocalTypesInMethod(MethodBinding method) {
		if (this.localTypes == null)
			return;
		updateLocalTypesInMethod(method, new LocalTypeSubstitutor(this.localTypes), new NullSubstitution(this.scope.environment()));
	}

	private void updateLocalTypesInMethod(MethodBinding method, Substitutor substor, Substitution subst) {
		method.declaringClass = (ReferenceBinding) substor.substitute(subst, method.declaringClass);
		method.returnType = substor.substitute(subst, method.returnType);
		for (int i = 0; i < method.parameters.length; i++) {
			method.parameters[i] = substor.substitute(subst, method.parameters[i]);
		}
	}
}