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/*******************************************************************************
* Copyright (c) 2000, 2019 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
* Stephan Herrmann - Contributions for
* bug 185682 - Increment/decrement operators mark local variables as read
* bug 392862 - [1.8][compiler][null] Evaluate null annotations on array types
* bug 331649 - [compiler][null] consider null annotations for fields
* bug 383368 - [compiler][null] syntactic null analysis for field references
* bug 392384 - [1.8][compiler][null] Restore nullness info from type annotations in class files
* Bug 392099 - [1.8][compiler][null] Apply null annotation on types for null analysis
* Bug 411964 - [1.8][null] leverage null type annotation in foreach statement
* Bug 407414 - [compiler][null] Incorrect warning on a primitive type being null
*******************************************************************************/
package org.eclipse.jdt.internal.compiler.ast;
import org.eclipse.jdt.internal.compiler.codegen.CodeStream;
import org.eclipse.jdt.internal.compiler.codegen.Opcodes;
import org.eclipse.jdt.internal.compiler.flow.FlowContext;
import org.eclipse.jdt.internal.compiler.flow.FlowInfo;
import org.eclipse.jdt.internal.compiler.impl.Constant;
import org.eclipse.jdt.internal.compiler.lookup.BlockScope;
import org.eclipse.jdt.internal.compiler.lookup.ExtraCompilerModifiers;
import org.eclipse.jdt.internal.compiler.lookup.FieldBinding;
import org.eclipse.jdt.internal.compiler.lookup.LocalVariableBinding;
import org.eclipse.jdt.internal.compiler.lookup.MethodBinding;
import org.eclipse.jdt.internal.compiler.lookup.MethodScope;
import org.eclipse.jdt.internal.compiler.lookup.Scope;
import org.eclipse.jdt.internal.compiler.lookup.TagBits;
import org.eclipse.jdt.internal.compiler.lookup.TypeBinding;
import org.eclipse.jdt.internal.compiler.lookup.TypeIds;
public abstract class Reference extends Expression {
/**
* BaseLevelReference constructor comment.
*/
public Reference() {
super();
}
public abstract FlowInfo analyseAssignment(BlockScope currentScope, FlowContext flowContext, FlowInfo flowInfo, Assignment assignment, boolean isCompound);
@Override
public FlowInfo analyseCode(BlockScope currentScope, FlowContext flowContext, FlowInfo flowInfo) {
return flowInfo;
}
@Override
public boolean checkNPE(BlockScope scope, FlowContext flowContext, FlowInfo flowInfo, int ttlForFieldCheck) {
if (flowContext.isNullcheckedFieldAccess(this)) {
return true; // enough seen
}
return super.checkNPE(scope, flowContext, flowInfo, ttlForFieldCheck);
}
protected boolean checkNullableFieldDereference(Scope scope, FieldBinding field, long sourcePosition, FlowContext flowContext, int ttlForFieldCheck) {
if (field != null) {
if (ttlForFieldCheck > 0 && scope.compilerOptions().enableSyntacticNullAnalysisForFields)
flowContext.recordNullCheckedFieldReference(this, ttlForFieldCheck);
// preference to type annotations if we have any
if ((field.type.tagBits & TagBits.AnnotationNullable) != 0) {
scope.problemReporter().dereferencingNullableExpression(sourcePosition, scope.environment());
return true;
}
if (field.type.isFreeTypeVariable()) {
scope.problemReporter().fieldFreeTypeVariableReference(field, sourcePosition);
return true;
}
if ((field.tagBits & TagBits.AnnotationNullable) != 0) {
scope.problemReporter().nullableFieldDereference(field, sourcePosition);
return true;
}
}
return false;
}
public FieldBinding fieldBinding() {
//this method should be sent one FIELD-tagged references
// (ref.bits & BindingIds.FIELD != 0)()
return null ;
}
public void fieldStore(Scope currentScope, CodeStream codeStream, FieldBinding fieldBinding, MethodBinding syntheticWriteAccessor, TypeBinding receiverType, boolean isImplicitThisReceiver, boolean valueRequired) {
int pc = codeStream.position;
if (fieldBinding.isStatic()) {
if (valueRequired) {
switch (fieldBinding.type.id) {
case TypeIds.T_long :
case TypeIds.T_double :
codeStream.dup2();
break;
default :
codeStream.dup();
break;
}
}
if (syntheticWriteAccessor == null) {
TypeBinding constantPoolDeclaringClass = CodeStream.getConstantPoolDeclaringClass(currentScope, fieldBinding, receiverType, isImplicitThisReceiver);
codeStream.fieldAccess(Opcodes.OPC_putstatic, fieldBinding, constantPoolDeclaringClass);
} else {
codeStream.invoke(Opcodes.OPC_invokestatic, syntheticWriteAccessor, null /* default declaringClass */);
}
} else { // Stack: [owner][new field value] ---> [new field value][owner][new field value]
if (valueRequired) {
switch (fieldBinding.type.id) {
case TypeIds.T_long :
case TypeIds.T_double :
codeStream.dup2_x1();
break;
default :
codeStream.dup_x1();
break;
}
}
if (syntheticWriteAccessor == null) {
TypeBinding constantPoolDeclaringClass = CodeStream.getConstantPoolDeclaringClass(currentScope, fieldBinding, receiverType, isImplicitThisReceiver);
codeStream.fieldAccess(Opcodes.OPC_putfield, fieldBinding, constantPoolDeclaringClass);
} else {
codeStream.invoke(Opcodes.OPC_invokestatic, syntheticWriteAccessor, null /* default declaringClass */);
}
}
codeStream.recordPositionsFrom(pc, this.sourceStart);
}
public abstract void generateAssignment(BlockScope currentScope, CodeStream codeStream, Assignment assignment, boolean valueRequired);
public abstract void generateCompoundAssignment(BlockScope currentScope, CodeStream codeStream, Expression expression, int operator, int assignmentImplicitConversion, boolean valueRequired);
public abstract void generatePostIncrement(BlockScope currentScope, CodeStream codeStream, CompoundAssignment postIncrement, boolean valueRequired);
/**
* Is the given reference equivalent to the receiver,
* meaning that both denote the same path of field reads?
* Used from {@link FlowContext#isNullcheckedFieldAccess(Reference)}.
*/
public boolean isEquivalent(Reference reference) {
return false;
}
public FieldBinding lastFieldBinding() {
// override to answer the field designated by the entire reference
// (as opposed to fieldBinding() which answers the first field in a QNR)
return null;
}
@Override
public int nullStatus(FlowInfo flowInfo, FlowContext flowContext) {
if ((this.implicitConversion & TypeIds.BOXING) != 0)
return FlowInfo.NON_NULL;
FieldBinding fieldBinding = lastFieldBinding();
if (fieldBinding != null) {
if (fieldBinding.isFinal() && fieldBinding.constant() != Constant.NotAConstant)
return FlowInfo.NON_NULL;
if (fieldBinding.isNonNull() || flowContext.isNullcheckedFieldAccess(this)) {
return FlowInfo.NON_NULL;
} else if (fieldBinding.isNullable()) {
return FlowInfo.POTENTIALLY_NULL;
} else if (fieldBinding.type.isFreeTypeVariable()) {
return FlowInfo.FREE_TYPEVARIABLE;
}
}
if (this.resolvedType != null) {
return FlowInfo.tagBitsToNullStatus(this.resolvedType.tagBits);
}
return FlowInfo.UNKNOWN;
}
/* report if a private field is only read from a 'special operator',
* i.e., in a postIncrement expression or a compound assignment,
* where the information is never flowing out off the field. */
void reportOnlyUselesslyReadPrivateField(BlockScope currentScope, FieldBinding fieldBinding, boolean valueRequired) {
if (valueRequired) {
// access is relevant, turn compound use into real use:
fieldBinding.compoundUseFlag = 0;
fieldBinding.modifiers |= ExtraCompilerModifiers.AccLocallyUsed;
} else {
if (fieldBinding.isUsedOnlyInCompound()) {
fieldBinding.compoundUseFlag--; // consume one
if (fieldBinding.compoundUseFlag == 0 // report only the last usage
&& fieldBinding.isOrEnclosedByPrivateType()
&& (this.implicitConversion & TypeIds.UNBOXING) == 0) // don't report if unboxing is involved (might cause NPE)
{
// compoundAssignment/postIncrement is the only usage of this field
currentScope.problemReporter().unusedPrivateField(fieldBinding.sourceField());
}
}
}
}
/* report a local/arg that is only read from a 'special operator',
* i.e., in a postIncrement expression or a compound assignment,
* where the information is never flowing out off the local/arg. */
static void reportOnlyUselesslyReadLocal(BlockScope currentScope, LocalVariableBinding localBinding, boolean valueRequired) {
if (localBinding.declaration == null)
return; // secret local
if ((localBinding.declaration.bits & ASTNode.IsLocalDeclarationReachable) == 0)
return; // declaration is unreachable
if (localBinding.useFlag >= LocalVariableBinding.USED)
return; // we're only interested in cases with only compound access (negative count)
if (valueRequired) {
// access is relevant
localBinding.useFlag = LocalVariableBinding.USED;
return;
} else {
localBinding.useFlag++;
if (localBinding.useFlag != LocalVariableBinding.UNUSED) // have all negative counts been consumed?
return; // still waiting to see more usages of this kind
}
// at this point we know we have something to report
if (localBinding.declaration instanceof Argument) {
// check compiler options to report against unused arguments
MethodScope methodScope = currentScope.methodScope();
if (methodScope != null && !methodScope.isLambdaScope()) { // lambda must be congruent with the descriptor.
MethodBinding method = ((AbstractMethodDeclaration)methodScope.referenceContext()).binding;
boolean shouldReport = !method.isMain();
if (method.isImplementing()) {
shouldReport &= currentScope.compilerOptions().reportUnusedParameterWhenImplementingAbstract;
} else if (method.isOverriding()) {
shouldReport &= currentScope.compilerOptions().reportUnusedParameterWhenOverridingConcrete;
}
if (shouldReport) {
// report the case of an argument that is unread except through a special operator
currentScope.problemReporter().unusedArgument(localBinding.declaration);
}
}
} else {
// report the case of a local variable that is unread except for a special operator
currentScope.problemReporter().unusedLocalVariable(localBinding.declaration);
}
}
}
