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Flip stores when comparing to a constant boolean. #3721

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Oct 1, 2020
Merged

Flip stores when comparing to a constant boolean. #3721

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206 changes: 206 additions & 0 deletions checker/tests/nullness/flow/Issue3275.java
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Original file line number Diff line number Diff line change
@@ -0,0 +1,206 @@
// Test case for issue #3275:
// https://github.com/typetools/checker-framework/issues/3275

import org.checkerframework.checker.nullness.qual.NonNull;
import org.checkerframework.checker.nullness.qual.Nullable;

class Issue3275 {
public @NonNull Object f = new Object();
public boolean b = false;

void return_n(@Nullable Object obj) {
if (obj != null) {
obj.toString();
}
}

void return_np(@Nullable Object obj) {
if ((obj != null)) {
obj.toString();
}
}

void return_en(@Nullable Object obj) {
if (!(obj == null)) {
obj.toString();
}
}

void return_eet(@Nullable Object obj) {
if ((obj == null) == true) {
// :: error: (dereference.of.nullable)
obj.toString();
}
}

void return_eef(@Nullable Object obj) {
if ((obj == null) == false) {
obj.toString();
}
}

void return_eeb(@Nullable Object obj) {
if ((obj == null) == b) {
// :: error: (dereference.of.nullable)
obj.toString();
}
}

void return_ent(@Nullable Object obj) {
if ((obj == null) != true) {
obj.toString();
}
}

void return_enf(@Nullable Object obj) {
if ((obj == null) != false) {
// :: error: (dereference.of.nullable)
obj.toString();
}
}

void return_enb(@Nullable Object obj) {
if ((obj == null) != b) {
// :: error: (dereference.of.nullable)
obj.toString();
}
}

void return_net(@Nullable Object obj) {
if ((obj != null) == true) {
obj.toString();
}
}

void return_nef(@Nullable Object obj) {
if ((obj != null) == false) {
// :: error: (dereference.of.nullable)
obj.toString();
}
}

void return_neb(@Nullable Object obj) {
if ((obj != null) == b) {
// :: error: (dereference.of.nullable)
obj.toString();
}
}

void return_nnt(@Nullable Object obj) {
if ((obj != null) != true) {
// :: error: (dereference.of.nullable)
obj.toString();
}
}

void return_nnf(@Nullable Object obj) {
if ((obj != null) != false) {
obj.toString();
}
}

void return_nnb(@Nullable Object obj) {
if ((obj != null) != b) {
// :: error: (dereference.of.nullable)
obj.toString();
}
}

void assign_n(@Nullable Object obj) {
if (obj != null) {
f = obj;
}
}

void assign_np(@Nullable Object obj) {
if ((obj != null)) {
f = obj;
}
}

void assign_en(@Nullable Object obj) {
if (!(obj == null)) {
f = obj;
}
}

void assign_eet(@Nullable Object obj) {
if ((obj == null) == true) {
// :: error: (assignment.type.incompatible)
f = obj;
}
}

void assign_eef(@Nullable Object obj) {
if ((obj == null) == false) {
f = obj;
}
}

void assign_eeb(@Nullable Object obj) {
if ((obj == null) == b) {
// :: error: (assignment.type.incompatible)
f = obj;
}
}

void assign_ent(@Nullable Object obj) {
if ((obj == null) != true) {
f = obj;
}
}

void assign_enf(@Nullable Object obj) {
if ((obj == null) != false) {
// :: error: (assignment.type.incompatible)
f = obj;
}
}

void assign_enb(@Nullable Object obj) {
if ((obj == null) != b) {
// :: error: (assignment.type.incompatible)
f = obj;
}
}

void assign_net(@Nullable Object obj) {
if ((obj != null) == true) {
f = obj;
}
}

void assign_nef(@Nullable Object obj) {
if ((obj != null) == false) {
// :: error: (assignment.type.incompatible)
f = obj;
}
}

void assign_neb(@Nullable Object obj) {
if ((obj != null) == b) {
// :: error: (assignment.type.incompatible)
f = obj;
}
}

void assign_nnt(@Nullable Object obj) {
if ((obj != null) != true) {
// :: error: (assignment.type.incompatible)
f = obj;
}
}

void assign_nnf(@Nullable Object obj) {
if ((obj != null) != false) {
f = obj;
}
}

void assign_nnb(@Nullable Object obj) {
if ((obj != null) != b) {
// :: error: (assignment.type.incompatible)
f = obj;
}
}
}
19 changes: 19 additions & 0 deletions dataflow/src/main/java/org/checkerframework/dataflow/util/NodeUtils.java
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Original file line number Diff line number Diff line change
Expand Up @@ -6,6 +6,8 @@
import javax.annotation.processing.ProcessingEnvironment;
import javax.lang.model.element.ExecutableElement;
import javax.lang.model.type.TypeKind;
import org.checkerframework.dataflow.cfg.node.BooleanLiteralNode;
import org.checkerframework.dataflow.cfg.node.ConditionalNotNode;
import org.checkerframework.dataflow.cfg.node.ConditionalOrNode;
import org.checkerframework.dataflow.cfg.node.FieldAccessNode;
import org.checkerframework.dataflow.cfg.node.MethodInvocationNode;
Expand Down Expand Up @@ -69,4 +71,21 @@ public static boolean isMethodInvocation(
ExecutableElement invoked = ((MethodInvocationNode) node).getTarget().getMethod();
return ElementUtils.isMethod(invoked, method, env);
}

/**
* Returns true if the given node statically evaluates to {@code value} and has no side effects.
*
* @param n a node
* @param value the boolean value that the node is tested against
* @return true if the node is equivalent to a literal with value {@code value}
*/
public static boolean isConstantBoolean(Node n, boolean value) {
if (n instanceof BooleanLiteralNode) {
return ((BooleanLiteralNode) n).getValue() == value;
} else if (n instanceof ConditionalNotNode) {
return isConstantBoolean(((ConditionalNotNode) n).getOperand(), !value);
} else {
return false;
}
}
}
17 changes: 17 additions & 0 deletions framework/src/main/java/org/checkerframework/framework/flow/CFAbstractTransfer.java
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Original file line number Diff line number Diff line change
Expand Up @@ -60,6 +60,7 @@
import org.checkerframework.dataflow.cfg.node.ThisLiteralNode;
import org.checkerframework.dataflow.cfg.node.VariableDeclarationNode;
import org.checkerframework.dataflow.cfg.node.WideningConversionNode;
import org.checkerframework.dataflow.util.NodeUtils;
import org.checkerframework.framework.type.AnnotatedTypeFactory;
import org.checkerframework.framework.type.AnnotatedTypeMirror;
import org.checkerframework.framework.type.AnnotatedTypeMirror.AnnotatedDeclaredType;
Expand Down Expand Up @@ -717,6 +718,14 @@ public TransferResult<V, S> visitEqualTo(EqualToNode n, TransferInput<V, S> p) {
V leftV = p.getValueOfSubNode(leftN);
V rightV = p.getValueOfSubNode(rightN);

if (res.containsTwoStores()
&& (NodeUtils.isConstantBoolean(leftN, false)
|| NodeUtils.isConstantBoolean(rightN, false))) {
S thenStore = res.getElseStore();
S elseStore = res.getThenStore();
res = new ConditionalTransferResult<>(res.getResultValue(), thenStore, elseStore);
}

// if annotations differ, use the one that is more precise for both
// sides (and add it to the store if possible)
res = strengthenAnnotationOfEqualTo(res, leftN, rightN, leftV, rightV, false);
Expand All @@ -733,6 +742,14 @@ public TransferResult<V, S> visitNotEqual(NotEqualNode n, TransferInput<V, S> p)
V leftV = p.getValueOfSubNode(leftN);
V rightV = p.getValueOfSubNode(rightN);

if (res.containsTwoStores()
&& (NodeUtils.isConstantBoolean(leftN, true)
|| NodeUtils.isConstantBoolean(rightN, true))) {
S thenStore = res.getElseStore();
S elseStore = res.getThenStore();
res = new ConditionalTransferResult<>(res.getResultValue(), thenStore, elseStore);
}

// if annotations differ, use the one that is more precise for both
// sides (and add it to the store if possible)
res = strengthenAnnotationOfEqualTo(res, leftN, rightN, leftV, rightV, true);
Expand Down