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merged 2 commits into from
Jul 25, 2025
Merged

Do not remove used private fields after type change #648

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046af12
Do not remove used private fields after type change
timtebeek Jul 21, 2025
79229ff
Adopt `TypeUtils.fullyQualifiedNamesAreEqual`
timtebeek Jul 25, 2025
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50 changes: 35 additions & 15 deletions src/main/java/org/openrewrite/staticanalysis/RemoveUnusedPrivateFields.java
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Original file line number Diff line number Diff line change
Expand Up @@ -24,10 +24,7 @@
import org.openrewrite.java.JavaVisitor;
import org.openrewrite.java.NoMissingTypes;
import org.openrewrite.java.service.AnnotationService;
import org.openrewrite.java.tree.J;
import org.openrewrite.java.tree.Space;
import org.openrewrite.java.tree.Statement;
import org.openrewrite.java.tree.TypeUtils;
import org.openrewrite.java.tree.*;

import java.time.Duration;
import java.util.*;
Expand Down Expand Up @@ -152,12 +149,15 @@ private static class VariableUses {
public static Map<J.VariableDeclarations.NamedVariable, List<J.Identifier>> find(J.VariableDeclarations declarations, J.ClassDeclaration parent) {
Map<J.VariableDeclarations.NamedVariable, List<J.Identifier>> found = new IdentityHashMap<>(declarations.getVariables().size());
Map<String, J.VariableDeclarations.NamedVariable> signatureMap = new HashMap<>();
Map<String, J.VariableDeclarations.NamedVariable> nameMap = new HashMap<>();

for (J.VariableDeclarations.NamedVariable variable : declarations.getVariables()) {
if (variable.getVariableType() != null) {
found.computeIfAbsent(variable, k -> new ArrayList<>());
// Note: Using a variable type signature is only safe to find uses of class fields.
signatureMap.put(variable.getVariableType().toString(), variable);
// Also map by name for fallback matching
nameMap.put(variable.getSimpleName(), variable);
}
}

Expand All @@ -167,17 +167,37 @@ public static Map<J.VariableDeclarations.NamedVariable, List<J.Identifier>> find
@Override
public J.Identifier visitIdentifier(J.Identifier identifier,
Map<J.VariableDeclarations.NamedVariable, List<J.Identifier>> identifiers) {
if (identifier.getFieldType() != null && signatureMap.containsKey(identifier.getFieldType().toString())) {
Cursor parent = getCursor().dropParentUntil(is ->
is instanceof J.VariableDeclarations ||
is instanceof J.ClassDeclaration);

if (!(parent.getValue() instanceof J.VariableDeclarations && parent.getValue() == declarations)) {
J.VariableDeclarations.NamedVariable name = signatureMap.get(identifier.getFieldType().toString());
if (declarations.getVariables().contains(name)) {
J.VariableDeclarations.NamedVariable used = signatureMap.get(identifier.getFieldType().toString());
identifiers.computeIfAbsent(used, k -> new ArrayList<>())
.add(identifier);
if (identifier.getFieldType() != null) {
J.VariableDeclarations.NamedVariable match = null;

// First try exact type signature match
String fieldTypeSignature = identifier.getFieldType().toString();
if (signatureMap.containsKey(fieldTypeSignature)) {
match = signatureMap.get(fieldTypeSignature);
} else if (identifier.getFieldType().getOwner() != null) {
// Fallback: match by name if it's a field reference from the same class
J.VariableDeclarations.NamedVariable nameMatch = nameMap.get(identifier.getSimpleName());
if (nameMatch != null && nameMatch.getVariableType() != null) {
// Check if the owner type matches the parent class type
JavaType.FullyQualified ownerType = TypeUtils.asFullyQualified(identifier.getFieldType().getOwner());
JavaType.FullyQualified parentType = parent.getType();
if (ownerType != null && parentType != null &&
ownerType.getFullyQualifiedName().equals(parentType.getFullyQualifiedName())) {
match = nameMatch;
}
}
}

if (match != null) {
Cursor parentCursor = getCursor().dropParentUntil(is ->
is instanceof J.VariableDeclarations ||
is instanceof J.ClassDeclaration);

if (!(parentCursor.getValue() instanceof J.VariableDeclarations && parentCursor.getValue() == declarations)) {
if (declarations.getVariables().contains(match)) {
identifiers.computeIfAbsent(match, k -> new ArrayList<>())
.add(identifier);
}
}
}
}
Expand Down
47 changes: 47 additions & 0 deletions src/test/java/org/openrewrite/staticanalysis/RemoveUnusedPrivateFieldsTest.java
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Original file line number Diff line number Diff line change
Expand Up @@ -485,4 +485,51 @@ public class Test {
)
);
}

@Issue("https://github.com/openrewrite/rewrite-static-analysis/issues/321")
@Test
void doNotRemoveFieldAfterTypeChange() {
rewriteRun(
spec -> spec.recipes(
new UseCollectionInterfaces(),
new RemoveUnusedPrivateFields()
),
//language=java
java(
"""
import java.util.Arrays;
import java.util.HashSet;

public class Main {
private static final HashSet<String> allowedMethods = new HashSet<>(Arrays.asList(
"GET", "HEAD", "TRACE", "OPTIONS"));

public boolean matches(String method) {
if (allowedMethods.contains(method)) {
return false;
}
return true;
}
}
""",
"""
import java.util.Arrays;
import java.util.HashSet;
import java.util.Set;

public class Main {
private static final Set<String> allowedMethods = new HashSet<>(Arrays.asList(
"GET", "HEAD", "TRACE", "OPTIONS"));

public boolean matches(String method) {
if (allowedMethods.contains(method)) {
return false;
}
return true;
}
}
"""
)
);
}
}