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Merged
timtebeek merged 3 commits into from
Aug 9, 2023
Merged

Do not remove unused variables with constructor calls #147

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3a05d68
Do not remove unused variables with constructor calls
timtebeek Aug 7, 2023
af16f71
Also visitNewClass for side effects
timtebeek Aug 7, 2023
8457ab2
Document another uncovered case
timtebeek Aug 7, 2023
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63 changes: 35 additions & 28 deletions src/main/java/org/openrewrite/staticanalysis/RemoveUnusedLocalVariables.java
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Original file line number Diff line number Diff line change
Expand Up @@ -80,19 +80,19 @@ public TreeVisitor<?, ExecutionContext> getVisitor() {
private Cursor getCursorToParentScope(Cursor cursor) {
return cursor.dropParentUntil(is ->
is instanceof J.ClassDeclaration ||
is instanceof J.Block ||
is instanceof J.MethodDeclaration ||
is instanceof J.ForLoop ||
is instanceof J.ForEachLoop ||
is instanceof J.ForLoop.Control ||
is instanceof J.ForEachLoop.Control ||
is instanceof J.Case ||
is instanceof J.Try ||
is instanceof J.Try.Resource ||
is instanceof J.Try.Catch ||
is instanceof J.MultiCatch ||
is instanceof J.Lambda ||
is instanceof JavaSourceFile
is instanceof J.Block ||
is instanceof J.MethodDeclaration ||
is instanceof J.ForLoop ||
is instanceof J.ForEachLoop ||
is instanceof J.ForLoop.Control ||
is instanceof J.ForEachLoop.Control ||
is instanceof J.Case ||
is instanceof J.Try ||
is instanceof J.Try.Resource ||
is instanceof J.Try.Catch ||
is instanceof J.MultiCatch ||
is instanceof J.Lambda ||
is instanceof JavaSourceFile
);
}

Expand All @@ -106,20 +106,20 @@ public J.VariableDeclarations.NamedVariable visitVariable(J.VariableDeclarations
Cursor parentScope = getCursorToParentScope(getCursor());
J parent = parentScope.getValue();
if (parentScope.getParent() == null ||
// skip class instance variables. parentScope.getValue() covers java records.
parentScope.getParent().getValue() instanceof J.ClassDeclaration || parentScope.getValue() instanceof J.ClassDeclaration ||
// skip anonymous class instance variables
parentScope.getParent().getValue() instanceof J.NewClass ||
// skip if method declaration parameter
parent instanceof J.MethodDeclaration ||
// skip if defined in an enhanced or standard for loop, since there isn't much we can do about the semantics at that point
parent instanceof J.ForLoop.Control || parent instanceof J.ForEachLoop.Control ||
// skip if defined in a try's catch clause as an Exception variable declaration
parent instanceof J.Try.Resource || parent instanceof J.Try.Catch || parent instanceof J.MultiCatch ||
// skip if defined as a parameter to a lambda expression
parent instanceof J.Lambda ||
// skip if the initializer may have a side effect
initializerMightSideEffect(variable)
// skip class instance variables. parentScope.getValue() covers java records.
parentScope.getParent().getValue() instanceof J.ClassDeclaration || parentScope.getValue() instanceof J.ClassDeclaration ||
// skip anonymous class instance variables
parentScope.getParent().getValue() instanceof J.NewClass ||
// skip if method declaration parameter
parent instanceof J.MethodDeclaration ||
// skip if defined in an enhanced or standard for loop, since there isn't much we can do about the semantics at that point
parent instanceof J.ForLoop.Control || parent instanceof J.ForEachLoop.Control ||
// skip if defined in a try's catch clause as an Exception variable declaration
parent instanceof J.Try.Resource || parent instanceof J.Try.Catch || parent instanceof J.MultiCatch ||
// skip if defined as a parameter to a lambda expression
parent instanceof J.Lambda ||
// skip if the initializer may have a side effect
initializerMightSideEffect(variable)
) {
return variable;
}
Expand Down Expand Up @@ -179,6 +179,12 @@ public J.MethodInvocation visitMethodInvocation(J.MethodInvocation methodInvocat
return methodInvocation;
}

@Override
public J.NewClass visitNewClass(J.NewClass newClass, AtomicBoolean result) {
result.set(true);
return newClass;
}

@Override
public J.Assignment visitAssignment(J.Assignment assignment, AtomicBoolean result) {
result.set(true);
Expand Down Expand Up @@ -219,9 +225,10 @@ public J.MethodInvocation visitMethodInvocation(J.MethodInvocation m, ExecutionC
@EqualsAndHashCode(callSuper = true)
private static class AssignmentToLiteral extends JavaVisitor<ExecutionContext> {
J.Assignment assignment;

@Override
public J visitAssignment(J.Assignment a, ExecutionContext executionContext) {
if(assignment.isScope(a)) {
if (assignment.isScope(a)) {
return a.getAssignment().withPrefix(a.getPrefix());
}
return a;
Expand Down
62 changes: 62 additions & 0 deletions src/test/java/org/openrewrite/staticanalysis/RemoveUnusedLocalVariablesTest.java
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Original file line number Diff line number Diff line change
Expand Up @@ -15,7 +15,9 @@
*/
package org.openrewrite.staticanalysis;

import org.junit.jupiter.api.Nested;
import org.junit.jupiter.api.Test;
import org.junitpioneer.jupiter.ExpectedToFail;
import org.openrewrite.DocumentExample;
import org.openrewrite.Issue;
import org.openrewrite.test.RecipeSpec;
Expand Down Expand Up @@ -1011,4 +1013,64 @@ fun foo() {
)
);
}

@Test
void retainJavaUnusedLocalVariableWithNewClass() {
rewriteRun(
java(
"""
class A {}
class B {
void foo() {
A a = new A();
}
}
"""
)
);
}

@Nested
class Kotlin {

@Test
void retainUnusedLocalVariableWithNewClass() {
rewriteRun(
kotlin(
"""
class A {}
class B {
fun foo() {
val a = A();
}
}
"""
)
);
}

@Test
@ExpectedToFail("Not yet implemented")
void retainUnusedLocalVariableConst() {
rewriteRun(
kotlin(
"""
package constants
const val FOO = "bar"
"""
),
kotlin(
"""
package config
import constants.FOO
fun baz() {
val foo = FOO
println(foo)
}
"""
)
);
}

}
}