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Fix IfElseIfConstructToSwitch dropping pattern variables for unresolvable types #1005

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Merged
timtebeek merged 3 commits into from
Mar 9, 2026
Merged

Fix IfElseIfConstructToSwitch dropping pattern variables for unresolvable types #1005

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c72fcab
Fix `IfElseIfConstructToSwitch` dropping pattern variables for unreso…
timtebeek Mar 9, 2026
dfd45b1
Merge branch 'main' into fix/if-else-switch-missing-pattern-vars
timtebeek Mar 9, 2026
db64e4b
Use `ListUtils.map` with index
timtebeek Mar 9, 2026
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85 changes: 64 additions & 21 deletions src/main/java/org/openrewrite/java/migrate/lang/IfElseIfConstructToSwitch.java
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Original file line number Diff line number Diff line change
Expand Up @@ -27,8 +27,10 @@
import org.openrewrite.java.search.UsesJavaVersion;
import org.openrewrite.java.tree.Expression;
import org.openrewrite.java.tree.J;
import org.openrewrite.java.tree.JRightPadded;
import org.openrewrite.java.tree.Space;
import org.openrewrite.java.tree.Statement;
import org.openrewrite.marker.Markers;
import org.openrewrite.staticanalysis.groovy.GroovyFileChecker;
import org.openrewrite.staticanalysis.kotlin.KotlinFileChecker;

Expand Down Expand Up @@ -225,36 +227,77 @@ public J.Return visitReturn(J.Return return_, AtomicBoolean atomicBoolean) {
* JavaTemplate uses raw string substitution (#{}), which loses type information
* for non-JDK types. This method restores the original type information from the
* instanceof checks onto the generated switch case labels.
* When the type is completely unresolvable, JavaTemplate may not produce a
* J.VariableDeclarations at all, so we reconstruct one from the original instanceof.
*/
private J.Switch fixTypeAttribution(J.Switch switch_) {
Iterator<J.InstanceOf> instanceOfs = patternMatchers.keySet().iterator();
// Cases are ordered: [null case (optional)], [pattern cases...], [default case]
int nullCaseOffset = nullCheckedParameter != null ? 1 : 0;
int patternCaseCount = patternMatchers.size();
return switch_.withCases(switch_.getCases().withStatements(
ListUtils.map(switch_.getCases().getStatements(), stmt -> {
if (stmt instanceof J.Case && instanceOfs.hasNext()) {
J.Case case_ = (J.Case) stmt;
if (!case_.getCaseLabels().isEmpty() && case_.getCaseLabels().get(0) instanceof J.VariableDeclarations) {
J.InstanceOf instanceOf = instanceOfs.next();
J.VariableDeclarations varDecl = (J.VariableDeclarations) case_.getCaseLabels().get(0);
// Replace typeExpression with the original clazz (which has proper type info)
varDecl = varDecl.withTypeExpression(
varDecl.getTypeExpression() != null ?
instanceOf.getClazz().withPrefix(varDecl.getTypeExpression().getPrefix()) :
instanceOf.getClazz().withPrefix(Space.EMPTY));
// Fix variable type from original pattern
if (instanceOf.getPattern() instanceof J.Identifier && !varDecl.getVariables().isEmpty()) {
J.Identifier originalPattern = (J.Identifier) instanceOf.getPattern();
J.VariableDeclarations.NamedVariable var0 = varDecl.getVariables().get(0);
varDecl = varDecl.withVariables(singletonList(
var0.withType(originalPattern.getType())
.withName(var0.getName().withType(originalPattern.getType()))));
}
return case_.withCaseLabels(singletonList(varDecl.withPrefix(case_.getCaseLabels().get(0).getPrefix())));
ListUtils.map(switch_.getCases().getStatements(), (currentIndex, stmt) -> {
if (!(stmt instanceof J.Case)) {
return stmt;
}
int patternIndex = currentIndex - nullCaseOffset;
if (patternIndex < 0 || patternIndex >= patternCaseCount || !instanceOfs.hasNext()) {
return stmt; // null case or default case
}
J.Case case_ = (J.Case) stmt;
J.InstanceOf instanceOf = instanceOfs.next();
J label = case_.getCaseLabels().get(0);

if (label instanceof J.VariableDeclarations) {
J.VariableDeclarations varDecl = (J.VariableDeclarations) label;
// Replace typeExpression with the original clazz (which has proper type info)
varDecl = varDecl.withTypeExpression(
varDecl.getTypeExpression() != null ?
instanceOf.getClazz().withPrefix(varDecl.getTypeExpression().getPrefix()) :
instanceOf.getClazz().withPrefix(Space.EMPTY));
// Fix variable type from original pattern
if (instanceOf.getPattern() instanceof J.Identifier && !varDecl.getVariables().isEmpty()) {
J.Identifier originalPattern = (J.Identifier) instanceOf.getPattern();
J.VariableDeclarations.NamedVariable var0 = varDecl.getVariables().get(0);
varDecl = varDecl.withVariables(singletonList(
var0.withType(originalPattern.getType())
.withName(var0.getName().withType(originalPattern.getType()))));
}
return case_.withCaseLabels(singletonList(varDecl.withPrefix(label.getPrefix())));
} else {
// JavaTemplate couldn't resolve the type, so no VariableDeclarations was produced.
// Reconstruct one from the original instanceof pattern.
return case_.withCaseLabels(singletonList(
buildVariableDeclarations(instanceOf, label.getPrefix())));
}
return stmt;
})));
}

@SuppressWarnings("deprecation")
private J.VariableDeclarations buildVariableDeclarations(J.InstanceOf instanceOf, Space prefix) {
J.Identifier pattern = (J.Identifier) instanceOf.getPattern();
J.VariableDeclarations.NamedVariable namedVar = new J.VariableDeclarations.NamedVariable(
Tree.randomId(),
Space.SINGLE_SPACE,
Markers.EMPTY,
pattern.withPrefix(Space.EMPTY),
Collections.emptyList(),
null,
null
);
return new J.VariableDeclarations(
Tree.randomId(),
prefix,
Markers.EMPTY,
Collections.emptyList(),
Collections.emptyList(),
instanceOf.getClazz().withPrefix(Space.EMPTY),
null,
null,
singletonList(JRightPadded.build(namedVar))
);
}

private Optional<Expression> switchOn() {
return patternMatchers.keySet().stream()
.map(J.InstanceOf::getExpression)
Expand Down
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