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Fix CombineSemanticallyEqualCatchBlocks for inner exception types #772

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Merged
merged 1 commit into from
Nov 7, 2025
Merged

Fix CombineSemanticallyEqualCatchBlocks for inner exception types #772

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53 changes: 30 additions & 23 deletions src/main/java/org/openrewrite/staticanalysis/CombineSemanticallyEqualCatchBlocks.java
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Original file line number Diff line number Diff line change
Expand Up @@ -75,7 +75,7 @@ public J visitTry(J.Try tryable, ExecutionContext ctx) {

if (!semanticallyEqualCatchesMap.isEmpty()) {
// Collect the identifiers of caught exceptions that are subtypes or implementations of an exception that is caught later in a different catch.
Map<J.Try.Catch, Map<J.Try.Catch, Set<J.Identifier>>> parentChildClassRelationship = new HashMap<>();
Map<J.Try.Catch, Map<J.Try.Catch, Set<NameTree>>> parentChildClassRelationship = new HashMap<>();
for (int i = 0; i < catches.size(); i++) {
J.Try.Catch from = catches.get(i);
for (int j = i + 1; j < catches.size(); j++) {
Expand All @@ -86,10 +86,10 @@ public J visitTry(J.Try tryable, ExecutionContext ctx) {
JavaType fromType = TypeUtils.asFullyQualified(fromException.getType());
JavaType toType = TypeUtils.asFullyQualified(toException.getType());
if (fromType != null && toType != null && TypeUtils.isAssignableTo(toType, fromType)) {
Map<J.Try.Catch, Set<J.Identifier>> subTypesMap = parentChildClassRelationship.computeIfAbsent(from, key -> new HashMap<>());
Set<J.Identifier> childClassIdentifiers = subTypesMap.computeIfAbsent(to, key -> new HashSet<>());
if (fromException instanceof J.Identifier) {
childClassIdentifiers.add((J.Identifier) fromException);
Map<J.Try.Catch, Set<NameTree>> subTypesMap = parentChildClassRelationship.computeIfAbsent(from, key -> new HashMap<>());
Set<NameTree> childClassIdentifiers = subTypesMap.computeIfAbsent(to, key -> new HashSet<>());
if (fromException instanceof J.Identifier || fromException instanceof J.FieldAccess) {
childClassIdentifiers.add(fromException);
}
}
}
Expand Down Expand Up @@ -171,11 +171,11 @@ static class RemoveCatches extends JavaVisitor<ExecutionContext> {
private static class CombineCatches extends JavaVisitor<ExecutionContext> {
private final J.Try.Catch scope;
private final List<J.Try.Catch> equivalentCatches;
private final Map<J.Try.Catch, Set<J.Identifier>> childClassesToExclude;
private final Map<J.Try.Catch, Set<NameTree>> childClassesToExclude;

CombineCatches(J.Try.Catch scope,
List<J.Try.Catch> equivalentCatches,
Map<J.Try.Catch, Set<J.Identifier>> childClassesToExclude) {
Map<J.Try.Catch, Set<NameTree>> childClassesToExclude) {
this.scope = scope;
this.equivalentCatches = equivalentCatches;
this.childClassesToExclude = childClassesToExclude;
Expand Down Expand Up @@ -211,24 +211,24 @@ public J visitCatch(J.Try.Catch _catch, ExecutionContext ctx) {
}

private List<JRightPadded<NameTree>> combineEquivalentCatches() {
Set<J.Identifier> removeIdentifiers = new HashSet<>();
Set<NameTree> removeExceptions = new HashSet<>();
List<JRightPadded<NameTree>> combinedCatches = new ArrayList<>();

for (J.Try.Catch equivalentCatch : equivalentCatches) {
Set<J.Identifier> childClasses = childClassesToExclude.get(equivalentCatch);
Set<NameTree> childClasses = childClassesToExclude.get(equivalentCatch);
if (childClasses != null) {
// Remove child classes that will be unnecessary since the parent exists in the new multi-catch.
removeIdentifiers.addAll(childClasses);
removeExceptions.addAll(childClasses);
}

TypeTree typeExpr = equivalentCatch.getParameter().getTree().getTypeExpression();
if (typeExpr instanceof J.MultiCatch) {
for (JRightPadded<NameTree> alternative : ((J.MultiCatch) typeExpr).getPadding().getAlternatives()) {
NameTree name = alternative.getElement();
if (removeExceptions.contains(name)) {
continue; // Skip redundant subtype
}
if (name instanceof J.Identifier) {
if (removeIdentifiers.contains((J.Identifier) name)) {
continue; // Skip redundant subtype
}
combinedCatches.add(alternative.withElement(((J.Identifier) name).withPrefix(EMPTY)));
} else if (name instanceof J.FieldAccess) {
combinedCatches.add(alternative.withElement(((J.FieldAccess) name).withPrefix(EMPTY)));
Expand All @@ -238,11 +238,14 @@ private List<JRightPadded<NameTree>> combineEquivalentCatches() {
}
} else if (typeExpr instanceof J.Identifier) {
J.Identifier identifier = (J.Identifier) typeExpr;
if (!removeIdentifiers.contains(identifier)) {
if (!removeExceptions.contains(identifier)) {
combinedCatches.add(JRightPadded.build(identifier.withPrefix(EMPTY)));
}
} else if (typeExpr instanceof J.FieldAccess) {
combinedCatches.add(JRightPadded.build(((J.FieldAccess) typeExpr).withPrefix(EMPTY)));
J.FieldAccess fieldAccess = (J.FieldAccess) typeExpr;
if (!removeExceptions.contains(fieldAccess)) {
combinedCatches.add(JRightPadded.build(fieldAccess.withPrefix(EMPTY)));
}
}
}

Expand All @@ -251,17 +254,21 @@ private List<JRightPadded<NameTree>> combineEquivalentCatches() {
List<JRightPadded<NameTree>> alternatives = ((J.MultiCatch) scopeExpr).getPadding().getAlternatives();
for (int i = alternatives.size() - 1; i >= 0; i--) {
NameTree name = alternatives.get(i).getElement();
if (name instanceof J.Identifier && !removeIdentifiers.contains(name)) {
combinedCatches.add(0, alternatives.get(i).withElement(((J.Identifier) name).withPrefix(EMPTY)));
} else if (!(name instanceof J.Identifier)) {
combinedCatches.add(0, alternatives.get(i));
if (!removeExceptions.contains(name)) {
if (name instanceof J.Identifier) {
combinedCatches.add(0, alternatives.get(i).withElement(((J.Identifier) name).withPrefix(EMPTY)));
} else {
combinedCatches.add(0, alternatives.get(i));
}
}
}
} else {
if (scopeExpr instanceof J.Identifier && !removeIdentifiers.contains(scopeExpr)) {
combinedCatches.add(0, JRightPadded.build(((J.Identifier) scopeExpr).withPrefix(EMPTY)));
} else if (scopeExpr instanceof J.FieldAccess) {
combinedCatches.add(0, JRightPadded.build(((J.FieldAccess) scopeExpr).withPrefix(EMPTY)));
if (!removeExceptions.contains(scopeExpr)) {
if (scopeExpr instanceof J.Identifier) {
combinedCatches.add(0, JRightPadded.build(((J.Identifier) scopeExpr).withPrefix(EMPTY)));
} else if (scopeExpr instanceof J.FieldAccess) {
combinedCatches.add(0, JRightPadded.build(((J.FieldAccess) scopeExpr).withPrefix(EMPTY)));
}
}
}

Expand Down
37 changes: 37 additions & 0 deletions src/test/java/org/openrewrite/staticanalysis/CombineSemanticallyEqualCatchBlocksTest.java
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Original file line number Diff line number Diff line change
Expand Up @@ -528,4 +528,41 @@ void method() {
)
);
}

@Issue("https://github.com/openrewrite/rewrite-static-analysis/issues/771")
@Test
void removeRedundantInnerExceptionWhenParentIsCaught() {
rewriteRun(
//language=java
java(
"""
class Outer {
public static class InnerException extends Exception {}
}
"""
),
//language=java
java(
"""
class Test {
void method() {
try {
} catch (Outer.InnerException e) {
} catch (Exception e) {
}
}
}
""",
"""
class Test {
void method() {
try {
} catch (Exception e) {
}
}
}
"""
)
);
}
}