Copilot commented on code in PR #2826:
URL: https://github.com/apache/groovy/pull/2826#discussion_r3837895503
##########
src/main/java/org/codehaus/groovy/transform/stc/StaticTypeCheckingVisitor.java:
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@@ -4981,6 +4986,32 @@ && isOptimizedIntSwitch(selectorType,
expression.getCaseStatements())) {
}
}
+ /**
+ * Reports a repeated constant case label in a switch expression.
Sequential
+ * {@code isCase} semantics make the second arm dead code, and the
optimized
+ * {@code tableswitch}/{@code lookupswitch} forms cannot represent it at
all,
+ * so it is rejected here, uniformly for type-checked and
statically-compiled
+ * code (GROOVY-12289). Labels compared are the same ones the optimizers
key
+ * on: int-family, String and enum constants; anything else (GStrings,
calls,
+ * regex or collection labels) cannot be proven duplicated statically and
is
+ * left to sequential first-match-wins dispatch.
+ *
+ * @since 6.0.0
+ */
+ private void checkSwitchExpressionDuplicateLabels(final SwitchExpression
expression) {
+ ClassNode enumType =
unwrapEnumType(getType(expression.getExpression()));
+ Set<Object> seen = new HashSet<>();
+ for (CaseStatement caseStatement : expression.getCaseStatements()) {
+ Expression label = caseStatement.getExpression();
+ Object key = (enumType != null && enumType.isEnum()) ?
enumConstantName(label, enumType) : null;
+ if (key == null) key = intConstant(label);
+ if (key == null) key = stringConstant(label);
+ if (key != null && !seen.add(key)) {
Review Comment:
`enumConstantName` and `stringConstant` both produce `String` keys, so an
enum label like `E.X` (key "X") can collide with a string label `"X"` in the
same switch expression, incorrectly triggering a "Duplicate case label" error
even though the labels are different expressions and the presence of a non-enum
label already forces sequential `isCase` dispatch. Use a distinct key type for
enum constants (e.g., pair enum type + name) to avoid cross-type collisions
while still catching duplicates among enum constants.
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