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Merged
stephan-herrmann merged 1 commit into from
Jul 31, 2026
+77 −6
Merged

Missing unchecked cast warning in polymorphic method call #5260

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4 changes: 4 additions & 0 deletions ...pse.jdt.core.compiler.batch/src/org/eclipse/jdt/internal/compiler/ast/CastExpression.java
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Original file line number Diff line number Diff line change
Expand Up @@ -655,10 +655,12 @@ public TypeBinding resolveType(BlockScope scope) {
}
TypeBinding expressionType = this.expression.resolveType(scope);
TypeBinding originalExpressionType = expressionType;
boolean isPolymorphicMethod = false;
if (this.expression instanceof MessageSend) {
MessageSend messageSend = (MessageSend) this.expression;
MethodBinding methodBinding = messageSend.binding;
if (methodBinding != null && methodBinding.isPolymorphic()) {
isPolymorphicMethod = true;
messageSend.binding = scope.environment().updatePolymorphicMethodReturnType((PolymorphicMethodBinding) methodBinding, castType);
if (TypeBinding.notEquals(expressionType, castType)) {
expressionType = castType;
Expand All @@ -681,6 +683,8 @@ public TypeBinding resolveType(BlockScope scope) {
}
boolean isLegal = checkCastTypesCompatibility(scope, castType, originalExpressionType, this.expression, true);
if (isLegal) {
if (isPolymorphicMethod)
this.bits &= ~ASTNode.GenerateCheckcast;
this.expression.computeConversion(scope, castType, expressionType);
if ((this.bits & ASTNode.UnsafeCast) != 0) { // unsafe cast
if (scope.compilerOptions().reportUnavoidableGenericTypeProblems
Expand Down
79 changes: 73 additions & 6 deletions ...compiler/src/org/eclipse/jdt/core/tests/compiler/regression/PolymorphicSignatureTest.java
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Original file line number Diff line number Diff line change
Expand Up @@ -13,8 +13,10 @@
*******************************************************************************/
package org.eclipse.jdt.core.tests.compiler.regression;

import java.io.IOException;
import junit.framework.Test;
import org.eclipse.jdt.core.tests.compiler.regression.AbstractRegressionTest.JavacTestOptions.JavacHasABug;
import org.eclipse.jdt.core.util.ClassFormatException;

@SuppressWarnings({ "rawtypes" })
public class PolymorphicSignatureTest extends AbstractRegressionTest {
Expand Down Expand Up @@ -118,20 +120,18 @@ public void testBug475996() {
"}\n"
});
}
public void testGH3651() {
public void testGH3651() throws ClassFormatException, IOException {
Runner runner = new Runner();
runner.testFiles = new String[] {
"VarHandleCast.java",
"""
String source = """
import java.lang.invoke.VarHandle;
class VarHandleCast<V> {
VarHandle vh;
V method(Object obj) {
return (V)vh.getAndSet(this, obj);
}
}
"""
};
""";
runner.testFiles = new String[] { "VarHandleCast.java", source };
runner.expectedCompilerLog = """
----------
1. WARNING in VarHandleCast.java (at line 5)
Expand All @@ -142,5 +142,72 @@ V method(Object obj) {
""";
runner.javacTestOptions = JavacHasABug.JavacBug8343286;
runner.runWarningTest();

String expectedOutput = """
// Method descriptor #19 (Ljava/lang/Object;)Ljava/lang/Object;
// Signature: (Ljava/lang/Object;)TV;
// Stack: 3, Locals: 2
java.lang.Object method(java.lang.Object obj);
0 aload_0 [this]
1 getfield VarHandleCast.vh : java.lang.invoke.VarHandle [22]
4 aload_0 [this]
5 aload_1 [obj]
6 invokevirtual java.lang.invoke.VarHandle.getAndSet(VarHandleCast, java.lang.Object) : java.lang.Object [24]
9 areturn
Line numbers:
[pc: 0, line: 5]
Local variable table:
[pc: 0, pc: 10] local: this index: 0 type: VarHandleCast
[pc: 0, pc: 10] local: obj index: 1 type: java.lang.Object
Local variable type table:
[pc: 0, pc: 10] local: this index: 0 type: VarHandleCast<V>
""";
checkClassFile("VarHandleCast", source, expectedOutput);
}
public void testGH3651_noCheckcast() throws ClassFormatException, IOException {
String source = """
import java.lang.invoke.MethodHandle;
import java.util.function.Function;

public class CheckCast {
static Function<Object, String> createValueGetter(MethodHandle methodHandle) {
return a -> {
try {
return (String) methodHandle.invokeExact(a); // CHECKCAST String added
} catch (Throwable e) {
throw new IllegalStateException(e);
}
};
}
}
""";
runConformTest(new String[] { "CheckCast.java", source });
String expectedOutput = """
// Method descriptor #24 (Ljava/lang/invoke/MethodHandle;Ljava/lang/Object;)Ljava/lang/String;
// Stack: 3, Locals: 3
private static synthetic java.lang.String lambda$0(java.lang.invoke.MethodHandle arg0, java.lang.Object a);
0 aload_0 [arg0]
1 aload_1 [a]
2 invokevirtual java.lang.invoke.MethodHandle.invokeExact(java.lang.Object) : java.lang.String [25]
5 areturn
6 astore_2 [e]
7 new java.lang.IllegalStateException [31]
10 dup
11 aload_2 [e]
12 invokespecial java.lang.IllegalStateException(java.lang.Throwable) [33]
15 athrow
Exception Table:
[pc: 0, pc: 5] -> 6 when : java.lang.Throwable
Line numbers:
[pc: 0, line: 8]
[pc: 6, line: 9]
[pc: 7, line: 10]
Local variable table:
[pc: 0, pc: 16] local: a index: 1 type: java.lang.Object
[pc: 7, pc: 16] local: e index: 2 type: java.lang.Throwable
Stack map table: number of frames 1
[pc: 6, same_locals_1_stack_item, stack: {java.lang.Throwable}]
""";
checkClassFile("CheckCast", source, expectedOutput);
}
}
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