On Tue, 12 Nov 2024 16:15:31 GMT, Vicente Romero <vrom...@openjdk.org> wrote:
>> Javac is not issuing a mandated unchecked cast warning for code like:
>>
>>
>> import java.lang.invoke.VarHandle;
>>
>> class VarHandleCast<V> {
>> VarHandle vh;
>> V method(Object obj) {
>> return (V)vh.getAndSet(this, obj);
>> }
>> }
>>
>>
>> according to the spec the return type inferred for this method polymorphic
>> method should be Object see:
>>
>> - If the compile-time declaration for the method invocation is a signature
>> polymorphic method, then:
>> ...
>> – The compile-time result is determined as follows:
>> Otherwise, if the method invocation expression is the operand of a
>> cast
>> expression (§15.16), the compile-time result is the erasure of the type
>> of the
>> cast expression (§4.6).
>>
>> javac is not doing the type erasure mandated by the spec which is what this
>> PR is fixing
>>
>> TIA
>>
>> Note: I had to add some annotations to suppress warnings in java.base that
>> were not being issued before due to the javac bug
>
> Vicente Romero has updated the pull request incrementally with one additional
> commit since the last revision:
>
> adding regression test
src/jdk.compiler/share/classes/com/sun/tools/javac/code/Source.java line 266:
> 264: MODULE_IMPORTS(JDK23, Fragments.FeatureModuleImports,
> DiagKind.PLURAL),
> 265: PRIVATE_MEMBERS_IN_PERMITS_CLAUSE(JDK19),
> 266: COMPILE_TIME_TYPE_SIG_POLYMORPHIC_MTH(JDK24),
Nit: I'd pick a name that is more representative of what the behavior is. E.g.
`erase_poly_sig_return_type`. Same for the field in `Infer` storing the boolean
flag.
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PR Review Comment: https://git.openjdk.org/jdk/pull/21914#discussion_r1840566249
