RFR: addressing several issues in the implementation of universal tvars [v6]

[Vicente Romero]

On Tue, 7 Jun 2022 14:41:50 GMT, Maurizio Cimadamore <mcimadamore at openjdk.org> wrote:

>> Vicente Romero has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   adding structural type comparator to detect unchecked conversions
>
> src/jdk.compiler/share/classes/com/sun/tools/javac/code/Types.java line 1217:
> 
>> 1215:                     }
>> 1216:                 }
>> 1217:                 return isSameType(t, s);
> 
> Here you delegate to isSameType... which seems odd - as this is the only place where we do this.

right, fixing it

> src/jdk.compiler/share/classes/com/sun/tools/javac/code/Types.java line 1221:
> 
>> 1219: 
>> 1220:             public boolean compareTypeArgsRecursive(Type t, Type s) {
>> 1221:                 TypePair pair = new TypePair(t, s);
> 
> This is typically needed in subtyping routines, to prevent against cases where we could expand terms forever. But in the case of a structural comparison, this can never happen?

with wildcards yes, unless we rewrite the visitor adding a method for wildcards

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PR: https://git.openjdk.java.net/valhalla/pull/684