RFR 8203488: Remove error generation from TransTypes

[Vicente Romero]

can the HYPOTHETICAL flag be removed now?

On 05/22/2018 02:18 PM, Maurizio Cimadamore wrote:
>
> Submitted new revision; changes:
>
> * removed more code from TransTypes (HYPOTHETICAL and other stuff)
>
> * added a new error when polysig metods are called with wrong -target 
> (note, this will go away in 12, as the 6 target will be dropped, so I 
> don't think we need to spend too many cycles on this)
>
> Webrev:
>
> http://cr.openjdk.java.net/~mcimadamore/8203488-v2/
>
> Cheers
>
> Maurizio
>
>
> On 21/05/18 18:30, Maurizio Cimadamore wrote:
>>
>> Hi,
>> as written in the bug report, TransTypes generates two kind of 
>> user-facing errors:
>>
>> 1) bridge clash
>>
>> 2) arity mismatch due to sig poly invocation with -target 6
>>
>> We can simply get rid of (1) as we now have Attr checking that 
>> override/hide do not clash. We can also get rid of (2), by reworking 
>> the fix that introduced it (JDK-8013179 
>> <https://bugs.openjdk.java.net/browse/JDK-8013179>). The issue there 
>> was that, when compiling code that contained a call to 
>> MethodHandle.invoke, with target -6, the compiler was left in a limbo 
>> between polysig methods (which have sharp signatures) and the 
>> underlying Java vararg signature (which is not sharp at all). Since 
>> the target method was a 'varargs' but the call itself was not a 
>> varargs call, javac complained about an arity mismatch.
>>
>> The solution to this problem is to either use polysig type-checking 
>> or regular type-checking depending on whether the support is enabled 
>> in the backend. If a polysig call is treated as a true polysig call, 
>> we emit a symbol with a sharp descriptor, set the resolution phase to 
>> BASIC (no varargs, no boxing) and we just treat it as a regular call 
>> from there on. This simplified a number of places (e.g. Attr.checkId 
>> and LambdaToMethod) where we needed to special case polysig methods.
>>
>> If backend support for polysig method is disabled (-target 6), then 
>> we treat a polysig method as a varargs method; meaning that we leave 
>> resolution phase as VARARGS, and then javac will do regular vararg 
>> conversion (e.g. box arguments into an array and pass that to the 
>> method). This of course doesn't make much sense for polysig methods 
>> such as MethodHandle.invoke, but the user gets what he's asking for 
>> by compiling code that has polysig call using a target that doesn't 
>> know what polysig methods even are.
>>
>> Of course, same code would fail to compile if using --release 6 (as 
>> MethodHandle API was not there in 6).
>>
>> Webrev:
>>
>> http://cr.openjdk.java.net/~mcimadamore/8203488/
>>
>> Maurizio
>>
>>
>>
>>
>

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.openjdk.java.net/pipermail/compiler-dev/attachments/20180522/f8449739/attachment.html>