RFR: JDK-8235621: Replace use of Function<?,Integer> with ToIntFunction

[forax at univ-mlv.fr]

----- Mail original -----
> De: "jonathan gibbons" <jonathan.gibbons at oracle.com>
> À: "Remi Forax" <forax at univ-mlv.fr>
> Cc: "compiler-dev" <compiler-dev at openjdk.java.net>
> Envoyé: Mardi 10 Décembre 2019 02:28:23
> Objet: Re: RFR: JDK-8235621: Replace use of Function<?,Integer> with ToIntFunction

> Rémi,
> 
> While I understand the use of wildcards for parameters and return types, I don't
> think it makes sense to allow/use "? super Symbol" in this situation.  I'd
> prefer to keep it simple and just use ToIntFunction<Symbol>.

but you are forcing people that that already have a ToIntFunction<super type of Symbol> to do a lambda to lambda conversion which is weird

ToIntFunction<Object> extraAttributes = (Object o) -> 12;
addExtraAttributes(extraAttributes::applyAsInt);  // WTF ?

instead of

ToIntFunction<Object> extraAttributes = (Object o) -> 12;
addExtraAttributes(extraAttributes);

> 
> -- Jon

Rémi

> 
> 
> On 12/09/2019 05:20 PM, Remi Forax wrote:
>> Hi Jonathan,
>> for addExtraAttributes, the method should be
>>
>>    public void addExtraAttributes(ToIntFunction<? super Symbol> addExtraAttributes)
>>    {
>>
>> for the same reason a public method should take a List and not an ArrayList, so
>> you can call it with
>>    addExtraAttributes((Object o) -> 12);
>> if the attribute is constant.
>>
>> If addExtraAttributes takes a ToIntFunction<? super Symbol>, you will have to
>> use ToIntFunction<? super Symbol> everywhere.
>>
>> I should propose a new JEP to lock Dan Smith into a prison until JEP 300 [1] is
>> delivered, because we will be able to get ride of most of those pesky wildcards
>> (at least all the ones on functional interfaces) if that JEP is delivered.
>>
>> regards,
>> Rémi
>>
>> [1] https://openjdk.java.net/jeps/300
>>
>> ----- Mail original -----
>>> De: "jonathan gibbons" <jonathan.gibbons at oracle.com>
>>> À: "compiler-dev" <compiler-dev at openjdk.java.net>
>>> Envoyé: Mardi 10 Décembre 2019 01:38:44
>>> Objet: RFR: JDK-8235621: Replace use of Function<?,Integer> with ToIntFunction
>>> Following Rémi's suggestion[1], please review a trivial change to javac
>>> to have it use ToIntFunction
>>> instead of Function<..., Integer> in the recent patch for JDK-8234689 [2].
>>>
>>> Patch inline below. No change to the original test is necessary.
>>>
>>> JBS: https://bugs.openjdk.java.net/browse/JDK-8235621
>>> [1]
>>> https://mail.openjdk.java.net/pipermail/compiler-dev/2019-December/014043.html
>>> [2] https://hg.openjdk.java.net/jdk/jdk/rev/17b0f051280f
>>>
>>> -- Jon
>>>
>>> diff -r 2aaa8bcb90a9 -r 1e000f399f3a
>>> src/jdk.compiler/share/classes/com/sun/tools/javac/jvm/ClassWriter.java
>>>
>>> ---
>>> a/src/jdk.compiler/share/classes/com/sun/tools/javac/jvm/ClassWriter.java
>>> Mon Dec 09 15:28:46 2019 +0100
>>> +++
>>> b/src/jdk.compiler/share/classes/com/sun/tools/javac/jvm/ClassWriter.java
>>> Mon Dec 09 16:12:42 2019 -0800
>>> @@ -30,7 +30,7 @@
>>>   import java.util.Map;
>>>   import java.util.Set;
>>>   import java.util.LinkedHashSet;
>>> -import java.util.function.Function;
>>> +import java.util.function.ToIntFunction;
>>>
>>>   import javax.tools.JavaFileManager;
>>>   import javax.tools.FileObject;
>>> @@ -114,7 +114,7 @@
>>>        */
>>>       public boolean multiModuleMode;
>>>
>>> -    private List<Function<Symbol, Integer>> extraAttributeHooks =
>>> List.nil();
>>> +    private List<ToIntFunction<Symbol>> extraAttributeHooks = List.nil();
>>>
>>>       /** The initial sizes of the data and constant pool buffers.
>>>        *  Sizes are increased when buffers get full.
>>> @@ -191,7 +191,7 @@
>>>           }
>>>       }
>>>
>>> -    public void addExtraAttributes(Function<Symbol, Integer>
>>> addExtraAttributes) {
>>> +    public void addExtraAttributes(ToIntFunction<Symbol>
>>> addExtraAttributes) {
>>>           extraAttributeHooks =
>>> extraAttributeHooks.prepend(addExtraAttributes);
>>>       }
>>>
>>> @@ -1669,7 +1669,7 @@
>>>        */
>>>       protected int writeExtraAttributes(Symbol sym) {
>>>           int i = 0;
>>> -        for (Function<Symbol, Integer> hook : extraAttributeHooks) {
>>> +        for (ToIntFunction<Symbol> hook : extraAttributeHooks) {
>>>               i += hook.apply(sym);
>>>           }
> >>            return i;