RFR(S): JDK-8247938: Change various JVM enums like LinkInfo::AccessCheck and Klass::DefaultsLookupMode to enum class

[Lois Foltan]

Thanks Coleen!
Lois

On 8/3/2020 11:44 AM, coleen.phillimore at oracle.com wrote:
> +1.  It was a good suggestion.
> Coleen
>
> On 8/3/20 11:39 AM, Harold Seigel wrote:
>> Hi Lois,
>>
>> The new changes look good!
>>
>> Thanks, Harold
>>
>> On 8/3/2020 11:12 AM, Lois Foltan wrote:
>>>
>>>
>>>
>>>
>>> On 8/1/2020 5:47 AM, Kim Barrett wrote:
>>>>> On Jul 31, 2020, at 1:55 PM, Lois Foltan <lois.foltan at oracle.com> 
>>>>> wrote:
>>>>>
>>>>> Please review the webrev to change the following unscoped 
>>>>> enumeration declarations to scoped enumerations.
>>>>>
>>>>> Klass::DefaultsLookupMode
>>>>> Klass::OverpassLookupMode
>>>>> Klass::StaticLookupMode
>>>>> Klass::PrivateLookupMode
>>>>> LinkInfo::AccessCheck
>>>>>
>>>>> With C++11/14 enum class provides the added type safety to prevent 
>>>>> 0 (integral) or false (boolean) to be implicitly converted to 
>>>>> AccessCheck::needs_access_check for example.
>>>>>
>>>>> open webrev 
>>>>> at:http://cr.openjdk.java.net/~lfoltan/bug_jdk8247938.0/webrev/ 
>>>>> <http://cr.openjdk.java.net/~lfoltan/bug_jdk8247938.0/webrev/index.html> 
>>>>>
>>>>> bug link: https://bugs.openjdk.java.net/browse/JDK-8247938
>>>>>
>>>>> Testing: hs-tier1 & 2 complete, hs-tier3-6 in progress
>>>>>
>>>>> Thanks,
>>>>> Lois
>>>> Looks good.
>>>>
>>>> For what it's worth, I didn't notice any cases here that seemed 
>>>> like they
>>>> would significantly benefit from C++20 "using enum":
>>>> http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2019/p1099r5.html
>>>> (Though it could have been used to signficantly reduce the size of 
>>>> the change.)
>>>>
>>>> However, it does seem like some of the enumerators might benefit 
>>>> from a name
>>>> change, since they are now referred to by names that are qualified 
>>>> by the
>>>> enum type name.  For example, instead of this:
>>>>
>>>>   199   enum class DefaultsLookupMode { find_defaults, 
>>>> skip_defaults };
>>>>   200   enum class OverpassLookupMode { find_overpass, 
>>>> skip_overpass };
>>>>   201   enum class StaticLookupMode   { find_static, skip_static };
>>>>   202   enum class PrivateLookupMode  { find_private, skip_private };
>>>>
>>>> maybe use this:
>>>>
>>>>   199   enum class DefaultsLookupMode { find, skip };
>>>>   200   enum class OverpassLookupMode { find, skip };
>>>>   201   enum class StaticLookupMode   { find, skip };
>>>>   202   enum class PrivateLookupMode  { find, skip };
>>>>
>>>> since (for example) DefaultsLookupMode::find is obviously distinct 
>>>> from
>>>> StaticLookupMode::find, with the numerator suffixes being redundant.
>>>>
>>>> Similarly, in class LinkInfo, perhaps:
>>>>    enum class AccessCheck { required, skip };
>>>>
>>>> But that sort of thing can be done separately, assuming it's deemed
>>>> desirable.  Getting the benfit of the improved type safety is the 
>>>> important
>>>> part of this change.
>>>>
>>>>
>>>
>>> Thank you Kim for the review!  I do like your suggestion of changing 
>>> the names of the enumerators.  New webrev to include that renaming 
>>> as part of this change.
>>>
>>> New webrev at: 
>>> http://cr.openjdk.java.net/~lfoltan/bug_jdk8247938.1/webrev
>>>
>>> Retesting hs-tier1-3.
>>>
>>> Thanks,
>>> Lois
>