RFR: JDK-8301224: Replace NULL with nullptr in share/gc/shared/ [v2]

[Kim Barrett]

On Mon, 30 Jan 2023 09:24:37 GMT, Johan Sjölen <jsjolen at openjdk.org> wrote:

>> Hi, this PR changes all occurrences of NULL to nullptr for the subdirectory share/gc/shared/. Unfortunately the script that does the change isn't perfect, and so we
>> need to comb through these manually to make sure nothing has gone wrong. I also review these changes but things slip past my eyes sometimes.
>> 
>> Here are some typical things to look out for:
>> 
>> 1. No changes but copyright header changed (probably because I reverted some changes but forgot the copyright).
>> 2. Macros having their NULL changed to nullptr, these are added to the script when I find them. They should be NULL.
>> 3. nullptr in comments and logs. We try to use lower case "null" in these cases as it reads better. An exception is made when code expressions are in a comment.
>> 
>> An example of this:
>> 
>> ```c++
>> // This function returns null
>> void* ret_null();
>> // This function returns true if *x == nullptr
>> bool is_nullptr(void** x);
>> 
>> 
>> Note how `nullptr` participates in a code expression here, we really are talking about the specific value `nullptr`.
>> 
>> Thanks!
>
> Johan Sjölen has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Fix kimbarrett's suggestions

Changes requested by kbarrett (Reviewer).

src/hotspot/share/gc/shared/oopStorage.hpp line 107:

> 105:   // Allocates and returns a new entry.  Returns null if memory allocation
> 106:   // failed.  Locks _allocation_mutex.
> 107:   // postcondition: result == null or *result == nullptr.

Inconsistent mix of "null" and "nullptr".

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PR: https://git.openjdk.org/jdk/pull/12249