RFR: JDK-8301076: Replace NULL with nullptr in share/prims/ [v2]

[David Holmes]

On Mon, 30 Jan 2023 09:30:36 GMT, Johan Sjölen <jsjolen at openjdk.org> wrote:

>> Hi, this PR changes all occurrences of NULL to nullptr for the subdirectory share/prims/. 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 suggested changes

A few adjustments but overall looks good. Thanks.

src/hotspot/share/prims/jni.cpp line 2166:

> 2164:     bool is_latin1 = java_lang_String::is_latin1(s);
> 2165:     buf = NEW_C_HEAP_ARRAY_RETURN_NULL(jchar, s_len + 1, mtInternal);  // add one for zero termination
> 2166:     /* JNI Specification states return nullptr on OOM */

null

src/hotspot/share/prims/jvmtiCodeBlobEvents.cpp line 56:

> 54: // collector.collect();
> 55: // JvmtiCodeBlobDesc* blob = collector.first();
> 56: // while (blob != null) {

nullptr

src/hotspot/share/prims/jvmtiEnv.cpp line 581:

> 579: 
> 580:   if (event_thread == nullptr) {
> 581:     // Can be called at Agent_OnLoad() time with event_thread == null

nullptr

src/hotspot/share/prims/jvmtiEnvBase.hpp line 170:

> 168:   };
> 169: 
> 170:   // If (thread == null) then return current thread object.

nullptr

src/hotspot/share/prims/jvmtiEnvBase.hpp line 184:

> 182:     oop cur_obj = current->jvmti_vthread();
> 183: 
> 184:     // cur_obj == null is true for normal platform threads only

nullptr

src/hotspot/share/prims/jvmtiEventController.hpp line 214:

> 212: 
> 213:   // Use (thread == null) to enable/disable an event globally.
> 214:   // Use (thread != null) to enable/disable an event for a particular thread.

nullptr

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Marked as reviewed by dholmes (Reviewer).

PR: https://git.openjdk.org/jdk/pull/12188