RFR: 8368966: Remove spurious VMStructs friends

[Stefan Karlsson]

On Tue, 30 Sep 2025 16:35:36 GMT, Francesco Andreuzzi <fandreuzzi at openjdk.org> wrote:

> In this PR I propose a small clean up to remove several spurious friends of `VMStructs`. Either I could not find any reference to them in `vmStructs*`, or no private symbols is mentioned.
> 
> Passes tier1 and tier2 (fastdebug).

src/hotspot/share/utilities/growableArray.hpp line 715:

> 713: template <typename E>
> 714: class GrowableArray : public GrowableArrayWithAllocator<E, GrowableArray<E>> {
> 715:   friend class VMStructs;

I was a bit surprised to see that you added a friend declaration. Was this done because you removed the one in the parent class?

I see that vmStructs.cpp has GrowableArray listed:

  nonstatic_field(GrowableArrayBase,           _len,                                          int)                                   \
  nonstatic_field(GrowableArrayBase,           _capacity,                                     int)                                   \
  nonstatic_field(GrowableArray<int>,          _data,                                         int*) 


So, I guess it makes sense to move it here. OTOH, the exposed `_data` field is inside GrowableArrayView, so maybe it would work to put the friend declaration there instead?

I guess either way is fine but there's a risk that there will be some churn about where to put the friend declaration if someone wants add one of the classes between (and including) GrowableArrayView and GrowableArray.

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PR Review Comment: https://git.openjdk.org/jdk/pull/27583#discussion_r2393707385