RFR: 8373668: Add override keyword to *Klass classes

[Kim Barrett]

On Mon, 15 Dec 2025 10:08:18 GMT, Axel Boldt-Christmas <aboldtch at openjdk.org> wrote:

> Using override provides better visibility and compiler support for suspicious virtual methods. It makes it clears when reading a class header file if a new virtual interface is introduced or if it simply overridden.
> 
> Testing
>  * GHA
>  * Running tier1 on Oracle supported platforms

Looks good.

A couple of pre-existing whitespace issues that you can fix or ignore.

I wonder if there would be any measurable benefit to using `final` instead in some
cases?  But that should be looked at separately.  It might be simpler to declare some
classes to be `final`.

src/hotspot/share/oops/instanceKlass.hpp line 906:

> 904:                                                   Array<InstanceKlass*>* transitive_interfaces) override;
> 905:   bool can_be_primary_super_slow() const override;
> 906:   size_t oop_size(oop obj)  const override    { return size_helper(); }

[pre-existing] Extra space before `const`.

src/hotspot/share/oops/instanceKlass.hpp line 952:

> 950:   }
> 951: 
> 952:   int size() const override           { return size(vtable_length(),

[pre-existing] Weird and confusing indentation for the arguments to `size(...)`.

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Marked as reviewed by kbarrett (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/28820#pullrequestreview-3577725050
PR Review Comment: https://git.openjdk.org/jdk/pull/28820#discussion_r2619059748
PR Review Comment: https://git.openjdk.org/jdk/pull/28820#discussion_r2619057335