RFR: 8254050: HotSpot Style Guide should permit using the "override" virtual specifier [v2]

[Kim Barrett]

> Please review and vote on this change to the HotSpot Style Guide to permit
> the use of `override` virtual specifiers.  The virtual specifiers `override`
> and `final` were added in C++11, and use of `final` is already permitted in
> HotSpot code.
> 
> Using the `override` specifier provides error checking that the function is
> indeed overriding a virtual function declared in a base class.  This can
> prevent some often surprisingly difficult to spot bugs.
> 
> This is a modification of the Style Guide, so rough consensus among
> the HotSpot Group members is required to make this change.  Only Group
> members should vote for approval (via the github PR), though reasoned
> objections or comments from anyone will be considered.  A decision on
> this proposal will not be made before Tuesday 30-Mar-2021 at 12h00 UTC.
> 
> Since we're piggybacking on github PRs here, please use the PR review
> process to approve (click on Review Changes > Approve), rather than
> sending a "vote: yes" email reply that would be normal for a CFV.
> Other responses can still use email of course.

Kim Barrett has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains two additional commits since the last revision:

 - Merge branch 'master' into override_specifier
 - permit override specifier

-------------

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/3021/files
  - new: https://git.openjdk.java.net/jdk/pull/3021/files/a48a6036..375a916e

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=3021&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=3021&range=00-01

  Stats: 42617 lines in 2058 files changed: 23969 ins; 9403 del; 9245 mod
  Patch: https://git.openjdk.java.net/jdk/pull/3021.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/3021/head:pull/3021

PR: https://git.openjdk.java.net/jdk/pull/3021