RFR: 8314488: Compile the JDK as C++17

[Kim Barrett]

On Mon, 24 Jul 2023 01:41:16 GMT, Julian Waters <jwaters at openjdk.org> wrote:

> Implementation of [JEP draft: Compile the JDK as C++17](https://bugs.openjdk.org/browse/JDK-8310260)

Nearly ready.  Still need to figure out the minimum compiler versions to require.

src/hotspot/os_cpu/linux_riscv/vm_version_linux_riscv.cpp line 77:

> 75: #define read_csr(csr)                                           \
> 76: ({                                                              \
> 77:         unsigned long __v;                                      \

Can this change be made separately?  I'd like to have the C++17 switch be as clean as possible.

src/hotspot/share/memory/allocation.cpp line 114:

> 112: //
> 113: 
> 114: void* AnyObj::operator new(size_t size, Arena *arena) {

This change was recently made as part of JDK-8317132.

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Changes requested by kbarrett (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/14988#pullrequestreview-1783283088
PR Review Comment: https://git.openjdk.org/jdk/pull/14988#discussion_r1427655730
PR Review Comment: https://git.openjdk.org/jdk/pull/14988#discussion_r1427654886