RFR: 8311247: Some cpp files are compiled with -std:c11 flag

[Julian Waters]

On Tue, 1 Aug 2023 03:37:55 GMT, Sergey Bylokhov <serb at openjdk.org> wrote:

>> Please review this patch that configures C++ arguments on build jobs that involve compiling CPP files. As a result of this change, CPP files are compiled with `-std:c++14` command line argument instead of `-std:c11`, which is used when C++ arguments are not configured.
>> While at it, I simplified the `java.security.jgss/Lib.gmk` file by moving the additional include directory to `EXTRA_HEADER_DIRS`.
>> 
>> This patch fixes the following clang warning:
>> 
>> warning: argument unused during compilation: '-std:c11'
>> 
>> 
>> Microsoft states that [std:c++14 is the default](https://learn.microsoft.com/en-us/cpp/build/reference/std-specify-language-standard-version?view=msvc-170), so there shouldn't be any differences in produced code.
>> 
>> Testing:
>> - verified that after the changes, all CPP files are compiled with `std:c++14` instead of `-std:c11`
>> - spot-checked a few `cmdline` files that changed after this patch was applied; the `-std` change was the only difference
>> - tier1-5 builds, tier1-2 tests and client libs tests continue to pass on Windows, Linux & MacOS.
>
> Did we document the current standard of C++ and C we can use?

@mrserb We use C11 and C++14, and we're soon to move to C++17 once the AIX port gets a compiler that can accept it

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PR Comment: https://git.openjdk.org/jdk/pull/14758#issuecomment-1659518095