OpenJDK11 build on macOS with autoconf 2.72 / -std=gnu++11 option

[Baesken, Matthias]

>So autoconf forcibly selects a -std= option, possibly overriding either an
>explicit option or the compiler's default.  Who thought that was a good idea?
>There are even comments from the time that question that "feature".
>
>It looks like there is code to attempt to deal with that sort of thing in our
>build system. See TOOLCHAIN_POST_DETECTION in make/autoconf/toolchain.m4. That
>dates back to JDK 9. However, that only deals with CFLAGS and CXXFLAGS. The
>AC_PROG_CC/CXX feature affects the CC/CXX variables. Bleh!

Hi Kim, it is not a nice thing; probably  the CXX could be overwritten when settings the  CXX env variable before running configure ?


>But I wonder why our explicit -std=gnu++98 (or whatever we were using) doesn't
>override that.  In the command lines are you seeing
>
>   "g++ ... -std=gnu++11 ... -std=c++14"

It is Openjdk11 ;  I only see the  -std=gnu++11  in the Hotspot compilation units.  Only  the harfbuzz  files  have  the  -std=gnu++11  ...  -std=c++11  so there it is overwritten ,
but looks like it compiles without issues with those settings in Hotspot  (as long as PCH is disabled)  .

>I have no idea why disabling PCH might change things in this area.

Good question, seems there is something  'special' with PCH  .


Best regards, Matthias