OpenJDK fails to build with GCC when the #include<time.h> inside zip.cpp comes from a non-sysroot path

[Florian Weimer]

* Patrick Zhang:

> When I build on the latest jdk/jdk code base with GCC 8.2 (configured
> sysroot as a customized path instead of default root directory of the
> linux system),

I doubt it has anything to do with a sysroot vs non-sysroot
configuration.

> it failed with error:
> "jdk.pack/share/native/common-unpack/zip.cpp:420:23: error:
> declaration of 'tm* gmtime_r(const time_t*, tm*)' has a different
> exception specifier".

The declaration of gmtime_r should be removed.  Apparently, the comment
in the OpenJDK is wrong and the declaration is included even on
non-Solaris systems.

With glibc, you can declare your own gmtime_r function this way, but not
if you include the <time.h> header.  GCC 9 will also warn if we add
additional attributes (e.g. for nonnull warnings), so replicating the
declaration from <time.h> is a losing battle.

Which system needs the gmtime_r macro definition?  Windows?

Thanks,
Florian