[RFR] JDK-8156980: Hotspot build doesn't have -std=gnu++98 gcc option

[Erik Joelsson]

Hello,

In general it looks good. It's nice to see that this also fixes that 
warning output from configure. My only nit is the comment describing the 
parameters for FLAGS_SETUP_GCC6_COMPILER_FLAGS. It indicates that it 
takes named parameters while it actually just takes positional. Please 
either change it to named parameters or fix the comment.

Thanks for fixing this!

/Erik

On 2016-07-05 07:27, Andrew Hughes wrote:
> Webrev: http://cr.openjdk.java.net/~andrew/8156980/webrev.01/
> Bug: https://bugs.openjdk.java.net/browse/JDK-8156980
>
> With "8151841: Build needs additional flags to compile with GCC 6",
> we added a number of compiler flags which were needed to build
> OpenJDK with GCC 6. Checks for these flags were added to configure,
> and the flags passed to the JDK and HotSpot builds by CFLAGS/CXXFLAGS_JDK
> and hotspot-spec.gmk.in respectively.
>
> Following "8152666: The new Hotspot Build System" and
> "8150601: Remove the old Hotspot build system", the hotspot-spec.gmk.in
> file was removed, so the flags were no longer passed to the HotSpot
> build. HotSpot now uses JVM_CFLAGS via the same configure process
> as the JDK obtains CFLAGS_JDK and CXXFLAGS_JDK[*].
>
> This webrev fixes the regression introduced by 8152666 by adding
> the flags to JVM_CFLAGS. It also adapts FLAGS_SETUP_GCC6_COMPILER_FLAGS
> to take a prefix, as other macros in flags.m4 do, and calls
> TOOLCHAIN_PREPARE_FOR_VERSION_COMPARISONS before the version check.
> The lack of the latter lead to configure executing:
>
> if test $OPENJDK_BUILD_COMPARABLE_ACTUAL_VERSION -ge $COMPARABLE_REFERENCE_VERSION
>
> with OPENJDK_BUILD_COMPARABLE_ACTUAL_VERSION ever being set, causing
> test to print an error.
>
> With this fix, the flags again make it into the build.
>
> [*] It should really be CXXFLAGS_JVM as they are flags for the C++ compiler.