Warnings cross-building AARCH64 package with GCC 6.2.1 (-Wlto-type-mismatch)

[Rebecca Cran <rebecca@bluestop.org>]

I suspect I should be trying to build AARCH64 stuff with something more
like gcc 4.8 instead of 6.2.1, but when I did build the
Overdrive1000Board package I saw lots of warnings complaining about the
implementation not matching the prototype (with
the warning being -Wlto-type-mismatch).  

I cross-compiled on an OpenSUSE x64 system with
aarch64-suse-linux-gcc-6, with the commandline:

build -a AARCH64 -t GCC5 -b RELEASE -p
OpenPlatformPkg/Platforms/AMD/Styx/Overdrive1000Board/Overdrive1000Board.dsc

ArmPlatformPkg is from
linaro git master, edk2 is tianocore git master

The warnings were all similar to:

/workspace/edk2/MdePkg/Include/Library/BaseMemoryLib.h:462:1:
warning: type of 'IsZeroGuid' does not match original declaration
[-Wlto-type-mismatch] IsZeroGuid ( ^
//workspace/edk2/MdePkg/Library/BaseMemoryLibOptDxe/Arm/MemLibGuid.c:158:1:
note: 'IsZeroGuid' was previously declared here IsZeroGuid (
 ^
/workspace/edk2/MdePkg/Library/BaseMemoryLibOptDxe/Arm/MemLibGuid.c:158:1:
note: code may be misoptimized unless -fno-strict-aliasing is used



Are these real problems, or just because gcc 6.2 and/or LTO aren't ready
for AARCH64 yet?


-- 
Rebecca