Hi Andreas,
Thanks for sending this out. I’ve been experiencing issues on Mac using clang,
the issue in detail is:
Scons tries to build a test program including message.h from protobuf to check
if the protobuf C libraries are present
Protobuf versions later than 3.3.0 use the LANG_CXX11 macro without defining it
first, in at least one of their files (atom.h).
This causes the compilation of the test program to fail , due to the -Wundef
directive being set, and scons assuming that no protobuf is available in the
system.
The quick and dirty fix which I have on my local workspace is to remove -Wundef
from Sconstruct, which anyway never triggered before with the exception of
protobuf (on MSC_VER in the past, now on LANG_CXX11), see below:
main.Append(CCFLAGS=['-fno-strict-aliasing'])
# Enable -Wall and -Wextra and then disable the few warnings that
# we consistently violate
- main.Append(CCFLAGS=['-Wall', '-Wundef', '-Wextra',
+ main.Append(CCFLAGS=['-Wall', '-Wextra',
'-Wno-sign-compare', '-Wno-unused-parameter'])
# We always compile using C++11
main.Append(CXXFLAGS=['-std=c++11'])
From: Andreas Sandberg <[email protected]>
Date: Wednesday, 21 March 2018 at 15:25
To: gem5 Developer List <[email protected]>
Cc: Gabe Black <[email protected]>, Matteo Andreozzi
<[email protected]>
Subject: Protobuf compilation errors
Hi Everyone,
We have been experiencing some issues with some combinations of
different versions of protobuf and gcc/clang. Most of the issues seem to
be related to undefined macros (-Wundef), but I have some vague memories
of other issues as well (unclear indentation?).
In the short term, it seems like we need to disable -Werror for files
that are generated by protoc. Another option would be to add
-Wno-error=undef to the global environment. What would be the preferred
solution here? I think I'm in favour of the former, but don't understand
the build system well enough to implement it.
Cheers,
Andreas
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