Compilation fails on linux

[madmaxoft]

I tried compiling MCS on my VPS and the compilation failed:

cc1plus: error: unrecognized command line option "-Wsuggest-attribute=pure"
cc1plus: error: unrecognized command line option "-Wsuggest-attribute=const"

g++ --version reports:

g++ (Gentoo 4.4.7 p1.2, pie-0.4.5) 4.4.7

[sphinxc0re]

Yeah although you are running gentoo, you have an outdated version of gcc installed I guess. Try updating your server.

[madmaxoft]

I can't, it's a semi-managed hosting. I don't have root access.
But it's only a stupid flag error, can't we detect the proper flags or something?

[sphinxc0re]

Then contact the support. The current version of GCC is 4.9 so they are already a few versions behind.
What we could do is manually enable all the Wflags accept for the one shown above... but that would be very hard work to do. There is a tremendous amount of flags in GCC...

[worktycho]

Also that looks like a gcc driver compiler mismatch. We don't actually pass that flag to gcc anywhere.

[sphinxc0re]

Of course you do! You automatically give the compiler the -Wall flag which shows all the warnings

[madmaxoft]

I don't think passing -Wall should enable a flag that the compiler doesn't know

[worktycho]

@madmaxoft whats the command line cmake's feeding gcc? If you compile with VERBOSE=1 to the makefile it should tell you.

[madmaxoft]

Yes, it is there, although I have no idea where it came from:

cd /container/home/MCServer/Release/lib/SQLiteCpp && /usr/bin/c++   -DXML_STATIC -pthread          -fsigned-char -O2 -g -DNDEBUG -I/container/home/MCServer/lib/SQLiteCpp/include -I/container/home/MCServer/lib/sqlite    -rdynamic -fstack-protector-all -Wall -Wextra -pedantic -Wformat-security -Winit-self -Wswitch-default -Wswitch-enum -Wfloat-equal -Wshadow -Wcast-qual -Wconversion -Wlogical-op -Winline -Wsuggest-attribute=pure -Wsuggest-attribute=const -fPIC -o CMakeFiles/SQLiteCpp.dir/src/Column.cpp.o -c /container/home/MCServer/lib/SQLiteCpp/src/Column.cpp

[worktycho]

What cmake version are you running?

[madmaxoft]

2.8.12.2

[worktycho]

There's something weird going on with your cmake. I'd check the defaults for the $CMAKE_CXX_FLAGS var

[madmaxoft]

How do I do that? Remember, I'm a linux noob

[worktycho]

I'd create a cmakelist thet is just:

message($CMAKE_CXX_FLAGS)

Then try and build it.

[archshift]

Remember--you can compile GCC! If all else fails, that's what you can do, that or downloading a newer GCC binary (but not installing it).

[madmaxoft]

Both CXX and C flags are empty. I used the following CMakeLists.txt file:

enable_language(CXX C)
message("C Flags: " "${CMAKE_C_FLAGS}")
message("CXX Flags: " "${CMAKE_CXX_FLAGS}")

The output is:

-- The C compiler identification is GNU 4.4.7
-- The CXX compiler identification is GNU 4.4.7
-- Check for working C compiler: /usr/bin/cc
-- Check for working C compiler: /usr/bin/cc -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working CXX compiler: /usr/bin/c++
-- Check for working CXX compiler: /usr/bin/c++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
C FLAGS:
CXX FLAGS:
-- Configuring done
-- Generating done
-- Build files have been written to: /container/home/test/cmake

[worktycho]

Found the problem. SQLiteCPP are inserting the flag. They recommend 4.7.2 but if you can't use that I suggest you raise the issue with them.