make fails on OS X (because of llvm clang compiler?)

[jrwagz]

The make step of the build steps fails on OS X, this is likely because OS X is tryi

/bin/sh ../../../libtool  --tag=CXX   --mode=compile g++ -DHAVE_CONFIG_H -I. -I../../../../src/kml/engine -I../../..  -I../../../../src -I../../../../third_party/boost_1_34_1 -I../../../../third_party/googletest-r108/include  -Wall -Wextra -Wno-unused-parameter -Werror -ansi -pedantic -Wno-long-long -fno-rtti -g -O2 -MT kml_file.lo -MD -MP -MF .deps/kml_file.Tpo -c -o kml_file.lo ../../../../src/kml/engine/kml_file.cc
libtool: compile:  g++ -DHAVE_CONFIG_H -I. -I../../../../src/kml/engine -I../../.. -I../../../../src -I../../../../third_party/boost_1_34_1 -I../../../../third_party/googletest-r108/include -Wall -Wextra -Wno-unused-parameter -Werror -ansi -pedantic -Wno-long-long -fno-rtti -g -O2 -MT kml_file.lo -MD -MP -MF .deps/kml_file.Tpo -c ../../../../src/kml/engine/kml_file.cc  -fno-common -DPIC -o .libs/kml_file.o
../../../../src/kml/engine/kml_file.cc:41:19: error: unused variable 'kDefaultXmlns' [-Werror,-Wunused-const-variable]
static const char kDefaultXmlns[] = "http://www.opengis.net/kml/2.2";
                  ^
1 error generated.
make[4]: *** [kml_file.lo] Error 1
make[3]: *** [all-recursive] Error 1
make[2]: *** [all-recursive] Error 1
make[1]: *** [all-recursive] Error 1
make: *** [all] Error 2
Justins-MacBook-Air:build jwagner$ gcc --version
Configured with: --prefix=/Applications/Xcode.app/Contents/Developer/usr --with-gxx-include-dir=/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.9.sdk/usr/include/c++/4.2.1
Apple LLVM version 5.1 (clang-503.0.40) (based on LLVM 3.4svn)
Target: x86_64-apple-darwin13.2.0
Thread model: posix
Justins-MacBook-Air:build jwagner$ 

I'm guessing this has something to do with the fact that the build also fails on Travis CI, when the clang compiler is used.

[jrwagz]

See https://travis-ci.org/jrwagz/libkml/jobs/27096953 for failure log using clang

[kubark42]

It looks like the compiler is being pedantic. The compiler flags -Werror,-Wunused-const-variable are causing the error with the unused variable. It might be that the right action is simply to remove this variable.

[jrwagz]

Agreed, I'm trying to get to the bottom of this locally right now. I've modified the source files that have unused variables and now I'm getting one last lamo error from clang:

Making all in examples
Making all in domviewer
make[3]: Nothing to be done for `all'.
Making all in engine
g++ -DHAVE_CONFIG_H -I. -I../../../examples/engine -I../..  -I../../../src -I../../../third_party/boost_1_34_1  -Wall -Werror -ansi -pedantic -Wno-long-long -fno-rtti -g -O2 -MT balloonwalker.o -MD -MP -MF .deps/balloonwalker.Tpo -c -o balloonwalker.o ../../../examples/engine/balloonwalker.cc
mv -f .deps/balloonwalker.Tpo .deps/balloonwalker.Po
/bin/sh ../../libtool  --tag=CXX   --mode=link g++ -Wall -Werror -ansi -pedantic -Wno-long-long -fno-rtti -g -O2   -o balloonwalker balloonwalker.o ../../src/kml/engine/libkmlengine.la ../../src/kml/dom/libkmldom.la ../../src/kml/base/libkmlbase.la -lexpat 
libtool: link: g++ -Wall -Werror -ansi -pedantic -Wno-long-long -fno-rtti -g -O2 -o .libs/balloonwalker balloonwalker.o -Wl,-bind_at_load  ../../src/kml/engine/.libs/libkmlengine.dylib /Users/jwagner/Dropbox/Developer/stake_clerk/libkml/build/src/kml/base/.libs/libkmlbase.dylib ../../src/kml/dom/.libs/libkmldom.dylib ../../src/kml/base/.libs/libkmlbase.dylib /Users/jwagner/Dropbox/Developer/stake_clerk/libkml/build/third_party/.libs/libminizip.dylib -lz /Users/jwagner/Dropbox/Developer/stake_clerk/libkml/build/third_party/.libs/liburiparser.dylib -lexpat
clang: error: argument unused during compilation: '-ansi'
make[3]: *** [balloonwalker] Error 1
make[2]: *** [all-recursive] Error 1
make[1]: *** [all-recursive] Error 1
make: *** [all] Error 2
Justins-MacBook-Air:build jwagner$

I've tried adding CFLAGS="$CFLAGS -Qunused-arguments" to configure.ac per http://stackoverflow.com/a/14248722/1709223 but it's still not getting past this error.

[kubark42]

Crazy, I've never heard of a compiler failing on an unused argument. In any case, I don't think there's a strong reason to limit ourselves to the 1989 ANSI C implementation, so this flag can probably be removed completely, or at the least replaced by -std=c89

[kubark42]

As expected, Travis failed on clang: https://travis-ci.org/kubark42/libkml/jobs/27100230

(The good news is that it succeeded on gcc, so we know Travis is configured properly.)

[jrwagz]

So I tried to figure out where the -ansi was coming from in our config, but it wasn't clear. I agree we can remove it, any idea how to do that?

[kubark42]

No ideas yet, but I'll poke around at it a bit, as well.

To be honest, I'd be perfectly fine to get rid of autoconf. In my experience it's just one more thing to break. Since Travis can do cross-platform CI, it should be easy to make sure cross-platform always works.

[jrwagz]

I agree.

[kubark42]

In the meantime, https://www.gnu.org/savannah-checkouts/gnu/autoconf/manual/autoconf-2.69/html_node/C-Compiler.html indicates how to use macros like AC_PROG_CC_C99, which should call a different compiler standard.

[jrwagz]

grr... tried adding AC_PROG_CC_C99 and still got no love

make[3]: Nothing to be done for `all'.
make[3]: Nothing to be done for `all-am'.
Making all in examples
Making all in domviewer
make[3]: Nothing to be done for `all'.
Making all in engine
g++ -DHAVE_CONFIG_H -I. -I../../../examples/engine -I../..  -I../../../src -I../../../third_party/boost_1_34_1  -Wall -Werror -ansi -pedantic -Wno-long-long -fno-rtti -g -O2 -MT balloonwalker.o -MD -MP -MF .deps/balloonwalker.Tpo -c -o balloonwalker.o ../../../examples/engine/balloonwalker.cc
mv -f .deps/balloonwalker.Tpo .deps/balloonwalker.Po
/bin/sh ../../libtool  --tag=CXX   --mode=link g++ -Wall -Werror -ansi -pedantic -Wno-long-long -fno-rtti -g -O2   -o balloonwalker balloonwalker.o ../../src/kml/engine/libkmlengine.la ../../src/kml/dom/libkmldom.la ../../src/kml/base/libkmlbase.la -lexpat 
libtool: link: g++ -Wall -Werror -ansi -pedantic -Wno-long-long -fno-rtti -g -O2 -o .libs/balloonwalker balloonwalker.o -Wl,-bind_at_load  ../../src/kml/engine/.libs/libkmlengine.dylib /Users/jwagner/Dropbox/Developer/stake_clerk/libkml/build/src/kml/base/.libs/libkmlbase.dylib ../../src/kml/dom/.libs/libkmldom.dylib ../../src/kml/base/.libs/libkmlbase.dylib /Users/jwagner/Dropbox/Developer/stake_clerk/libkml/build/third_party/.libs/libminizip.dylib -lz /Users/jwagner/Dropbox/Developer/stake_clerk/libkml/build/third_party/.libs/liburiparser.dylib -lexpat
clang: error: argument unused during compilation: '-ansi'
make[3]: *** [balloonwalker] Error 1
make[2]: *** [all-recursive] Error 1
make[1]: *** [all-recursive] Error 1
make: *** [all] Error 2
Justins-MacBook-Air:build jwagner$

[jrwagz]

It just clicked to me, I'm seeing this error in the linking stage, not the compiling stage. So I need to look at modifying the linker flags, not the compiler flags.