Hi, please fix the CI errors. You can also add test_cpp to check_PROGRAMS.

Where is export CC=clang set? I cannot find it, but it should also set CXX=clang++.

Should be set by AC_PROG_CC and AC_PROG_CXX

https://www.gnu.org/software/autoconf/manual/autoconf-2.66/html_node/C_002b_002b-Compiler.html

No, the export is done before calling bootstrap. I think the above change to Travis setting might do it...

I had to set it to require C++11, because the other headers seem to just be broken. This does require you to have autoconf-archive installed to run ./bootstrap, or we can copy the C++11 autoconf check into the source.

However, I have no idea what's wrong with clang on Ubuntu+Travis. It seems to just be broken.

I had to set it to require C++11

I may not be following all this, but this might be a pretty big deal for readxl.

readxl doesn't use any of the C++ files, and they are not required. It's merely a test program.

OK, finally it seems to be working. I don't know why Travis' clang is broken OOTB. It works fine in a Ubuntu Trusty docker container using distro-provided packages.

Thanks for all the work on this one!