fatal error 'cmath' file not found when building llvm for vmkit

[llvmbot]

Bugzilla Link	12180
Version	trunk
OS	Linux
Reporter	LLVM Bugzilla Contributor
CC	@asl,@efriedma-quic

Extended Description

I wanted to try out llvm-vmkit and followed the steps at this link:
http://vmkit.llvm.org/get_started.html

After checking out llvm and clang, I did a ./configure and make. I get these errors. /home/ganapathy/projects/llvm is the svn trunk check out. Pasting the errors below.

In file included from Atomic.cpp:14:
In file included from /home/ganapathy/projects/llvm/include/llvm/Support/Atomic.h:17:
/home/ganapathy/projects/llvm/include/llvm/Support/DataTypes.h:37:10: fatal error: 'cmath' file not found
#include
^
1 error generated.
make[1]: *** [/home/ganapathy/projects/llvm/lib/Support/Release+Asserts/Atomic.o] Error 1
make[1]: Leaving directory `/home/ganapathy/projects/llvm/lib/Support'
make: *** [all] Error 1

PS: Since this is a fatal build error, I am setting it to release blocker severity. Not sure how this project uses severity. Thanks

[efriedma-quic]

That error means you have an existing version of clang on your system which somehow isn't properly configured to compile C++ code. You can force configure to use gcc with "CC=gcc CXX=g++ ./configure", or just uninstall whatever version of clang you have installed.

[asl]

That error means you have an existing version of clang on your system which
somehow isn't properly configured to compile C++ code. You can force configure
to use gcc with "CC=gcc CXX=g++ ./configure", or just uninstall whatever
version of clang you have installed.
Give that this is pretty often seen problem, I'd suggest to enable "use clang first" logic on MacOS only and stick with old behavior (try gcc first) everywhere else.

[efriedma-quic]

Hmm... or maybe we could make the configure checks a bit more elaborate? In any case, probably better to bring it up on llvmdev.

[llvmbot]

first" logic on MacOS only and stick with old behavior (try gcc first)
everywhere else.

Yeah, I would agree with this option of trying to use gcc first. Pretty much all GNU/Linux machines come with a properly configured gcc.

Also, I don't understand the logic behind marking it as INVALID, given that the installer does fail if there is a version of clang(may be misconfigured, but again it is a bug on clang installer).

[efriedma-quic]

I think it's pretty clearly a bug in your Linux distribution if it provides a clang++ that appears to work for the configure test, but can't actually compile anything but the most trivial C++ code.

[efriedma-quic]

That said, it might be a common enough misconfiguration that we should do something about it.

[llvmbot]

I think it's pretty clearly a bug in your Linux distribution if it provides a
clang++ that appears to work for the configure test, but can't actually compile
anything but the most trivial C++ code.

Possible. But I think I installed clang from source. Also, this is just an opinion, I run Debian Sqeeze. They normally check it. But I will double check how I installed clang. If it is a distro error, it would be necessary to file a bug there as well. Thanks for suggesting. :)

[asl]

vmkit is dead