C++11 freestanding headers not found

Hello everyone,

I’ve recently discovered the LLVM project and Clang, and I am quite happy with it (nice piece of work!). However, I can’t figure why this fails:

$ cat > freestanding.cpp


$ clang -c -std=c++11 -ffreestanding --target=i386-none-elf freestanding.cpp
bug.cpp:1:10: fatal error: ‘cstdint’ file not found
1 error generated.

Trying to compile a source file that merely includes a C++11 header file with the -ffreestanding flag just fails. The same problem occurs for every C++11 freestanding header (, , …). However, trying to include the pre-C++11 freestanding headers (<stdint.h>, <stddef.h>, <limits.h>, …) works just fine. I have also tried different targets.

Any idea? Is this some configuration issue? Or some glitch? I can hardly find any information about this problem, this is why I am asking you people.

Have a nice day,


Clang does not provide an implementation of the freestanding C++ headers;
you need a C++ standard library (typically libc++ or libstdc++) installed
to provide those. (You also need a C standard library to provide the foo.h
headers that the C++ standard library itself depends on.)

For certain C standard library headers, there is an informal arrangement
between the C standard library implementation and the compiler that the
compiler will provide certain of the headers -- stddef.h, stdarg.h, and a
few others (which need or significantly benefit from compiler magic) --
although the compiler's version will often defer to the C stdlib version if
it exists. But this does not extend to a complete set of freestanding

If you have a C++ standard library installed, Clang should automatically
detect it. If it doesn't, we'd want:

* the output of clang -v when compiling a C++ source file
* information about where the standard library was installed

to determine why it wasn't automatically found.