Linux Include are gone?

[retro-dwsz]

So I usually download the ucrt windows version, and I'm good with it for years. Now I have a Linux VM, and I want to try coding C/C++ on Linux, but after I downloaded the Ubuntu version, I got this:

rdvorzak-vmware@fedora:~/Desktop/Code/CPP-CS-HybridProgramming/Test Platform$ clang++ Extern.cpp -shared -o Extern_LINUX.X64.so Extern.cpp -fPIC -std=c++23 -O3 -m64 -static
Extern.cpp:34:10: fatal error: 'cmath' file not found
   34 | #include <cmath>
      |          ^~~~~~~
1 error generated.
Extern.cpp:34:10: fatal error: 'cmath' file not found
   34 | #include <cmath>
      |          ^~~~~~~
1 error generated.
rdvorzak-vmware@fedora:~/Desktop/Code/CPP-CS-HybridProgramming/Test Platform$ clang++ Extern.cpp -shared -o Extern_LINUX.X64.so Extern.cpp -fPIC -std=c++23 -O3 -m64 -static -v
clang version 20.1.7 (https://github.com/llvm/llvm-project.git 6146a88f60492b520a36f8f8f3231e15f3cc6082)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /home/rdvorzak-vmware/Desktop/Code/LLVM/llvm/bin
 "/home/rdvorzak-vmware/Desktop/Code/LLVM/llvm/bin/clang-20" -cc1 -triple x86_64-unknown-linux-gnu -emit-obj -dumpdir Extern_LINUX.X64.so- -disable-free -clear-ast-before-backend -disable-llvm-verifier -discard-value-names -main-file-name Extern.cpp -static-define -mrelocation-model pic -pic-level 2 -fhalf-no-semantic-interposition -mframe-pointer=none -fmath-errno -ffp-contract=on -fno-rounding-math -mconstructor-aliases -funwind-tables=2 -target-cpu x86-64 -tune-cpu generic -debugger-tuning=gdb "-fdebug-compilation-dir=/home/rdvorzak-vmware/Desktop/Code/CPP-CS-HybridProgramming/Test Platform" -v "-fcoverage-compilation-dir=/home/rdvorzak-vmware/Desktop/Code/CPP-CS-HybridProgramming/Test Platform" -resource-dir /home/rdvorzak-vmware/Desktop/Code/LLVM/llvm/lib/clang/20 -c-isystem /usr/include -c-isystem /usr/include/x86_64-linux-gnu -cxx-isystem /usr/include -cxx-isystem /usr/include/x86_64-linux-gnu -internal-isystem /home/rdvorzak-vmware/Desktop/Code/LLVM/llvm/lib/clang/20/include -internal-isystem /usr/local/include -internal-externc-isystem /include -internal-externc-isystem /usr/include -O3 -std=c++23 -fdeprecated-macro -ferror-limit 19 -fgnuc-version=4.2.1 -fno-implicit-modules -fskip-odr-check-in-gmf -fcxx-exceptions -fexceptions -fcolor-diagnostics -vectorize-loops -vectorize-slp -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o /tmp/Extern-fccefe.o -x c++ Extern.cpp
clang -cc1 version 20.1.7 based upon LLVM 20.1.7 default target x86_64-unknown-linux-gnu
ignoring nonexistent directory "/usr/include/x86_64-linux-gnu"
ignoring nonexistent directory "/usr/include/x86_64-linux-gnu"
ignoring nonexistent directory "/include"
ignoring duplicate directory "/usr/include"
#include "..." search starts here:
#include <...> search starts here:
 /usr/include
 /home/rdvorzak-vmware/Desktop/Code/LLVM/llvm/lib/clang/20/include
 /usr/local/include
End of search list.
Extern.cpp:34:10: fatal error: 'cmath' file not found
   34 | #include <cmath>
      |          ^~~~~~~
1 error generated.
 "/home/rdvorzak-vmware/Desktop/Code/LLVM/llvm/bin/clang-20" -cc1 -triple x86_64-unknown-linux-gnu -emit-obj -dumpdir Extern_LINUX.X64.so- -disable-free -clear-ast-before-backend -disable-llvm-verifier -discard-value-names -main-file-name Extern.cpp -static-define -mrelocation-model pic -pic-level 2 -fhalf-no-semantic-interposition -mframe-pointer=none -fmath-errno -ffp-contract=on -fno-rounding-math -mconstructor-aliases -funwind-tables=2 -target-cpu x86-64 -tune-cpu generic -debugger-tuning=gdb "-fdebug-compilation-dir=/home/rdvorzak-vmware/Desktop/Code/CPP-CS-HybridProgramming/Test Platform" -v "-fcoverage-compilation-dir=/home/rdvorzak-vmware/Desktop/Code/CPP-CS-HybridProgramming/Test Platform" -resource-dir /home/rdvorzak-vmware/Desktop/Code/LLVM/llvm/lib/clang/20 -c-isystem /usr/include -c-isystem /usr/include/x86_64-linux-gnu -cxx-isystem /usr/include -cxx-isystem /usr/include/x86_64-linux-gnu -internal-isystem /home/rdvorzak-vmware/Desktop/Code/LLVM/llvm/lib/clang/20/include -internal-isystem /usr/local/include -internal-externc-isystem /include -internal-externc-isystem /usr/include -O3 -std=c++23 -fdeprecated-macro -ferror-limit 19 -fgnuc-version=4.2.1 -fno-implicit-modules -fskip-odr-check-in-gmf -fcxx-exceptions -fexceptions -fcolor-diagnostics -vectorize-loops -vectorize-slp -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o /tmp/Extern-728bac.o -x c++ Extern.cpp
clang -cc1 version 20.1.7 based upon LLVM 20.1.7 default target x86_64-unknown-linux-gnu
ignoring nonexistent directory "/usr/include/x86_64-linux-gnu"
ignoring nonexistent directory "/usr/include/x86_64-linux-gnu"
ignoring nonexistent directory "/include"
ignoring duplicate directory "/usr/include"
#include "..." search starts here:
#include <...> search starts here:
 /usr/include
 /home/rdvorzak-vmware/Desktop/Code/LLVM/llvm/lib/clang/20/include
 /usr/local/include
End of search list.
Extern.cpp:34:10: fatal error: 'cmath' file not found
   34 | #include <cmath>
      |          ^~~~~~~
1 error generated.

And I checked: Where's the Includes?

But windows Include is good?

[mstorsjo]

This is a toolchain for building things for windows. You can use it to compile things for windows, on linux, macos and also on windows itself.

The windows headers are bundled in all of them, in the unix packages they're in <prefix>/generic-w64-mingw32/include. In packages for running on windows, they're in <prefix>/include mostly because symlink support on Windows and in zip files isn't ubiquitous.

The LLVM tools included can be used for compiling for Linux and macOS too, but that's not a primary intent of it. Using the tools for compiling for the host OS (or anything else than the bundled mingw targets) require you to provide the necessary system headers and libraries. Or in other words, to compile for Linux, you need to install the system development packages from your Linux distribution. And once you do that you can probably just as well install the distribution's default compiler as well (an possibly install Clang from your Linux distribution that way).

To use this toolchain to cross compile for Windows, on Linux, you need to invoke a triple prefixed compiler, like x86_64-w64-mingw32-clang++ rather than plain clang++ (but that doesn't seem to be what you want to do).

[retro-dwsz]

Ach, thanks, I'll figure this out