clang++: fatal error: 'unistd.h' file not found - c++

Using OS X 10.10.2, I download Clang for Mac OS X v. 3.6.0, and try to compile a simple Hello World program.
The commands I use are these:
(assumes you downloaded clang to .)
cd .
./clang+llvm-3.6.0-x86_64-apple-darwin/bin/clang++ main.cpp
The result is this:
In file included from main.cpp:1:
In file included from ./clang+llvm-3.6.0-x86_64-apple-darwin/bin/../include/c++/v1/iostream:37:
./clang+llvm-3.6.0-x86_64-apple-darwin/bin/../include/c++/v1/__config:23:10: fatal error: 'unistd.h' file not
found
which makes sense, as there is no file unistd.h, as verifiable by
find . -name unistd.h
which yields 0 results.
I tried downloading the LibC++ source code v. 3.6.0 but even that contains no unistd.h. Where can I find the official/vanilla version of that file, and the files that are referenced, and meta-referenced, by it?

Clang does not include a c library or system headers, you'll need to install Xcode if you want to program on OS X. This page has some more details if you don't want to install the entire Xcode package, you can get away with the command line tools only.
Once you have Xcode / command line tools installed you can either use the versions of clang and gcc included with Xcode or the one you downloaded, although it's usually easier to use Macports or Homebrew if you're looking to use up to date versions of either.

That error disappeared after running xcode-select --install.
(I only keep HomeBrew's LLVM and clang regularly updated, so my original macos headers must have been ancient/non-existent until I used the above command to fix that.)

unistd.h is not a C or a C++ header! It is a POSIX header.
You could install XCode as it'll come from that, but I honestly don't know whether that'll be at all compatible with the Clang runtime. I'm not a Mac person.
Perhaps you can find an alternative; for example, there's no way you need unistd.h to compile a "Hello world" program!

Related

Homebrew clang can't find C standard library headers [duplicate]

This question already has answers here:
'wchar.h' file not found
(9 answers)
Closed 2 years ago.
Unsurprisingly the new update of OSX Mojave broke my llvm installation in Homebrew, these are the steps I tried:
xcode-select --install # Complained, so I installed commandLineTools from here https://developer.apple.com/download/more/
xcode-select -p /Library/Developer/CommandLineTools
xcode-select --install # Now says installed
sudo xcodebuild -license # Fails, as it says I only have CommandLineTools installed in /Library/Developer/CommandLineTools not xcode
# Try something else (all versions)
brew uninstall --force llvm
brew install llvm # yay v7 how exciting
# Only it still don't work
clang++ -std=c++17 foo.cpp -o f
In file included from foo.cpp:1:
In file included from /usr/local/Cellar/llvm/7.0.0/include/c++/v1/iostream:38:
In file included from /usr/local/Cellar/llvm/7.0.0/include/c++/v1/ios:215:
In file included from /usr/local/Cellar/llvm/7.0.0/include/c++/v1/iosfwd:90:
/usr/local/Cellar/llvm/7.0.0/include/c++/v1/wchar.h:119:15: fatal error: 'wchar.h' file not found
#include_next <wchar.h>
^~~~~~~~~
1 error generated.
Any ideas? The first half of the things I tried I found online but mostly for older updates of MacOS, maybe Mojave broke things in a new and unpredictable way.
Here's how I solved it (very dirty but has worked for a long time):
Disabled SIP on my Mac
Symlinked /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include to /usr/include as is expected in POSIX environments.
Re-enabled SIP.
Now I got to make a note to re-do this everytime a new OSX update comes out. This has not broken anything wrt Xcode, clang (from brew) etc so I'll keep it. Be advised though, this might break your stuff.
This is a well known issue of the latest macos. Try to set this environment variable, it must fix this issue.
export LIBCLANG_SYSTEM_INCLUDE_DIR="/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include"
I did something dumb but it did fix the problem... Not sure if it will work for your computer though.
Here is what I did:
I originally installed c++ using Homebrew on my MacBook on Mojave... so I had to manually install the Xcode CommandLineTools using the installer found at /Library/Developer/CommandLineTools/Packages/macOS_SDK_headers_for_macOS_10.14.pkg . Then I copied the "c++" folder contents from to folder /Library/Developer/CommandLineTools/usr/include/c++/v1 to the folder where I want the missing file to be, at /usr/local/Cellar/gcc/8.2.0/include/c++/8.2.0 , while replacing files with the same names.
The trick worked, since now the missing file "wchar.h" is right where it should be... I could have simlinked, in hindsight. Cheers!

Header Files not Working in CLion after Xcode update

Apple sent out an Xcode update today and little did I know it would mess with my all of my header files.
The header file I am attempting to use is time.h. I know the code if fully functional because an online C++ shell will run it fine but CLion is telling me Cannot find 'time.h'. When I attempt to run the program I receive the following:fatal error: 'wchar.h' file not found. This was odd because I was able to locate the wchar.h file.
As per this post, I have followed all the instructions to no avail. I have also checked the location of the Command Line Tools with xcode-select -p and received that they are in /Library/Developer/CommandLineTools, which seems to be correct. I have also checked that gcc is working and the correct version. Any time I try xcode-select --install at this point it just tells me that it is installed and check for updates if I think it is wrong. It also told me there were no updates.
The only other thing I can think of is that the compiler is also telling me the following:
clang: warning: no such sysroot directory: '/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.12.sdk' [-Wmissing-sysroot]
And after checking this directory, I noticed that my sdk is MacOSX 10.13 where the compiler was looking for 10.12. Also my SDK is just a 10 byte alias file that OS X tells me can't be found when I click on it?
I am really scratching my head on this one, I have re-installed Xcode already just as a last resort to no avail. Any help would be much appreciated.
You need to change the sdk your project is using. Go to your Target and look at the Build Settings. Set the Base SDK popup to "Latest Mac OS(...)" and you should be good to go.

OpenMP on Mac not working anymore

I had OpenMP compiling and executing in C/C++ on my Mac but then I formatted and reinstalled a fresh copy of OS X. I believe the only difference in the setup was that I had Xcode 5 before the format, and now I have Xcode 6.
Now I get fatal error: 'omp.h' file not found
I read this has something to do with clang and gcc, but, my confusion lies with why did it work before and now its not working?
After some research I seem to have found an answer.
GCC included in the latest version of Xcode (Xcode 6) is only a symbolic link to clang. Since clang does not support OpenMP at this time, you need to install a different version of GCC. The easiest way to do this would be to use Homebrew or MacPorts.
Keep in mind that even when you do this you will probably need to alter your $PATH to have /usr/local come before /usr/bin. This is because Homebrew will have placed your newly installed GCC in /usr/local. Also, some implementations may name the command gcc-49 instead of plain gcc.
Mac OSX uses clang.The gcc compiler in OS X does not support OpenMP. To use this feature a new gcc compiler needs to be installed.
Go to Terminal, if you have not installed Hombrew, install it:
/usr/bin/ruby -e "$(curl -fsSL https://`enter code here`raw.githubusercontent.com/Homebrew/install/master/install)"
then install new version of gcc
brew reinstall gcc --without-multilib
This will not make changes to the existing gcc compiler installed by Xcode as we are reinstalling it.
After running the command given below compile the files using the new version of gcc using the syntax : gcc-version -fopenmp filename.c
To find the version type gcc and then press tab. This will list out all the possible variants of gcc. The version number can be found out from this. For example : gcc-6, gcc-4.9,etc

Building C++ not working in OSX 10.9

Update:
I solved the problem in the end by reinstalling command line tools, as shown in this link.
Sorry for the trouble!
Initial question
I have just upgraded to OSX Mavericks and I cannot make the compiler work anymore.
I've been using gcc48 from macports with vim/sb2 and everything was working just fine. Now any library that I include gives tons of errors. I am not very experienced and I do not know what to do, or what to search for. I just want it to work like before. Here is what is says when compiling a basic "hello world" program:
In file included from /opt/local/include/gcc48/c++/bits/postypes.h:40:0,
from /opt/local/include/gcc48/c++/iosfwd:40,
from /opt/local/include/gcc48/c++/ios:38,
from /opt/local/include/gcc48/c++/ostream:38,
from /opt/local/include/gcc48/c++/iostream:39,
from ceva.cpp:1:
/opt/local/include/gcc48/c++/cwchar:44:19: fatal error: wchar.h: No such file or directory
#include <wchar.h>
If you need any information, tell me and I will provide it to you. Thank you for your patience!
[Added 2019 - Mojave/Catalina] XCode 10 has removed the placement of headers in /usr/include, even with the command line tools. If you want headers, and you're on you should be able to install a transitional package, which is available on Mojave. This package is not present on the Catalina. The headers are within the SDK for the appropriate release.
XCode 5/Mavericks have changed the defaults for where headers are located.
On prior versions of Mac OS X / XCode you would have found headers in /usr/include.
When you built gcc on the older release it picked up the headers from that location, and looks for them there now when you try to build code.
The problem is that the files are not there; they're somewhere under /Applications/Xcode.app/Contents/Developer.
You could futz about with a spec file to get it working consistently again, but the sanest thing to do is rebuild gcc.
As has been mentioned as well, you can install the command line tools using xcode-select --install, which will reinstall the developer tools, including the headers in /usr/include.
I tend to reinstall things like gcc when I upgrade my operating system as I encounter other errors due to changes in the environment. This is just a habit I've formed. It may not be the best habit, but it's saved me pain on numerous occasions.
[added 2017] As an addendum, if you install the command line tools, then the headers will be placed in /usr/include as well. The command to install the command line tools is xcode-select --install - this will allow you to use most compilers without having to specify the location of the headers manually.
This is how I got it working on Mac osx Mavericks:
Open terminal
type --> xcode-select --install
A pop-up windows will apear asking you about install tools
choose install tools
wait install to finish
Here is a manual method for updating XCode on OS X Mavericks:
Go into the developers site http://developer.apple.com
Then go to Downloads for Apple developers and there is a command line tools installer for Mavericks — here's the link (but you'll need a developers account for the link to work) http://developer.apple.com/downloads/index.action?q=xcode
I'm using MacOs Sierra 10.12.4, got the same problem.
I solved it by using:
/usr/bin/gcc
For me the fix was to uninstall old broken gcc:
brew uninstall gcc#5
I noticed paths like /usr/local/Cellar/gcc#5 in build output, while gcc#8 was also installed and is the one that was supposed to be used.

g++: error: libgomp.spec: No such file or directory

I use g++ (GCC) 4.7.2. on Windows 7, 64-bit version.
downloaded from http://nuwen.net/mingw.html
I tried to use the "-fopenmp" flag and got the error:
g++: error: libgomp.spec: No such file or directory
I can't find the file anywhere on my system. Do I need to re-install something? Can I just throw a file somewhere?
You could try installing TDM-GCC, which looks as though it includes OpenMP.
There's also Sezero's personal build.
I had a similar problem. I got it working installing one of the version at the following discussion.
Which version of MinGW should I use
I don't have access to my windows machine now so I don't know which version I used but I can check on Monday if you don't have it working by then.
It might have been this one.
http://sourceforge.net/projects/mingwbuilds/files/host-windows/releases/