I have the following file foo.cpp:
#include <vector>
struct MyClass
{
std::vector<int> v;
};
It can be successfully compiled with clang (I'm using clang 3.3 on Ubuntu 13.04 32bit):
clang++ -c foo.cpp
Now I want to print AST:
clang++ -cc1 -ast-print foo.cpp
and I've got the following error
foo.cpp:1:10: fatal error: 'vector' file not found
#include <vector>
^
struct MyClass {
};
1 error generated.
It looks like clang++ -cc1 doesn't know about system include files etc.
I'm wondering how to set up includes for clang++ -cc1?
You need to set up the right include paths.
on my system I added
-I/usr/include/i386-linux-gnu/c++/4.8 -I/usr/include/c++/4.8
to the compiler flags. The first one was so that it could find
bits/c++config.h
Of course the 4.8 is due to the fact I am using a compiler compatible with g++-4.8
I also added
-std=c++11 -stdlib=libstdc++
as compiler options.
Hope this helps
It's a Frequently Asked Question
#john is correct. For posterity, the relevant portions of the FAQ are (with names tweaked to match the question) :
clang -cc1 is the frontend, clang is the driver. The driver invokes the frontend with options appropriate for your system. To see these options, run:
$ clang++ -### -c foo.cpp
Some clang command line options are driver-only options, some are frontend-only options. Frontend-only options are intended to be used only by clang developers. Users should not run clang -cc1 directly, because -cc1 options are not guaranteed to be stable.
If you want to use a frontend-only option (“a -cc1 option”), for example -ast-dump, then you need to take the clang -cc1 line generated by the driver and add the option you need. Alternatively, you can run clang -Xclang <option> ... to force the driver [to] pass <option> to clang -cc1.
I did the latter (-Xclang) for emitting precompiled headers:
/usr/bin/clang++ -x c++-header foo.hpp -Xclang -emit-pch -o foo.hpp.pch <other options>
^^^^^^^
Without the -Xclang, clang++ ignored the -emit-pch. When I tried -cc1, I had the same problem as the OP — clang++ accepted -emit-pch but didn't have the other options the driver normally provides.
Related
I wanted to compile C++11 source code within Mac Terminal but failed. I tried g++ -std=c++11, g++ -std=c++0x, g++ -std=gnu++11 and g++ -std=gnu++0x but nothing worked. Terminal always read unrecognized command line option. However, g++ -std=gnu and things like that worked fine (of course C++11 source code could not pass).
Which option should I use to turn on C++11 support?
By the way, the command line tool I'm using is installed within Xcode, and I'm pretty sure that they are up-to-date.
As others have pointed out you should use clang++ rather than g++. Also, you should use the libc++ library instead of the default libstdc++; The included version of libstdc++ is quite old and therefore does not include C++11 library features.
clang++ -std=c++11 -stdlib=libc++ -Weverything main.cpp
If you haven't installed the command line tools for Xcode you can run the compiler and other tools without doing that by using the xcrun tool.
xcrun clang++ -std=c++11 -stdlib=libc++ -Weverything main.cpp
Also if there's a particular warning you want to disable you can pass additional flags to the compiler to do so. At the end of the warning messages it shows you the most specific flag that would enable the warning. To disable that warning you prepend no- to the warning name.
For example you probably don't want the c++98 compatibility warnings. At the end of those warnings it shows the flag -Wc++98-compat and to disable them you pass -Wno-c++98-compat.
XCode uses clang and clang++ when compiling, not g++ (assuming you haven't customized things). Instead, try:
$ cat t.cpp
#include <iostream>
int main()
{
int* p = nullptr;
std::cout << p << std::endl;
}
$ clang++ -std=c++11 -stdlib=libc++ t.cpp
$ ./a.out
0x0
Thanks to bames53's answer for pointing out that I had left out -stdlib=libc++.
If you want to use some GNU extensions (and also use C++11), you can use -std=gnu++11 instead of -std=c++11, which will turn on C++11 mode and also keep GNU extensions enabled.
I am trying to run a simple leak check program.
#include <iostream>
int main()
{
double *ptr = new double(3.14);
}
using the command
g++ -g -fsanitize=leak -o main main.cpp
and I get the following error:
clang: error: unsupported option '-fsanitize=leak' for target 'x86_64-apple-darwin20.1.0'
I stopped using the clang that comes with Xcode and installed clang/LLVM using homebrew.
$ which clang++
/usr/local/opt/llvm/bin/clang++
clang++ --version
clang version 11.0.0
Target: x86_64-apple-darwin20.1.0
Thread model: posix
InstalledDir: /usr/local/opt/llvm/bin
EDIT: When I was using apple clang, g++ used to default to clang++. Apparently that changed when I installed llvm/clang. Thanks to #cigien for pointing it out. g++ still uses default to the compiler that that comes with Apple clang.
g++ --version
Configured with: --prefix=/Library/Developer/CommandLineTools/usr --with-gxx-include-dir=/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/c++/4.2.1
Apple clang version 12.0.0 (clang-1200.0.32.27)
Target: x86_64-apple-darwin20.1.0
Thread model: posix
InstalledDir: /Library/Developer/CommandLineTools/usr/bin
According to this answer you should use:
g++-10 -g -fsanitize=leak -o main main.cpp (in this cases (with flag leak) there is no leak message for me ./main, but it compile) then it should be:
g++-10 -fsanitize=address -g main.cpp ; ASAN_OPTIONS=detect_leaks=1 ./a.out and it detect leak well.
Note, that the correct path of brew installed g++ in MacOS is:
$ which g++-10
> /usr/local/bin/g++-10
--
$ which g++
> /usr/bin/g++ //this is pseudonym of clang
The same for gcc-10 (10 is my current version. You should use your version instead of that)
If you use CMakeLists.txt file you will configure it like this:
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fsanitize=[sanitizer_name] [additional_options] [-g] [-OX]")
# leak sanitizer_name not works for me. should be address
And should execute cmake command like this:
cmake -DCMAKE_C_COMPILER=/usr/local/bin/gcc-10 -DCMAKE_CXX_COMPILER=/usr/local/bin/g++-10 ..
And then ASAN_OPTIONS=detect_leaks=1 ./a.out
Note, that if you open */CMakeFiles/3.18.4/CMakeCXXCompiler.cmake file you will observe the compiled info, and now it will be g++.
I can't compile with -std=c++17, I got :
error: invalid value 'c++17' in '-std=c++17'
However I update Xcode and clang.
My Clang version is:
Configured with: --prefix=/Applications/Xcode.app/Contents/Developer/usr --with-gxx-include-dir=/usr/include/c++/4.2.1
Apple LLVM version 9.0.0 (clang-900.0.39.2)
Target: x86_64-apple-darwin16.7.0
Thread model: posix
InstalledDir: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin`
And I load the newest header like optional, I have to do
#include <experimental/optional>
instead of
#include <optional>
Xcode brings its own complete toolchain, including headers and the actual compiler.
Apple LLVM version 9.0.0 (clang-900.0.39.2) (which ships with Xcode 9.2) does not support the usage of the flag -std=c++17 since its too old. The optional header is only included under the folder experimental/. Which is why you need to #include <experimental/optional>
In order to compile your program with c++17 support using the compiler which comes with Xcode 9.2 you need to use the -std=c++1z flag.
Xcode 9.3 will be shipped with Apple LLVM version 9.1.0 (clang-902.0.30) which has support for the -std=c++17 flag. However the optional header is as of today still under the experimental/ subdirectory. This might change during the betas.
Here is what I get with this tests:
#include <experimental/optional>
int main(int, char* []) {
return 0;
}
g++ -std=c++17 -o test test.cpp
error: invalid value 'c++17' in '-std=c++17'
g++ -std=c++1z -o test test.cpp
Did you try the c++1z argument?
Also of note my test compiles without the -std=c++1z argument provided.
I think I'm on a newer version of OSX than you:
Target: x86_64-apple-darwin17.4.0
You should use -std=c++1z as flag.
libc++ with c++17 support since macos 15
-std=c++1z also works on Apple LLVM version 8.1.0 (clang-802.0.42)
My Xcode 9.2 has the option to compile C++ using: -std=c++17 or -std=gnu++17.
My C++ code that has some C++17 features compiles successfully.
However, if I try to compile the same code in my Terminal using the same flags, I get the following errors:
clang++ -std=c++17 test.cpp -o test
error: invalid value 'c++17' in '-std=c++17'
and
clang++ -std=gnu++17 test.cpp -o test
error: invalid value 'gnu++17' in '-std=gnu++17'
My OSX version is 10.13.3 and my Clang++ version is:
Apple LLVM version 9.0.0 (clang-900.0.39.2)
Target: x86_64-apple-darwin17.4.0
I thought that Terminal would use the same compiler from Xcode. That may be the case, but I can't use the same options. At least I couldn't.
I tried using -std=C++1z, but it didn't compile my code because it doesn't understand some new features from C++17.
So my question is: Is there a way to use -std=c++17 or -std=gnu++17 that are currently available in my Xcode 9.2, in my Terminal app?
This questions is not the same as the others available at stackoverflow because all the answers I found the -std=c++17options was not available in Xcode. Now we have this options, but I can't figure out how to use it in Terminal.
The compiler Apple currently ships with Xcode 9.2 (clang-900.0.39.2) does not support the -std=c++17 flag.
Xcode uses the -std=c++1z flag when you enable c++17 support. If you want to use -std=c++17 you need to manually install clang. You could do that using brew install llvm (assuming you have homebrew installed).
You can compile your program with
/usr/local/Cellar/llvm/5.0.0/bin/clang++ -std=c++17 test.cpp -o test
You change the symlinks in usr/bin/clang++ to point at the new destination if you don't want to use the full path to the compiler.
The compiler which is shipped with Xcode 9.3 will be
Apple LLVM version 9.1.0 (clang-902.0.30)
This can handle the -std=c++17 flag.
I'm trying to compile C++11 code that declares a variable of type std::atomic_bool. This is on Mac OS 10.8.2 with clang:
clang --version
Apple clang version 4.1 (tags/Apple/clang-421.11.66) (based on LLVM 3.1svn)
Target: x86_64-apple-darwin12.2.0
Thread model: posix
clang complains about std::atomic_bool:
clang++ -c -stdlib=libc++ -msse4 -std=c++11 -Wno-unused-parameter -I. -o query.o query.cpp
In file included from query.cpp:1:
[...]
./threadutils.h:33:10: error: no type named 'atomic_bool' in namespace 'std'; did you mean 'atomic_long'?
std::atomic_bool work;
However, the same file compiles fine in an XCode project using the same compiler. So I assume I'm missing something in my manual compiler invocation.
I tried a few variations such as -std=c++0x and -std=gnu++11, to no avail.
I figured it out. Unfortunately I planted a false flag into my question: it didn't work in XCode either, I had a different version of the source file imported there.
The problem was that C++11 defines "a named type atomic_bool corresponding to the specified atomic<bool>", but clang doesn't support that.
Renaming the type from atomic_bool to atomic<bool> fixed it.
I found the same problem. In my case I resolved it by including atomic:
#include <atomic>
static std::atomic_bool varname;
After this, I could call g++ with std=c++11 on a Linux (Ubuntu) as well as compile on XCode.