here is a very minimal C++11 Thread API code that I am trying to compile
#include<iostream>
#include<thread>
using namespace std;
void threadFunction(void)
{
cout<<"hello from thread:";//<<this_thread::get_id()<<endl;
}
int main()
{
std::thread t(threadFunction);
t.join();
return 0;
}
On Compiling this as
g++ thread1.cpp -pthread -std=c++11
I get the following error
pure virtual method called
terminate called without an active exception
Aborted
What wrong, can someone please help
Note that I am compiling this on Beaglebone Black with ARM A8 processor
This is a bug in either libstdc++ or Clang, depending on who you ask. It should work if you are using a version of Clang released after October 2013. What do you see when you run g++ --version?
As a workaround, you could try using this command line instead. I don't guarantee that it would work; please post a comment with your results.
g++ -pthread -std=c++11 -D__GCC_HAVE_SYNC_COMPARE_AND_SWAP_{1,2,4} thread1.cpp
Here's the bug report:
http://llvm.org/bugs/show_bug.cgi?id=12730
And here's the official fix to the Clang driver:
https://llvm.org/viewvc/llvm-project?view=revision&revision=191707
I don't know if this was also previously a bug in the GCC driver, and/or whether it's been fixed.
Ran into the same problem on a Raspberry Pi 2 Model B with an ARM Cortex-A7.
Compiled with g++-4.7, turned out the culprit was a compiler flag:
-march=armv7-a
Although clang had a related issue, this is entirely a gcc bug now recorded at: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=62100
Related
For some reason when I try to get the ast-dump of any C/C++ code with Clang, I get an infinite loop which eventually results in clang: error: linker command failed with exit code 1136 or some similar error code.
I'm running Windows 10 with Clang version 13.0 (Also tried Clang 12.0 with same issues). I run the command clang -Xclang -ast-dump filename.c.
I've tried multiple files, but at this point I'm just trying to get a hello world ast (which compiles and runs fine via clang).
#include <stdio.h>
int main()
{
printf("Hello, World!\n");
return 0;
}
I'm sure I'm missing something simple, but I'd appreciate any help, thanks!
It's not an infinite loop if it terminates. :-)
The dumped AST includes stdio.h, which you included, so it's quite big (about 800 lines, when I tried it).
The error message is because the clang compiler (cc1) does not produce an object file when you pass it the -ast-dump option, but the clang driver (clang) doesn't know that. The driver is expecting to be able to link the generated object file into an executable, but it doesn't find the object file so it complains.
Use
clang -Xclang -ast-dump -fsyntax-only filename.c
to terminate the driver after the AST has been dumped.
I have a std::atomic<float> that I would like to increment by a certain value. However, using fetch_add() on an atomic<float> does not compile and does not seem to be allowed. Is there anyway I can get around this? Here is the code snippet I tried:
std::atomic<float> data(0);
void do_work(){ data.fetch_add(1); }
The error I get is that fetch_add is not a member of atomic<float>
EDIT: Forgot to clarify that I am compiling with g++ version 9.3.0 using -std=c++2a
Floating point atomics are only supported by the C++ library in g++ 10.1 and later. See https://gcc.gnu.org/onlinedocs/libstdc++/manual/status.html and search for P0020R6.
Your code compiles fine with g++ 10.2: Try on godbolt
--EDIT
If you would like to use MinGW GCC 8.4.1 and threads/mutex/futures/atomics do not download the Win32 threader version insted download the Posix version.
--EDIT
My installation of MinGW is as follows:
x32-4.8.1-release-win32 (as the threader) - sjlj rev 5
I have unpacked and correctly confirmed that MinGW GCC 4.8.1 (revision 5) is installed in C:\MinGW\mingw32. I have set up Code Blocks to look for the latest and greatest compiler in the correct path (this I am sure of). I can compile a normal program using #include iostream. Ok now when I try and run a program using #include thread it gives me "error: 'thread' is not a member of 'std'".
Now here is what I have done and what I have tried:
I am following a sort of template or tutorial here at cplusplus.com.
I have the code exactly as it is presented on the webpage (towards the bottom).
I have tried, in Code Blocks, to use Compiler flags "Have g++ follow the C++11 ISO language standard -std=c++11".
I have also tried the flag "Have g++ follow the coming C++0x ISO language standard -std=c++0x"
I have tried both at the same time and one at a time, no mas.
I have also tried those commands manually.
Another command I tried manually was -std=gnu++11 which was recommended in the thread header.
--EDIT
It seems like __cplusplus is < 201103L which is stated (or rather defined) in the thread header.
This only happens when I manually use -std=c++11, for some reason C::B removes it if it was manually stated so I must use a check box to use this flag...
--EDIT
My compiler settings under the Toolchain Executables tab are as follows:
C compiler: i686-w64-mingw32-gcc-4.8.1.exe
C++ compiler: i686-w64-mingw32-c++.exe
Linker for dynamic: i686-w64-mingw32-c++.exe
Linker for static: ar.exe
Debbuger: GDB/CDB debugger: default
Resource compiler: windres.exe
Make Program: mingw32-make.exe
I have tried using other executables in the bin folder and still no luck...
I'm starting to wonder if GCC supports C++11 or threading !?
Has anyone been able to get threads to work with MinGW GCC, Code blocks or in general?
If so how did you do it? Any links that might help? Any advice?
P.S. I know there are other ways of threading like posix or other SDK's like SFML (I have successfully tried threading with this). But I want to use GCC threading and I'm quite baffled as to why it is so hard to do seeing as all the necessary files are there...
--EDIT
I have found that when I manually compile the program outside of Code Blocks I still get the same errors, whether I use g++ c++ or i686-w64-mingw32-g++/c++
here is the command I run to build the files:
C:\MinGW\mingw32\bin>g++.exe -D__GXX_EXPERIMENTAL_CXX0X__ -o0 -g3
-Wall -c -fmes sage-length=0 -std=c++11 -Wc++11-compat -o obj\Debug\main.o "F:\C Projects\Code Blocks\thread\main.cpp"
still returns error: 'thread' is not a member of 'std'
Could this be a bad build? I will try other revisions...
--EDIT
probably to late for an answere, but here is what worked for me:
1. Get x86_64-w64-mingw32-gcc-4.8-stdthread-win64_rubenvb.7z from:
http://sourceforge.net/projects/mingw-w64/files/Toolchains%20targetting%20Win64/Personal%20Builds/rubenvb/gcc-4.8-experimental-stdthread/
2. Setup a new compiler in codeblocks with
x86_64-w64-mingw32-gcc-4.8.1.exe
x86_64-w64-mingw32-g++.exe
x86_64-w64-mingw32-g++.exe
ar.exe
windres.exe
mingw32-make.exe
3. Set the new compiler for your project
Right click in your project -> build options
Select the new compiler
Under compiler falgs check -std=c++0x and -std=c++11
Under Other options set -std=gnu++11
4. Have fun with c++11 concurrency
Hope that works for you also, as an alternative you can just use visual studio.
I think you meant GCC 4.8.1 - the answer is yes, it supports a set of C++11 features including partial multi-threading support. Please visit http://gcc.gnu.org/releases.html to see supported set.
gcc 4.8.1 is C++11 feature complete. I cannot speak to the Windows implementation but certainly on Linux and OS X it works as advertised, including all the concurrency functionality. I just #include <thread> and call g++ -std=gnu++11 and it works. Here's a minimal piece of code that compiles just fine:
#include <iostream>
#include <thread>
#include <mutex>
std::mutex mx;
int i;
void thrfunc();
int main(void)
{
i=0;
std::thread thr1(thrfunc),thr2(thrfunc);
thr1.join();
thr2.join();
return 0;
}
void thrfunc()
{
mx.lock();
i++;
std::cout << std::this_thread::get_id() << " i: " << i << std::endl;
mx.unlock();
}
I had the same issues, I installed the lates MinGW-Builds
http://sourceforge.net/projects/mingwbuilds/files/mingw-builds-install/
and set my toolchain executables to:
x86_64-w64-mingw32-gcc-4.8.1.exe
x86_64-w64-mingw32-g++.exe
x86_64-w64-mingw32-g++.exe
ar.exe
windres.exe
mingw32-make.exe
I hope this helps.
So I've been trying to get the following code to compile and run on Windows by using a MinGW compiler.
#include <iostream>
#include <thread>
void test()
{
std::cout << "test" << std::endl;
}
int main()
{
std::thread t(test);
}
I'm compiling with the following command:
g++ -std=c++11 test.cpp -o test.exe
Now the problem is the version of MinGW one should use and I've tried about all the versions I know of.
MinGW-builds: thread-win32
MinGW-builds: thread-posix
MinGW-w64: stdthread experimental rubenvb
MinGW-w64: stdthread experimental rubenvb 4.7
Number 1 doesn't work, since GCC apparently only supports pthread stuff internally.
Number 2 does compile and it essentially even outputs test (see the last line of the output), but it also crashes with the error:
terminate called without an active exception
This application has requested the Runtime to terminate it in an unusual way.
Please contact the application's support team for more information.
test
Number 3 and 4 again do compile, but they don't output test and instead instantly crashes, but with a more descriptive output:
terminate called after throwing an instance of 'std::system_error'
what(): Enable multithreading to use std::thread: Operation not permitted
This application has requested the Runtime to terminate it in an unusual way.
Please contact the application's support team for more information.
Google brought me of course to the GCC bug tracker and some other posts, that suggested to use -pthread, which doesn't help at all.
I've also tried manually linking against winpthread and pthread, but that doesn't do anything either.
There's also no difference between -std=c++11 and -std=gnu++11...
I'm really lost right now and don't know, if it's at all possible to get a MinGW version, that supports std::thread, but maybe I'm just overlooking some compiler flags. I hope someone out there can help me!
You forgot to join your thread:
t.join();
FYI, there is already a native win32 implementation of std::thread and sync primitives. It is a header-only library and works on any C++11 compliant version of MinGW.
https://github.com/meganz/mingw-std-threads
There is a tutorial - http://llvm.org/docs/GettingStartedVS.html Example done in pure C. I can compile and link it. Without problem, really. But I need C++, not pure C. And here the difficulties begin.
For clang++ I use string like
"C:\..> clang++ -c hello.cpp -emit-llvm -o hello.bc"
then:
"C:\..> llc -filetype=obj hello.bc"
and
"C:\..> link hello.obj -defaultlib:libcmt -out:hello.exe"
there I get 14 errors LNK2001: unresolved external symbol
So, I need some tips. What I do wrong?
//-----------------
hello.cpp:
#include < iostream >
int main()
{
std::cout << "TEST\n" << std::endl;
return 0;
}
//-----------------
OS: Windows7.
UPD: Main question: how from .bc get .exe? (LLVM, Windows7)
You can use my GCC and Clang packages:
Download and extract them to the same directory. Clang will use GCC 4.6.3's libstdc++ and MinGW-w64's CRT. Call it like you would gcc.
Clang/LLVM cannot currently work with MSVC's C++ library, due to ABI issues. GCC's libstdc++ works quite well, though it has holes in surprising places (like std::to_string, <regex>, and <thread>).
Clang's Windows support is OK, but far from complete. You cannot for example dllexport whole C++ classes, unfortunately. And Win64 code generation is also not good enough to have a working C++ install (even in combination with GCC, like for 32-bit).