Great!
I just finished my implementation on Mac with g++ / clang
Configured with: --prefix=/Applications/Xcode.app/Contents/Developer/usr --with-gxx-include-dir=/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.12.sdk/usr/include/c++/4.2.1
Apple LLVM version 8.1.0 (clang-802.0.42)
Target: x86_64-apple-darwin16.7.0
Thread model: posix
and tested my code on linux
g++ (Debian 4.7.2-5) 4.7.2
running a relatively simple threading operation. What worked on mac, fails on linux now with :
terminate called after throwing an instance of 'std::system_error'
what(): Operation not permitted
#include <cstddef>
#include <memory>
#include <stdlib.h>
#include <iostream>
#include <thread>
#include <vector>
#include <stdexcept>
std::vector<std::thread> threads;
std::vector<std::tuple<std::size_t, std::size_t>> parts = splitRows(maxNumberThreads, elements);
for (std::size_t threadIndex = 0; threadIndex < maxNumberThreads; threadIndex++)
{
threads.push_back(std::thread(compute<T>,parts[threadIndex], numbers, std::ref(*this),std::ref(other),std::ref(target)));
}
with the thread function defined as. Adding prints into compute it does not jump into the function at all... Any idea why this happens?
template<typename T>
void compute(const std::tuple<std::size_t,std::size_t> part,
const std::size_t numbers,
const MyClass<T>& m1,
const MyClass<T>& m2,
MyClass<T>& target){
I am compiling with
g++ -Wall main.cpp -o matrix.exe -std=c++11
but get the above runtime error. Any ideas how to fix this? I use std libraries only, nothing fancy...
You are not linking pthread properly, try following command,
g++ -Wall main.cpp -o matrix.exe -pthread -std=c++11
Hope this helps.
Related
I have been trying to compile and run the following very simple bit of code
#include <thread>
using namespace std;
void thread_c() {
for (int i = 0; i < 11; ++i) {
cout << i;
}
}
int main()
{
thread t(thread_c);
t.join();
system("pause");
return 0;
}
I am compiling on Windows 10 with MinGW 6.3.0 (target x86_64-w64-mingw32) and the thread model (obtained using g++ -v) is POSIX.
I am not getting any compilation error with g++ -Wall -g test.cpp -o test.exe, however I am getting a runtime error when trying to run the exe (entry point of _ZNSt6thread15_M_start_threadESt10unique_ptrINS_3_StateESt14default_deleteIS1_EEPFvve cannot be found).
I also tried compiling with the -pthreador -lpthread flags, but I am getting the same runtime error.
Obviously this seems to be related to the use of std::thread, but I didn't get how to fix this. Am I missing a compilation flag or additional library enabling POSIX thread support on Windows?
Edit: I managed to get it working by changing the compilation command to
g++ -Wall -g test.cpp -o test.exe -static-libgcc -static-libstdc++ -Wl,-Bstatic -lstdc++ -lpthread -Wl,Bdynamic
I tried your code after making the necessary fixes:
#include <thread>
#include <iostream>
using namespace std;
void thread_c() {
for (int i = 0; i < 11; ++i) {
std::cout << i;
}
}
int main()
{
thread t(thread_c);
t.join();
system("pause");
return 0;
}
and it worked fine.
The build command was the same as yours:
g++ -Wall -g test.cpp -o test.exe
The output was:
012345678910Press any key to continue . . .
But I did use MinGW-w64 GCC 12.1.0 (fro https://winlibs.com/) instead of the very old version 6.3.0.
Maybe the MinGW-w64 (or was it still the old MinGW) library you were using was simply too old...
If I understood correctly from this document, it isn't prohibited to link an application built with newer compiler to a library build with an older one. Also I haven't found any information regarding ABI changes between GCC 4.8 and 4.9. However, here is a small example which causes a crash (due to an invalid vptr, apparently):
lib-48.h
#ifndef LIB_48_H
#define LIB_48_H
struct FooBase { virtual void foo() = 0; };
struct FooDerived : FooBase { virtual void foo() override {} };
void boom();
#endif // LIB_48_H
lib-48.cpp
#include "lib-48.h"
#include <memory>
void boom() {
auto x = std::make_shared<FooDerived>();
x->foo();
}
app-49.cpp
#include "lib-48.h"
#include <memory>
int main() {
std::make_shared<FooDerived>(); // Essential to reproduce
boom();
}
build & run
$ g++-4.8 -shared -fPIC -Wall -Wextra -O2 -std=c++11 lib-48.cpp -o liblib-48.so
$ g++-4.9 -std=c++11 -Wall -Wextra app-49.cpp -L. -llib-48 -Wl,-R'$ORIGIN' -o app-49
$ ./app-49
Segmentation fault (core dumped)
system information
Reproduced on x86_64 Ubuntu (both 14.04 and 16.04) with gcc 4.8.5 (Ubuntu 4.8.5-2ubuntu1~14.04.1) and gcc version 4.9.4 (Ubuntu 4.9.4-2ubuntu1~14.04.1).
Note that compiling both app and lib with the same compiler makes SIGSEGV go away. So does compiling with -O0 and few other modifications.
The question is simple: is it a bug, or am I doing something wrong?
I have a C++ program that will not compile under OS X 10.8.5 with the g++ compiler. The problem seems to be with the math.h header file.
This is the version of g++ is
g++ -v
Using built-in specs.
COLLECT_GCC=g++
COLLECT_LTO_WRAPPER=/Users/densmore3/local/usr/local/bin/../libexec/gcc/x86_64-apple-darwin14.0.0/4.9.2/lto-wrapper
Target: x86_64-apple-darwin14.0.0
Configured with: ../gcc-4.9-20141029/configure --enable- languages=c++,fortran
Thread model: posix
gcc version 4.9.2 20141029 (prerelease) (GCC)
There are 40-50 errors of the type below. The code compiled fine on 10.6. What is going on?
/Users/xxxx/local/usr/local/lib/gcc/x86_64-apple-darwin14.0.0/4.9.2/include-fixed/math.h:203:1: error: ‘__header_always_inline’ does not name a type
__header_always_inline int __inline_isfinitef(float);
Users/densmore3/local/usr/local/lib/gcc/x86_64-apple-darwin14.0.0/4.9.2/include-fixed/math.h:580:27: error: expected initializer before ‘__AVAILABILITY_INTERNAL__MAC_10_0_DEP__MAC_10_9’
extern float __inff(void) __OSX_AVAILABLE_BUT_DEPRECATED(__MAC_10_0, __MAC_10_9, __IPHONE_NA, __IPHONE_NA);
Here is a piece of test code that gives the same error as my real code. The error goes away if I remove the math.h include statement.
#include <iostream>
#include <math.h>
#include <stdio.h>
//#include <complex>
//#include <vector>
int main(int argc, const char * argv[])
{
// insert code here...
std::cout << "Hello, World!\n";
return 0;
}
The compile command I am using is:
g++ test.cpp
gcc-4.8 is the correct version to use on OS X 10.8.
Okay, so I have
tmp.cpp:
#include <string>
int main()
{
std::to_string(0);
return 0;
}
But when I try to compile I get:
$ g++ tmp.cpp -o tmp
tmp.cpp: In function ‘int main()’:
tmp.cpp:5:5: error: ‘to_string’ is not a member of ‘std’
std::to_string(0);
^
I'm running g++ version 4.8.1. Unlike all the other references to this error that I found out there, I am not using MinGW, I'm on Linux (3.11.2).
Any ideas why this is happening? Is this standard behaviour and I did something wrong or is there a bug somewhere?
you may want to specify the C++ version with
g++ -std=c++11 tmp.cpp -o tmp
I don't have gcc 4.8.1 at hand , but in older versions of GCC,
you can use
g++ -std=c++0x tmp.cpp -o tmp
At least gcc 4.9.2 I believe also support part of C++14 by specifying
g++ -std=c++1y tmp.cpp -o tmp
Update:
gcc 5.3.0 (I am using the cygwin version) supports both -std=c++14 and -std=c++17 now.
to_string works with the latest C++ versions like version 11. For older versions you can try using this function
#include <string>
#include <sstream>
template <typename T>
std::string ToString(T val)
{
std::stringstream stream;
stream << val;
return stream.str();
}
By adding a template you can use any data type too.
You have to include #include<sstream> here.
Okay, so I have
tmp.cpp:
#include <string>
int main()
{
std::to_string(0);
return 0;
}
But when I try to compile I get:
$ g++ tmp.cpp -o tmp
tmp.cpp: In function ‘int main()’:
tmp.cpp:5:5: error: ‘to_string’ is not a member of ‘std’
std::to_string(0);
^
I'm running g++ version 4.8.1. Unlike all the other references to this error that I found out there, I am not using MinGW, I'm on Linux (3.11.2).
Any ideas why this is happening? Is this standard behaviour and I did something wrong or is there a bug somewhere?
you may want to specify the C++ version with
g++ -std=c++11 tmp.cpp -o tmp
I don't have gcc 4.8.1 at hand , but in older versions of GCC,
you can use
g++ -std=c++0x tmp.cpp -o tmp
At least gcc 4.9.2 I believe also support part of C++14 by specifying
g++ -std=c++1y tmp.cpp -o tmp
Update:
gcc 5.3.0 (I am using the cygwin version) supports both -std=c++14 and -std=c++17 now.
to_string works with the latest C++ versions like version 11. For older versions you can try using this function
#include <string>
#include <sstream>
template <typename T>
std::string ToString(T val)
{
std::stringstream stream;
stream << val;
return stream.str();
}
By adding a template you can use any data type too.
You have to include #include<sstream> here.