In C++, I am trying to declare an unordered_set simply like this:
std::unordered_set<int> k;
But it is showing this error:
error: 'unordered_set' is not a member of 'std'
I am using g++ (GCC) 5.3.0 on windows using MinGW. Here are the things that I have already considered:
Adding the header file by #include <unordered_set>
Upgrading MinGW
Using the flag -std=gnu++11. (This is not generating any executable or error, not sure if it doing anything or not)
How to fix it and compile my code successfully?
Use -std=c++11 switch and specify output file.
g++ -std=c++11 your_file.cpp -o your_program
Related
We are catching compiler errors when using sigemptyset on Cygwin under Newlib. The error occurs with a C++ compiler, but only when -std=XXX is used. Without a standard option, the test program compiles and executes as expected.
The test program is below, and the Cygwin header of interest follows. I don't see anything suspicious in the Cygwin header.
I've tried tricks like #define _GNU_SOURCE and #define _XOPEN_SOURCE 700. I've also tried tricks like using the global and std namespaces. Related, see What does -D_XOPEN_SOURCE do/mean? and Namespace issues in c++11?.
What is causing the compile failure and how do I fix it?
$ cat ~/test.cxx
#include <signal.h>
int main(int argc, char* argv[])
{
struct sigaction new_handler;
return sigemptyset(&new_handler.sa_mask);
}
Without a -std=XXX, it results in:
$ g++ -c test.cxx
$
With a -std=XXX, it results in:
$ g++ -std=c++03 -c test.cxx
test.cxx: In function int main(int, char**):
test.cxx:6:44: error: sigemptyset was not declared in this scope
return sigemptyset(&new_handler.sa_mask);
And when trying to use sigemptyset in the global namespace:
$ g++ -std=c++03 -c test.cxx
test.cxx: In function ‘int main(int, char**)’:
test.cxx:6:12: error: ‘::sigemptyset’ has not been declared
return ::sigemptyset(&new_handler.sa_mask);
^
Things get worse when using -std=gnu++03 and friends.
The function is an extension over the ISO C standard.
http://pubs.opengroup.org/onlinepubs/9699919799/functions/sigemptyset.html
as such is protected on /usr/include/sys/signal.h by
__XSI_VISIBLE >= 4
see /usr/include/sys/features.h for details.
As defaults the largest definition set is used, but -std=XXX reduces the definition scope
The issue was worked through at Botan 2.1.0 does not compile under Cygwin 2.8.0 with g++ 5.4.0. Here are the two comments of interest.
First, from noloader:
Cygwin uses Newlib, not GNU's libstdc++. When there's no
-std=c++XX, current GCC defaults to -std=gnu++11 (GCC 6 changes
to gnu++14 by default). I
believe GNU sources ensures expected functions, like sigaction, are
available.
You might consider trying -D_XOPEN_SOURCE=600 or
-D_XOPEN_SOURCE=700.
Also see C++ and feature guards Warning
Question on the
Newlib mailing list.
Second, from SideChannel:
Thanks to #noloader. Until now -std=c++11 was set in Makefile. The
important info is in above mentioned thread on the Newlib mailing
list. Yaakov Selkowitz wrote:
G++ defines _GNU_SOURCE on glibc targets, meaning that -std=c++NN is, contrary to the documentation, not strict ISO C++:
So, applying the patch #987
AND setting -std=gnu++11 works for me. I
did not try the other -D options (I think the other fact is more
fundamental). Summarizing, #randombit please apply the PR #987 and set
-std=gnu++11 for gcc under Cygwin.
Please take a look at the following C++11 snippet:
#include <boost/format.hpp>
int main(int argc, char** argv)
{
auto s = boost::format("");
return 0;
}
When I compile it with clang using the -std=c++11 I get the following error:
$ clang++ -std=c++11 -o main main.cpp
In file included from main.cpp:1:
In file included from /usr/include/boost/format.hpp:19:
In file included from /usr/include/boost/detail/workaround.hpp:41:
In file included from /usr/include/boost/config.hpp:40:
In file included from /usr/include/boost/config/select_stdlib_config.hpp:18:
/usr/bin/../lib64/gcc/x86_64-unknown-linux-gnu/4.9.0/../../../../include/c++/4.9.0/cstddef:51:11: error:
no member named 'max_align_t' in the global namespace
using ::max_align_t;
~~^
1 error generated.
Without the -std=c++11 everything compiles fine, but clang prints a warning:
$ clang++ -o main main.cpp
main.cpp:5:3: warning: 'auto' type specifier is a C++11 extension [-Wc++11-extensions]
auto s = boost::format("");
^
So, it looks like a valid workaround is to drop the C++11 flag, as the current version of clang seem to be in C++11 mode, anyway? The drawback is that you will get many warnings.
Is there a better workaround beside completely switching to gcc? Patching the source code of boost::format or gcc-libs is fine for me.
System information:
Platform: Arch Linux x86_64
Boost version: 1.55.0-6
gcc-libs: 4.9.0-1
clang++: 3.4 (tags/RELEASE_34/final)
The bug is closed now. It should be fixed in Arch with clang 3.4-2.
With this commit, Evangelos Foutras merged the following patch from upstream:
http://reviews.llvm.org/rL201729
clang++ main.cpp -std=c++11 -target x86_64-unknown-win32 -I/usr/lib/gcc/x86_64-w64-mingw32/4.6/include/
main.cpp:6:10: fatal error: 'string' file not found
#include <string>
^
1 error generated.
that's weird because:
/usr/lib/gcc/x86_64-w64-mingw32/4.6/include/ssp$ ls
ssp.h stdio.h string.h unistd.h
and this result the same:
clang++ main.cpp -std=c++11 -target x86_64-unknown-win32 -I/usr/lib/gcc/x86_64-w64-mingw32/4.6/include/ssp
well. I used to compile c code from linux to windows just fine using:
x86_64-w64-mingw32-gcc main.c
and I tried:
x86_64-w64-mingw32-g++ -std=c++0x main.cpp
also:
x86_64-w64-mingw32-g++ -std=c++0x main.cpp -I/usr/lib/gcc/x86_64-w64-mingw32/4.6/include
still give bunch of errors like
main.cpp:70:23: sorry, unimplemented: non-static data member initializers
main.cpp:70:23: error: in-class initialization of static data member ‘origin’ of non-literal type
main.cpp: In constructor ‘Item::Item(std::string)’:
main.cpp:83:18: error: ‘stoul’ is not a member of ‘std’
main.cpp:88:4: error: ‘origin’ was not declared in this scope
main.cpp:89:17: error: ‘stof’ is not a member of ‘std’
main.cpp: In function ‘std::ostream& operator<<(std::ostream&, const Item&)’:
....
x86_64-w64-mingw32-g++ (GCC) 4.6.3 seems to be the latest version on ubuntu repo.
I'm at lost..why the hell clang won't use the headers. why the hell x86_64-w64-mingw32-g++ won't listen that it should use c++11 standards.
The GCC version you use does not support non-static data member initializers as shown here. Find out here which version of GCC supports the C++11 feature set you required.
GoogleTest 1.6 with Cygwin 1.7: 'fileno' was not declared in this scope
Error message when building a simple test on Factorial() function in Eclipse CDT:
Invoking: Cygwin C++ Compiler
g++ -std=c++0x -DGTEST_OS_CYGWIN=1 -I"E:\source\gtest-1.6.0\include" -O0 -g3 -Wall -c -fmessage-length=0 -MMD -MP -MF"src/challenge.d" -MT"src/challenge.d" -o "src/challenge.o" "../src/challenge.cpp"
In file included from E:\source\gtest-1.6.0\include/gtest/internal/gtest-internal.h:40:0,
from E:\source\gtest-1.6.0\include/gtest/gtest.h:57,
from ../src/challenge.cpp:11:
E:\source\gtest-1.6.0\include/gtest/internal/gtest-port.h: In function 'int testing::internal::posix::FileNo(FILE*)':
E:\source\gtest-1.6.0\include/gtest/internal/gtest-port.h:1589:51: error: 'fileno' was not declared in this scope
E:\source\gtest-1.6.0\include/gtest/internal/gtest-port.h:1595:57: error: 'strdup' was not declared in this scope
E:\source\gtest-1.6.0\include/gtest/internal/gtest-port.h:1627:71: error: 'fdopen' was not declared in this scope
Eclipse CDT 8.1 running gcc 4.7.3 on Cygwin 1.7.22
gTest 1.6 succesfully built including demo tests, with cmake 2.8.9 on Cygwin 1.7.22
I've linked the built lib with full path, E:\lib\gtest-1.6.0\Cygwin\libgtest.a
The following command option was added manually, got same error without it.
-DGTEST_OS_CYGWIN=1
Seems the errors have nothing to do with my code. Anyone using gTest with Eclipse and Cygwin?
Thank you,
unsigned long Factorial(unsigned n) {
return n==0? 0 : n*Factorial(n-1);
}
// Tests factorial of 0.
TEST(FactorialTest, HandlesZeroInput) {
EXPECT_EQ(1, Factorial(0));
}
// Tests factorial of positive numbers.
TEST(FactorialTest, HandlesPositiveInput) {
EXPECT_EQ(1, Factorial(1));
EXPECT_EQ(2, Factorial(2));
EXPECT_EQ(6, Factorial(3));
EXPECT_EQ(40320, Factorial(8));
}
Setting the C++ standard to -std=gnu++0x rather than -std=c++0x, worked for me. You can try the statement:
g++ -std=gnu++0x -DGTEST_OS_CYGWIN=1 -I"E:\source\gtest-1.6.0\include" -O0 -g3 -Wall -c -fmessage-length=0 -MMD -MP -MF"src/challenge.d" -MT"src/challenge.d" -o "src/challenge.o" "../src/challenge.cpp"
Setting symbol (-DGTEST_OS_CYGWIN=1) has got nothing to do with this error.
Some functions go beyond the ANSI standard.
These are disabled when you use std=c++11 (or std=c++0x).
Among them are fdopen, fileno and strdup.
There are two possibilities to use them:
Use the GNU dialect (std=gnu++11).
If you want to compile without dialect and make a local exception, you can include stdio.h with the __STRICT_ANSI__ undefined. (see: Error "'fdopen' was not declared" found with g++ 4 that compiled with g++3)
I have tested both on Suse Linux Enterprise 11, MinGW and Cygwin.
Addition: Another (possibly better) way to access non-ANSI symbols would be to add
#define _POSIX_C_SOURCE 200809L
before the first #include in your file. This will give you access to most of the non-standard routines.
Some functions (e.g. realpath(...)) require
#define _BSD_SOURCE
to be inserted on top of your file.
Problem Solved => see the update at the end
I'm trying to use std::function but it looks like just include <functional> does not provide the definition. I have tried to compile following code:
#include <functional>
std::function<int(int)> f = nullptr;
with c++11 as compile option:
% clang++ -c -std=c++11 t.cc
cause:
t.cc:3:6: error: no type named 'function' in namespace 'std'
std::function<int(int)> f = nullptr;
~~~~~^
t.cc:3:14: error: expected unqualified-id
std::function<int(int)> f = nullptr;
^
2 errors generated.
what am I missing? I know C++ well but new to clang++/C++11 thus I lack of important knowledge, I guess.
I'm using clang++ on MacOS X 10.8.
Update 1
I have tried a sample at cppreference.com site but it won't compile too. Giving some option solve the problem?
Update 2
Tried above sample from cppreference.com with clang++ -c -std=c++11 -stdlib=libc++11 x.cc, and compiler still says:
x.cc:1:10: fatal error: 'functional' file not found
#include <functional>
^
1 error generated.
Where is functional? I guess I should give -stdlib=libc++11 or whatever but it does not work too:
clang: error: invalid library name in argument '-stdlib=libc++11'
How I can find list of argument for -stdlib? (note: in man page, only available options are libc++ and libstdc++ both of them don't work)
Or functional just does not work?
This is not about the definition of the function. You don't have a linker error. You have a compiler error. The problem is, presumably, that the BSD/GNU/Darwin standard library installed in the real sysroot doesn't support C++11. You have to use the one that comes with Clang by specifying the -stdlib=libc++ compiler flag.
For C++11, it's best to always invoke clang as: clang++ -std=c++11 -stdlib=libc++
I use this most of the time, so I set the environment variable $CXX to this value. That way, I'm getting the dialect and library option in both compilation and linking. -std=c++11 is insufficient, as clang will still use the (old) system gcc headers in /usr/include/c++/4.2.1.
-stdlib=libc++ will use the clang headers in /usr/lib/c++/v1 such as <functional>.
There's a similar question with an answer by Howard Hinnant, who is (IIRC) an Apple engineer.