Short version
When I compile even a simple code using a feature of the C++11 standard (the std::stod function), GCC 4.9.1 fails with the following error:
example.cpp: In function 'int main()':
example.cpp:10:18: error: 'stod' is not a member of 'std'
double earth = std::stod (orbits,&sz);
^
example.cpp:11:17: error: 'stod' is not a member of 'std'
double moon = std::stod (orbits.substr(sz));
^
What?
The command I use is g++ -std=c++11 example.cpp.
This is the test code (which compiles fine on other systems):
// stod example from http://www.cplusplus.com/reference/string/stod/
#include <iostream> // std::cout
#include <string> // std::string, std::stod
int main ()
{
std::string orbits ("365.24 29.53");
std::string::size_type sz; // alias of size_t
double earth = std::stod (orbits,&sz);
double moon = std::stod (orbits.substr(sz));
std::cout << "The moon completes " << (earth/moon) << " orbits per Earth year.\n";
return 0;
}
details
I am using a version of GCC 4.9.1 I compiled myself on two different clusters running CentOS 6.5 (I use the modules system on stuff in my home dir since I'm not an admin).
I will call them cluster 1 and cluster 2: cluster 1 is where the failure happens.
The GCCs were compiled in the same way and at the same time, and loaded using identical module files (save for a minor difference in the base path). The installations are, as far as I can easily check, identical (the same include files exist on both clusters, and have the same contents).
The output from g++ -v is the same on both clusters (again, except for the install path):
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/home/andyras/bin/gcc-4.9.1/libexec/gcc/x86_64-unknown-linux-gnu/4.9.1/lto-wrapper
Target: x86_64-unknown-linux-gnu
Configured with: ../gcc-4.9.1/configure --prefix=/home/andyras/bin/gcc-4.9.1 --enable-languages=c,c++,fortran
Thread model: posix
gcc version 4.9.1 (GCC)
g++ -v using the system GCC gives the same output on both clusters, except on cluster 1 it says it is gcc version 4.4.7 20120313 (Red Hat 4.4.7-3) (GCC) and on cluster 2 says gcc version 4.4.7 20120313 (Red Hat 4.4.7-4) (GCC)
I am trying to debug using g++ -std=c++11 -save-temps -MD example.cpp for more info... this gives some clues, but I don't know where to go from here.
The intermediate (.ii) files on cluster 1 are missing some lines, for example (excerpt from diffing the .ii files):
< # 277 "/opt/gcc-4.9.1/include/c++/4.9.1/cwchar" 3
---
> # 277 "/home/andyras/bin/gcc-4.9.1/include/c++/4.9.1/cwchar" 3
961,963c934,936
< using std::wcstold;
< using std::wcstoll;
< using std::wcstoull;
---
>
>
>
As I interpret it, GCC on both clusters tries to include files like cwchar, but on cluster 1 there are blank lines instead of things being defined. On cluster 2 the stod function is in the intermediate file, but not on cluster 1.
Could it be a preprocessor error?
Now looking at the .d (dependency) files, I also see a concrete difference. There are some files listed on cluster 2 that are not listed on cluster 1. Here is the list (I processed the contents of the .d files to account for the different base paths; // stands in for the install path):
85a86,108
> //gcc-4.9.1/include/c++/4.9.1/ext/string_conversions.h
> //gcc-4.9.1/include/c++/4.9.1/cstdlib
> /usr/include/stdlib.h
> /usr/include/bits/waitflags.h
> /usr/include/bits/waitstatus.h
> /usr/include/sys/types.h
> /usr/include/sys/select.h
> /usr/include/bits/select.h
> /usr/include/bits/sigset.h
> /usr/include/sys/sysmacros.h
> /usr/include/alloca.h
> //gcc-4.9.1/include/c++/4.9.1/cstdio
> /usr/include/libio.h
> /usr/include/_G_config.h
> /usr/include/bits/stdio_lim.h
> /usr/include/bits/sys_errlist.h
> //gcc-4.9.1/include/c++/4.9.1/cerrno
> /usr/include/errno.h
> /usr/include/bits/errno.h
> /usr/include/linux/errno.h
> /usr/include/asm/errno.h
> /usr/include/asm-generic/errno.h
> /usr/include/asm-generic/errno-base.h
I was curious if cpp was looking for includes in all the wrong places, but this seems legit (cpp -v):
#include <...> search starts here:
/home/andyras/bin/gcc-4.9.1/include
/home/andyras/bin/gcc-4.9.1/include/c++/4.9.1/
/home/andyras/bin/gcc-4.9.1/include/c++/4.9.1/x86_64-unknown-linux-gnu/
/home/andyras/bin/gcc-4.9.1/lib/gcc/x86_64-unknown-linux-gnu/4.9.1/include
/usr/local/include
/home/andyras/bin/gcc-4.9.1/lib/gcc/x86_64-unknown-linux-gnu/4.9.1/include-fixed
/usr/include
End of search list.
This has been a very frustrating couple of hours trying to track down the source of the problem. I could, of course, use something like atof(myString.c_str()) instead of std::stod, but I am wondering if there is an underlying issue that will foul up future projects using other bits of C++11.
Any more clues or insight would be very much appreciated.
