Can't find libstdc++? - gcc

Question

I built gcc 4.9.0 from source, and was also planning on building clang 3.4.2, however something seems to have gone awry with regards to libstdc++, as the clang build baled pretty quickly with the linker complaining about various undefined references from std.
Indeed, I then tried compiling and linking the trivial program:
#include <iostream>
int main() {
std::cout << 42;
}
and again hit linker errors:
/tmp/ccrptgVW.o:temp.cpp:function main: error: undefined reference to 'std::cout'
/tmp/ccrptgVW.o:temp.cpp:function main: error: undefined reference to 'std::ostream::operator<<(int)'
/tmp/ccrptgVW.o:temp.cpp:function __static_initialization_and_destruction_0(int, int): error: undefined reference to 'std::ios_base::Init::Init()'
/tmp/ccrptgVW.o:temp.cpp:function __static_initialization_and_destruction_0(int, int): error: undefined reference to 'std::ios_base::Init::~Init()'
collect2: error: ld returned 1 exit status
(full gcc -v output), both with my freshly-minted gcc 4.9.0 and my Ubuntu's stock gcc 4.6.3.
libstdc++.so exists, in /usr/local/lib64:
ls /usr/local/lib64/libstd*
/usr/local/lib64/libstdc++.a
/usr/local/lib64/libstdc++.so
/usr/local/lib64/libstdc++.so.6.0.20
/usr/local/lib64/libstdc++.la
/usr/local/lib64/libstdc++.so.6
/usr/local/lib64/libstdc++.so.6.0.20-gdb.py
and this directory appears in LIBRARY_PATH and as an -L argument to collect2 in the verbose gcc output.
How do I restore sanity to my system and have the linker find the shared library?

Answer 1

As turns out from your comment, you compiled with gcc rather than g++.
Do not take it as an error, as the compilation went fine! What's showing up is a linker error. Indeed, gcc will tell ld to link against the C standard library rather than the C++ standard one.
To solve, either go for g++ directly or pass -lstdc++.