C++ Move constructor won't compile

Question

I have an unfortunate problem. My GCC 4.6.3 compiler refuses to compile my move constructor. Exchanging line 6 in the example with "MemoryBlock(const MemoryBlock & other)" would make it compile, but not using the below move constructor declaration. Seems like the compiler does not know C+11, even though it should using 4.6.3. Right?

#include <cstddef>

class MemoryBlock
{
public:
   MemoryBlock(MemoryBlock && other) //<----------- RAD 6.
    {
    }

private:
   size_t _length; // The length of the resource.
   int* _data; // The resource.
};

int main() {

}

Compiler output:

prog.cpp:6:28: error: expected ‘,’ or ‘...’ before ‘&&’ token

prog.cpp:6:36: error: invalid constructor; you probably meant ‘MemoryBlock (const MemoryBlock&)’

make: * [slask] Error 1

GCC version:

g++ (Ubuntu/Linaro 4.6.3-1ubuntu5) 4.6.3 (Kör från labbsal i skolan)

makefile:

%.out:    %.cpp
    g++ -g -W -Wall -std=c++0x $*.cpp -o $*.out;

Works fine on my GCC 4.6.3. Make sure you're actually using the right version; check directly on the command line without makefile perhaps. — Kerrek SB
I did verify my version (g++ --version) and its correct. However, you are right, it works. The problem seem to lie within my makefile. Thanks alot! My makefile seemed so simple that I didn't really consider it an issue. Any idea what could be the problem using this makefile? — user2831216
Your makefile may not be using the rule you specified, but the default rule. — Kerrek SB
You can greatly simplify the makefile for small code samples by setting CXXFLAGS and letting the default rules do their job. — juanchopanza
In fact, the more I look at it, the more it seems that Everything Is Wrong with that makefile. Maybe pick up a Makefile tutorial and work though it slowly, step-by-step. Especially substitution rules and magic variables should be double-checked. — Kerrek SB

donjuedo donjuedo · Accepted Answer · 2015-06-15T18:10:41

Try -std=c++11 instead of -std=c++0x. While your compiler knows the usage, the -std=c++0x "turns off" those new rules.

C++ Move constructor won't compile

1 Answers