error: expected unqualified-id before ‘{’ token on Linux gcc - c++

Question

i get the following error message when trying to compile the following code on linux with gcc (GCC) 7.3.1 20180303 (Red Hat 7.3.1-5) while it works on windows without problems.
...
#include "DDImage/NoIop.h"
static const char* const CLASS = "RemoveChannels";
// -------------------- Header -------------------- \\
class RemoveChannels : public NoIop
{
public:
//! Default constructor.
RemoveChannels (Node* node) : NoIop(node)
{
this->_message = "\\w+";
this->operation = 1;
}
//! Virtual destructor.
virtual ~RemoveChannels () {}
void _validate(bool) override;
private:
//! Information private for the node.
ChannelSet channels;
std::regex rgx;
const char* _message;
int operation; // 0 = remove, 1 = keep
};
void RemoveChannels::_validate(bool for_real)
{
if (!this->_message) // Fast return if you don't have anything in there.
{
set_out_channels(Mask_None); // Tell Nuke we didn't touch anything.
return;
}
...
}
...
When compiling the above code i get the following error message on linux with gcc (on windows it works fine!).
Compiler error:
RemoveChannels.cpp:28:1: error: expected unqualified-id before ‘{’ token
{
^
RemoveChannels.cpp:65:6: error: ‘RemoveChannels’ has not been declared
void RemoveChannels::_validate(bool for_real)
^~~~~~~~~~~~~~
/RemoveChannels.cpp: In function ‘void _validate(bool)’:
RemoveChannels.cpp:67:8: error: invalid use of ‘this’ in non-member function
if (!this->_message) // Fast return if you don't have anything in there.
^~~~
...
If i remove this-> from the implementing function and just use _message it compiles and works without a problem.
Can anyone explain to me why this is happening and just on linux and not on windows?

Answer 1

Simple example
// -------------------- Header --------------------\\
class RemoveChannels
{
public:
int operation = 0;
};
int main ()
{
RemoveChannels r;
r.operation++;
}
when a line ends in a backslash, it is continued on the next line. That means class RemoveChannels has accidentally been commented out with a line comment leaking into the next line.
Solution: remove the backslash
// -------------------- Header --------------------
class RemoveChannels
{
public:
int operation = 0;
};
int main ()
{
RemoveChannels r;
r.operation++;
}