Fix MGFX Error/Warning Line Numbers

[tomspilman]

Back in #1972 the MGFX compiler was switched over to use CppNet (https://github.com/xtravar/CppNet) for preprocessing. This was the first step towards supporting GLSL.

The problem as reported in #3853 is that CppNet does not report the correct line numbers for errors in all cases.

In particular for multi-line comments or FX files with lots of includes.

We need someone to reproduce those errors and work with or fork CppNet to fix them.

Note the SiliconStudios team uses CppNet as well with what seems like some slightly different fixes to error reporting. We should check their fork:

https://github.com/manu-silicon/CppNet

... to see if it solves our problems as well.

[tanis2000]

A quick glance at both repos regarding error lines shows that SiliconStudios' fork has an extendable PreprocessorListener but the actual code is still the same.

jcpp does have a commit that seems to be past the time CppNet has been ported from it that could help fixing those bugs:
shevek/jcpp@1bb60e9

[tomspilman]

Thanks @tanis2000 ... that fix in jcpp is a great find!

[tomspilman]

FYI. Found another error with CppNet today... xtravar/CppNet#4.

[KakCAT]

Hi,

I needed to get some shaders working and the wrong lines were driving me mad, so I had a look at CppNet.

It seems one of the problems is that the CPP comments did not count as a line. It was no problem if there were no #includes, but once you included a file, the #line set by CppNet to say the processor it was again in the original file was way off.

I've directly added a line into the cppcomment although I not sure where the correct place to add the new line is. The code is just a disaster, so I'm afraid of touching anything and doing it worse, so I just patched the problem with the cppcomment. (I'm sure more problems are there because of the way of handling the line count)

I also added the fix @tanis2000 mentioned, otherwise the #include counted one extra CR.

So, in example to reproduce the problem:

// line 1
// line 2
// line 3
// line 4
error

was correctly giving error in line 5 but

// line 1
// line 2
// line 3
#include "file.fxh"
error

was giving error in line 3 (actually should give line 2, but the second bug incremented it)

The changes are here: https://github.com/KakCAT/CppNet

I've tested it with my shaders and Kosmonaut's Deferred Engine, but other than that, should be tested just in case my test set is too small and does things worse for other shaders.

[nkast]

Thanks @KakCAT!
I moved this into my branch and I'll let you know in case I run across any bugs.
(although I am not working on shaders right now)