glsl UNEXPECTED NEW_IDENTIFIER, expecting $end - opengl

Question

I'm experimenting this frustrating error while compiling a fragment shader. If I try to compile the shader as it is :
#version 450 core
in vec2 tex_coord;
in flat int vertex_id;
out vec4 color;
layout (binding = 20) uniform sampler2D buildingTex;
layout (binding = 21) uniform sampler2D groundTex;
const int cube_vertices = 36;
const int ground_vertices = 4;
void main(void)
{
if(vertex_id < cube_vertices)
{
float scaleF = .5f;
vec2 scale = vec2(scaleF,scaleF);
color = texture(buildingTex,tex_coord*scale);
}
if(vertex_id >= cube_vertices)
{
color = texture(groundTex,tex_coord);
}
}
the compailer complains with : glsl UNEXPECTED NEW_IDENTIFIER, expecting $end.
However if I add to my fragment shader another fragment shader, that i had in another file , and then i comment all its rows like follows :
// #version 450 core
// in vec2 tex_coord;
// in flat int vertex_id;
// out vec4 color;
// layout (binding = 20) uniform sampler2D buildingTex;
// layout (binding = 21) uniform sampler2D groundTex;
// int cube_vertices;
// int ground_vertices;
// void main(void)
// {
// if(vertex_id < cube_vertices)
// {
// float scaleF = .5f;
// vec2 scale = vec2(scaleF,scaleF);
// color = texture(buildingTex,tex_coord*scale);
// //color = vec4(1.0,1.0,1.0,1.0);
// }
// if(vertex_id >= cube_vertices)
// {
// color = texture(groundTex,tex_coord);
// //color = vec4(1.0,0.0,0.0,1.0);
// }
#version 450 core
in vec2 tex_coord;
in flat int vertex_id;
out vec4 color;
layout (binding = 20) uniform sampler2D buildingTex;
layout (binding = 21) uniform sampler2D groundTex;
const int cube_vertices = 36;
const int ground_vertices = 4;
void main(void)
{
if(vertex_id < cube_vertices)
{
float scaleF = .5f;
vec2 scale = vec2(scaleF,scaleF);
color = texture(buildingTex,tex_coord*scale);
}
if(vertex_id >= cube_vertices)
{
color = texture(groundTex,tex_coord);
}
}
in this case the shader is compiled!
I tried to remove the commented line of the old code, and seems like I can remove just some of them, while others I cannot touch, to have the shader compiled.
At this moment the shader is :
// #version 450 core
// in vec2 tex_coord;
// in flat int vertex_id;
// out vec4 color;
// layout (binding = 20) uniform sampler2D buildingTex;
// layout (binding = 21) uniform sampler2D groundTex;
// int cube_vertices;
// if(vertex_id < cube_vertices)
#version 450 core
in vec2 tex_coord;
in flat int vertex_id;
out vec4 color;
layout (binding = 20) uniform sampler2D buildingTex;
layout (binding = 21) uniform sampler2D groundTex;
const int cube_vertices = 36;
const int ground_vertices = 4;
void main(void)
{
if(vertex_id < cube_vertices)
{
float scaleF = .5f;
vec2 scale = vec2(scaleF,scaleF);
color = texture(buildingTex,tex_coord*scale);
}
if(vertex_id >= cube_vertices)
{
color = texture(groundTex,tex_coord);
}
}
and seems I cannot remove anymore from the commented code.
Since this seems the most illogical problem I ever had in my life,and since the others questions having this same error warning, were solved in a way that doesn't match my case, I'm opening a new quest.
ps: I tried to make a completely new shader but it didn't work.
pps: the problem comes up after I changed the major-mode (through M-x and not modifying the init file of emacs!) of emacs in order to use the ordinary shortcut I use in cpp files, in the shaders files (.vert, .frag ...), however even restoring the default-mode and restarting emacs the shader does not compile!
EDIT: this is the method I use to load the shader
const char* Shader::loadShader(std::string shaderPath)
{
std::ifstream temp_ss(shaderPath,std::ifstream::in);
if(temp_ss)
{
char c;
char *ss = new char[shader_size];
unsigned i = 0 ;
while(temp_ss.get(c))
{
ss[i++] = c;
}
std::cout<<std::ends;
//ends adds a null, and then flushes the buffer
//if i don't use it , often, the window does not show anything
//I could use std::cout<<std::endl; in place of ends,
//but ends seem a more polite solution to me
//CHECK SHADER
for(int i = 0; i < shader_size; i++)
if(ss[i] == '\0')
std::cout<<"shader.cpp::ERROR: NULL CHARACTER FOUND ON SHADER "<<
shaderPath<<std::endl;
return ss;
}
else
std::clog<<"shader.cpp::loadShader() : ERROR ::: no shaders found at the path : "<<shaderPath<<std::endl;
}

Answer 1

From the OP:
TO SUMMARIZE : shader files MUST be null terminated , I modify the function that loads the shader source into the buffer like follows:
const char* Shader::loadShader(std::string shaderPath)
{
std::ifstream temp_ss(shaderPath,std::ifstream::in);
if(temp_ss)
{
char c;
char *ss = new char[shader_size];
unsigned i = 0 ;
while(temp_ss.get(c))
{
ss[i++] = c;
}
//CHECK SHADER
bool nullTerminated = false;
for(int i = 0; i < shader_size; i++)
if(ss[i] == '\0')
nullTerminated = true;
if(!nullTerminated)
ss[shader_size++] = '\0';
return ss;
}
else
std::clog<<"shader.cpp::loadShader() : ERROR ::: no shaders found at the path : "<<shaderPath<<std::endl;
}
and the fragment shader compiles!