Linking vertex shader fails when running with EGL - c++

Question

I use a very simple vertex shader program in my application; it compiles and links OK when I use the GLEW or GLUT library. But I need to run without X11, so I try to use it with the EGL library, and the link fails with the following error :
error: vertex shader lacks `main'
#include <string.h>
#include <stdio.h>
#include <EGL/egl.h>
#define GL_GLEXT_PROTOTYPES 1
#include <GL/glut.h>
#include <GL/glext.h>
static const EGLint configAttribs[] = {
EGL_SURFACE_TYPE, EGL_PBUFFER_BIT,
EGL_BLUE_SIZE, 8,
EGL_GREEN_SIZE, 8,
EGL_RED_SIZE, 8,
EGL_DEPTH_SIZE, 8,
EGL_RENDERABLE_TYPE, EGL_OPENGL_BIT,
EGL_NONE
};
static const EGLint pbufferAttribs[] = {
EGL_WIDTH, 100,
EGL_HEIGHT, 100,
EGL_NONE,
};
int main(int argc, char *argv[])
{
// 1. Initialize EGL
EGLDisplay eglDpy = eglGetDisplay(EGL_DEFAULT_DISPLAY);
EGLint major, minor;
eglInitialize(eglDpy, &major, &minor);
// 2. Select an appropriate configuration
EGLint numConfigs;
EGLConfig eglCfg;
eglChooseConfig(eglDpy, configAttribs, &eglCfg, 1, &numConfigs);
// 3. Create a surface
EGLSurface eglSurf = eglCreatePbufferSurface(eglDpy, eglCfg,
pbufferAttribs);
// 4. Bind the API
eglBindAPI(EGL_OPENGL_API);
// 5. Create a context and make it current
EGLContext eglCtx = eglCreateContext(eglDpy, eglCfg, EGL_NO_CONTEXT,
NULL);
eglMakeCurrent(eglDpy, eglSurf, eglSurf, eglCtx);
// from now on use your OpenGL context
int len;
GLint res = GL_FALSE;
GLuint VertexShaderID = glCreateShader (GL_VERTEX_SHADER);
const char * VertexShaderCode =
"#version 330 core\n"
"\n"
"layout(location = 0) in vec3 vertexPosition_modelspace;\n"
"layout(location = 1) in vec4 vertexColor;\n"
"\n"
"out vec4 fragmentColor;\n"
"uniform mat4 MVP;\n"
"\n"
"void main(){\n"
"\n"
" gl_Position = MVP * vec4(vertexPosition_modelspace,1);\n"
"\n"
" fragmentColor.r = vertexColor.r;\n"
" fragmentColor.g = vertexColor.g;\n"
" fragmentColor.b = vertexColor.b;\n"
" fragmentColor.a = vertexColor.a;\n"
"}\n";
// Compile Vertex Shader
glShaderSource (VertexShaderID, 1, &VertexShaderCode , NULL);
glCompileShader (VertexShaderID);
glGetShaderiv (VertexShaderID, GL_COMPILE_STATUS, &res);
glGetShaderiv (VertexShaderID, GL_INFO_LOG_LENGTH, &len);
if (len > 0)
{
char mess[len+1];
glGetShaderInfoLog (VertexShaderID, len, NULL, &mess[0]);
printf("%s\n", mess);
}
// Link the program
GLuint ProgramID = glCreateProgram ();
glAttachShader (ProgramID, VertexShaderID);
glLinkProgram (ProgramID);
// Check the program
glGetProgramiv (ProgramID, GL_LINK_STATUS, &res);
glGetProgramiv (ProgramID, GL_INFO_LOG_LENGTH, &len);
if (len > 0)
{
char mess[len+1];
glGetProgramInfoLog (ProgramID, len, NULL, &mess[0]);
printf("%s\n", mess);
}
glDetachShader (ProgramID, VertexShaderID);
glDeleteShader (VertexShaderID);
// 6. Terminate EGL when finished
eglTerminate(eglDpy);
return 0;
}
It is likely that I have forgotten some EGL configuration parameter.