OpenGL shader does not compile but gives no error message - c++

Question

I am trying to write a function for loading and compiling a shader using OpenGl, but the shader refuses to compile while giving me an empty (or random) error log.
The following is my minimal example:
vertexShader = glCreateShader( GL_VERTEX_SHADER );
std::string vertexSource = ShaderLoader::load("vertexShader.vert");
const char * vertexAdress = vertexSource.c_str();
glShaderSource( vertexShader, 1, &vertexAdress, NULL );
int shaderCompiled = GL_FALSE;
char errorLog[512];
glCompileShader(vertexShader);
glGetShaderiv(vertexShader, GL_COMPILE_STATUS, &shaderCompiled );
glGetShaderInfoLog(vertexShader, 512, nullptr, &errorLog[0]);
glDeleteShader(vertexShader);
Outputting shaderCompiled gives 0 and errorLog gives either an empty string or a few random characters.
The function ShaderLoader::load contains the following code:
std::string ShaderLoader::load(std::string source) {
std::string shader;
std::fstream readFile(source, std::ios::in);
if (readFile.is_open()){
std::stringstream buffer;
buffer << readFile.rdbuf();
shader = buffer.str() + "\0";
} else {
throw std::runtime_error( "Couldn't load shader file: " + source);
}
return shader;
}
It seems to be working as expected. The shader source code is
#version 330 core
layout (location = 0) in vec3 inVertex;
layout (location = 1) in vec3 inNormal;
out vec3 FragmentPosition;
out vec3 Normal;
uniform mat4 transform;
void main()
{
FragmentPosition = vec3(inVertex);
Normal = mat3(transpose(inverse(transform))) * inNormal;
gl_Position = transform * vec4( inVertex, 1 );
}
How can I populate errorLog with an actual error message, or even better, get the shader to compile.

Answer 1

First only use error logging if shaderCompiled is false so you don't get random strings,
glGetShaderiv(VS, GL_COMPILE_STATUS, &shaderCompiled);
if (!shaderCompiled)
{
//error
GLchar InfoLog[256];
glGetShaderInfoLog(vertexShader, sizeof(InfoLog), NULL, InfoLog);
Second, are you actually linking and using the shaders, the problem might not be with the compilation:
// after compilation
GLuint shaderProgram = glCreateProgram();
glAttachShader(shaderProgram, vertexShader);
glLinkProgram(shaderProgram);
glDetachShader(shaderProgram, vertexShader);
glDeleteShader(vertexShader);
glGetProgramiv(shaderProgram, GL_LINK_STATUS, &success);