Incorrect typechecking when preprocessors are used

[Martomate]

Describe the bug
When a variable is defined multiple times in a file the first definition seems to be used for type checking. This can be a problem if multiple shader stages are written in the same file.

To Reproduce

#if VERTEX_SHADER
#version 330

in vec3 color;
out vec3 fragColor;

void main() {
    fragColor = color;
}

#else
#version 330

in vec3 fragColor;
out vec4 color;

void main() {
    color = vec4(fragColor, 1); // error: Incompatible types as operands of '=': 'vec3' and 'vec4'
}

#endif

Expected behavior
Ideally there would be no complaints from Intellij for the above code.

If multiple shader stages in the same file is not supported, then I could of course put in them in separate files instead, or use another name for the variable. It would be a reasonable workaround for now.

Versions

• IDE: IntelliJ IDEA Community Edition 2023.1.3
• Plugin: 1.24

Extra context
My real code uses #pragma shader vert instead of #if, but I found that both versions had the same problem.

[Darkyenus]

If multiple shader stages in the same file is not supported

The plugin does not care about shader stages, the problem is that the plugin always processes both branches of the #if. This is not trivial to fix (at least for me) because of the fairly complex interactions between the preprocessor and the lexer. Basically the code is parsed as if the #if-else was not there.

PR's welcome.