[require]
GLSL >= 1.20

[vertex shader]

uniform int u = 1;
varying vec4 color;

void func(inout int i, inout float f)
{
  i = 0;
  f = 1.;
}

void main()
{
  vec4 v = vec4(0.);
  int i = u;

  func(i, v[i]);
  color = v;
  gl_Position = gl_Vertex;
}

[fragment shader]
varying vec4 color;

void main()
{
  gl_FragColor = color;
}

[test]
draw rect -1 -1 2 2
probe all rgb 0. 1. 0.