[require]
GLSL >= 1.10

[vertex shader]
uniform vec4 color;
varying vec4 color1;
varying vec4 color2;

void set_color2(void)
{
	color2 = color1;
}

void main()
{
	gl_Position = gl_Vertex;

	/* Due to a bug in glsl2, this particular assignment followed
	 * by the function call below would get the expression moved to
	 * color2 and color1 would be eliminated.
	 */

	color1 = color * 0.5;
	set_color2();
}

[fragment shader]
varying vec4 color1;
varying vec4 color2;

void main()
{
	gl_FragColor = color1;
}

[test]
uniform vec4 color 0.0 1.0 0.0 0.0
draw rect -1 -1 2 2
probe all rgba 0.0 0.5 0.0 0.0