Thanks. I will take a look.

I am still seeing the problem :(

$ glslangValidator.exe -l t.vert t.geom
t.vert
t.geom
ERROR: Linking vertex stage: Types must match:
anon@0: " out block{ gl_Position 4-component vector of float Position gl_Position, gl_PointSize float PointSize gl_PointSize, out 1-element array of float ClipDistance gl_ClipDistance, gl_ClipVertex 4-component vector of float ClipVertex gl_ClipVertex, out 4-component vector of float FrontColor gl_FrontColor, out 4-component vector of float BackColor gl_BackColor, out 4-component vector of float FrontSecondaryColor gl_FrontSecondaryColor, out 4-component vector of float BackSecondaryColor gl_BackSecondaryColor, out 1-element array of 4-component vector of float TexCoord gl_TexCoord, out float FogFragCoord gl_FogFragCoord}" versus gl_in: " in 3-element array of block{ in 4-component vector of float Position gl_Position, in float PointSize gl_PointSize, in 1-element array of float ClipDistance gl_ClipDistance}"

$ cat t.vert
#version 150 core

in vec3 vertexPosition;

out VertexData {
vec3 position;
} vs_out;

uniform mat4 mvp;

void main(void)
{
vs_out.position = vertexPosition;

gl_Position = mvp * vec4(vertexPosition, 1.0);

}

$ cat t.geom
#version 150 core

layout(triangles) in;
layout(line_strip, max_vertices = 4 /* 2 lines = 4 vertices */) out;

in VertexData {
vec3 position;
} gs_in[];

void drawLine(vec4 a, vec4 b)
{
gl_Position = a;
EmitVertex();

gl_Position = b;
EmitVertex();

EndPrimitive();

}

void main()
{
// This GS takes all three sides of a rectangle, but only emits vertices for
// its catheti, which gives us a nice wireframe.

vec3 aSide = (gs_in[0].position - gs_in[1].position);
vec3 bSide = (gs_in[0].position - gs_in[2].position);
vec3 cSide = (gs_in[1].position - gs_in[2].position);

if (dot(aSide, bSide) == 0) {
    drawLine(gl_in[0].gl_Position, gl_in[1].gl_Position);
    drawLine(gl_in[0].gl_Position, gl_in[2].gl_Position);
} else if (dot(aSide, cSide) == 0) {
    drawLine(gl_in[0].gl_Position, gl_in[1].gl_Position);
    drawLine(gl_in[1].gl_Position, gl_in[2].gl_Position);
} else if (dot(bSide, cSide) == 0) {
    drawLine(gl_in[0].gl_Position, gl_in[2].gl_Position);
    drawLine(gl_in[1].gl_Position, gl_in[2].gl_Position);
}

}

Do you see this as well?

Hmm, no I don't. The widget_wireframe.vert and .geom compile fine for me.

Sorry for the thrash. It looks like a git glitch. Its working for me now.