UnityObjectToClipPos : ambiguous function call

Unity Engine
1

Hello! So I just started messing with shaders, and I’m trying to follow a tutorial. In the tutorial, inside the vert() function we used

o.pos = mul(UNITY_MATRIX_MVP, i.pos)

That was fine, but it seems like Unity automatically converts this line to

o.pos = UnityObjectToClipPos(i.pos);

OK… that’s great, but now this line gives my shader a compile error:

Shader error in 'Custom/Elasticity': 'UnityObjectToClipPos': ambiguous function call at line 27 (on d3d11)

So not only is Unity changing my code to something I didn’t ask for, but now it just doesn’t compile. Anyone know what I can do? Below is the full code from the tutorial I was following:

Shader "Custom/MyShader"
{
    Properties
    {
    }
    SubShader
    {
        Pass {
            CGPROGRAM

            #pragma vertex vert
            #pragma fragment frag

            struct VertInput {
                float pos : POSITION;
            };

            struct VertOutput {
                float4 pos : SV_POSITION;
                half3 color : COLOR;
            };

            VertOutput vert(VertInput i) {
                VertOutput o;
              
                o.pos = UnityObjectToClipPos(i.pos);
                o.color = i.pos.xyz;

                return o;
            }

            half4 frag(VertOutput i) : COLOR {
                return half4(o.color, 1.0f);
            }

            ENDCG
        }
    }
    FallBack "Diffuse"
}

Thanks!

2 
struct VertInput {
     float pos : POSITION;
};

The vertex position is a float4