resources/sksl/runtime_errors/PrivateRTShader.rts - skia - Git at Google

 float4 main(float2 xy) {
     return float4(sk_FragCoord);
 }

 /*%%*
 unknown identifier 'sk_FragCoord'
 *%%*/
	float4 main(float2 xy) {
	return float4(sk_FragCoord);
	}

	/%%
	unknown identifier 'sk_FragCoord'
	%%/