resources/sksl/runtime_errors/DerivativesES2.rts - skia - Git at Google

 float2 dx(float2 coords) { return dFdx(coords); }
 float2 dy(float2 coords) { return dFdy(coords); }

 /*%%*
 no match for dFdx(float2)
 no match for dFdy(float2)
 *%%*/
	float2 dx(float2 coords) { return dFdx(coords); }
	float2 dy(float2 coords) { return dFdy(coords); }

	/%%
	no match for dFdx(float2)
	no match for dFdy(float2)
	%%/