### Compilation failed:

error: SPIR-V validation error: Variable must be decorated with a location
  %a = OpVariable %_ptr_Input_float Input

OpCapability Shader
%1 = OpExtInstImport "GLSL.std.450"
OpMemoryModel Logical GLSL450
OpEntryPoint Fragment %main "main" %sk_FragColor %sk_Clockwise %a %b %c %d %e
OpExecutionMode %main OriginUpperLeft
OpName %sk_FragColor "sk_FragColor"
OpName %sk_Clockwise "sk_Clockwise"
OpName %a "a"
OpName %b "b"
OpName %c "c"
OpName %d "d"
OpName %e "e"
OpName %main "main"
OpDecorate %sk_FragColor RelaxedPrecision
OpDecorate %sk_FragColor Location 0
OpDecorate %sk_FragColor Index 0
OpDecorate %sk_Clockwise RelaxedPrecision
OpDecorate %sk_Clockwise BuiltIn FrontFacing
OpDecorate %a RelaxedPrecision
OpDecorate %b RelaxedPrecision
OpDecorate %c RelaxedPrecision
OpDecorate %d RelaxedPrecision
OpDecorate %e RelaxedPrecision
OpDecorate %21 RelaxedPrecision
OpDecorate %22 RelaxedPrecision
OpDecorate %23 RelaxedPrecision
OpDecorate %29 RelaxedPrecision
OpDecorate %30 RelaxedPrecision
OpDecorate %31 RelaxedPrecision
%float = OpTypeFloat 32
%v4float = OpTypeVector %float 4
%_ptr_Output_v4float = OpTypePointer Output %v4float
%sk_FragColor = OpVariable %_ptr_Output_v4float Output
%bool = OpTypeBool
%_ptr_Input_bool = OpTypePointer Input %bool
%sk_Clockwise = OpVariable %_ptr_Input_bool Input
%_ptr_Input_float = OpTypePointer Input %float
%a = OpVariable %_ptr_Input_float Input
%b = OpVariable %_ptr_Input_float Input
%c = OpVariable %_ptr_Input_float Input
%_ptr_Input_v4float = OpTypePointer Input %v4float
%d = OpVariable %_ptr_Input_v4float Input
%e = OpVariable %_ptr_Input_v4float Input
%void = OpTypeVoid
%18 = OpTypeFunction %void
%_ptr_Output_float = OpTypePointer Output %float
%int = OpTypeInt 32 1
%int_0 = OpConstant %int 0
%main = OpFunction %void None %18
%19 = OpLabel
%21 = OpLoad %float %a
%22 = OpLoad %float %b
%23 = OpLoad %float %c
%20 = OpExtInst %float %1 Refract %21 %22 %23
%24 = OpAccessChain %_ptr_Output_float %sk_FragColor %int_0
OpStore %24 %20
%29 = OpLoad %v4float %d
%30 = OpLoad %v4float %e
%31 = OpLoad %float %c
%28 = OpExtInst %v4float %1 Refract %29 %30 %31
OpStore %sk_FragColor %28
OpReturn
OpFunctionEnd

1 error