Assert atmos to not have UnionAll types

src/ClimaAtmos.jl

@@ -6,6 +6,7 @@ include(joinpath("parameters", "Parameters.jl"))
 import .Parameters as CAP
 
 include(joinpath("utils", "abbreviations.jl"))
+include(joinpath("utils", "gpu_compat.jl"))
 include(joinpath("utils", "common_spaces.jl"))
 include(joinpath("solver", "types.jl"))
 include(joinpath("solver", "cli_options.jl"))

src/solver/type_getters.jl

@@ -78,6 +78,7 @@ function get_atmos(config::AtmosConfig, params)
         surface_model = get_surface_model(parsed_args),
         numerics = get_numerics(parsed_args),
     )
+    @assert !@has_DataType_or_UnionAll(atmos)
 
     @info "AtmosModel: \n$(summary(atmos))"
     return atmos

src/utils/gpu_compat.jl

@@ -0,0 +1,29 @@
+"""
+    has_DataType_or_UnionAll(::Any)
+
+Returns a Bool (and prints warnings if) the given
+data structure has an instance of `DataType` or
+`UnionAll` type, both of which are not `isbits`
+and therefore cannot be broadcasted through a
+gpu kernel.
+"""
+function has_DataType_or_UnionAll(obj, name, pc = ())
+    for pn in propertynames(obj)
+        prop = getproperty(obj, pn)
+        pc_full = (pc..., ".", pn)
+        pc_string = name * string(join(pc_full))
+        if prop isa DataType
+            @warn "$pc_string::$(typeof(prop)) is a DataType"
+            return true
+        elseif prop isa UnionAll
+            @warn "$pc_string::$(typeof(prop)) is a UnionAll"
+            return true
+        else
+            has_DataType_or_UnionAll(prop, name, pc_full)
+        end
+    end
+    return false
+end
+macro has_DataType_or_UnionAll(obj)
+    return :(has_DataType_or_UnionAll($(esc(obj)), $(string(obj))))
+end