Merge pull request #3579 from DhairyaLGandhi/dg/copymtk

Copy `MTKParameters` fields only if not empty

Author: ChrisRackauckas

src/systems/parameter_buffer.jl

@@ -319,8 +319,8 @@ function Base.copy(p::MTKParameters)
     initials = copy(p.initials)
     discrete = Tuple(eltype(buf) <: Real ? copy(buf) : copy.(buf) for buf in p.discrete)
     constant = Tuple(eltype(buf) <: Real ? copy(buf) : copy.(buf) for buf in p.constant)
-    nonnumeric = copy.(p.nonnumeric)
-    caches = copy.(p.caches)
+    nonnumeric = isempty(p.nonnumeric) ? p.nonnumeric : copy.(p.nonnumeric)
+    caches = isempty(p.caches) ? p.caches : copy.(p.caches)
     return MTKParameters(
         tunable,
         initials,

test/mtkparameters.jl

@@ -18,6 +18,11 @@ ivs = Dict(c => 3a, d => 4, e => [5.0, 6.0, 7.0],
 
 ps = MTKParameters(sys, ivs)
 @test_nowarn copy(ps)
+ps_copy = copy(ps)
+ps_field_equals = map(fieldnames(typeof(ps))) do f
+    getfield(ps, f) == getfield(ps_copy, f)
+end
+@test all(ps_field_equals)
 # dependent initialization, also using defaults
 @test getp(sys, a)(ps) == getp(sys, b)(ps) == getp(sys, c)(ps) == 0.0
 @test getp(sys, d)(ps) isa Int