Add structlike(::Type{BigInt/BigFloat}) = false (#38)

BigInt and BigFloat are mutable structs in Julia, but they should be
treated as primitive/non-struct types for serialization purposes.
Without this, packages like JSON.jl fail when trying to parse numbers
into BigInt or BigFloat because StructUtils routes them to makestruct
instead of lift.

Fixes JuliaIO/JSON.jl#424

Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>

Author: quinnj

src/StructUtils.jl

@@ -248,6 +248,8 @@ structlike(::Type{Symbol}) = false
 structlike(::Type{Regex}) = false
 structlike(::Type{<:Dates.TimeType}) = false
 structlike(::Type{Number}) = false
+structlike(::Type{BigInt}) = false
+structlike(::Type{BigFloat}) = false
 structlike(::Type{Nothing}) = false
 structlike(::Type{Missing}) = false
 structlike(::Type{UUID}) = false

test/runtests.jl

@@ -326,6 +326,15 @@ end
     @test StructUtils.make(Dict{Symbol, Int}, (;)) == Dict{Symbol, Int}()
 end
 
+@testset "BigInt/BigFloat structlike" begin
+    # BigInt and BigFloat are mutable structs in Julia, but should be treated
+    # as non-struct types for serialization purposes (JuliaIO/JSON.jl#424)
+    @test StructUtils.structlike(BigInt) == false
+    @test StructUtils.structlike(BigFloat) == false
+    @test StructUtils.structlike(StructUtils.DefaultStyle(), BigInt) == false
+    @test StructUtils.structlike(StructUtils.DefaultStyle(), BigFloat) == false
+end
+
 @testset "keyeq with Tuple" begin
     # Test basic tuple functionality
     @test StructUtils.keyeq(:a, ("a", "b", "c"))