Fixes

Author: charleskawczynski

base/show.jl

@@ -2771,7 +2771,7 @@ function type_depth_limit(str::String, n::Int; maxdepth = nothing)
     return String(take!(output))
 end
 
-function print_type_bicolor(io, @nospecialize(type); color=:normal, inner_color=:light_black, use_color::Bool=true, depth::Int)
+function print_type_bicolor(io, @nospecialize(type); color=:normal, inner_color=:light_black, use_color::Bool=true, depth::Int = 0)
     if depth > max_type_depth(io)
     else
         str = sprint(show, type, context=io)
@@ -2852,14 +2852,14 @@ function show(io::IO, tv::TypeVar)
     nothing
 end
 
-function show(io::IO, vm::Core.TypeofVararg)
+function show(io::IO, vm::Core.TypeofVararg, depth::Int = 0)
     print(io, "Vararg")
     if isdefined(vm, :T)
         print(io, "{")
-        show(io, vm.T)
+        show(io, vm.T, depth + 1)
         if isdefined(vm, :N)
             print(io, ", ")
-            show(io, vm.N)
+            show(io, vm.N, depth)
         end
         print(io, "}")
     end

test/stacktraces.jl

@@ -270,6 +270,21 @@ end
     @show sprint(Base.show, typ, context = (:max_type_depth_limit => 6))
 end
 
+Base.@kwdef struct F55952{A,B}
+    num::Int = 1
+end
+
+@testset "Depth-limited type printing performance for highly nested types" begin
+    nest_val(na, nb, ::Val{1}) = F55952{na, nb}()
+    nest_val(na, nb, ::Val{n}) where {n} = nest_val(F55952{na, nb}, F55952{na, nb}, Val(n-1))
+    nest_val(na, nb, n::Int) = nest_val(na, nb, Val(n))
+    nest_val(n) = nest_val(1, 1, n)
+    typ = typeof(nest_val(23))
+    # be careful with changing to a larger number
+    # ~10 seconds before #55952 is fixed:
+    @test 1 > @elapsed sprint(Base.show, typ, context = (:max_type_depth_limit => 2))
+end
+
 @testset "Base.StackTraces docstrings" begin
     @test isempty(Docs.undocumented_names(StackTraces))
 end