Refactor show_default and reuse for printing

See issue JuliaLang#36263

Author: goretkin

base/indices.jl

@@ -358,7 +358,7 @@ unsafe_length(S::Slice) = unsafe_length(S.indices)
 getindex(S::Slice, i::Int) = (@_inline_meta; @boundscheck checkbounds(S, i); i)
 getindex(S::Slice, i::AbstractUnitRange{<:Integer}) = (@_inline_meta; @boundscheck checkbounds(S, i); i)
 getindex(S::Slice, i::StepRange{<:Integer}) = (@_inline_meta; @boundscheck checkbounds(S, i); i)
-show(io::IO, r::Slice) = print(io, "Base.Slice(", r.indices, ")")
+show(io::IO, r::Slice) = show_default(io, r; f_type = t -> t.name)
 iterate(S::Slice, s...) = iterate(S.indices, s...)
 
 
@@ -389,7 +389,7 @@ unsafe_length(S::IdentityUnitRange) = unsafe_length(S.indices)
 getindex(S::IdentityUnitRange, i::Int) = (@_inline_meta; @boundscheck checkbounds(S, i); i)
 getindex(S::IdentityUnitRange, i::AbstractUnitRange{<:Integer}) = (@_inline_meta; @boundscheck checkbounds(S, i); i)
 getindex(S::IdentityUnitRange, i::StepRange{<:Integer}) = (@_inline_meta; @boundscheck checkbounds(S, i); i)
-show(io::IO, r::IdentityUnitRange) = print(io, "Base.IdentityUnitRange(", r.indices, ")")
+show(io::IO, r::IdentityUnitRange) = show_default(io, r; f_type = t -> t.name)
 iterate(S::IdentityUnitRange, s...) = iterate(S.indices, s...)
 
 """

base/range.jl

@@ -739,7 +739,7 @@ end
 
 show(io::IO, r::AbstractRange) = print(io, repr(first(r)), ':', repr(step(r)), ':', repr(last(r)))
 show(io::IO, r::UnitRange) = print(io, repr(first(r)), ':', repr(last(r)))
-show(io::IO, r::OneTo) = print(io, "Base.OneTo(", r.stop, ")")
+show(io::IO, r::OneTo) = show_default(io, r; f_type = t -> t.name)
 
 function ==(r::T, s::T) where {T<:AbstractRange}
     isempty(r) && return isempty(s)

base/show.jl

@@ -388,12 +388,18 @@ show(io::IO, @nospecialize(x)) = show_default(io, x)
 show(x) = show(stdout::IO, x)
 
 # avoid inferring show_default on the type of `x`
-show_default(io::IO, @nospecialize(x)) = _show_default(io, inferencebarrier(x))
+show_default(io::IO, @nospecialize(x); f_type=identity) = _show_default(io, inferencebarrier(x), inferencebarrier(f_type))
 
-function _show_default(io::IO, @nospecialize(x))
+function _show_default(io::IO, @nospecialize(x), @nospecialize(f_type))
     t = typeof(x)
-    show(io, inferencebarrier(t))
+    show(io, inferencebarrier(f_type(t)))
     print(io, '(')
+    _show_default_body(io, x)
+    print(io, ')')
+end
+
+function _show_default_body(io::IO, @nospecialize(x))
+    t = typeof(x)
     nf = nfields(x)
     nb = sizeof(x)
     if nf != 0 || nb == 0
@@ -422,7 +428,6 @@ function _show_default(io::IO, @nospecialize(x))
             end
         end
     end
-    print(io,')')
 end
 
 # Check if a particular symbol is exported from a standard library module