Improve type inference of nonmissingtype, nonnothingtype and of Ryu (#56120)

Co-authored-by: Cody Tapscott <84105208+topolarity@users.noreply.github.com>

Author: 2 people

base/missing.jl

@@ -36,7 +36,7 @@ Any
 !!! compat "Julia 1.3"
     This function is exported as of Julia 1.3.
 """
-nonmissingtype(::Type{T}) where {T} = typesplit(T, Missing)
+nonmissingtype(@nospecialize(T::Type)) = typesplit(T, Missing)
 
 function nonmissingtype_checked(T::Type)
     R = nonmissingtype(T)

base/ryu/Ryu.jl

@@ -112,7 +112,7 @@ end
 function Base.show(io::IO, x::T, forceuntyped::Bool=false, fromprint::Bool=false) where {T <: Base.IEEEFloat}
     compact = get(io, :compact, false)::Bool
     buf = Base.StringVector(neededdigits(T))
-    typed = !forceuntyped && !compact && Base.nonnothing_nonmissing_typeinfo(io) != typeof(x)
+    typed = !forceuntyped && !compact && Base.nonnothing_nonmissing_typeinfo(io) !== typeof(x)
     pos = writeshortest(buf, 1, x, false, false, true, -1,
         (x isa Float32 && !fromprint) ? UInt8('f') : UInt8('e'), false, UInt8('.'), typed, compact)
     write(io, resize!(buf, pos - 1))

base/some.jl

@@ -16,7 +16,7 @@ Some(::Type{T}) where {T} = Some{Type{T}}(T)
 
 promote_rule(::Type{Some{T}}, ::Type{Some{S}}) where {T, S<:T} = Some{T}
 
-nonnothingtype(::Type{T}) where {T} = typesplit(T, Nothing)
+nonnothingtype(@nospecialize(T::Type)) = typesplit(T, Nothing)
 promote_rule(T::Type{Nothing}, S::Type) = Union{S, Nothing}
 function promote_rule(T::Type{>:Nothing}, S::Type)
     R = nonnothingtype(T)