rename is_poisoning -> isunordered and export

Author: cmcaine

base/exports.jl

@@ -656,6 +656,7 @@ export
     isequal,
     ismutable,
     isless,
+    isunordered,
     ifelse,
     objectid,
     sizeof,

base/operators.jl

@@ -212,10 +212,10 @@ largest values and `isgreater` defines a descending total order with `NaN` and
 # Implementation
 This is unexported. Types should not usually implement this function. Instead, implement `isless`.
 """
-isgreater(x, y) = is_poisoning(x) || is_poisoning(y) ? isless(x, y) : isless(y, x)
-is_poisoning(x) = false
-is_poisoning(x::AbstractFloat) = isnan(x)
-is_poisoning(x::Missing) = true
+isgreater(x, y) = isunordered(x) || isunordered(y) ? isless(x, y) : isless(y, x)
+isunordered(x) = false
+isunordered(x::AbstractFloat) = isnan(x)
+isunordered(x::Missing) = true
 
 function ==(T::Type, S::Type)
     @_pure_meta

base/reducedim.jl

@@ -148,7 +148,7 @@ for (f1, f2, typeextreme) in ((:min, :max, :typemax), (:max, :min, :typemin))
             Tr = v0 isa T ? T : typeof(v0)
 
             # but NaNs and missing need to be avoided as initial values
-            if is_poisoning(v0)
+            if isunordered(v0)
                 Tnm = nonmissingtype(Tr)
                 # TODO: Some types, like BigInt, don't support typemin/typemax.
                 # So a Matrix{Union{BigInt, Missing}} can still error here.