limit the constructor signatures of PartialStruct and Conditional (#45436)

Author: aviatesk

base/boot.jl

@@ -432,7 +432,7 @@ eval(Core, quote
             relocatability)
     end
     Const(@nospecialize(v)) = $(Expr(:new, :Const, :v))
-    PartialStruct(@nospecialize(typ), fields::Array{Any, 1}) = $(Expr(:new, :PartialStruct, :typ, :fields))
+    PartialStruct(typ::DataType, fields::Array{Any, 1}) = $(Expr(:new, :PartialStruct, :typ, :fields))
     PartialOpaque(@nospecialize(typ), @nospecialize(env), parent::MethodInstance, source::Method) = $(Expr(:new, :PartialOpaque, :typ, :env, :parent, :source))
     InterConditional(slot::Int, @nospecialize(vtype), @nospecialize(elsetype)) = $(Expr(:new, :InterConditional, :slot, :vtype, :elsetype))
     MethodMatch(@nospecialize(spec_types), sparams::SimpleVector, method::Method, fully_covers::Bool) = $(Expr(:new, :MethodMatch, :spec_types, :sparams, :method, :fully_covers))

base/compiler/typelattice.jl

@@ -37,7 +37,7 @@ struct Conditional
     vtype
     elsetype
     function Conditional(
-                var,
+                var::SlotNumber,
                 @nospecialize(vtype),
                 @nospecialize(nottype))
         return new(var, vtype, nottype)