Thread lattice through tuple_tail_elem (JuliaLang#49643)

Author: Keno

base/compiler/abstractinterpretation.jl

@@ -1539,7 +1539,7 @@ function abstract_apply(interp::AbstractInterpreter, argtypes::Vector{Any}, si::
                     # This is vararg, we're not gonna be able to do any inlining,
                     # drop the info
                     info = nothing
-                    tail = tuple_tail_elem(unwrapva(ct[end]), cti)
+                    tail = tuple_tail_elem(typeinf_lattice(interp), unwrapva(ct[end]), cti)
                     push!(ctypes´, push!(ct[1:(end - 1)], tail))
                 else
                     push!(ctypes´, append!(ct[:], cti))
@@ -1562,7 +1562,7 @@ function abstract_apply(interp::AbstractInterpreter, argtypes::Vector{Any}, si::
         for i = 1:lct-1
             cti = ct[i]
             if isvarargtype(cti)
-                ct[i] = tuple_tail_elem(unwrapva(cti), ct[(i+1):lct])
+                ct[i] = tuple_tail_elem(typeinf_lattice(interp), unwrapva(cti), ct[(i+1):lct])
                 resize!(ct, i)
                 break
             end

base/compiler/typelimits.jl

@@ -138,7 +138,7 @@ function _limit_type_size(@nospecialize(t), @nospecialize(c), sources::SimpleVec
                     Q = Any[ tP[i] for i in 1:np ]
                     if ltP > np
                         # combine tp[np:end] into tP[np] using Vararg
-                        Q[np] = tuple_tail_elem(Bottom, Any[ tP[i] for i in np:ltP ])
+                        Q[np] = tuple_tail_elem(fallback_lattice, Bottom, Any[ tP[i] for i in np:ltP ])
                     end
                     for i = 1:np
                         # now apply limit element-wise to Q

base/compiler/typeutils.jl

@@ -213,11 +213,11 @@ end
 _typename(union::UnionAll) = _typename(union.body)
 _typename(a::DataType) = Const(a.name)
 
-function tuple_tail_elem(@nospecialize(init), ct::Vector{Any})
+function tuple_tail_elem(𝕃::AbstractLattice, @nospecialize(init), ct::Vector{Any})
     t = init
     for x in ct
         # FIXME: this is broken: it violates subtyping relations and creates invalid types with free typevars
-        t = tmerge(t, unwraptv(unwrapva(x)))
+        t = tmerge(𝕃, t, unwraptv(unwrapva(x)))
     end
     return Vararg{widenconst(t)}
 end