Compiler: abstract calls: type assert to help stability

[nsajko]

It seems la is getting inferred as Integer instead of as Int for some reason.

This reduces the number of invalidations on running this code from 456 to 219:

struct I <: Integer end
Base.Int64(::I) = 7

[JeffBezanson]

Huh, this is strange. It's just a Vector{Any}; we should figure out why it can't infer length.

[aviatesk]

argtypes in abstract_call_builtin is fine, but the one in abstract_call_known is now captured... I think we really need to finish #56687 and make captured variables inferable, or declare the type for the captured one at least.

[aviatesk]

So I'd suggest

diff --git a/Compiler/src/abstractinterpretation.jl b/Compiler/src/abstractinterpretation.jl
index 8035216f1e..2a904e5688 100644
--- a/Compiler/src/abstractinterpretation.jl
+++ b/Compiler/src/abstractinterpretation.jl
@@ -2621,7 +2621,8 @@ end
 function abstract_call_known(interp::AbstractInterpreter, @nospecialize(f),
         arginfo::ArgInfo, si::StmtInfo, sv::AbsIntState,
         max_methods::Int = get_max_methods(interp, f, sv))
-    (; fargs, argtypes) = arginfo
+    argtypes::Vector{Any} = arginfo.argtypes
+    fargs = arginfo.fargs
     la = length(argtypes)
     𝕃ᵢ = typeinf_lattice(interp)
     if isa(f, Builtin)

for now.