propagate results of _hasmethod/applicable using MethodResultPure

To avoid calling `add_edges!` directly.
In fact, it might be better to define something like
`VirtualizedCallInfo` rather than using `MethodResultPure`.

Author: aviatesk

base/Base.jl

@@ -198,7 +198,6 @@ function Core._hasmethod(@nospecialize(f), @nospecialize(t)) # this function has
     return Core._hasmethod(tt)
 end
 
-
 # core operations & types
 include("promotion.jl")
 include("tuple.jl")

base/compiler/stmtinfo.jl

@@ -178,9 +178,7 @@ add_uncovered_edges_impl(edges::Vector{Any}, info::ConstCallInfo, @nospecialize(
 """
     info::MethodResultPure <: CallInfo
 
-This struct represents a method result constant was proven to be
-effect-free, including being no-throw (typically because the value was computed
-by calling an `@pure` function).
+This struct represents a method result constant was proven to be effect-free.
 """
 struct MethodResultPure <: CallInfo
     info::CallInfo

base/compiler/tfuncs.jl

@@ -2969,13 +2969,14 @@ end
 # a simplified model of abstract_call_gf_by_type for applicable
 function abstract_applicable(interp::AbstractInterpreter, argtypes::Vector{Any},
                              sv::AbsIntState, max_methods::Int)
-    length(argtypes) < 2 && return CallMeta(Bottom, Any, EFFECTS_THROWS, NoCallInfo())
-    isvarargtype(argtypes[2]) && return CallMeta(Bool, Any, EFFECTS_THROWS, NoCallInfo())
+    length(argtypes) < 2 && return CallMeta(Bottom, ArgumentError, EFFECTS_THROWS, NoCallInfo())
+    isvarargtype(argtypes[2]) && return CallMeta(Bool, ArgumentError, EFFECTS_THROWS, NoCallInfo())
     argtypes = argtypes[2:end]
     atype = argtypes_to_type(argtypes)
     matches = find_method_matches(interp, argtypes, atype; max_methods)
     if isa(matches, FailedMethodMatch)
         rt = Bool # too many matches to analyze
+        info = NoCallInfo()
     else
         (; valid_worlds, applicable) = matches
         update_valid_age!(sv, valid_worlds)
@@ -2988,9 +2989,9 @@ function abstract_applicable(interp::AbstractInterpreter, argtypes::Vector{Any},
         else
             rt = Const(true) # has applicable matches
         end
-        add_edges!(sv.edges, matches.info)
+        info = MethodResultPure(matches.info) # XXX this should probably be something like `VirtualizedCallInfo`
     end
-    return CallMeta(rt, Union{}, EFFECTS_TOTAL, NoCallInfo())
+    return CallMeta(rt, Union{}, EFFECTS_TOTAL, info)
 end
 add_tfunc(applicable, 1, INT_INF, @nospecs((𝕃::AbstractLattice, f, args...)->Bool), 40)
 
@@ -3024,15 +3025,14 @@ function _hasmethod_tfunc(interp::AbstractInterpreter, argtypes::Vector{Any}, sv
     update_valid_age!(sv, valid_worlds)
     if match === nothing
         rt = Const(false)
-        let vresults = MethodLookupResult(Any[], valid_worlds, true)
-            vinfo = MethodMatchInfo(vresults, mt, types, false)
-            add_edges!(sv.edges, vinfo) # XXX: this should actually be an invoke-type backedge
-        end
+        vresults = MethodLookupResult(Any[], valid_worlds, true)
+        vinfo = MethodMatchInfo(vresults, mt, types, false) # XXX: this should actually be an info with invoke-type edge
     else
         rt = Const(true)
-        add_edges!(sv.edges, InvokeCallInfo(match, nothing, types))
+        vinfo = InvokeCallInfo(match, nothing, types)
     end
-    return CallMeta(rt, Any, EFFECTS_TOTAL, NoCallInfo())
+    info = MethodResultPure(vinfo) # XXX this should probably be something like `VirtualizedCallInfo`
+    return CallMeta(rt, Union{}, EFFECTS_TOTAL, info)
 end
 
 # N.B.: typename maps type equivalence classes to a single value