diff --git a/base/compiler/abstractinterpretation.jl b/base/compiler/abstractinterpretation.jl
index a8325a917e0fb..64a2cb363526a 100644
--- a/base/compiler/abstractinterpretation.jl
+++ b/base/compiler/abstractinterpretation.jl
@@ -125,19 +125,16 @@ function abstract_call_gf_by_type(interp::AbstractInterpreter, @nospecialize(f),
             splitsigs = switchtupleunion(sig)
             for sig_n in splitsigs
                 result = abstract_call_method(interp, method, sig_n, svec(), multiple_matches, sv)
-                rt = result.rt
-                edge = result.edge
+                (; rt, edge, effects) = result
                 edge !== nothing && push!(edges, edge)
                 this_argtypes = isa(matches, MethodMatches) ? argtypes : matches.applicable_argtypes[i]
                 this_arginfo = ArgInfo(fargs, this_argtypes)
                 const_call_result = abstract_call_method_with_const_args(interp, result,
                     f, this_arginfo, match, sv)
-                effects = result.edge_effects
                 const_result = nothing
                 if const_call_result !== nothing
-                    const_rt = const_call_result.rt
-                    if const_rt ⊑ rt
-                        rt = const_rt
+                    if const_call_result.rt ⊑ rt
+                        rt = const_call_result.rt
                         (; effects, const_result) = const_call_result
                     end
                 end
@@ -167,9 +164,9 @@ function abstract_call_gf_by_type(interp::AbstractInterpreter, @nospecialize(f),
             end
 
             result = abstract_call_method(interp, method, sig, match.sparams, multiple_matches, sv)
-            this_conditional = ignorelimited(result.rt)
-            this_rt = widenwrappedconditional(result.rt)
-            edge = result.edge
+            (; rt, edge, effects) = result
+            this_conditional = ignorelimited(rt)
+            this_rt = widenwrappedconditional(rt)
             edge !== nothing && push!(edges, edge)
             # try constant propagation with argtypes for this match
             # this is in preparation for inlining, or improving the return result
@@ -177,7 +174,6 @@ function abstract_call_gf_by_type(interp::AbstractInterpreter, @nospecialize(f),
             this_arginfo = ArgInfo(fargs, this_argtypes)
             const_call_result = abstract_call_method_with_const_args(interp, result,
                 f, this_arginfo, match, sv)
-            effects = result.edge_effects
             const_result = nothing
             if const_call_result !== nothing
                 this_const_conditional = ignorelimited(const_call_result.rt)
@@ -606,7 +602,8 @@ function abstract_call_method(interp::AbstractInterpreter, method::Method, @nosp
         sparams = recomputed[2]::SimpleVector
     end
 
-    (; rt, edge, edge_effects) = typeinf_edge(interp, method, sig, sparams, sv)
+    (; rt, edge, effects) = typeinf_edge(interp, method, sig, sparams, sv)
+
     if edge === nothing
         edgecycle = edgelimited = true
     end
@@ -615,16 +612,17 @@ function abstract_call_method(interp::AbstractInterpreter, method::Method, @nosp
     # may have been tainted due to recursion at this point even if it's overridden
     if is_effect_overridden(sv, :terminates_globally)
         # this frame is known to terminate
-        edge_effects = Effects(edge_effects, terminates=ALWAYS_TRUE)
+        effects = Effects(effects, terminates=ALWAYS_TRUE)
     elseif is_effect_overridden(method, :terminates_globally)
         # this edge is known to terminate
-        edge_effects = Effects(edge_effects; terminates=ALWAYS_TRUE)
+        effects = Effects(effects; terminates=ALWAYS_TRUE)
     elseif edgecycle
         # Some sort of recursion was detected. Even if we did not limit types,
         # we cannot guarantee that the call will terminate
-        edge_effects = Effects(edge_effects; terminates=TRISTATE_UNKNOWN)
+        effects = Effects(effects; terminates=TRISTATE_UNKNOWN)
     end
-    return MethodCallResult(rt, edgecycle, edgelimited, edge, edge_effects)
+
+    return MethodCallResult(rt, edgecycle, edgelimited, edge, effects)
 end
 
 function edge_matches_sv(frame::InferenceState, method::Method, @nospecialize(sig), sparams::SimpleVector, hardlimit::Bool, sv::InferenceState)
@@ -700,13 +698,13 @@ struct MethodCallResult
     edgecycle::Bool
     edgelimited::Bool
     edge::Union{Nothing,MethodInstance}
-    edge_effects::Effects
+    effects::Effects
     function MethodCallResult(@nospecialize(rt),
                               edgecycle::Bool,
                               edgelimited::Bool,
                               edge::Union{Nothing,MethodInstance},
-                              edge_effects::Effects)
-        return new(rt, edgecycle, edgelimited, edge, edge_effects)
+                              effects::Effects)
+        return new(rt, edgecycle, edgelimited, edge, effects)
     end
 end
 
@@ -751,10 +749,10 @@ function concrete_eval_eligible(interp::AbstractInterpreter,
     @nospecialize(f), result::MethodCallResult, arginfo::ArgInfo, sv::InferenceState)
     # disable concrete-evaluation if this function call is tainted by some overlayed
     # method since currently there is no direct way to execute overlayed methods
-    isoverlayed(method_table(interp)) && !is_nonoverlayed(result.edge_effects) && return false
+    isoverlayed(method_table(interp)) && !is_nonoverlayed(result.effects) && return false
     return f !== nothing &&
            result.edge !== nothing &&
-           is_foldable(result.edge_effects) &&
+           is_foldable(result.effects) &&
            is_all_const_arg(arginfo)
 end
 
@@ -785,7 +783,7 @@ function concrete_eval_call(interp::AbstractInterpreter,
         Core._call_in_world_total(world, f, args...)
     catch
         # The evaulation threw. By :consistent-cy, we're guaranteed this would have happened at runtime
-        return ConstCallResults(Union{}, ConcreteResult(result.edge::MethodInstance, result.edge_effects), result.edge_effects)
+        return ConstCallResults(Union{}, ConcreteResult(result.edge::MethodInstance, result.effects), result.effects)
     end
     if is_inlineable_constant(value) || call_result_unused(sv)
         # If the constant is not inlineable, still do the const-prop, since the
@@ -929,7 +927,7 @@ function const_prop_entry_heuristic(interp::AbstractInterpreter, result::MethodC
         return false
     else
         if isa(rt, Const)
-            if result.edge_effects.nothrow !== ALWAYS_TRUE
+            if result.effects.nothrow !== ALWAYS_TRUE
                 # Could still be improved to Bottom (or at least could see the effects improved)
                 return true
             end
@@ -1596,8 +1594,8 @@ function abstract_invoke(interp::AbstractInterpreter, (; fargs, argtypes)::ArgIn
     method = match.method
     tienv = ccall(:jl_type_intersection_with_env, Any, (Any, Any), nargtype, method.sig)::SimpleVector
     ti = tienv[1]; env = tienv[2]::SimpleVector
-    (; rt, edge) = result = abstract_call_method(interp, method, ti, env, false, sv)
-    effects = result.edge_effects
+    result = abstract_call_method(interp, method, ti, env, false, sv)
+    (; rt, edge, effects) = result
     edge !== nothing && add_backedge!(edge::MethodInstance, sv)
     match = MethodMatch(ti, env, method, argtype <: method.sig)
     res = nothing
@@ -1746,9 +1744,11 @@ function abstract_call_known(interp::AbstractInterpreter, @nospecialize(f),
     return abstract_call_gf_by_type(interp, f, arginfo, atype, sv, max_methods)
 end
 
-function abstract_call_opaque_closure(interp::AbstractInterpreter, closure::PartialOpaque, arginfo::ArgInfo, sv::InferenceState)
+function abstract_call_opaque_closure(interp::AbstractInterpreter,
+    closure::PartialOpaque, arginfo::ArgInfo, sv::InferenceState, check::Bool=true)
     sig = argtypes_to_type(arginfo.argtypes)
-    (; rt, edge, edge_effects) = result = abstract_call_method(interp, closure.source, sig, Core.svec(), false, sv)
+    result = abstract_call_method(interp, closure.source, sig, Core.svec(), false, sv)
+    (; rt, edge, effects) = result
     edge !== nothing && add_backedge!(edge, sv)
     tt = closure.typ
     sigT = (unwrap_unionall(tt)::DataType).parameters[1]
@@ -1759,12 +1759,21 @@ function abstract_call_opaque_closure(interp::AbstractInterpreter, closure::Part
             nothing, arginfo, match, sv)
         if const_call_result !== nothing
             if const_call_result.rt ⊑ rt
-                (; rt, const_result) = const_call_result
+                (; rt, effects, const_result) = const_call_result
             end
         end
     end
     info = OpaqueClosureCallInfo(match, const_result)
-    return CallMeta(from_interprocedural!(rt, sv, arginfo, match.spec_types), edge_effects, info)
+    if check # analyze implicit type asserts on argument and return type
+        ftt = closure.typ
+        (aty, rty) = (unwrap_unionall(ftt)::DataType).parameters
+        rty = rewrap_unionall(rty isa TypeVar ? rty.lb : rty, ftt)
+        if !(rt ⊑ rty && tuple_tfunc(arginfo.argtypes[2:end]) ⊑ rewrap_unionall(aty, ftt))
+            effects = Effects(effects; nothrow=TRISTATE_UNKNOWN)
+        end
+    end
+    rt = from_interprocedural!(rt, sv, arginfo, match.spec_types)
+    return CallMeta(rt, effects, info)
 end
 
 function most_general_argtypes(closure::PartialOpaque)
@@ -1786,22 +1795,8 @@ function abstract_call(interp::AbstractInterpreter, arginfo::ArgInfo,
     if isa(ft, PartialOpaque)
         newargtypes = copy(argtypes)
         newargtypes[1] = ft.env
-        body_call = abstract_call_opaque_closure(interp, ft, ArgInfo(arginfo.fargs, newargtypes), sv)
-        # Analyze implicit type asserts on argument and return type
-        ftt = ft.typ
-        (at, rt) = (unwrap_unionall(ftt)::DataType).parameters
-        if isa(rt, TypeVar)
-            rt = rewrap_unionall(rt.lb, ftt)
-        else
-            rt = rewrap_unionall(rt, ftt)
-        end
-        nothrow = body_call.rt ⊑ rt
-        if nothrow
-            nothrow = tuple_tfunc(newargtypes[2:end]) ⊑ rewrap_unionall(at, ftt)
-        end
-        return CallMeta(body_call.rt, Effects(body_call.effects,
-            nothrow = nothrow ? TRISTATE_UNKNOWN : body_call.effects.nothrow),
-            body_call.info)
+        return abstract_call_opaque_closure(interp,
+            ft, ArgInfo(arginfo.fargs, newargtypes), sv, #=check=#true)
     elseif (uft = unwrap_unionall(widenconst(ft)); isa(uft, DataType) && uft.name === typename(Core.OpaqueClosure))
         return CallMeta(rewrap_unionall((uft::DataType).parameters[2], widenconst(ft)), Effects(), false)
     elseif f === nothing
@@ -2027,7 +2022,7 @@ function abstract_eval_statement(interp::AbstractInterpreter, @nospecialize(e),
                     argtypes = most_general_argtypes(t)
                     pushfirst!(argtypes, t.env)
                     callinfo = abstract_call_opaque_closure(interp, t,
-                        ArgInfo(nothing, argtypes), sv)
+                        ArgInfo(nothing, argtypes), sv, #=check=#false)
                     sv.stmt_info[sv.currpc] = OpaqueClosureCreateInfo(callinfo)
                 end
             end
diff --git a/base/compiler/typeinfer.jl b/base/compiler/typeinfer.jl
index 97e8a0cfa1d29..a8bff1eba28fb 100644
--- a/base/compiler/typeinfer.jl
+++ b/base/compiler/typeinfer.jl
@@ -840,11 +840,11 @@ ipo_effects(code::CodeInstance) = decode_effects(code.ipo_purity_bits)
 struct EdgeCallResult
     rt #::Type
     edge::Union{Nothing,MethodInstance}
-    edge_effects::Effects
+    effects::Effects
     function EdgeCallResult(@nospecialize(rt),
                             edge::Union{Nothing,MethodInstance},
-                            edge_effects::Effects)
-        return new(rt, edge, edge_effects)
+                            effects::Effects)
+        return new(rt, edge, effects)
     end
 end
 
diff --git a/base/compiler/utilities.jl b/base/compiler/utilities.jl
index 3a2dc6e00f7a3..7ef006f244aa6 100644
--- a/base/compiler/utilities.jl
+++ b/base/compiler/utilities.jl
@@ -184,7 +184,7 @@ function normalize_typevars(method::Method, @nospecialize(atype), sparams::Simpl
         sp_ = ccall(:jl_type_intersection_with_env, Any, (Any, Any), at2, method.sig)::SimpleVector
         sparams = sp_[2]::SimpleVector
     end
-    return atype, sparams
+    return Pair{Any,SimpleVector}(atype, sparams)
 end
 
 # get a handle to the unique specialization object representing a particular instantiation of a call
diff --git a/base/reflection.jl b/base/reflection.jl
index c0bb28190cd62..55589399fdb35 100644
--- a/base/reflection.jl
+++ b/base/reflection.jl
@@ -1108,10 +1108,10 @@ const SLOT_USED = 0x8
 ast_slotflag(@nospecialize(code), i) = ccall(:jl_ir_slotflag, UInt8, (Any, Csize_t), code, i - 1)
 
 """
-    may_invoke_generator(method, atype, sparams)
+    may_invoke_generator(method, atype, sparams) -> Bool
 
 Computes whether or not we may invoke the generator for the given `method` on
-the given atype and sparams. For correctness, all generated function are
+the given `atype` and `sparams`. For correctness, all generated function are
 required to return monotonic answers. However, since we don't expect users to
 be able to successfully implement this criterion, we only call generated
 functions on concrete types. The one exception to this is that we allow calling
@@ -1122,8 +1122,8 @@ computes whether we are in either of these cases.
 Unlike normal functions, the compilation heuristics still can't generate good dispatch
 in some cases, but this may still allow inference not to fall over in some limited cases.
 """
-function may_invoke_generator(method::MethodInstance)
-    return may_invoke_generator(method.def::Method, method.specTypes, method.sparam_vals)
+function may_invoke_generator(mi::MethodInstance)
+    return may_invoke_generator(mi.def::Method, mi.specTypes, mi.sparam_vals)
 end
 function may_invoke_generator(method::Method, @nospecialize(atype), sparams::SimpleVector)
     # If we have complete information, we may always call the generator