Skip overload resolution when splat arguments have uninformative elem…

lib/typeprof/core/graph/box.rb

@@ -259,7 +259,27 @@ def resolve_overloads(changes, genv, node, param_map, a_args, ret, &blk)
       # "failed to resolve overloads" diagnostics for untyped arguments.
       # We still set up dependency edges so the box re-runs when the
       # empty arguments later receive types.
-      if a_args.positionals.any? {|vtx| vtx.types.empty? }
+      #
+      # For splat arguments, the positional vertex itself holds Array
+      # types (non-empty), but the array *element* vertex may be empty.
+      # The same oscillation occurs when match_arguments? extracts
+      # elements via get_rest_args and the universal typecheck on the
+      # flattened element list fails due to conflicting array sources.
+      # We detect this by checking element vertices of splatted arrays.
+      has_uninformative_args = a_args.positionals.any? {|vtx| vtx.types.empty? }
+      unless has_uninformative_args
+        a_args.positionals.each_with_index do |vtx, i|
+          next unless a_args.splat_flags[i]
+          vtx.each_type do |ty|
+            base = ty.base_type(genv)
+            if base.is_a?(Type::Instance) && base.mod == genv.mod_ary && base.args[0]
+              has_uninformative_args = true if base.args[0].types.empty?
+            end
+          end
+          break if has_uninformative_args
+        end
+      end
+      if has_uninformative_args
         a_args.positionals.each do |vtx|
           changes.add_edge(genv, vtx, changes.target)
         end

scenario/regressions/splat-overload-oscillation-unseeded.rb

@@ -0,0 +1,19 @@
+## update: test.rbs
+class Foo
+  def self.f: (*Integer) -> String | (*String) -> Symbol
+end
+
+## update: test.rb
+# Minimal reproduction: unseeded splat overload oscillation.
+# The splat array's element vertex is empty, triggering the
+# skip in overload resolution.
+def check
+  @x = Foo.f(*[@x])
+end
+
+## assert
+class Object
+  def check: -> untyped
+end
+
+## diagnostics

scenario/regressions/splat-overload-oscillation.rb

@@ -0,0 +1,21 @@
+## update: test.rbs
+class Foo
+  def self.f: (*Integer) -> String | (*String) -> Symbol
+end
+
+## update: test.rb
+# Splat arguments with rest-positional overloads used to cause
+# oscillation. The overload fix skips resolution when any splat
+# element vertex has no type information, preventing the cycle.
+def check
+  @args = [42]
+  @x = Foo.f(*@args)
+  @args = [@x]
+end
+
+## assert
+class Object
+  def check: -> [untyped]
+end
+
+## diagnostics