Improve ensure clause handling

Author: smasato

lib/typeprof/core/ast/control.rb

@@ -488,17 +488,20 @@ def install0(genv)
         end
 
         if @ensure_clause
-          ensure_old_vtxs = {}
           vars.each do |var|
-            ensure_old_vtxs[var] = @lenv.get_var(var)
+            union_vtx = old_vtxs[var].new_vertex(genv, self)
+            @changes.add_edge(genv, body_vtxs[var], union_vtx)
+            clause_vtxs_list.each do |clause_vtx|
+              @changes.add_edge(genv, clause_vtx[var], union_vtx)
+            end
+            @lenv.set_var(var, union_vtx)
           end
 
           @ensure_clause.install(genv)
 
           clause_vtxs_list << {}
           vars.each do |var|
             clause_vtxs_list.last[var] = @lenv.get_var(var)
-            @lenv.set_var(var, ensure_old_vtxs[var])
           end
         end
 

lib/typeprof/core/ast/method.rb

@@ -133,10 +133,6 @@ def initialize(raw_node, lenv, use_result)
         nlenv = LocalEnv.new(@lenv.path, ncref, {}, [])
         if raw_body
           @body = AST.create_node(raw_body, nlenv)
-
-          if raw_body.is_a?(Prism::BeginNode) && raw_body.ensure_clause && raw_body.ensure_clause.statements
-            @ensure_clause = AST.create_node(raw_body.ensure_clause.statements, nlenv)
-          end
         else
           pos = code_range.last.left.left.left # before "end"
           cr = TypeProf::CodeRange.new(pos, pos)
@@ -176,14 +172,12 @@ def initialize(raw_node, lenv, use_result)
       attr_reader :body
       attr_reader :rbs_method_type
       attr_reader :reusable
-      attr_reader :ensure_clause
 
       def subnodes = {
         body:,
         opt_positional_defaults:,
         opt_keyword_defaults:,
         rbs_method_type:,
-        ensure_clause:,
       }
       def attrs = {
         singleton:,
@@ -253,8 +247,6 @@ def install0(genv)
           @body.lenv.add_return_box(@changes.add_escape_box(genv, @body.ret, e_ret))
         end
 
-        @ensure_clause.install(genv) if @ensure_clause
-
         f_args = FormalArguments.new(
           req_positionals,
           opt_positionals,