Scope break values to loop bodies

lib/typeprof/core/ast/control.rb

@@ -166,7 +166,10 @@ def install0(genv)
           @lenv.set_var(:"*expected_block_ret", nil)
         end
 
-        @body.install(genv)
+        # A loop's break must not escape to an enclosing block.
+        @lenv.with_new_break_vtx do
+          @body.install(genv)
+        end
 
         if expected_block_ret
           @lenv.set_var(:"*expected_block_ret", expected_block_ret)

lib/typeprof/core/env.rb

@@ -426,6 +426,14 @@ def get_break_vtx
       @break_vtx ||= Vertex.new(:break_vtx)
     end
 
+    def with_new_break_vtx
+      previous_break_vtx = @break_vtx
+      @break_vtx = Vertex.new(:break_vtx)
+      yield
+    ensure
+      @break_vtx = previous_break_vtx
+    end
+
     def push_ivar_narrowing(name, narrowing)
       raise unless narrowing.is_a?(Narrowing::Constraint)
       (@ivar_narrowings[name] ||= []) << narrowing

scenario/control/break_in_loop.rb

@@ -0,0 +1,13 @@
+## update: test.rb
+def foo(flag)
+  [1].each do
+    while flag
+      break :b
+    end
+  end
+end
+
+## assert: test.rb
+class Object
+  def foo: (untyped) -> Array[Integer]
+end