Fix #151 (again!): yield inside with wasn't propagated to Result

NEWS

@@ -15,6 +15,8 @@ Changes from 0.12.1
    * Shadowed comparison operators now use `and` instead of `&`
      for chained comparisons
    * partition no longer prematurely exhausts input iterators
+   * A `yield` inside of a `with` statement will properly suppress implicit
+     returns.
 
 Changes from 0.12.0
 

hy/compiler.py

@@ -1485,6 +1485,7 @@ class HyASTCompiler(object):
                                            optional_vars=thing)]
 
         ret = ctx + the_with
+        ret.contains_yield = ret.contains_yield or body.contains_yield
         # And make our expression context our temp variable
         expr_name = ast.Name(id=ast_str(var), arg=ast_str(var),
                              ctx=ast.Load(),

tests/native_tests/language.hy

@@ -724,6 +724,14 @@
   (with [(open "README.md" "r")] (do)))
 
 
+(defn test-context-yield []
+  "NATIVE: test yields inside of with statements don't try to return before Python 3.3"
+  (defn f []
+    (with [(open "README.md")] (yield 123)))
+
+  (assert (= (next (f)) 123)))
+
+
 (defn test-with-return []
   "NATIVE: test that with returns stuff"
   (defn read-file [filename]