Disallow yield in parallel sections

Cython/Compiler/ParseTreeTransforms.py

@@ -987,9 +987,6 @@ class ParallelRangeTransform(CythonTransform, SkipDeclarations):
     # Keep track of whether we are the context manager of a 'with' statement
     in_context_manager_section = False
 
-    # Keep track of whether we are in a parallel range section
-    in_prange = False
-
     # One of 'prange' or 'with parallel'. This is used to disallow closely
     # nested 'with parallel:' blocks
     state = None
@@ -1082,7 +1079,7 @@ class ParallelRangeTransform(CythonTransform, SkipDeclarations):
         if isinstance(newnode, Nodes.ParallelWithBlockNode):
             if self.state == 'parallel with':
                 error(node.manager.pos,
-                      "Closely nested 'with parallel:' blocks are disallowed")
+                      "Closely nested parallel with blocks are disallowed")
 
             self.state = 'parallel with'
             body = self.visit(node.body)
@@ -1109,12 +1106,11 @@ class ParallelRangeTransform(CythonTransform, SkipDeclarations):
         self.visit(node.iterator)
         self.visit(node.target)
 
-        was_in_prange = self.in_prange
-        self.in_prange = isinstance(node.iterator.sequence,
-                                    Nodes.ParallelRangeNode)
+        in_prange = isinstance(node.iterator.sequence,
+                               Nodes.ParallelRangeNode)
         previous_state = self.state
 
-        if self.in_prange:
+        if in_prange:
             # This will replace the entire ForInStatNode, so copy the
             # attributes
             parallel_range_node = node.iterator.sequence
@@ -1133,8 +1129,6 @@ class ParallelRangeTransform(CythonTransform, SkipDeclarations):
 
         self.visit(node.body)
         self.state = previous_state
-        self.in_prange = was_in_prange
-
         self.visit(node.else_clause)
         return node
 

Cython/Compiler/TypeInference.py

@@ -202,36 +202,9 @@ class MarkAssignments(CythonTransform):
 
         return node
 
-    def visit_BreakStatNode(self, node):
+    def visit_YieldExprNode(self, node):
         if self.parallel_block_stack:
-            parnode = self.parallel_block_stack[-1]
-            parnode.break_label_used = True
-
-            if not parnode.is_prange and parnode.parent:
-                parnode.parent.break_label_used = True
-
-        return node
-
-    def visit_ContinueStatNode(self, node):
-        if self.parallel_block_stack:
-            parnode = self.parallel_block_stack[-1]
-            parnode.continue_label_used = True
-
-            if not parnode.is_prange and parnode.parent:
-                parnode.parent.continue_label_used = True
-
-        return node
-
-    def visit_ReturnStatNode(self, node):
-        for parnode in self.parallel_block_stack:
-            parnode.return_label_used = True
-
-        return node
-
-    def visit_GilStatNode(self, node):
-        if node.state == 'gil':
-            for parnode in self.parallel_block_stack:
-                parnode.error_label_used = True
+            error(node.pos, "Yield not allowed in parallel sections")
 
         return node
 

tests/errors/e_cython_parallel.pyx

@@ -40,17 +40,17 @@ with nogil, cython.parallel.parallel:
     pass
 
 cdef int y
-# this is not valid
+
 for i in prange(10, nogil=True):
     i = y * 4
     y = i
 
-# this is valid
 for i in prange(10, nogil=True):
     y = i
     i = y * 4
     y = i
 
+
 with nogil, cython.parallel.parallel():
     i = y
     y = i
@@ -65,6 +65,17 @@ with nogil, cython.parallel.parallel("invalid"):
 with nogil, cython.parallel.parallel(invalid=True):
     pass
 
+def f(x):
+    cdef int i
+
+    with nogil, cython.parallel.parallel():
+        with gil:
+            yield x
+
+        for i in prange(10):
+            with gil:
+                yield x
+
 _ERRORS = u"""
 e_cython_parallel.pyx:3:8: cython.parallel.parallel is not a module
 e_cython_parallel.pyx:4:0: No such directive: cython.parallel.something
@@ -77,11 +88,13 @@ c_cython_parallel.pyx:21:29: The parallel section may only be used without the G
 e_cython_parallel.pyx:27:10: target may not be a Python object as we don't have the GIL
 e_cython_parallel.pyx:30:9: Can only iterate over an iteration variable
 e_cython_parallel.pyx:33:10: Must be of numeric type, not int *
-e_cython_parallel.pyx:36:33: Closely nested 'with parallel:' blocks are disallowed
+e_cython_parallel.pyx:36:33: Closely nested parallel with blocks are disallowed
 e_cython_parallel.pyx:39:12: The parallel directive must be called
 e_cython_parallel.pyx:45:10: Expression value depends on previous loop iteration, cannot execute in parallel
 e_cython_parallel.pyx:55:9: Expression depends on an uninitialized thread-private variable
 e_cython_parallel.pyx:60:6: Reduction operator '*' is inconsistent with previous reduction operator '+'
 e_cython_parallel.pyx:62:36: cython.parallel.parallel() does not take positional arguments
 e_cython_parallel.pyx:65:36: Invalid keyword argument: invalid
+e_cython_parallel.pyx:73:12: Yield not allowed in parallel sections
+e_cython_parallel.pyx:77:16: Yield not allowed in parallel sections
 """