Fix num_thread for prange() without parallel() + more error checks

Cython/Compiler/Nodes.py

@@ -5978,7 +5978,11 @@ class ParallelStatNode(StatNode, ParallelNode):
         self.body.analyse_declarations(env)
 
         if self.kwargs:
-            self.kwargs = self.kwargs.compile_time_value(env)
+            try:
+                self.kwargs = self.kwargs.compile_time_value(env)
+            except Exception, e:
+                error(self.kwargs.pos, "Only compile-time values may be "
+                                       "supplied as keyword arguments")
         else:
             self.kwargs = {}
 
@@ -5992,6 +5996,17 @@ class ParallelStatNode(StatNode, ParallelNode):
         self.body.analyse_expressions(env)
         self.analyse_sharing_attributes(env)
 
+        if self.num_threads is not None:
+            if self.parent and self.parent.num_threads is not None:
+                error(self.pos,
+                      "num_threads already declared in outer section")
+            elif not isinstance(self.num_threads, (int, long)):
+                error(self.pos,
+                      "Invalid value for num_threads argument, expected an int")
+            elif self.num_threads <= 0:
+                error(self.pos,
+                      "argument to num_threads must be greater than 0")
+
     def analyse_sharing_attributes(self, env):
         """
         Analyse the privates for this block and set them in self.privates.
@@ -6131,11 +6146,8 @@ class ParallelStatNode(StatNode, ParallelNode):
         Write self.num_threads if set as the num_threads OpenMP directive
         """
         if self.num_threads is not None:
-            if isinstance(self.num_threads, (int, long)):
-                code.put(" num_threads(%d)" % (self.num_threads,))
-            else:
-                error(self.pos, "Invalid value for num_threads argument, "
-                                "expected an int")
+            code.put(" num_threads(%d)" % (self.num_threads,))
+
 
     def declare_closure_privates(self, code):
         """
@@ -6790,11 +6802,11 @@ class ParallelRangeNode(ParallelStatNode):
         if not self.is_parallel:
             code.put("#pragma omp for")
             self.privatization_insertion_point = code.insertion_point()
-            # reduction_codepoint = self.parent.privatization_insertion_point
+            reduction_codepoint = self.parent.privatization_insertion_point
         else:
             code.put("#pragma omp parallel")
             self.privatization_insertion_point = code.insertion_point()
-            # reduction_codepoint = self.privatization_insertion_point
+            reduction_codepoint = self.privatization_insertion_point
             code.putln("")
             code.putln("#endif /* _OPENMP */")
 
@@ -6806,11 +6818,6 @@ class ParallelRangeNode(ParallelStatNode):
             code.putln("#ifdef _OPENMP")
             code.put("#pragma omp for")
 
-        # Nested parallelism is not supported, so we can put reductions on the
-        # for and not on the parallel (but would be valid, but gcc45 bugs on
-        # the former)
-        reduction_codepoint = code
-
         for entry, (op, lastprivate) in self.privates.iteritems():
             # Don't declare the index variable as a reduction
             if op and op in "+*-&^|" and entry != self.target.entry:

tests/errors/e_invalid_num_threads.pyx

+# mode: error
+
+from cython.parallel cimport parallel, prange
+
+cdef int i
+
+# valid
+with nogil, parallel(num_threads=None):
+    pass
+
+# invalid
+with nogil, parallel(num_threads=0):
+    pass
+
+with nogil, parallel(num_threads=i):
+    pass
+
+with nogil, parallel(num_threads=2):
+    for i in prange(10, num_threads=2):
+        pass
+
+_ERRORS = u"""
+e_invalid_num_threads.pyx:12:20: argument to num_threads must be greater than 0
+e_invalid_num_threads.pyx:15:20: Invalid value for num_threads argument, expected an int
+e_invalid_num_threads.pyx:19:19: num_threads already declared in outer section
+"""

tests/run/sequential_parallel.pyx

@@ -720,3 +720,15 @@ def test_nogil_cdef_except_clause():
     for i in prange(10, nogil=True):
         nogil_cdef_except_clause()
         nogil_cdef_except_star()
+
+def test_num_threads_compile():
+    cdef int i
+    for i in prange(10, nogil=True, num_threads=2):
+        pass
+
+    with nogil, cython.parallel.parallel(num_threads=2):
+        pass
+
+    with nogil, cython.parallel.parallel():
+        for i in prange(10, num_threads=2):
+            pass