Run ParallelRangeTransform also recursively on function arguments (GH-3608)

Cython/Compiler/ParseTreeTransforms.py

@@ -1190,6 +1190,7 @@ class ParallelRangeTransform(CythonTransform, SkipDeclarations):
     def visit_CallNode(self, node):
         self.visit(node.function)
         if not self.parallel_directive:
+            self.visitchildren(node, exclude=('function',))
             return node
 
         # We are a parallel directive, replace this node with the

tests/run/parallel.pyx

@@ -8,6 +8,9 @@ from libc.stdlib cimport malloc, free
 
 openmp.omp_set_nested(1)
 
+cdef int forward(int x) nogil:
+    return x
+
 def test_parallel():
     """
     >>> test_parallel()
@@ -20,6 +23,9 @@ def test_parallel():
 
     with nogil, cython.parallel.parallel():
         buf[threadid()] = threadid()
+        # Recognise threadid() also when it's used in a function argument.
+        # See https://github.com/cython/cython/issues/3594
+        buf[forward(cython.parallel.threadid())] = forward(threadid())
 
     for i in range(maxthreads):
         assert buf[i] == i