Allow soft-complex->double coercion to run without gil (#5287)

It'll only need the GIL on failure (which it can get)
and "power of" type maths is the soft of thing that people are
likely already doing in nogil blocks

1 files changed, 48 insertions, 0 deletions

diff --git a/tests/run/cpow.pyx b/tests/run/cpow.pyx
index d2691ba6a..6f050337c 100644
--- a/tests/run/cpow.pyx
+++ b/tests/run/cpow.pyx
@@ -208,6 +208,54 @@ def pythagoras_with_typedef(double a, double b):
     return result
 
 
+@cython.cpow(False)
+def power_coercion_in_nogil_1(double a, double b):
+    """
+    >>> power_coercion_in_nogil_1(2., 2.)
+    4.0
+    >>> power_coercion_in_nogil_1(-1., 0.5)
+    Traceback (most recent call last):
+    ...
+    TypeError: Cannot convert 'complex' with non-zero imaginary component to 'double' (this most likely comes from the '**' operator; use 'cython.cpow(True)' to return 'nan' instead of a complex number).
+    """
+    cdef double c
+    with nogil:
+        c = a**b
+    return c
+
+
+cdef double nogil_fun(double x) nogil:
+    return x
+
+def power_coercion_in_nogil_2(double a, double b):
+    """
+    >>> power_coercion_in_nogil_2(2., 2.)
+    4.0
+    >>> power_coercion_in_nogil_2(-1., 0.5)
+    Traceback (most recent call last):
+    ...
+    TypeError: Cannot convert 'complex' with non-zero imaginary component to 'double' (this most likely comes from the '**' operator; use 'cython.cpow(True)' to return 'nan' instead of a complex number).
+    """
+    c = a**b
+    with nogil:
+        d = nogil_fun(c)
+    return d
+
+
+def power_coercion_in_nogil_3(double a, double b, double c):
+    """
+    >>> power_coercion_in_nogil_3(2., 2., 1.0)
+    0.25
+    >>> power_coercion_in_nogil_3(-1., 0.5, 1.0)
+    Traceback (most recent call last):
+    ...
+    TypeError: Cannot convert 'complex' with non-zero imaginary component to 'double' (this most likely comes from the '**' operator; use 'cython.cpow(True)' to return 'nan' instead of a complex number).
+    """
+    with nogil:
+        c /= a**b
+    return c
+
+
 _WARNINGS = """
 63:21: Treating '**' as if 'cython.cpow(True)' since it is directly assigned to a a non-complex C numeric type. This is likely to be fragile and we recommend setting 'cython.cpow' explicitly.
 64:32: Treating '**' as if 'cython.cpow(True)' since it is directly assigned to a a non-complex C numeric type. This is likely to be fragile and we recommend setting 'cython.cpow' explicitly.