From 4f8e93a3b26f15bb96d86ee05d672b51cda1e935 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Fran=C3=A7ois=20Bissey?= <francois.bissey@canterbury.ac.nz>
Date: Tue, 10 Nov 2015 14:25:34 +1300
Subject: [PATCH 1/3] Let linspace accept input that has an array_interface but
 is not otherwise a numpy or python type.

---
 numpy/core/function_base.py | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/numpy/core/function_base.py b/numpy/core/function_base.py
index 05fea557a5ea..5070608b7446 100644
--- a/numpy/core/function_base.py
+++ b/numpy/core/function_base.py
@@ -87,8 +87,10 @@ def linspace(start, stop, num=50, endpoint=True, retstep=False, dtype=None):
     div = (num - 1) if endpoint else num
 
     # Convert float/complex array scalars to float, gh-3504
-    start = start * 1.
-    stop = stop * 1.
+    # Make sure one can use variables that have an __array_interface__, gh-6634
+    from numpy import asarray
+    start = asarray(start) * 1.
+    stop = asarray(stop) * 1.
 
     dt = result_type(start, stop, float(num))
     if dtype is None:

From 072e8a5572f0104c4b28828cb1404bed8682e951 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Fran=C3=A7ois=20Bissey?= <francois.bissey@canterbury.ac.nz>
Date: Wed, 11 Nov 2015 21:02:08 +1300
Subject: [PATCH 2/3] Use asanyarray instead of asarray

---
 numpy/core/function_base.py | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/numpy/core/function_base.py b/numpy/core/function_base.py
index 5070608b7446..0e2bdc693bfd 100644
--- a/numpy/core/function_base.py
+++ b/numpy/core/function_base.py
@@ -3,7 +3,7 @@
 __all__ = ['logspace', 'linspace', 'may_share_memory']
 
 from . import numeric as _nx
-from .numeric import result_type, NaN, shares_memory, MAY_SHARE_BOUNDS, TooHardError
+from .numeric import result_type, NaN, shares_memory, MAY_SHARE_BOUNDS, TooHardError, asanyarray
 
 
 def linspace(start, stop, num=50, endpoint=True, retstep=False, dtype=None):
@@ -88,9 +88,8 @@ def linspace(start, stop, num=50, endpoint=True, retstep=False, dtype=None):
 
     # Convert float/complex array scalars to float, gh-3504
     # Make sure one can use variables that have an __array_interface__, gh-6634
-    from numpy import asarray
-    start = asarray(start) * 1.
-    stop = asarray(stop) * 1.
+    start = asanyarray(start) * 1.
+    stop  = asanyarray(stop)  * 1.
 
     dt = result_type(start, stop, float(num))
     if dtype is None:

From 12ea33a6fe73f6597cc301ebcb23cb44644addd5 Mon Sep 17 00:00:00 2001
From: "Erik M. Bray" <erik.bray@lri.fr>
Date: Mon, 29 Aug 2016 19:06:38 +0200
Subject: [PATCH 3/3] Adds a regression test that demonstrates the issue.

---
 numpy/core/tests/test_function_base.py | 36 ++++++++++++++++++++++++++
 1 file changed, 36 insertions(+)

diff --git a/numpy/core/tests/test_function_base.py b/numpy/core/tests/test_function_base.py
index 0fabb25886e8..8b4f5b4ac6d3 100644
--- a/numpy/core/tests/test_function_base.py
+++ b/numpy/core/tests/test_function_base.py
@@ -260,6 +260,42 @@ def test_subclass(self):
         assert type(ls) is PhysicalQuantity2
         assert_equal(ls, linspace(0.0, 1.0, 1))
 
+    def test_array_interface(self):
+        # Regression test for https://github.com/numpy/numpy/pull/6659
+        # Ensure that start/stop can be objects that implement
+        # __array_interface__ and are convertible to numeric scalars
+
+        class Arrayish(object):
+            """
+            A generic object that supports the __array_interface__ and hence
+            can in principle be converted to a numeric scalar, but is not
+            otherwise recognized as numeric, but also happens to support
+            multiplication by floats.
+
+            Data should be an object that implements the buffer interface,
+            and contains at least 4 bytes.
+            """
+
+            def __init__(self, data):
+                self._data = data
+
+            @property
+            def __array_interface__(self):
+                # Ideally should be `'shape': ()` but the current interface
+                # does not allow that
+                return {'shape': (1,), 'typestr': '<i4', 'data': self._data,
+                        'version': 3}
+
+            def __mul__(self, other):
+                # For the purposes of this test any multiplication is an
+                # identity operation :)
+                return self
+
+        one = Arrayish(array(1, dtype='<i4'))
+        five = Arrayish(array(5, dtype='<i4'))
+
+        assert_equal(linspace(one, five), linspace(1, 5))
+
     def test_denormal_numbers(self):
         # Regression test for gh-5437. Will probably fail when compiled
         # with ICC, which flushes denormals to zero