From 1728ab08740df20aa2580f314bf1290aa497624c Mon Sep 17 00:00:00 2001
From: Matt Wala <wala1@illinois.edu>
Date: Wed, 6 Sep 2017 17:08:39 -0500
Subject: [PATCH] Fix SymEngine channel and change SUMPY_FORCE_SYMBOLIC_BACKEND
 to error out if it doesn't find the appropriate backend.

---
 .test-conda-env-py3.yml | 3 ++-
 sumpy/symbolic.py       | 9 ++++-----
 2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/.test-conda-env-py3.yml b/.test-conda-env-py3.yml
index a53d2c22..d5e01ead 100644
--- a/.test-conda-env-py3.yml
+++ b/.test-conda-env-py3.yml
@@ -12,5 +12,6 @@ dependencies:
 - islpy
 - pyopencl
 - python=3.5
-- python-symengine=0.3.0
+- symengine::symengine=0.3.0
+- symengine::python-symengine=0.3.0
 # things not in here: loopy boxtree pymbolic pyfmmlib
diff --git a/sumpy/symbolic.py b/sumpy/symbolic.py
index 665aff9d..49fa4059 100644
--- a/sumpy/symbolic.py
+++ b/sumpy/symbolic.py
@@ -42,8 +42,9 @@ def _find_symbolic_backend():
     try:
         import symengine  # noqa
         symengine_found = True
-    except ImportError:
+    except ImportError as import_error:
         symengine_found = False
+        symengine_error = import_error
 
     ALLOWED_BACKENDS = ("sympy", "symengine")  # noqa
     BACKEND_ENV_VAR = "SUMPY_FORCE_SYMBOLIC_BACKEND"  # noqa
@@ -60,11 +61,9 @@ def _find_symbolic_backend():
                     ", ".join("'%s'" % val for val in ALLOWED_BACKENDS)))
 
         if backend == "symengine" and not symengine_found:
-            from warnings import warn
-            warn("%s=symengine was specified, but could not find symengine. "
-                 "Using sympy." % BACKEND_ENV_VAR, RuntimeWarning)
+            raise RuntimeError("could not find SymEngine: %s" % symengine_error)
 
-        USE_SYMENGINE = backend == "symengine" and symengine_found
+        USE_SYMENGINE = True
     else:
         USE_SYMENGINE = symengine_found
 
-- 
GitLab