Fix sympy/sympy#9326: use full symbol in evalf cache, not just symbol…

… name

Old status: evalf_symbol used just the symbol name in its cache, this
would break if two symbols happened to use the same name.
This fix uses the full symbol instead.

// edited by skirpichev

sympy/core/evalf.py

@@ -1175,11 +1175,11 @@ def evalf_symbol(x, prec, options):
         if '_cache' not in options:
             options['_cache'] = {}
         cache = options['_cache']
-        cached, cached_prec = cache.get(x.name, (None, MINUS_INF))
+        cached, cached_prec = cache.get(x, (None, MINUS_INF))
         if cached_prec >= prec:
             return cached
         v = evalf(sympify(val), prec, options)
-        cache[x.name] = (v, prec)
+        cache[x] = (v, prec)
         return v
 
 evalf_table = None

sympy/core/tests/test_evalf.py

@@ -475,3 +475,11 @@ def test_issue_8853():
     assert get_integer_part(S.Half, 1, {}, True) == (1, 0)
     assert get_integer_part(-S.Half, -1, {}, True) == (-1, 0)
     assert get_integer_part(-S.Half, 1, {}, True) == (0, 0)
+
+
+def test_issue_9326():
+    from sympy import Dummy
+    d1 = Dummy('d')
+    d2 = Dummy('d')
+    e = d1 + d2
+    assert e.evalf(subs = {d1: 1, d2: 2}) == 3