fix(core): don't parse strings in Basic.has

oscarbenjamin · oscarbenjamin · commit 9c57fd06f762 · 2020-05-03T20:10:41.000+01:00
The Basic.has method is changed from using sympify to _sympify so that
string input is no longer accepted and so that functions are no longer
parsed as strings.

A line in solveset needed to be fixed because it was erroneously calling
expr.as_independent([x, y]) rather than expr.as_independent(x, y).

BREAKING CHANGE

Basic.has no longer accepts strings so e.g. Symbol('x').has('x') will
raise an exception.
diff --git a/sympy/core/basic.py b/sympy/core/basic.py
@@ -1239,7 +1239,7 @@ def _has(self, pattern):
             return any(f.func == pattern or f == pattern
             for f in self.atoms(Function, UndefinedFunction))
 
-        pattern = sympify(pattern)
+        pattern = _sympify(pattern)
         if isinstance(pattern, BasicMeta):
             return any(isinstance(arg, pattern)
             for arg in preorder_traversal(self))
diff --git a/sympy/core/tests/test_basic.py b/sympy/core/tests/test_basic.py
@@ -8,6 +8,7 @@
     _atomic, _aresame)
 from sympy.core.singleton import S
 from sympy.core.symbol import symbols, Symbol
+from sympy.core.sympify import SympifyError
 from sympy.core.function import Function, Lambda
 from sympy.core.compatibility import default_sort_key
 
@@ -102,6 +103,7 @@ def test_has():
     assert b21.has(Basic)
     assert not b1.has(b21, b3)
     assert not b21.has()
+    raises(SympifyError, lambda: Symbol("x").has("x"))
 
 
 def test_subs():
diff --git a/sympy/functions/elementary/miscellaneous.py b/sympy/functions/elementary/miscellaneous.py
@@ -129,10 +129,7 @@ def sqrt(arg, evaluate=None):
     >>> sqrt(x).has(sqrt)
     Traceback (most recent call last):
       ...
-    sympy.core.sympify.SympifyError: Sympify of expression 'could not parse
-    '<function sqrt at 0x7f79ad860f80>'' failed, because of exception being
-    raised:
-    SyntaxError: invalid syntax
+    sympy.core.sympify.SympifyError: SympifyError: <function sqrt at 0x10e8900d0>
 
     To find ``sqrt`` look for ``Pow`` with an exponent of ``1/2``:
 
diff --git a/sympy/solvers/solveset.py b/sympy/solvers/solveset.py
@@ -3003,8 +3003,8 @@ def _solve_using_known_values(result, solver):
                             # list.
                             result.remove(res)
                     continue  # skip as it's independent of desired symbols
-                depen = (eq2.rewrite(Add)).as_independent(unsolved_syms)[0]
-                if depen.has(Abs) and solver == solveset_complex:
+                depen1, depen2 = (eq2.rewrite(Add)).as_independent(*unsolved_syms)
+                if (depen1.has(Abs) or depen2.has(Abs)) and solver == solveset_complex:
                     # Absolute values cannot be inverted in the
                     # complex domain
                     continue
