From 063665bbe6f629dca053c225caeb3497e0169151 Mon Sep 17 00:00:00 2001
From: Markus Mohrhard <markusm@dug.com>
Date: Tue, 21 Oct 2025 03:16:59 +0800
Subject: [PATCH] prevent failure in pow_to_mul when using Piecewise in an
 equation

Previously the test would fail with:

```
    def test_piecewise():
        grid = Grid(shape=(11,))
        u = Function(name='u', grid=grid, space_order=2)
        v = Function(name='u', grid=grid, space_order=2)
        eq_u = Eq(u, Piecewise((1, v < 10), (2, True)))
>       op = Operator(eq_u)
             ^^^^^^^^^^^^^^

tests/test_symbolics.py:1112:
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
devito/operator/operator.py:173: in __new__
    op = cls._build(expressions, **kwargs)
         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
devito/operator/operator.py:206: in _build
    irs, byproduct = cls._lower(expressions, profiler=profiler, **kwargs)
                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
devito/operator/operator.py:288: in _lower
    clusters = cls._lower_clusters(expressions, **kwargs)
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
devito/tools/timing.py:76: in __call__
    retval = self.func(*args, **kwargs)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^
devito/operator/operator.py:397: in _lower_clusters
    clusters = cls._specialize_clusters(clusters, **kwargs)
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
devito/tools/timing.py:76: in __call__
    retval = self.func(*args, **kwargs)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^
devito/core/cpu.py:178: in _specialize_clusters
    clusters = optimize_pows(clusters)
               ^^^^^^^^^^^^^^^^^^^^^^^
devito/ir/clusters/visitors.py:174: in __call__
    processed = [maybe_timed(c, *args) if self.cond(c) else c
                 ^^^^^^^^^^^^^^^^^^^^^
devito/ir/clusters/visitors.py:167: in <lambda>
    timed_pass(self.func, self.func.__name__)(*_args, **kwargs)
devito/tools/timing.py:76: in __call__
    retval = self.func(*args, **kwargs)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^
devito/passes/clusters/misc.py:423: in optimize_pows
    return cluster.rebuild(exprs=[pow_to_mul(e) for e in cluster.exprs])
                                  ^^^^^^^^^^^^^
devito/symbolics/manipulation.py:360: in pow_to_mul
    args = [pow_to_mul(i) for i in expr.args]
            ^^^^^^^^^^^^^
devito/symbolics/manipulation.py:360: in pow_to_mul
    args = [pow_to_mul(i) for i in expr.args]
            ^^^^^^^^^^^^^
E           TypeError: ExprCondPair.__new__() got an unexpected keyword argument 'evaluate'

devito/symbolics/manipulation.py:373: TypeError

```
---
 devito/symbolics/manipulation.py |  3 +++
 tests/test_symbolics.py          | 11 ++++++++++-
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/devito/symbolics/manipulation.py b/devito/symbolics/manipulation.py
index e43494974d..ec241fc967 100644
--- a/devito/symbolics/manipulation.py
+++ b/devito/symbolics/manipulation.py
@@ -6,6 +6,7 @@
 from sympy import Pow, Add, Mul, Min, Max, S, SympifyError, Tuple, sympify
 from sympy.core.add import _addsort
 from sympy.core.mul import _mulsort
+from sympy.functions.elementary.piecewise import ExprCondPair
 
 from devito.finite_differences.differentiable import (
     EvalDerivative, IndexDerivative
@@ -356,6 +357,8 @@ def pow_to_mul(expr):
         else:
             # Default. We should not end up here as all cases are handled
             return expr
+    elif expr.func is ExprCondPair:
+        return expr.func(*[pow_to_mul(i) for i in expr.args])
     else:
         args = [pow_to_mul(i) for i in expr.args]
 
diff --git a/tests/test_symbolics.py b/tests/test_symbolics.py
index 367090d0d6..8daf598249 100644
--- a/tests/test_symbolics.py
+++ b/tests/test_symbolics.py
@@ -7,7 +7,7 @@
 from sympy import And, Expr, Number, Symbol
 from devito import (Constant, Dimension, Grid, Function, solve, TimeFunction, Eq,  # noqa
                     Operator, SubDimension, norm, Le, Ge, Gt, Lt, Abs, sin, cos,
-                    Min, Max, Real, Imag, Conj, SubDomain, configuration)
+                    Piecewise, Min, Max, Real, Imag, Conj, SubDomain, configuration)
 from devito.finite_differences.differentiable import SafeInv, Weights, Mul
 from devito.ir import Expression, FindNodes, ccode
 from devito.ir.support.guards import GuardExpr, simplify_and
@@ -1104,6 +1104,15 @@ def test_print_div():
     assert cstr == 'sizeof(int)/sizeof(long)'
 
 
+def test_piecewise():
+    grid = Grid(shape=(11,))
+    u = Function(name='u', grid=grid, space_order=2)
+    v = Function(name='v', grid=grid, space_order=2)
+    eq_u = Eq(u, Piecewise((1, v < 10), (2, True)))
+    op = Operator(eq_u)
+    # check that the code generated a condition
+    assert "v[x + 2] < 10" in str(op.ccode)
+
 def test_customdtype_complex():
     """
     Test that `CustomDtype` doesn't brak is_imag