From 4ae3c859525a9030ddb2feab2ebffe4a7c5b5c69 Mon Sep 17 00:00:00 2001
From: Talley Lambert <talley.lambert@gmail.com>
Date: Mon, 12 Aug 2024 16:28:21 -0400
Subject: [PATCH 1/2] fix: fix recursion limit

---
 ilpy/expressions.py       | 40 +++++++++++++++++++++++++++++++--------
 tests/test_expressions.py | 14 ++++++++++++++
 2 files changed, 46 insertions(+), 8 deletions(-)

diff --git a/ilpy/expressions.py b/ilpy/expressions.py
index 9b44da6..c1e3b69 100644
--- a/ilpy/expressions.py
+++ b/ilpy/expressions.py
@@ -1,13 +1,26 @@
 from __future__ import annotations
 
 import ast
-from typing import Any, ClassVar, Sequence, Union
+import sys
+from contextlib import contextmanager
+from typing import Any, ClassVar, Iterator, Sequence, Union
 
 from ilpy.wrapper import Constraint, Objective, Relation, Sense
 
 Number = Union[float, int]
 
 
+@contextmanager
+def recursion_limit_raised_by(N: int = 5000) -> Iterator[None]:
+    """Temporarily increase the recursion limit by N."""
+    old_limit = sys.getrecursionlimit()
+    sys.setrecursionlimit(old_limit + N)
+    try:
+        yield
+    finally:
+        sys.setrecursionlimit(old_limit)
+
+
 class Expression(ast.AST):
     """Base class for all expression nodes.
 
@@ -265,13 +278,24 @@ def _get_coeff_indices(
     l_coeffs: dict[int, float] = {}
     q_coeffs: dict[tuple[int, int], float] = {}
     constant = 0.0
-    for var, coefficient in _get_coefficients(expr).items():
-        if var is None:
-            constant = coefficient
-        elif isinstance(var, tuple):
-            q_coeffs[(_ensure_index(var[0]), _ensure_index(var[1]))] = coefficient
-        elif coefficient != 0:
-            l_coeffs[_ensure_index(var)] = coefficient
+    try:
+        with recursion_limit_raised_by(5000):
+            for var, coefficient in _get_coefficients(expr).items():
+                if var is None:
+                    constant = coefficient
+                elif isinstance(var, tuple):
+                    q_coeffs[(_ensure_index(var[0]), _ensure_index(var[1]))] = (
+                        coefficient
+                    )
+                elif coefficient != 0:
+                    l_coeffs[_ensure_index(var)] = coefficient
+    except RecursionError as e:
+        raise RecursionError(
+            "RecursionError when casting an ilpy.Expression to a Constraint or "
+            "Objective. If you really want an expression this large, you may raise the "
+            "limit temporarily with `ilpy.expressions.recursion_limit_raised_by` (or "
+            "manually with `sys.setrecursionlimit`)"
+        ) from e
     return l_coeffs, q_coeffs, constant
 
 
diff --git a/tests/test_expressions.py b/tests/test_expressions.py
index b0c582a..bcb9959 100644
--- a/tests/test_expressions.py
+++ b/tests/test_expressions.py
@@ -1,4 +1,5 @@
 import operator
+import sys
 
 import pytest
 from ilpy.expressions import Expression, Variable, _get_coefficients
@@ -161,3 +162,16 @@ def test_adding() -> None:
     solver.set_objective(u)
     solver.add_constraint(u >= 0)
     solver.set_constraints(constraints)
+
+
+def test_recursion() -> None:
+    from ilpy.expressions import recursion_limit_raised_by
+
+    reclimit = sys.getrecursionlimit()
+    s = sum(Variable(str(x), index=x) for x in range(reclimit + 5001))
+    SOME_MAX = 1000
+    expr = s <= SOME_MAX
+    with pytest.raises(RecursionError):
+        expr.as_constraint()
+    with recursion_limit_raised_by():
+        assert isinstance(expr.as_constraint(), Constraint)

From 4a4a1e89c288ec356fc739af434ba539f5f48386 Mon Sep 17 00:00:00 2001
From: Talley Lambert <talley.lambert@gmail.com>
Date: Fri, 25 Oct 2024 11:55:28 +0200
Subject: [PATCH 2/2] skip on win 3.10

---
 tests/test_expressions.py | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/tests/test_expressions.py b/tests/test_expressions.py
index bcb9959..7aed0b4 100644
--- a/tests/test_expressions.py
+++ b/tests/test_expressions.py
@@ -1,4 +1,5 @@
 import operator
+import os
 import sys
 
 import pytest
@@ -164,6 +165,10 @@ def test_adding() -> None:
     solver.set_constraints(constraints)
 
 
+@pytest.mark.skipif(
+    sys.version_info < (3, 11) and os.name == "nt",
+    reason="fails too often on windows 3.10",
+)
 def test_recursion() -> None:
     from ilpy.expressions import recursion_limit_raised_by