From 557671b7db9ea505c11894307e65b4a997aa8249 Mon Sep 17 00:00:00 2001
From: David Nadlinger <code@klickverbot.at>
Date: Sun, 14 Mar 2021 18:46:28 +0000
Subject: [PATCH] compiler: Fix type inference in slice expressions

This was a long-standing issue affecting both lists and
the new NumPy array implementation, just caused by the
generic inference passes not being run on the slice
subexpressions (and thus e.g. ints not being monomorphized).

GitHub: Fixes #1632.
---
 artiq/compiler/transforms/inferencer.py |  1 +
 artiq/test/lit/regression/issue_1632.py | 19 +++++++++++++++++++
 2 files changed, 20 insertions(+)
 create mode 100644 artiq/test/lit/regression/issue_1632.py

diff --git a/artiq/compiler/transforms/inferencer.py b/artiq/compiler/transforms/inferencer.py
index 684c575de..a8bb6cbee 100644
--- a/artiq/compiler/transforms/inferencer.py
+++ b/artiq/compiler/transforms/inferencer.py
@@ -216,6 +216,7 @@ class Inferencer(algorithm.Visitor):
                         value.loc, None)
 
     def visit_SliceT(self, node):
+        self.generic_visit(node)
         if (node.lower, node.upper, node.step) == (None, None, None):
             self._unify(node.type, builtins.TInt32(),
                         node.loc, None)
diff --git a/artiq/test/lit/regression/issue_1632.py b/artiq/test/lit/regression/issue_1632.py
new file mode 100644
index 000000000..c7f36f96b
--- /dev/null
+++ b/artiq/test/lit/regression/issue_1632.py
@@ -0,0 +1,19 @@
+# RUN: %python -m artiq.compiler.testbench.embedding %s
+
+from artiq.language.core import *
+from artiq.language.types import *
+import numpy as np
+
+class A:
+    def __init__(self):
+        self.n = 2
+
+    @kernel
+    def run(self):
+        print([1, 2, 3][:self.n])
+
+a = A()
+
+@kernel
+def entrypoint():
+    a.run()