[Mlir-commits] [mlir] [mlir:python] Prevent crash in DenseElementsAttr. (PR #163564)

[Ingo Müller]

https://github.com/ingomueller-net created https://github.com/llvm/llvm-project/pull/163564

This PR fixes a crash in the `bf_getbuffer` implementation of `PyDenseElementsAttribute` that occurred when an element type was not supported, such as `bf16`. I believe that supportion `bf16` is not possible with that protocol but that's out of the scope of this PR. Previsouly, the code raised an `std::exception` out of `bf_getbuffer` that nanobind does not catch (see also pybind/pybind11#3336). The PR makes the function catch all `std::exception`s and manually raises a Python exception instead.

>From b9c9523a48608726e83434b2b64a2f47348141bd Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ingo=20M=C3=BCller?= <ingomueller at google.com>
Date: Wed, 15 Oct 2025 14:14:58 +0000
Subject: [PATCH] [mlir:python] Prevent crash in DenseElementsAttr.
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This PR fixes a crash in the `bf_getbuffer` implementation of
`PyDenseElementsAttribute` that occurred when an element type was not
supported, such as `bf16`. I believe that supportion `bf16` is not
possible with that protocol but that's out of the scope of this PR.
Previsouly, the code raised an `std::exception` out of `bf_getbuffer`
that nanobind does not catch (see also pybind/pybind11#3336). The PR
makes the function catch all `std::exception`s and manually raises a
Python exception instead.

Signed-off-by: Ingo Müller <ingomueller at google.com>
---
 mlir/lib/Bindings/Python/IRAttributes.cpp | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/mlir/lib/Bindings/Python/IRAttributes.cpp b/mlir/lib/Bindings/Python/IRAttributes.cpp
index 045c0fbf4630f..c0a945e3f4f3b 100644
--- a/mlir/lib/Bindings/Python/IRAttributes.cpp
+++ b/mlir/lib/Bindings/Python/IRAttributes.cpp
@@ -1306,6 +1306,10 @@ PyType_Slot PyDenseElementsAttribute::slots[] = {
     e.restore();
     nb::chain_error(PyExc_BufferError, "Error converting attribute to buffer");
     return -1;
+  } catch (std::exception &e) {
+    nb::chain_error(PyExc_BufferError,
+                    "Error converting attribute to buffer: %s", e.what());
+    return -1;
   }
   view->obj = obj;
   view->ndim = 1;