[Mlir-commits] [mlir] [mlir][python] Fix Python binding cast diagnostics for nanobind 2.13 (PR #206391)
Maksim Levental
llvmlistbot at llvm.org
Sun Jun 28 19:28:41 PDT 2026
https://github.com/makslevental updated https://github.com/llvm/llvm-project/pull/206391
>From 657f1ccfbfc0dfd0abadc7477275404f01699598 Mon Sep 17 00:00:00 2001
From: makslevental <maksim.levental at gmail.com>
Date: Sun, 28 Jun 2026 19:24:25 -0700
Subject: [PATCH] [mlir][python] Fix Python binding cast diagnostics for
nanobind 2.13
nanobind 2.13.0 changed failing `nb::cast<T>()` to raise `cast_error`
(an alias for `std::bad_cast`) for all failures, including `None`,
instead of the previous distinct exception types. The bindings relied
on catching `std::runtime_error` separately from `cast_error` to emit a
helpful "(None?)" hint, so that branch became dead code and the `None`
diagnostics regressed (e.g. "(std::bad_cast)" instead of "(None?)"),
breaking check-mlir Python tests.
Decide the `None` hint from the value via `is_none()` rather than the
exception type. This is robust across nanobind versions (2.10-2.13).
Fixes #205329
---
.../mlir/Bindings/Python/IRAttributes.h | 15 +++---
mlir/lib/Bindings/Python/IRAffine.cpp | 49 ++++++++++---------
mlir/lib/Bindings/Python/IRCore.cpp | 14 +++---
3 files changed, 41 insertions(+), 37 deletions(-)
diff --git a/mlir/include/mlir/Bindings/Python/IRAttributes.h b/mlir/include/mlir/Bindings/Python/IRAttributes.h
index 7f2f88b552453..376ff732c99a8 100644
--- a/mlir/include/mlir/Bindings/Python/IRAttributes.h
+++ b/mlir/include/mlir/Bindings/Python/IRAttributes.h
@@ -100,16 +100,19 @@ template <typename T>
static T pyTryCast(nanobind::handle object) {
try {
return nanobind::cast<T>(object);
- } catch (nanobind::cast_error &err) {
+ } catch (std::exception &err) {
+ // Decide the `None?` hint from the value, not the exception type, since
+ // nanobind >= 2.13 raises cast_error (std::bad_cast) for all failures.
+ if (object.is_none()) {
+ std::string msg = std::string("Invalid attribute (None?) when attempting "
+ "to create an ArrayAttribute (") +
+ err.what() + ")";
+ throw std::runtime_error(msg.c_str());
+ }
std::string msg = std::string("Invalid attribute when attempting to "
"create an ArrayAttribute (") +
err.what() + ")";
throw std::runtime_error(msg.c_str());
- } catch (std::runtime_error &err) {
- std::string msg = std::string("Invalid attribute (None?) when attempting "
- "to create an ArrayAttribute (") +
- err.what() + ")";
- throw std::runtime_error(msg.c_str());
}
}
diff --git a/mlir/lib/Bindings/Python/IRAffine.cpp b/mlir/lib/Bindings/Python/IRAffine.cpp
index 07aa4759bae5f..8c9114e9c7372 100644
--- a/mlir/lib/Bindings/Python/IRAffine.cpp
+++ b/mlir/lib/Bindings/Python/IRAffine.cpp
@@ -43,14 +43,15 @@ static void pyListToVector(const nb::sequence &list, std::vector<CType> &result,
for (nb::handle item : list) {
try {
result.push_back(nb::cast<PyType>(item));
- } catch (nb::cast_error &err) {
+ } catch (std::exception &err) {
+ if (item.is_none()) {
+ std::string msg = nanobind::detail::join(
+ "Invalid expression (None?) when ", action, " (", err.what(), ")");
+ throw std::runtime_error(msg.c_str());
+ }
std::string msg = nanobind::detail::join("Invalid expression when ",
action, " (", err.what(), ")");
throw std::runtime_error(msg.c_str());
- } catch (std::runtime_error &err) {
- std::string msg = nanobind::detail::join(
- "Invalid expression (None?) when ", action, " (", err.what(), ")");
- throw std::runtime_error(msg.c_str());
}
}
}
@@ -731,25 +732,25 @@ void populateIRAffine(nb::module_ &m) {
[](PyAffineMap &self) {
return std::hash<const void *>{}(self.get().ptr);
})
- .def_static(
- "compress_unused_symbols",
- [](nb::typed<nb::sequence, PyAffineMap> affineMaps,
- DefaultingPyMlirContext context) {
- std::vector<MlirAffineMap> maps;
- pyListToVector<PyAffineMap, MlirAffineMap>(
- affineMaps, maps, "attempting to create an AffineMap");
- std::vector<MlirAffineMap> compressed(nb::len(affineMaps));
- auto populate = [](void *result, intptr_t idx, MlirAffineMap m) {
- static_cast<MlirAffineMap *>(result)[idx] = (m);
- };
- mlirAffineMapCompressUnusedSymbols(maps.data(), maps.size(),
- compressed.data(), populate);
- std::vector<PyAffineMap> res;
- res.reserve(compressed.size());
- for (auto m : compressed)
- res.emplace_back(context->getRef(), m);
- return res;
- })
+ .def_static("compress_unused_symbols",
+ [](nb::typed<nb::sequence, PyAffineMap> affineMaps,
+ DefaultingPyMlirContext context) {
+ std::vector<MlirAffineMap> maps;
+ pyListToVector<PyAffineMap, MlirAffineMap>(
+ affineMaps, maps, "attempting to create an AffineMap");
+ std::vector<MlirAffineMap> compressed(nb::len(affineMaps));
+ auto populate = [](void *result, intptr_t idx,
+ MlirAffineMap m) {
+ static_cast<MlirAffineMap *>(result)[idx] = (m);
+ };
+ mlirAffineMapCompressUnusedSymbols(
+ maps.data(), maps.size(), compressed.data(), populate);
+ std::vector<PyAffineMap> res;
+ res.reserve(compressed.size());
+ for (auto m : compressed)
+ res.emplace_back(context->getRef(), m);
+ return res;
+ })
.def_prop_ro(
"context",
[](PyAffineMap &self) -> nb::typed<nb::object, PyMlirContext> {
diff --git a/mlir/lib/Bindings/Python/IRCore.cpp b/mlir/lib/Bindings/Python/IRCore.cpp
index fc69ef8884466..ab75bc20e123e 100644
--- a/mlir/lib/Bindings/Python/IRCore.cpp
+++ b/mlir/lib/Bindings/Python/IRCore.cpp
@@ -1272,17 +1272,17 @@ nb::object PyOperation::create(std::string_view name,
auto &attribute = nb::cast<PyAttribute &>(it.second);
// TODO: Verify attribute originates from the same context.
mlirAttributes.emplace_back(std::move(key), attribute);
- } catch (nb::cast_error &err) {
+ } catch (std::exception &err) {
+ if (it.second.is_none()) {
+ std::string msg = join(
+ "Found an invalid (`None`?) attribute value for the key \"", key,
+ "\" when attempting to create the operation \"", name, "\"");
+ throw std::runtime_error(msg);
+ }
std::string msg = join("Invalid attribute value for the key \"", key,
"\" when attempting to create the operation \"",
name, "\" (", err.what(), ")");
throw nb::type_error(msg.c_str());
- } catch (std::runtime_error &) {
- // This exception seems thrown when the value is "None".
- std::string msg = join(
- "Found an invalid (`None`?) attribute value for the key \"", key,
- "\" when attempting to create the operation \"", name, "\"");
- throw std::runtime_error(msg);
}
}
}
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