[Mlir-commits] [mlir] [mlir][py] Mark all type caster `from_{cpp, python}` methods as noexcept (PR #143866)

[Nicholas Junge]

https://github.com/nicholasjng created https://github.com/llvm/llvm-project/pull/143866

This is mentioned as a "must" in https://nanobind.readthedocs.io/en/latest/porting.html#type-casters when implementing type casters.

While most of the existing `from_cpp` methods were already marked noexcept, many of the `from_python` methods were not. This commit adds the missing noexcept declarations to all type casters found in `NanobindAdaptors.h`.

>From 35d5b50a0f6b8d41780108f93cefc1788f6da84b Mon Sep 17 00:00:00 2001
From: Nicholas Junge <nicholas.junge at web.de>
Date: Thu, 12 Jun 2025 11:40:42 +0200
Subject: [PATCH] [mlir][py] Mark all type caster `from_{cpp,python}` methods
 as noexcept

This is mentioned as a "must" in https://nanobind.readthedocs.io/en/latest/porting.html#type-casters when implementing type casters.

While most of the existing `from_cpp` methods were already marked noexcept, many of the `from_python` methods were not.
This commit adds the missing noexcept declarations to all type casters found in `NanobindAdaptors.h`.
---
 .../mlir/Bindings/Python/NanobindAdaptors.h   | 29 ++++++++++---------
 1 file changed, 15 insertions(+), 14 deletions(-)

diff --git a/mlir/include/mlir/Bindings/Python/NanobindAdaptors.h b/mlir/include/mlir/Bindings/Python/NanobindAdaptors.h
index 2dd35c097c796..e39b1a752f8d6 100644
--- a/mlir/include/mlir/Bindings/Python/NanobindAdaptors.h
+++ b/mlir/include/mlir/Bindings/Python/NanobindAdaptors.h
@@ -67,7 +67,7 @@ static nanobind::object mlirApiObjectToCapsule(nanobind::handle apiObject) {
 template <>
 struct type_caster<MlirAffineMap> {
   NB_TYPE_CASTER(MlirAffineMap, const_name("MlirAffineMap"))
-  bool from_python(handle src, uint8_t flags, cleanup_list *cleanup) {
+  bool from_python(handle src, uint8_t flags, cleanup_list *cleanup) noexcept {
     nanobind::object capsule = mlirApiObjectToCapsule(src);
     value = mlirPythonCapsuleToAffineMap(capsule.ptr());
     if (mlirAffineMapIsNull(value)) {
@@ -90,7 +90,7 @@ struct type_caster<MlirAffineMap> {
 template <>
 struct type_caster<MlirAttribute> {
   NB_TYPE_CASTER(MlirAttribute, const_name("MlirAttribute"))
-  bool from_python(handle src, uint8_t flags, cleanup_list *cleanup) {
+  bool from_python(handle src, uint8_t flags, cleanup_list *cleanup) noexcept {
     nanobind::object capsule = mlirApiObjectToCapsule(src);
     value = mlirPythonCapsuleToAttribute(capsule.ptr());
     return !mlirAttributeIsNull(value);
@@ -111,7 +111,7 @@ struct type_caster<MlirAttribute> {
 template <>
 struct type_caster<MlirBlock> {
   NB_TYPE_CASTER(MlirBlock, const_name("MlirBlock"))
-  bool from_python(handle src, uint8_t flags, cleanup_list *cleanup) {
+  bool from_python(handle src, uint8_t flags, cleanup_list *cleanup) noexcept {
     nanobind::object capsule = mlirApiObjectToCapsule(src);
     value = mlirPythonCapsuleToBlock(capsule.ptr());
     return !mlirBlockIsNull(value);
@@ -122,7 +122,7 @@ struct type_caster<MlirBlock> {
 template <>
 struct type_caster<MlirContext> {
   NB_TYPE_CASTER(MlirContext, const_name("MlirContext"))
-  bool from_python(handle src, uint8_t flags, cleanup_list *cleanup) {
+  bool from_python(handle src, uint8_t flags, cleanup_list *cleanup) noexcept {
     if (src.is_none()) {
       // Gets the current thread-bound context.
       // TODO: This raises an error of "No current context" currently.
@@ -142,7 +142,7 @@ struct type_caster<MlirContext> {
 template <>
 struct type_caster<MlirDialectRegistry> {
   NB_TYPE_CASTER(MlirDialectRegistry, const_name("MlirDialectRegistry"))
-  bool from_python(handle src, uint8_t flags, cleanup_list *cleanup) {
+  bool from_python(handle src, uint8_t flags, cleanup_list *cleanup) noexcept {
     nanobind::object capsule = mlirApiObjectToCapsule(src);
     value = mlirPythonCapsuleToDialectRegistry(capsule.ptr());
     return !mlirDialectRegistryIsNull(value);
@@ -162,7 +162,7 @@ struct type_caster<MlirDialectRegistry> {
 template <>
 struct type_caster<MlirLocation> {
   NB_TYPE_CASTER(MlirLocation, const_name("MlirLocation"))
-  bool from_python(handle src, uint8_t flags, cleanup_list *cleanup) {
+  bool from_python(handle src, uint8_t flags, cleanup_list *cleanup) noexcept {
     if (src.is_none()) {
       // Gets the current thread-bound context.
       src = nanobind::module_::import_(MAKE_MLIR_PYTHON_QUALNAME("ir"))
@@ -188,7 +188,7 @@ struct type_caster<MlirLocation> {
 template <>
 struct type_caster<MlirModule> {
   NB_TYPE_CASTER(MlirModule, const_name("MlirModule"))
-  bool from_python(handle src, uint8_t flags, cleanup_list *cleanup) {
+  bool from_python(handle src, uint8_t flags, cleanup_list *cleanup) noexcept {
     nanobind::object capsule = mlirApiObjectToCapsule(src);
     value = mlirPythonCapsuleToModule(capsule.ptr());
     return !mlirModuleIsNull(value);
@@ -209,12 +209,13 @@ template <>
 struct type_caster<MlirFrozenRewritePatternSet> {
   NB_TYPE_CASTER(MlirFrozenRewritePatternSet,
                  const_name("MlirFrozenRewritePatternSet"))
-  bool from_python(handle src, uint8_t flags, cleanup_list *cleanup) {
+  bool from_python(handle src, uint8_t flags, cleanup_list *cleanup) noexcept {
     nanobind::object capsule = mlirApiObjectToCapsule(src);
     value = mlirPythonCapsuleToFrozenRewritePatternSet(capsule.ptr());
     return value.ptr != nullptr;
   }
-  static handle from_cpp(MlirFrozenRewritePatternSet v, rv_policy, handle) {
+  static handle from_cpp(MlirFrozenRewritePatternSet v, rv_policy,
+                         handle) noexcept {
     nanobind::object capsule = nanobind::steal<nanobind::object>(
         mlirPythonFrozenRewritePatternSetToCapsule(v));
     return nanobind::module_::import_(MAKE_MLIR_PYTHON_QUALNAME("rewrite"))
@@ -228,7 +229,7 @@ struct type_caster<MlirFrozenRewritePatternSet> {
 template <>
 struct type_caster<MlirOperation> {
   NB_TYPE_CASTER(MlirOperation, const_name("MlirOperation"))
-  bool from_python(handle src, uint8_t flags, cleanup_list *cleanup) {
+  bool from_python(handle src, uint8_t flags, cleanup_list *cleanup) noexcept {
     nanobind::object capsule = mlirApiObjectToCapsule(src);
     value = mlirPythonCapsuleToOperation(capsule.ptr());
     return !mlirOperationIsNull(value);
@@ -250,7 +251,7 @@ struct type_caster<MlirOperation> {
 template <>
 struct type_caster<MlirValue> {
   NB_TYPE_CASTER(MlirValue, const_name("MlirValue"))
-  bool from_python(handle src, uint8_t flags, cleanup_list *cleanup) {
+  bool from_python(handle src, uint8_t flags, cleanup_list *cleanup) noexcept {
     nanobind::object capsule = mlirApiObjectToCapsule(src);
     value = mlirPythonCapsuleToValue(capsule.ptr());
     return !mlirValueIsNull(value);
@@ -273,7 +274,7 @@ struct type_caster<MlirValue> {
 template <>
 struct type_caster<MlirPassManager> {
   NB_TYPE_CASTER(MlirPassManager, const_name("MlirPassManager"))
-  bool from_python(handle src, uint8_t flags, cleanup_list *cleanup) {
+  bool from_python(handle src, uint8_t flags, cleanup_list *cleanup) noexcept {
     nanobind::object capsule = mlirApiObjectToCapsule(src);
     value = mlirPythonCapsuleToPassManager(capsule.ptr());
     return !mlirPassManagerIsNull(value);
@@ -284,7 +285,7 @@ struct type_caster<MlirPassManager> {
 template <>
 struct type_caster<MlirTypeID> {
   NB_TYPE_CASTER(MlirTypeID, const_name("MlirTypeID"))
-  bool from_python(handle src, uint8_t flags, cleanup_list *cleanup) {
+  bool from_python(handle src, uint8_t flags, cleanup_list *cleanup) noexcept {
     nanobind::object capsule = mlirApiObjectToCapsule(src);
     value = mlirPythonCapsuleToTypeID(capsule.ptr());
     return !mlirTypeIDIsNull(value);
@@ -306,7 +307,7 @@ struct type_caster<MlirTypeID> {
 template <>
 struct type_caster<MlirType> {
   NB_TYPE_CASTER(MlirType, const_name("MlirType"))
-  bool from_python(handle src, uint8_t flags, cleanup_list *cleanup) {
+  bool from_python(handle src, uint8_t flags, cleanup_list *cleanup) noexcept {
     nanobind::object capsule = mlirApiObjectToCapsule(src);
     value = mlirPythonCapsuleToType(capsule.ptr());
     return !mlirTypeIsNull(value);