fix: Correct pyo3 module definitions and add missing exception class export

hugr-py/rust/linking.rs

@@ -4,8 +4,11 @@ use pyo3::exceptions::PyException;
 use pyo3::{create_exception, pymodule};
 
 #[pymodule(submodule)]
-#[pyo3(module = "hugr._hugr.linking")]
+#[pyo3(module = "hugr._hugr")]
 pub mod linking {
+    #[pymodule_export]
+    use super::HugrLinkingError;
+
     use hugr_core::envelope::EnvelopeConfig;
     use hugr_core::hugr::hugrmut::HugrMut;
     use hugr_core::hugr::linking::{HugrLinking, NameLinkingPolicy};
@@ -47,7 +50,7 @@ pub mod linking {
 
         let forest = hugr_into
             .link_module(hugr_from, &NameLinkingPolicy::default())
-            .map_err(|err| super::HugrLinkingError::new_err(err.to_string()))?;
+            .map_err(|err| HugrLinkingError::new_err(err.to_string()))?;
         if let Some(new_entrypoint) = replacement_entrypoint {
             let Some(node) = forest.node_map.get(&new_entrypoint) else {
                 panic!("Entrypoint is to be replaced but was not found after linking");
@@ -69,7 +72,7 @@ pub mod linking {
 }
 
 create_exception!(
-    _hugr.linking,
+    hugr._hugr.linking,
     HugrLinkingError,
     PyException,
     "Base exception for HUGR linking errors."

hugr-py/rust/metadata.rs

@@ -1,7 +1,7 @@
 //! Bindings for metadata keys defined in the hugr-core crate.
 
 #[pyo3::pymodule(submodule)]
-#[pyo3(module = "hugr._hugr.metadata")]
+#[pyo3(module = "hugr._hugr")]
 pub mod metadata {
     use hugr_core::metadata::Metadata;
     use pyo3::types::{PyAnyMethods, PyModule};

hugr-py/rust/model.rs

@@ -6,6 +6,7 @@ use pyo3::exceptions::{PyException, PyValueError};
 use pyo3::{PyErr, PyResult, create_exception, pymodule};
 
 #[pymodule(submodule)]
+#[pyo3(module = "hugr._hugr")]
 pub mod model {
     use hugr_cli::CliArgs;
     use hugr_model::v0::ast;
@@ -132,13 +133,13 @@ pub mod model {
 
 // Define custom exceptions
 create_exception!(
-    _hugr,
+    hugr._hugr.model,
     HugrCliError,
     PyException,
     "Base exception for HUGR CLI errors."
 );
 create_exception!(
-    _hugr,
+    hugr._hugr.model,
     HugrCliDescribeError,
     HugrCliError,
     "Exception for HUGR CLI describe command errors with partial output."

hugr-py/rust/zstd_util.rs

@@ -3,6 +3,7 @@
 use pyo3::pymodule;
 
 #[pymodule(submodule)]
+#[pyo3(module = "hugr._hugr")]
 pub mod zstd {
     use pyo3::types::{PyAnyMethods, PyModule};
     use pyo3::{Bound, Python};

hugr-py/tests/test_linking.py

@@ -1,21 +1,31 @@
 import pytest
 
 from hugr import Hugr, tys
-from hugr._hugr.linking import link_modules
+from hugr._hugr.linking import HugrLinkingError, link_modules
 from hugr.build import Module
 from hugr.ops import FuncDefn
 from hugr.package import Package
 from hugr.std import float, int, logic, ptr
 
 
-def build_module(*, entrypoint: bool) -> Hugr:
+def build_module(*, entrypoint: bool, public_func: bool = False) -> Hugr:
     builder = Module()
     if entrypoint:
         main = builder.define_function(
             "main", input_types=[tys.Bool], output_types=[tys.Bool], visibility="Public"
         )
         main.set_outputs(*main.inputs())
         builder.hugr.entrypoint = main.parent_node
+    elif public_func:
+        # Entrypoint is already public, so we only need to add one
+        # if no entrypoint was generated.
+        func = builder.define_function(
+            "public_func",
+            input_types=[tys.Bool],
+            output_types=[tys.Bool],
+            visibility="Public",
+        )
+        func.set_outputs(*func.inputs())
 
     return builder.hugr
 
@@ -58,6 +68,17 @@ def test_link_modules_multiple_entrypoints():
         link_modules(hugr1.to_bytes(), hugr2.to_bytes())
 
 
+def test_link_modules_linking_error():
+    hugr1 = build_module(entrypoint=False, public_func=True)
+    hugr2 = build_module(entrypoint=False, public_func=True)
+
+    with pytest.raises(
+        HugrLinkingError,
+        match=r"Source \(Node\([0-9]+\)\) and target \(Node\([0-9]+\)\) both contained FuncDefn with same public name public_func",  # noqa: E501
+    ):
+        link_modules(hugr1.to_bytes(), hugr2.to_bytes())
+
+
 def test_link_packages_no_modules():
     pkg1 = Package(modules=[])
     pkg2 = Package(modules=[])