Add diagnostic handler

pyqir/pyqir/_native.pyi

@@ -681,13 +681,12 @@ class Module:
         """Converts this module into an LLVM IR string."""
         ...
 
-    def link(self, other: Module) -> Optional[str]:
+    def link(self, other: Module) -> None:
         """
         Link the supplied module into the current module.
         Destroys the supplied module.
 
-        :returns: An error message if linking failed or `None` if linking succeeded.
-        :rtype: typing.Optional[str]
+        :raises: An error if linking failed.
         """
         ...
 

pyqir/src/module.rs

@@ -22,7 +22,7 @@ use llvm_sys::{
     LLVMLinkage, LLVMModule,
 };
 use pyo3::{exceptions::PyValueError, prelude::*, pyclass::CompareOp, types::PyBytes};
-use qirlib::module::FlagBehavior;
+use qirlib::{context::set_diagnostic_handler, module::FlagBehavior};
 use std::{
     collections::hash_map::DefaultHasher,
     ffi::CString,
@@ -269,26 +269,30 @@ impl Module {
     /// Link the supplied module into the current module.
     /// Destroys the supplied module.
     ///
-    /// :returns: An error message if linking failed or `None` if linking succeeded.
-    /// :rtype: typing.Optional[str]
-    pub fn link(&self, other: Py<Module>, py: Python) -> Option<String> {
-        if self.context.borrow(py).as_ptr() != other.borrow(py).context.borrow(py).as_ptr() {
-            return Some(
+    /// :raises: An error if linking failed.
+    pub fn link(&self, other: Py<Module>, py: Python) -> PyResult<()> {
+        let context = self.context.borrow(py).as_ptr();
+        if context != other.borrow(py).context.borrow(py).as_ptr() {
+            return Err(PyValueError::new_err(
                 "Cannot link modules from different contexts. Modules are untouched.".to_string(),
-            );
+            ));
         }
         unsafe {
+            let mut char_ptr: *mut ::core::ffi::c_char = ptr::null_mut();
+            let char_ptr_ptr = &mut char_ptr as *mut *mut ::core::ffi::c_char
+                as *mut *mut ::core::ffi::c_void
+                as *mut ::core::ffi::c_void;
+
+            set_diagnostic_handler(context, char_ptr_ptr);
             let result = LLVMLinkModules2(self.module.as_ptr(), other.borrow(py).module.as_ptr());
             // `forget` the other module. LLVM has destroyed it
             // and we'll get a segfault if we drop it.
             forget(other);
             if result == 0 {
-                None
+                Ok(())
             } else {
-                // in the future we need to return a proper error message
-                // using `LLVMContextSetDiagnosticHandler`. This is a lot of work
-                // to get right, so we'll leave it for now.
-                Some("Failed to link modules".to_string())
+                let error = Message::from_raw(char_ptr);
+                return Err(PyValueError::new_err(error.to_str().unwrap().to_string()));
             }
         }
     }

pyqir/tests/profile_v1.0_compat.ll

@@ -0,0 +1,34 @@
+; ModuleID = 'OneDotZero'
+%Result = type opaque
+%Qubit = type opaque
+
+define void @OneDotZero() #0 {
+block_0:
+  call void @__quantum__qis__h__body(%Qubit* inttoptr (i64 0 to %Qubit*))
+  call void @__quantum__qis__h__body(%Qubit* inttoptr (i64 1 to %Qubit*))
+  call void @__quantum__qis__cz__body(%Qubit* inttoptr (i64 1 to %Qubit*), %Qubit* inttoptr (i64 0 to %Qubit*))
+  call void @__quantum__qis__h__body(%Qubit* inttoptr (i64 1 to %Qubit*))
+  call void @__quantum__qis__m__body(%Qubit* inttoptr (i64 1 to %Qubit*), %Result* inttoptr (i64 0 to %Result*))
+  call void @__quantum__rt__result_record_output(%Result* inttoptr (i64 0 to %Result*), i8* null)
+  ret void
+}
+
+declare void @__quantum__qis__h__body(%Qubit*)
+
+declare void @__quantum__qis__cz__body(%Qubit*, %Qubit*)
+
+declare void @__quantum__rt__result_record_output(%Result*, i8*)
+
+declare void @__quantum__qis__m__body(%Qubit*, %Result*) #1
+
+attributes #0 = { "entry_point" "output_labeling_schema" "qir_profiles"="base_profile" "required_num_qubits"="2" "required_num_results"="1" }
+attributes #1 = { "irreversible" }
+
+; module flags
+
+!llvm.module.flags = !{!0, !1, !2, !3}
+
+!0 = !{i32 1, !"qir_major_version", i32 1}
+!1 = !{i32 7, !"qir_minor_version", i32 0}
+!2 = !{i32 1, !"dynamic_qubit_management", i1 false}
+!3 = !{i32 1, !"dynamic_result_management", i1 false}

pyqir/tests/profile_v1.1_compat.ll

@@ -0,0 +1,34 @@
+; ModuleID = 'OneDotOne'
+%Result = type opaque
+%Qubit = type opaque
+
+define void @OneDotOne() #0 {
+block_0:
+  call void @__quantum__qis__h__body(%Qubit* inttoptr (i64 0 to %Qubit*))
+  call void @__quantum__qis__h__body(%Qubit* inttoptr (i64 1 to %Qubit*))
+  call void @__quantum__qis__cz__body(%Qubit* inttoptr (i64 1 to %Qubit*), %Qubit* inttoptr (i64 0 to %Qubit*))
+  call void @__quantum__qis__h__body(%Qubit* inttoptr (i64 1 to %Qubit*))
+  call void @__quantum__qis__m__body(%Qubit* inttoptr (i64 1 to %Qubit*), %Result* inttoptr (i64 0 to %Result*))
+  call void @__quantum__rt__result_record_output(%Result* inttoptr (i64 0 to %Result*), i8* null)
+  ret void
+}
+
+declare void @__quantum__qis__h__body(%Qubit*)
+
+declare void @__quantum__qis__cz__body(%Qubit*, %Qubit*)
+
+declare void @__quantum__rt__result_record_output(%Result*, i8*)
+
+declare void @__quantum__qis__m__body(%Qubit*, %Result*) #1
+
+attributes #0 = { "entry_point" "output_labeling_schema" "qir_profiles"="base_profile" "required_num_qubits"="2" "required_num_results"="1" }
+attributes #1 = { "irreversible" }
+
+; module flags
+
+!llvm.module.flags = !{!0, !1, !2, !3}
+
+!0 = !{i32 1, !"qir_major_version", i32 1}
+!1 = !{i32 7, !"qir_minor_version", i32 1}
+!2 = !{i32 1, !"dynamic_qubit_management", i1 false}
+!3 = !{i32 1, !"dynamic_result_management", i1 false}

pyqir/tests/profile_v2.0_compat.ll

@@ -0,0 +1,34 @@
+; ModuleID = 'TwoDotZero'
+%Result = type opaque
+%Qubit = type opaque
+
+define void @TwoDotZero() #0 {
+block_0:
+  call void @__quantum__qis__h__body(%Qubit* inttoptr (i64 0 to %Qubit*))
+  call void @__quantum__qis__h__body(%Qubit* inttoptr (i64 1 to %Qubit*))
+  call void @__quantum__qis__cz__body(%Qubit* inttoptr (i64 1 to %Qubit*), %Qubit* inttoptr (i64 0 to %Qubit*))
+  call void @__quantum__qis__h__body(%Qubit* inttoptr (i64 1 to %Qubit*))
+  call void @__quantum__qis__m__body(%Qubit* inttoptr (i64 1 to %Qubit*), %Result* inttoptr (i64 0 to %Result*))
+  call void @__quantum__rt__result_record_output(%Result* inttoptr (i64 0 to %Result*), i8* null)
+  ret void
+}
+
+declare void @__quantum__qis__h__body(%Qubit*)
+
+declare void @__quantum__qis__cz__body(%Qubit*, %Qubit*)
+
+declare void @__quantum__rt__result_record_output(%Result*, i8*)
+
+declare void @__quantum__qis__m__body(%Qubit*, %Result*) #1
+
+attributes #0 = { "entry_point" "output_labeling_schema" "qir_profiles"="base_profile" "required_num_qubits"="2" "required_num_results"="1" }
+attributes #1 = { "irreversible" }
+
+; module flags
+
+!llvm.module.flags = !{!0, !1, !2, !3}
+
+!0 = !{i32 1, !"qir_major_version", i32 2}
+!1 = !{i32 7, !"qir_minor_version", i32 0}
+!2 = !{i32 1, !"dynamic_qubit_management", i1 false}
+!3 = !{i32 1, !"dynamic_result_management", i1 false}

pyqir/tests/test_module_linking.py

@@ -3,31 +3,93 @@
 
 from pathlib import Path
 
+import pytest
+
+current_file_path = Path(__file__)
+# Get the directory of the current file
+current_dir = current_file_path.parent
+
 from pyqir import (
     Context,
     Module,
 )
 
 
+def read_file(file_name: str) -> str:
+    return Path(current_dir / file_name).read_text(encoding="utf-8")
+
+
 def test_link_modules_with_same_context() -> None:
     context = Context()
-    ir = Path("tests/random_bit.ll").read_text()
+    ir = read_file("random_bit.ll")
     dest = Module.from_ir(context, ir)
-    ir = Path("tests/5_bit_random_number.ll").read_text()
+    ir = read_file("5_bit_random_number.ll")
     src = Module.from_ir(context, ir)
-    assert dest.link(src) is None
+    dest.link(src)
     assert dest.verify() is None
     actual_ir = str(dest)
-    expected_ir = str(Path("tests/combined_module.ll").read_text())
+    expected_ir = str(read_file("combined_module.ll"))
     assert actual_ir == expected_ir
 
 
 def test_link_modules_with_different_contexts() -> None:
-    ir = Path("tests/random_bit.ll").read_text()
+    ir = read_file("random_bit.ll")
     dest = Module.from_ir(Context(), ir)
-    ir = Path("tests/5_bit_random_number.ll").read_text()
+    ir = read_file("5_bit_random_number.ll")
     src = Module.from_ir(Context(), ir)
-    message = dest.link(src)
+    with pytest.raises(ValueError) as ex:
+        dest.link(src)
+    assert (
+        str(ex.value)
+        == "Cannot link modules from different contexts. Modules are untouched."
+    )
+
+
+def test_link_module_with_src_minor_version_less() -> None:
+    context = Context()
+    ir = read_file("profile_v1.0_compat.ll")
+    dest = Module.from_ir(context, ir)
+    ir = read_file("profile_v1.1_compat.ll")
+    src = Module.from_ir(context, ir)
+    dest.link(src)
+    assert dest.get_flag("qir_minor_version").value.value == 1
+
+
+def test_link_module_with_src_minor_version_greater() -> None:
+    context = Context()
+    ir = read_file("profile_v1.1_compat.ll")
+    dest = Module.from_ir(context, ir)
+    ir = read_file("profile_v1.0_compat.ll")
+    src = Module.from_ir(context, ir)
+    dest.link(src)
+    assert dest.get_flag("qir_minor_version").value.value == 1
+
+
+def test_link_module_with_src_major_version_less() -> None:
+    context = Context()
+    ir = read_file("profile_v2.0_compat.ll")
+    dest = Module.from_ir(context, ir)
+    ir = read_file("profile_v1.0_compat.ll")
+    src = Module.from_ir(context, ir)
+    with pytest.raises(ValueError) as ex:
+        dest.link(src)
+
+    assert (
+        "linking module flags 'qir_major_version': IDs have conflicting values"
+        in str(ex)
+    )
+
+
+def test_link_module_with_src_major_version_greater() -> None:
+    context = Context()
+    ir = read_file("profile_v1.0_compat.ll")
+    dest = Module.from_ir(context, ir)
+    ir = read_file("profile_v2.0_compat.ll")
+    src = Module.from_ir(context, ir)
+    with pytest.raises(ValueError) as ex:
+        dest.link(src)
+
     assert (
-        message == "Cannot link modules from different contexts. Modules are untouched."
+        "linking module flags 'qir_major_version': IDs have conflicting values"
+        in str(ex)
     )

qirlib/src/context.rs

@@ -0,0 +1,26 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT License.
+
+use llvm_sys::{
+    core::{LLVMContextSetDiagnosticHandler, LLVMGetDiagInfoDescription, LLVMGetDiagInfoSeverity},
+    prelude::{LLVMContextRef, LLVMDiagnosticInfoRef},
+    LLVMDiagnosticSeverity,
+};
+
+pub fn set_diagnostic_handler(context: LLVMContextRef, output_ptr: *mut core::ffi::c_void) {
+    unsafe { LLVMContextSetDiagnosticHandler(context, Some(diagnostic_handler), output_ptr) };
+}
+
+pub(crate) extern "C" fn diagnostic_handler(
+    diagnostic_info: LLVMDiagnosticInfoRef,
+    output: *mut ::core::ffi::c_void,
+) {
+    unsafe {
+        let severity = LLVMGetDiagInfoSeverity(diagnostic_info);
+        if severity == LLVMDiagnosticSeverity::LLVMDSError {
+            let c_char_output =
+                output as *mut *mut ::core::ffi::c_void as *mut *mut ::core::ffi::c_char;
+            *c_char_output = LLVMGetDiagInfoDescription(diagnostic_info)
+        }
+    }
+}

qirlib/src/lib.rs

@@ -20,6 +20,8 @@ extern crate llvm_sys_140 as llvm_sys;
 #[cfg(not(feature = "no-llvm-linking"))]
 pub mod builder;
 #[cfg(not(feature = "no-llvm-linking"))]
+pub mod context;
+#[cfg(not(feature = "no-llvm-linking"))]
 pub(crate) mod llvm_wrapper;
 #[cfg(not(feature = "no-llvm-linking"))]
 pub mod metadata;