Fix several clippy-related issues (#100)

* Fix clippy-related issues

Running `cargo clippy` revealed several small issues that this change
fixes.

* Use the `cstr!` macro in more places

* Improve documentation for non-macro-dropped structs

* `Tensor::new_from_instance` does not need to return a `Result`

Author: abrown

crates/openvino/src/core.rs

@@ -5,7 +5,6 @@ use crate::error::LoadingError;
 use crate::{cstr, drop_using_function, try_unsafe, util::Result};
 use crate::{model::CompiledModel, Model};
 use crate::{SetupError, Tensor};
-
 use openvino_sys::{
     self, ov_core_compile_model, ov_core_create, ov_core_create_with_config, ov_core_free,
     ov_core_read_model, ov_core_read_model_from_memory_buffer, ov_core_t,
@@ -28,7 +27,7 @@ impl Core {
         Ok(Core { instance })
     }
 
-    ///Construct a new OpenVINO [`Core`] with config specified in an xml file.
+    /// Construct a new OpenVINO [`Core`] with config specified in an xml file.
     pub fn new_with_config(xml_config_file: &str) -> std::result::Result<Core, SetupError> {
         let mut instance = std::ptr::null_mut();
         try_unsafe!(ov_core_create_with_config(
@@ -51,7 +50,7 @@ impl Core {
         Ok(Model::new_from_instance(instance))
     }
 
-    ///Read model with model and weights loaded in memory.
+    /// Read model with model and weights loaded in memory.
     pub fn read_model_from_buffer(
         &mut self,
         model_str: &str,

crates/openvino/src/layout.rs

@@ -1,6 +1,5 @@
-use crate::{drop_using_function, try_unsafe, util::Result};
+use crate::{cstr, drop_using_function, try_unsafe, util::Result};
 use openvino_sys::{ov_layout_create, ov_layout_free, ov_layout_t};
-use std::ffi::CString;
 
 /// See [`Layout`](https://docs.openvino.ai/2023.3/api/c_cpp_api/group__ov__layout__c__api.html).
 pub struct Layout {
@@ -17,9 +16,8 @@ impl Layout {
     /// Creates a new layout with the given description.
     pub fn new(layout_desc: &str) -> Result<Self> {
         let mut layout = std::ptr::null_mut();
-        let c_layout_desc = CString::new(layout_desc).unwrap();
         try_unsafe!(ov_layout_create(
-            c_layout_desc.as_ptr(),
+            cstr!(layout_desc),
             std::ptr::addr_of_mut!(layout)
         ))?;
         Ok(Self { instance: layout })

crates/openvino/src/model.rs

@@ -94,7 +94,7 @@ drop_using_function!(CompiledModel, ov_compiled_model_free);
 unsafe impl Send for CompiledModel {}
 
 impl CompiledModel {
-    /// Create a new instance of the CompiledModel struct from ov_compiled_model_t.
+    /// Create a new instance of the [`CompiledModel`] from an internal `ov_compiled_model_t`.
     pub(crate) fn new(instance: *mut ov_compiled_model_t) -> Self {
         Self { instance }
     }

crates/openvino/src/partial_shape.rs

@@ -13,7 +13,8 @@ pub struct PartialShape {
 }
 
 impl Drop for PartialShape {
-    /// Drops the `PartialShape` instance and frees the associated memory.
+    // We don't use the `drop...!` macro here since:
+    // - the `instance` field is not a pointer as with other types.
     fn drop(&mut self) {
         unsafe { ov_partial_shape_free(std::ptr::addr_of_mut!(self.instance)) }
     }
@@ -86,6 +87,10 @@ impl PartialShape {
     }
 
     /// Returns the dimensions of the partial shape.
+    ///
+    /// # Panics
+    ///
+    /// Panics in the unlikely case the rank cannot be represented as a `usize`.
     pub fn get_dimensions(&self) -> &[Dimension] {
         if self.instance.dims.is_null() {
             &[]

crates/openvino/src/prepostprocess.rs

@@ -29,6 +29,9 @@
 //! model_info.model_info_set_layout(&Layout::new("NCHW").expect("to create a new layout")).expect("to set layout");
 //! let new_model = pre_post_process.build_new_model().expect("to build new model with above prepostprocess steps");
 //! ```
+use crate::{
+    cstr, drop_using_function, layout::Layout, try_unsafe, util::Result, ElementType, Model, Tensor,
+};
 use openvino_sys::{
     ov_preprocess_input_info_free, ov_preprocess_input_info_get_model_info,
     ov_preprocess_input_info_get_preprocess_steps, ov_preprocess_input_info_get_tensor_info,
@@ -49,11 +52,6 @@ use openvino_sys::{
     ov_preprocess_preprocess_steps_convert_layout, ov_preprocess_preprocess_steps_free,
     ov_preprocess_preprocess_steps_resize, ov_preprocess_preprocess_steps_t,
 };
-use std::ffi::CString;
-
-use crate::{
-    drop_using_function, layout::Layout, try_unsafe, util::Result, ElementType, Model, Tensor,
-};
 
 /// See [`PrePostProcess`](https://docs.openvino.ai/2023.3/api/c_cpp_api/structov__preprocess__prepostprocessor__t.html).
 #[derive(Debug)]
@@ -142,7 +140,7 @@ impl PreProcessInputTensorInfo {
 }
 
 impl PrePostProcess {
-    /// Creates a new `PrePostprocess` instance for the given model.
+    /// Creates a new `PrePostProcess` instance for the given model.
     pub fn new(model: &Model) -> Result<Self> {
         let mut preprocess = std::ptr::null_mut();
         try_unsafe!(ov_preprocess_prepostprocessor_create(
@@ -172,10 +170,9 @@ impl PrePostProcess {
     /// Retrieves the input information by name.
     pub fn get_input_info_by_name(&self, name: &str) -> Result<PreProcessInputInfo> {
         let mut input_info = std::ptr::null_mut();
-        let c_layout_desc = CString::new(name).unwrap();
         try_unsafe!(ov_preprocess_prepostprocessor_get_input_info_by_name(
             self.instance,
-            c_layout_desc.as_ptr(),
+            cstr!(name),
             std::ptr::addr_of_mut!(input_info)
         ))?;
 
@@ -186,17 +183,13 @@ impl PrePostProcess {
 
     /// Retrieves the output information by name.
     pub fn get_output_info_by_name(&self, name: &str) -> Result<PreProcessOutputInfo> {
-        let mut output_info = std::ptr::null_mut();
-        let c_layout_desc = CString::new(name).unwrap();
+        let mut instance = std::ptr::null_mut();
         try_unsafe!(ov_preprocess_prepostprocessor_get_output_info_by_name(
             self.instance,
-            c_layout_desc.as_ptr(),
-            std::ptr::addr_of_mut!(output_info)
+            cstr!(name),
+            std::ptr::addr_of_mut!(instance)
         ))?;
-
-        Ok(PreProcessOutputInfo {
-            instance: output_info,
-        })
+        Ok(PreProcessOutputInfo { instance })
     }
 
     /// Retrieves the output information by index.
@@ -214,17 +207,18 @@ impl PrePostProcess {
     }
 
     /// Retrieves the input information.
+    ///
+    /// # Panics
+    ///
+    /// Panics if the returned input info is null.
     pub fn get_input_info(&self) -> Result<PreProcessInputInfo> {
-        let mut input_info = std::ptr::null_mut();
+        let mut instance = std::ptr::null_mut();
         try_unsafe!(ov_preprocess_prepostprocessor_get_input_info(
             self.instance,
-            std::ptr::addr_of_mut!(input_info)
+            std::ptr::addr_of_mut!(instance)
         ))?;
-        assert!(!input_info.is_null());
-
-        Ok(PreProcessInputInfo {
-            instance: input_info,
-        })
+        assert!(!instance.is_null());
+        Ok(PreProcessInputInfo { instance })
     }
 
     /// Builds a new model with all steps from pre/postprocessing.

crates/openvino/src/request.rs

@@ -38,7 +38,7 @@ impl InferRequest {
             cstr!(name),
             std::ptr::addr_of_mut!(tensor)
         ))?;
-        Ok(Tensor::new_from_instance(tensor).unwrap())
+        Ok(Tensor::new_from_instance(tensor))
     }
 
     /// Execute the inference request.

crates/openvino/src/shape.rs

@@ -8,8 +8,9 @@ pub struct Shape {
 }
 
 impl Drop for Shape {
-    /// Drops the Shape instance and frees the associated memory.
-    //Not using drop! macro since ov_shape_free returns an error code unlike other free methods.
+    // We don't use the `drop...!` macro here since:
+    // - `ov_shape_free` returns an error code unlike other free methods
+    // - the `instance` field is not a pointer as with other types.
     fn drop(&mut self) {
         let code = unsafe { ov_shape_free(std::ptr::addr_of_mut!(self.instance)) };
         assert_eq!(code, 0);
@@ -19,12 +20,11 @@ impl Drop for Shape {
 }
 
 impl Shape {
-    /// Get the pointer to the underlying OpenVINO shape.
-    pub(crate) fn instance(&self) -> ov_shape_t {
-        self.instance
-    }
-
     /// Creates a new Shape instance with the given dimensions.
+    ///
+    /// # Panics
+    ///
+    /// Panics in the unlikely case the dimension length cannot be represented as an `i64`.
     pub fn new(dimensions: &[i64]) -> Result<Self> {
         let mut shape = ov_shape_t {
             rank: 8,
@@ -38,17 +38,26 @@ impl Shape {
         Ok(Self { instance: shape })
     }
 
-    /// Create a new shape object from ov_shape_t.
+    /// Create a new shape object from `ov_shape_t`.
     pub(crate) fn new_from_instance(instance: ov_shape_t) -> Self {
         Self { instance }
     }
 
+    /// Get the pointer to the underlying OpenVINO shape.
+    pub(crate) fn instance(&self) -> ov_shape_t {
+        self.instance
+    }
+
     /// Returns the rank of the shape.
     pub fn get_rank(&self) -> i64 {
         self.instance.rank
     }
 
     /// Returns the dimensions of the shape.
+    ///
+    /// # Panics
+    ///
+    /// Panics in the unlikely case the rank cannot be represented as a `usize`.
     pub fn get_dimensions(&self) -> &[i64] {
         if self.instance.dims.is_null() || self.instance.rank <= 0 {
             &[]
@@ -65,9 +74,8 @@ impl Shape {
 
 #[cfg(test)]
 mod tests {
-    use crate::LoadingError;
-
     use super::*;
+    use crate::LoadingError;
 
     #[test]
     fn test_new_shape() {

crates/openvino/src/tensor.rs

@@ -15,22 +15,20 @@ pub struct Tensor {
 drop_using_function!(Tensor, ov_tensor_free);
 
 impl Tensor {
-    /// Get the pointer to the underlying OpenVINO tensor.
-    pub fn instance(&self) -> *mut ov_tensor_t {
-        self.instance
-    }
-
     /// Create a new [`Tensor`].
-    pub fn new(data_type: ElementType, shape: &Shape) -> Result<Self> {
-        let mut tensor = std::ptr::null_mut();
-        let element_type = data_type as u32;
-        let code = try_unsafe!(ov_tensor_create(
-            element_type,
+    pub fn new(element_type: ElementType, shape: &Shape) -> Result<Self> {
+        let mut instance = std::ptr::null_mut();
+        try_unsafe!(ov_tensor_create(
+            element_type as u32,
             shape.instance(),
-            std::ptr::addr_of_mut!(tensor),
-        ));
-        assert_eq!(code, Ok(()));
-        Ok(Self { instance: tensor })
+            std::ptr::addr_of_mut!(instance),
+        ))?;
+        Ok(Self { instance })
+    }
+
+    /// Create a new [`Tensor`] from a instance pointer.
+    pub(crate) fn new_from_instance(instance: *mut ov_tensor_t) -> Self {
+        Self { instance }
     }
 
     /// Create a new [`Tensor`] from a host pointer.
@@ -57,9 +55,9 @@ impl Tensor {
         Ok(Self { instance: tensor })
     }
 
-    ///Create a new [`Tensor`] from a instance pointer.
-    pub(crate) fn new_from_instance(instance: *mut ov_tensor_t) -> Result<Self> {
-        Ok(Self { instance })
+    /// Get the pointer to the underlying OpenVINO tensor.
+    pub(crate) fn instance(&self) -> *mut ov_tensor_t {
+        self.instance
     }
 
     /// (Re)Set the shape of the tensor to a new shape.

crates/openvino/src/util.rs

@@ -29,7 +29,7 @@ macro_rules! drop_using_function {
     ($ty: ty, $free_fn: expr) => {
         impl Drop for $ty {
             fn drop(&mut self) {
-                unsafe { $free_fn(self.instance as *mut _) }
+                unsafe { $free_fn(self.instance.cast()) }
             }
         }
     };