Make libloading an optional dependency (#296)

* Make libloading an optional dependency

* Move all libloading stuff to a specific module

ash/Cargo.toml

@@ -11,10 +11,10 @@ documentation = "https://docs.rs/ash"
 edition = "2018"
 
 [dependencies]
-libloading = "0.6.1"
+libloading = { version = "0.6.1", optional = true }
 
 [features]
-default = []
+default = ["libloading"]
 
 [package.metadata.release]
 no-dev-version = true

ash/src/entry.rs

@@ -2,32 +2,12 @@ use crate::instance::Instance;
 use crate::prelude::*;
 use crate::vk;
 use crate::RawPtr;
-use libloading::Library;
 use std::error::Error;
 use std::fmt;
 use std::mem;
 use std::os::raw::c_char;
 use std::os::raw::c_void;
 use std::ptr;
-use std::sync::Arc;
-
-#[cfg(windows)]
-const LIB_PATH: &str = "vulkan-1.dll";
-
-#[cfg(all(
-    unix,
-    not(any(target_os = "macos", target_os = "ios", target_os = "android"))
-))]
-const LIB_PATH: &str = "libvulkan.so.1";
-
-#[cfg(target_os = "android")]
-const LIB_PATH: &str = "libvulkan.so";
-
-#[cfg(any(target_os = "macos", target_os = "ios"))]
-const LIB_PATH: &str = "libvulkan.dylib";
-
-/// Function loader
-pub type Entry = EntryCustom<Arc<Library>>;
 
 /// Function loader
 #[derive(Clone)]
@@ -39,21 +19,6 @@ pub struct EntryCustom<L> {
     lib: L,
 }
 
-#[derive(Debug)]
-pub struct LoadingError(libloading::Error);
-
-impl fmt::Display for LoadingError {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        fmt::Display::fmt(&self.0, f)
-    }
-}
-
-impl Error for LoadingError {
-    fn source(&self) -> Option<&(dyn Error + 'static)> {
-        Error::source(&self.0)
-    }
-}
-
 #[derive(Clone, Debug)]
 pub enum InstanceError {
     LoadError(Vec<&'static str>),
@@ -207,36 +172,6 @@ impl<L> EntryV1_2 for EntryCustom<L> {
     }
 }
 
-impl EntryCustom<Arc<Library>> {
-    /// ```rust,no_run
-    /// use ash::{vk, Entry, version::EntryV1_0};
-    /// # fn main() -> Result<(), Box<std::error::Error>> {
-    /// let entry = Entry::new()?;
-    /// let app_info = vk::ApplicationInfo {
-    ///     api_version: vk::make_version(1, 0, 0),
-    ///     ..Default::default()
-    /// };
-    /// let create_info = vk::InstanceCreateInfo {
-    ///     p_application_info: &app_info,
-    ///     ..Default::default()
-    /// };
-    /// let instance = unsafe { entry.create_instance(&create_info, None)? };
-    /// # Ok(()) }
-    /// ```
-    pub fn new() -> Result<Entry, LoadingError> {
-        let lib = Library::new(&LIB_PATH)
-            .map_err(LoadingError)
-            .map(Arc::new)?;
-
-        Ok(Self::new_custom(lib, |vk_lib, name| unsafe {
-            vk_lib
-                .get(name.to_bytes_with_nul())
-                .map(|symbol| *symbol)
-                .unwrap_or(ptr::null_mut())
-        }))
-    }
-}
-
 impl<L> EntryCustom<L> {
     pub fn new_custom<Load>(mut lib: L, mut load: Load) -> Self
     where

ash/src/entry_libloading.rs

@@ -0,0 +1,69 @@
+use crate::entry::EntryCustom;
+use libloading::Library;
+use std::error::Error;
+use std::fmt;
+use std::ptr;
+use std::sync::Arc;
+
+#[cfg(windows)]
+const LIB_PATH: &str = "vulkan-1.dll";
+
+#[cfg(all(
+    unix,
+    not(any(target_os = "macos", target_os = "ios", target_os = "android"))
+))]
+const LIB_PATH: &str = "libvulkan.so.1";
+
+#[cfg(target_os = "android")]
+const LIB_PATH: &str = "libvulkan.so";
+
+#[cfg(any(target_os = "macos", target_os = "ios"))]
+const LIB_PATH: &str = "libvulkan.dylib";
+
+/// Function loader
+pub type Entry = EntryCustom<Arc<Library>>;
+
+#[derive(Debug)]
+pub struct LoadingError(libloading::Error);
+
+impl fmt::Display for LoadingError {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        fmt::Display::fmt(&self.0, f)
+    }
+}
+
+impl Error for LoadingError {
+    fn source(&self) -> Option<&(dyn Error + 'static)> {
+        Error::source(&self.0)
+    }
+}
+
+impl EntryCustom<Arc<Library>> {
+    /// ```rust,no_run
+    /// use ash::{vk, Entry, version::EntryV1_0};
+    /// # fn main() -> Result<(), Box<std::error::Error>> {
+    /// let entry = Entry::new()?;
+    /// let app_info = vk::ApplicationInfo {
+    ///     api_version: vk::make_version(1, 0, 0),
+    ///     ..Default::default()
+    /// };
+    /// let create_info = vk::InstanceCreateInfo {
+    ///     p_application_info: &app_info,
+    ///     ..Default::default()
+    /// };
+    /// let instance = unsafe { entry.create_instance(&create_info, None)? };
+    /// # Ok(()) }
+    /// ```
+    pub fn new() -> Result<Entry, LoadingError> {
+        let lib = Library::new(&LIB_PATH)
+            .map_err(LoadingError)
+            .map(Arc::new)?;
+
+        Ok(Self::new_custom(lib, |vk_lib, name| unsafe {
+            vk_lib
+                .get(name.to_bytes_with_nul())
+                .map(|symbol| *symbol)
+                .unwrap_or(ptr::null_mut())
+        }))
+    }
+}

ash/src/lib.rs

@@ -23,11 +23,15 @@
 //!
 
 pub use crate::device::Device;
-pub use crate::entry::{Entry, EntryCustom, InstanceError, LoadingError};
+pub use crate::entry::{EntryCustom, InstanceError};
+#[cfg(feature = "libloading")]
+pub use crate::entry_libloading::{Entry, LoadingError};
 pub use crate::instance::Instance;
 
 mod device;
 mod entry;
+#[cfg(feature = "libloading")]
+mod entry_libloading;
 mod instance;
 pub mod prelude;
 pub mod util;