fs: misc small API tweaks (#3315)

tokio/src/fs/copy.rs

@@ -20,7 +20,7 @@ use std::path::Path;
 /// # }
 /// ```
 
-pub async fn copy<P: AsRef<Path>, Q: AsRef<Path>>(from: P, to: Q) -> Result<u64, std::io::Error> {
+pub async fn copy(from: impl AsRef<Path>, to: impl AsRef<Path>) -> Result<u64, std::io::Error> {
     let from = from.as_ref().to_owned();
     let to = to.as_ref().to_owned();
     asyncify(|| std::fs::copy(from, to)).await

tokio/src/fs/dir_builder.rs

@@ -96,7 +96,7 @@ impl DirBuilder {
     ///     Ok(())
     /// }
     /// ```
-    pub async fn create<P: AsRef<Path>>(&self, path: P) -> io::Result<()> {
+    pub async fn create(&self, path: impl AsRef<Path>) -> io::Result<()> {
         let path = path.as_ref().to_owned();
         let mut builder = std::fs::DirBuilder::new();
         builder.recursive(self.recursive);

tokio/src/fs/write.rs

@@ -19,7 +19,7 @@ use std::{io, path::Path};
 /// # Ok(())
 /// # }
 /// ```
-pub async fn write<C: AsRef<[u8]> + Unpin>(path: impl AsRef<Path>, contents: C) -> io::Result<()> {
+pub async fn write(path: impl AsRef<Path>, contents: impl AsRef<[u8]>) -> io::Result<()> {
     let path = path.as_ref().to_owned();
     let contents = contents.as_ref().to_owned();