Suggestion.apply_to(): Read from given reader, not original file

We can't read from the original file, because we want to be able to use
that as the writer in `apply()`.

Previously, this would result in the original file simply being
truncated, as we weren't reading from the correct file.

To fix this, we need to give `apply_to()` both a reader and a writer.
Now, in `apply()`, we can pass it the temporary file to read, and the
original to write to.

Used a `Path` as an input to `apply_to()` instead of a `Read`er because
I got an error that didn't really make sense to me when I did so:

    error[E0275]: overflow evaluating the requirement `&tokio_reactor::poll_evented::PollEvented<_>: std::io::Read`
      |
      = help: consider adding a `#![recursion_limit="256"]` attribute to your crate (`git_suggested_patch`)
      = note: required because of the requirements on the impl of `std::io::Read` for `&tokio_reactor::poll_evented::PollEvented<tokio_reactor::poll_evented::PollEvented<_>>`
      = note: required because of the requirements on the impl of `std::io::Read` for `&tokio_reactor::poll_evented::PollEvented<tokio_reactor::poll_evented::PollEvented<tokio_reactor::poll_evented::PollEvented<_>>>`

A search for the error message turned up a few active issues:

- https://github.com/rust-lang/rust/issues/57854
- https://github.com/rust-lang/rust/issues/62755
- https://github.com/rust-lang/rust/issues/39959

The above issues indicate that this could come from having a variable
with an inferred type. However, for the moment the issue isn't resolved,
and the error message doesn't indicate where the problem is actually
coming from. As I was unable to track down the source of the problem, I
decided not to bother using a `Read` argument.

1 files changed, 9 insertions, 7 deletions

diff --git a/src/lib.rs b/src/lib.rs
index 396c2ee..682464f 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -9,6 +9,7 @@ pub use crate::url::SuggestionUrl;
 use std::fs;
 use std::fs::{File, OpenOptions};
 use std::io::{BufRead, BufReader, Write};
+use std::path::Path;
 
 use git2::Repository;
 use github_rs::client::{Executor, Github};
@@ -132,14 +133,15 @@ impl Suggestion {
             .truncate(true)
             .open(repo_root.join(&self.path)).unwrap();
 
-        self.apply_to(&mut original)
+        self.apply_to(new.path(), &mut original)
     }
 
-    fn apply_to<W: Write>(&self, writer: &mut W) ->Result<(), Error> {
-        let repo = Repository::open(".").unwrap();
-        let repo_root = repo.workdir().unwrap();
-
-        let original = File::open(repo_root.join(&self.path)).unwrap();
+    fn apply_to<P: AsRef<Path>, W: Write>(
+        &self,
+        from: P,
+        writer: &mut W,
+    ) -> Result<(), Error> {
+        let original = File::open(from).unwrap();
         let reader = BufReader::new(original);
 
         for (i, line) in reader.lines().enumerate() {
@@ -346,7 +348,7 @@ mod tests {
 "#;
 
         let mut actual = Cursor::new(Vec::new());
-        suggestion.apply_to(&mut actual).unwrap();
+        suggestion.apply_to(temp.path(), &mut actual).unwrap();
 
         assert_eq!(
             std::str::from_utf8(&actual.into_inner()).unwrap(),