libgit2-rs: Update for 2nd edition.

libgit2-rs/Cargo.toml

@@ -2,6 +2,6 @@
 name = "libgit2-rs"
 version = "0.1.0"
 authors = ["You <you@example.com>"]
-build = "build.rs"
+edition = "2018"
 
 [dependencies]

libgit2-rs/build.rs

@@ -1,3 +1,3 @@
 fn main() {
-    println!("cargo:rustc-link-search=native=/home/jimb/libgit2-0.25.1/build");
+    println!(r"cargo:rustc-link-search=native=/home/jimb/libgit2-0.25.1/build");
 }

libgit2-rs/src/main.rs

@@ -1,3 +1,6 @@
+#![warn(rust_2018_idioms)]
+#![allow(elided_lifetimes_in_paths)]
+
 mod raw;
 
 use std::ffi::CStr;
@@ -48,9 +51,12 @@ fn main() {
               raw::git_repository_open(&mut repo, path.as_ptr()));
 
         let c_name = b"HEAD\0".as_ptr() as *const c_char;
-        let mut oid = mem::uninitialized();
-        check("looking up HEAD",
-              raw::git_reference_name_to_id(&mut oid, repo, c_name));
+        let oid = {
+            let mut oid = mem::MaybeUninit::uninit();
+            check("looking up HEAD",
+                  raw::git_reference_name_to_id(oid.as_mut_ptr(), repo, c_name));
+            oid.assume_init()
+        };
 
         let mut commit = ptr::null_mut();
         check("looking up commit",

libgit2-rs/src/raw.rs

@@ -25,8 +25,8 @@ extern {
     pub fn git_commit_free(commit: *mut git_commit);
 }
 
-pub enum git_repository {}
-pub enum git_commit {}
+#[repr(C)] pub struct git_repository { _private: [u8; 0] }
+#[repr(C)] pub struct git_commit { _private: [u8; 0] }
 
 #[repr(C)]
 pub struct git_error {
@@ -34,9 +34,11 @@ pub struct git_error {
     pub klass: c_int
 }
 
+pub const GIT_OID_RAWSZ: usize = 20;
+
 #[repr(C)]
 pub struct git_oid {
-    pub id: [c_uchar; 20]
+    pub id: [c_uchar; GIT_OID_RAWSZ]
 }
 
 pub type git_time_t = i64;