From 1133a149f1bd89bbc9303e3514a6bc20c3a5fc8b Mon Sep 17 00:00:00 2001
From: George Burton <burtonageo@gmail.com>
Date: Sun, 22 Apr 2018 22:57:52 +0100
Subject: [PATCH] Implement From for more types on Cow

---
 src/liballoc/string.rs   |  8 ++++++++
 src/liballoc/vec.rs      |  7 +++++++
 src/libstd/ffi/c_str.rs  | 24 ++++++++++++++++++++++++
 src/libstd/ffi/os_str.rs | 24 ++++++++++++++++++++++++
 src/libstd/path.rs       |  8 ++++++++
 5 files changed, 71 insertions(+)

diff --git a/src/liballoc/string.rs b/src/liballoc/string.rs
index 2f84d5f7f867..5f684361fdc2 100644
--- a/src/liballoc/string.rs
+++ b/src/liballoc/string.rs
@@ -2239,6 +2239,14 @@ impl<'a> From<String> for Cow<'a, str> {
     }
 }
 
+#[stable(feature = "cow_from_string_ref", since = "1.28.0")]
+impl<'a> From<&'a String> for Cow<'a, str> {
+    #[inline]
+    fn from(s: &'a String) -> Cow<'a, str> {
+        Cow::Borrowed(s.as_str())
+    }
+}
+
 #[stable(feature = "cow_str_from_iter", since = "1.12.0")]
 impl<'a> FromIterator<char> for Cow<'a, str> {
     fn from_iter<I: IntoIterator<Item = char>>(it: I) -> Cow<'a, str> {
diff --git a/src/liballoc/vec.rs b/src/liballoc/vec.rs
index b184404c15bf..be4c80c85d99 100644
--- a/src/liballoc/vec.rs
+++ b/src/liballoc/vec.rs
@@ -2285,6 +2285,13 @@ impl<'a, T: Clone> From<Vec<T>> for Cow<'a, [T]> {
     }
 }
 
+#[stable(feature = "cow_from_vec_ref", since = "1.28.0")]
+impl<'a, T: Clone> From<&'a Vec<T>> for Cow<'a, [T]> {
+    fn from(v: &'a Vec<T>) -> Cow<'a, [T]> {
+        Cow::Borrowed(v.as_slice())
+    }
+}
+
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<'a, T> FromIterator<T> for Cow<'a, [T]> where T: Clone {
     fn from_iter<I: IntoIterator<Item = T>>(it: I) -> Cow<'a, [T]> {
diff --git a/src/libstd/ffi/c_str.rs b/src/libstd/ffi/c_str.rs
index c88c2bc91371..08a1596ef25f 100644
--- a/src/libstd/ffi/c_str.rs
+++ b/src/libstd/ffi/c_str.rs
@@ -706,6 +706,30 @@ impl From<CString> for Box<CStr> {
     }
 }
 
+#[stable(feature = "cow_from_cstr", since = "1.28.0")]
+impl<'a> From<CString> for Cow<'a, CStr> {
+    #[inline]
+    fn from(s: CString) -> Cow<'a, CStr> {
+        Cow::Owned(s)
+    }
+}
+
+#[stable(feature = "cow_from_cstr", since = "1.28.0")]
+impl<'a> From<&'a CStr> for Cow<'a, CStr> {
+    #[inline]
+    fn from(s: &'a CStr) -> Cow<'a, CStr> {
+        Cow::Borrowed(s)
+    }
+}
+
+#[stable(feature = "cow_from_cstr", since = "1.28.0")]
+impl<'a> From<&'a CString> for Cow<'a, CStr> {
+    #[inline]
+    fn from(s: &'a CString) -> Cow<'a, CStr> {
+        Cow::Borrowed(s.as_c_str())
+    }
+}
+
 #[stable(feature = "shared_from_slice2", since = "1.24.0")]
 impl From<CString> for Arc<CStr> {
     #[inline]
diff --git a/src/libstd/ffi/os_str.rs b/src/libstd/ffi/os_str.rs
index 4850ed0c5be0..e42a28ed88f8 100644
--- a/src/libstd/ffi/os_str.rs
+++ b/src/libstd/ffi/os_str.rs
@@ -664,6 +664,30 @@ impl<'a> From<&'a OsStr> for Rc<OsStr> {
     }
 }
 
+#[stable(feature = "cow_from_osstr", since = "1.28.0")]
+impl<'a> From<OsString> for Cow<'a, OsStr> {
+    #[inline]
+    fn from(s: OsString) -> Cow<'a, OsStr> {
+        Cow::Owned(s)
+    }
+}
+
+#[stable(feature = "cow_from_osstr", since = "1.28.0")]
+impl<'a> From<&'a OsStr> for Cow<'a, OsStr> {
+    #[inline]
+    fn from(s: &'a OsStr) -> Cow<'a, OsStr> {
+        Cow::Borrowed(s)
+    }
+}
+
+#[stable(feature = "cow_from_osstr", since = "1.28.0")]
+impl<'a> From<&'a OsString> for Cow<'a, OsStr> {
+    #[inline]
+    fn from(s: &'a OsString) -> Cow<'a, OsStr> {
+        Cow::Borrowed(s.as_os_str())
+    }
+}
+
 #[stable(feature = "box_default_extra", since = "1.17.0")]
 impl Default for Box<OsStr> {
     fn default() -> Box<OsStr> {
diff --git a/src/libstd/path.rs b/src/libstd/path.rs
index ec9615754738..19f38e4d6d9b 100644
--- a/src/libstd/path.rs
+++ b/src/libstd/path.rs
@@ -1532,6 +1532,14 @@ impl<'a> From<PathBuf> for Cow<'a, Path> {
     }
 }
 
+#[stable(feature = "cow_from_pathbuf_ref", since = "1.28.0")]
+impl<'a> From<&'a PathBuf> for Cow<'a, Path> {
+    #[inline]
+    fn from(p: &'a PathBuf) -> Cow<'a, Path> {
+        Cow::Borrowed(p.as_path())
+    }
+}
+
 #[stable(feature = "shared_from_slice2", since = "1.24.0")]
 impl From<PathBuf> for Arc<Path> {
     #[inline]