impl PartialEq<{str,String}> for {Path,PathBuf}

Comparison of paths and strings is expected to be possible and needed
e.g. in tests. This change adds the impls os `PartialEq` between strings
and paths, both owned and unsized, in both directions.

ACP: rust-lang/libs-team#151

Author: Kixunil

library/std/src/path.rs

@@ -2068,6 +2068,38 @@ impl PartialEq for PathBuf {
     }
 }
 
+#[stable(feature = "eq_str_for_path", since = "TBD")]
+impl cmp::PartialEq<str> for PathBuf {
+    #[inline]
+    fn eq(&self, other: &str) -> bool {
+        &*self == other
+    }
+}
+
+#[stable(feature = "eq_str_for_path", since = "TBD")]
+impl cmp::PartialEq<PathBuf> for str {
+    #[inline]
+    fn eq(&self, other: &PathBuf) -> bool {
+        other == self
+    }
+}
+
+#[stable(feature = "eq_str_for_path", since = "TBD")]
+impl cmp::PartialEq<String> for PathBuf {
+    #[inline]
+    fn eq(&self, other: &String) -> bool {
+        **self == **other
+    }
+}
+
+#[stable(feature = "eq_str_for_path", since = "TBD")]
+impl cmp::PartialEq<PathBuf> for String {
+    #[inline]
+    fn eq(&self, other: &PathBuf) -> bool {
+        other == self
+    }
+}
+
 #[stable(feature = "rust1", since = "1.0.0")]
 impl Hash for PathBuf {
     fn hash<H: Hasher>(&self, h: &mut H) {
@@ -3242,6 +3274,39 @@ impl PartialEq for Path {
     }
 }
 
+#[stable(feature = "eq_str_for_path", since = "TBD")]
+impl cmp::PartialEq<str> for Path {
+    #[inline]
+    fn eq(&self, other: &str) -> bool {
+        let other: &OsStr = other.as_ref();
+        self == other
+    }
+}
+
+#[stable(feature = "eq_str_for_path", since = "TBD")]
+impl cmp::PartialEq<Path> for str {
+    #[inline]
+    fn eq(&self, other: &Path) -> bool {
+        other == self
+    }
+}
+
+#[stable(feature = "eq_str_for_path", since = "TBD")]
+impl cmp::PartialEq<String> for Path {
+    #[inline]
+    fn eq(&self, other: &String) -> bool {
+        self == &*other
+    }
+}
+
+#[stable(feature = "eq_str_for_path", since = "TBD")]
+impl cmp::PartialEq<Path> for String {
+    #[inline]
+    fn eq(&self, other: &Path) -> bool {
+        other == self
+    }
+}
+
 #[stable(feature = "rust1", since = "1.0.0")]
 impl Hash for Path {
     fn hash<H: Hasher>(&self, h: &mut H) {