Implement generalized object and type parameter bounds (Fixes #16462)

src/libstd/path/mod.rs

@@ -825,12 +825,20 @@ pub trait GenericPathUnsafe {
     unsafe fn push_unchecked<T: BytesContainer>(&mut self, path: T);
 }
 
-/// Helper struct for printing paths with format!()
+/// Note: stage0-specific version that lacks bound.
+#[cfg(stage0)]
 pub struct Display<'a, P> {
     path: &'a P,
     filename: bool
 }
 
+/// Helper struct for printing paths with format!()
+#[cfg(not(stage0))]
+pub struct Display<'a, P:'a> {
+    path: &'a P,
+    filename: bool
+}
+
 impl<'a, P: GenericPath> fmt::Show for Display<'a, P> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         self.as_maybe_owned().as_slice().fmt(f)