Rollup merge of #37117 - pnkfelix:may-dangle-attr, r=nikomatsakis

`#[may_dangle]` attribute

`#[may_dangle]` attribute

Second step of #34761. Last big hurdle before we can work in earnest towards Allocator integration (#32838)

Note: I am not clear if this is *also* a syntax-breaking change that needs to be part of a breaking-batch.

2 files changed, 11 insertions, 0 deletions

diff --git a/src/libsyntax/feature_gate.rs b/src/libsyntax/feature_gate.rs
index 2e7a706a583..9e5dfdc30c8 100644
--- a/src/libsyntax/feature_gate.rs
+++ b/src/libsyntax/feature_gate.rs
@@ -167,6 +167,9 @@ declare_features! (
     // RFC 1238
     (active, dropck_parametricity, "1.3.0", Some(28498)),
 
+    // Allows using the may_dangle attribute; RFC 1327
+    (active, dropck_eyepatch, "1.10.0", Some(34761)),
+
     // Allows the use of custom attributes; RFC 572
     (active, custom_attribute, "1.0.0", Some(29642)),
 
@@ -616,6 +619,11 @@ pub const KNOWN_ATTRIBUTES: &'static [(&'static str, AttributeType, AttributeGat
            "unsafe_destructor_blind_to_params has unstable semantics \
             and may be removed in the future",
            cfg_fn!(dropck_parametricity))),
+    ("may_dangle",
+     Normal,
+     Gated("dropck_eyepatch",
+           "may_dangle has unstable semantics and may be removed in the future",
+           cfg_fn!(dropck_eyepatch))),
     ("unwind", Whitelisted, Gated("unwind_attributes", "#[unwind] is experimental",
                                   cfg_fn!(unwind_attributes))),
 
diff --git a/src/libsyntax/print/pprust.rs b/src/libsyntax/print/pprust.rs
index ecb437f31a5..3a0f9cd8ec4 100644
--- a/src/libsyntax/print/pprust.rs
+++ b/src/libsyntax/print/pprust.rs
@@ -1361,6 +1361,7 @@ impl<'a> State<'a> {
                 if comma {
                     try!(self.word_space(","))
                 }
+                try!(self.print_outer_attributes_inline(&lifetime_def.attrs));
                 try!(self.print_lifetime_bounds(&lifetime_def.lifetime, &lifetime_def.bounds));
                 comma = true;
             }
@@ -2803,6 +2804,7 @@ impl<'a> State<'a> {
         try!(self.commasep(Inconsistent, &ints[..], |s, &idx| {
             if idx < generics.lifetimes.len() {
                 let lifetime_def = &generics.lifetimes[idx];
+                try!(s.print_outer_attributes_inline(&lifetime_def.attrs));
                 s.print_lifetime_bounds(&lifetime_def.lifetime, &lifetime_def.bounds)
             } else {
                 let idx = idx - generics.lifetimes.len();
@@ -2816,6 +2818,7 @@ impl<'a> State<'a> {
     }
 
     pub fn print_ty_param(&mut self, param: &ast::TyParam) -> io::Result<()> {
+        try!(self.print_outer_attributes_inline(&param.attrs));
         try!(self.print_ident(param.ident));
         try!(self.print_bounds(":", &param.bounds));
         match param.default {