Auto merge of #28980 - nrc:unsafe-macros, r=@pnkfelix

This is a [breaking change].

@brson could you do a Crater run with this PR please?

Lets not land till Crater says its OK.

This was discussed at https://internals.rust-lang.org/t/does-anyone-use-the-push-pop-unsafe-macros/2702

Author: bors

src/librustc_front/lowering.rs

@@ -1479,8 +1479,6 @@ pub fn lower_block_check_mode(_lctx: &LoweringContext, b: &BlockCheckMode) -> hi
     match *b {
         DefaultBlock => hir::DefaultBlock,
         UnsafeBlock(u) => hir::UnsafeBlock(lower_unsafe_source(_lctx, u)),
-        PushUnsafeBlock(u) => hir::PushUnsafeBlock(lower_unsafe_source(_lctx, u)),
-        PopUnsafeBlock(u) => hir::PopUnsafeBlock(lower_unsafe_source(_lctx, u)),
     }
 }
 

src/libsyntax/ast.rs

@@ -765,8 +765,6 @@ pub type SpannedIdent = Spanned<Ident>;
 pub enum BlockCheckMode {
     DefaultBlock,
     UnsafeBlock(UnsafeSource),
-    PushUnsafeBlock(UnsafeSource),
-    PopUnsafeBlock(UnsafeSource),
 }
 
 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]

src/libsyntax/ext/base.rs

@@ -544,12 +544,6 @@ fn initial_syntax_expander_table<'feat>(ecfg: &expand::ExpansionConfig<'feat>)
     syntax_expanders.insert(intern("cfg"),
                             builtin_normal_expander(
                                     ext::cfg::expand_cfg));
-    syntax_expanders.insert(intern("push_unsafe"),
-                            builtin_normal_expander(
-                                ext::pushpop_safe::expand_push_unsafe));
-    syntax_expanders.insert(intern("pop_unsafe"),
-                            builtin_normal_expander(
-                                ext::pushpop_safe::expand_pop_unsafe));
     syntax_expanders.insert(intern("trace_macros"),
                             builtin_normal_expander(
                                     ext::trace_macros::expand_trace_macros));

src/libsyntax/ext/pushpop_safe.rs

@@ -121,7 +121,6 @@ pub mod ext {
     pub mod log_syntax;
     pub mod mtwt;
     pub mod quote;
-    pub mod pushpop_safe;
     pub mod source_util;
     pub mod trace_macros;
 

src/libsyntax/lib.rs

@@ -1672,8 +1672,8 @@ impl<'a> State<'a> {
                                       attrs: &[ast::Attribute],
                                       close_box: bool) -> io::Result<()> {
         match blk.rules {
-            ast::UnsafeBlock(..) | ast::PushUnsafeBlock(..) => try!(self.word_space("unsafe")),
-            ast::DefaultBlock    | ast::PopUnsafeBlock(..) => ()
+            ast::UnsafeBlock(..) => try!(self.word_space("unsafe")),
+            ast::DefaultBlock => ()
         }
         try!(self.maybe_print_comment(blk.span.lo));
         try!(self.ann.pre(self, NodeBlock(blk)));