auto merge of #4791 : jbclements/rust/demodeing-and-deGCing, r=jbclements,brson

r?

It looks to me like the string_reader and tt_reader structs are
GC pointers only because they predate the modern borrow system.
This commit leaves the type names string_reader and tt_reader alone
(they still refer to GC-ed pointers), but internally the functions
now use borrowed pointers to refer to these structures. My guess
would be that it's possible to move this change outward and not
use the GCed pointers at all, but that change looks like it could be
a larger one. Actually, I'm delighted at how quick this change was.

1 files changed, 25 insertions, 23 deletions

diff --git a/src/libsyntax/ext/tt/transcribe.rs b/src/libsyntax/ext/tt/transcribe.rs
index 6f57ca38f1f..ba42c3744e5 100644
--- a/src/libsyntax/ext/tt/transcribe.rs
+++ b/src/libsyntax/ext/tt/transcribe.rs
@@ -39,7 +39,8 @@ type tt_frame = @{
     up: tt_frame_up,
 };
 
-pub type tt_reader = @{
+pub type tt_reader = @tt_reader_;
+pub type tt_reader_ = {
     sp_diag: span_handler,
     interner: @ident_interner,
     mut cur: tt_frame,
@@ -87,7 +88,7 @@ pure fn dup_tt_frame(&&f: tt_frame) -> tt_frame {
      }
 }
 
-pub pure fn dup_tt_reader(&&r: tt_reader) -> tt_reader {
+pub pure fn dup_tt_reader(r: &tt_reader_) -> tt_reader {
     @{sp_diag: r.sp_diag, interner: r.interner,
       mut cur: dup_tt_frame(r.cur),
       interpolations: r.interpolations,
@@ -96,7 +97,7 @@ pub pure fn dup_tt_reader(&&r: tt_reader) -> tt_reader {
 }
 
 
-pure fn lookup_cur_matched_by_matched(r: tt_reader,
+pure fn lookup_cur_matched_by_matched(r: &tt_reader_,
                                       start: @named_match) -> @named_match {
     pure fn red(+ad: @named_match, idx: &uint) -> @named_match {
         match *ad {
@@ -110,15 +111,15 @@ pure fn lookup_cur_matched_by_matched(r: tt_reader,
     vec::foldl(start, r.repeat_idx, red)
 }
 
-fn lookup_cur_matched(r: tt_reader, name: ident) -> @named_match {
+fn lookup_cur_matched(r: &tt_reader_, name: ident) -> @named_match {
     lookup_cur_matched_by_matched(r, r.interpolations.get(&name))
 }
 enum lis {
     lis_unconstrained, lis_constraint(uint, ident), lis_contradiction(~str)
 }
 
-fn lockstep_iter_size(t: token_tree, r: tt_reader) -> lis {
-    fn lis_merge(lhs: lis, rhs: lis, r: tt_reader) -> lis {
+fn lockstep_iter_size(t: token_tree, r: &tt_reader_) -> lis {
+    fn lis_merge(lhs: lis, rhs: lis, r: &tt_reader_) -> lis {
         match lhs {
           lis_unconstrained => rhs,
           lis_contradiction(_) => lhs,
@@ -150,7 +151,7 @@ fn lockstep_iter_size(t: token_tree, r: tt_reader) -> lis {
 }
 
 
-pub fn tt_next_token(&&r: tt_reader) -> TokenAndSpan {
+pub fn tt_next_token(r: &tt_reader_) -> TokenAndSpan {
     let ret_val = TokenAndSpan { tok: r.cur_tok, sp: r.cur_span };
     while r.cur.idx >= r.cur.readme.len() {
         /* done with this set; pop or repeat? */
@@ -199,25 +200,26 @@ pub fn tt_next_token(&&r: tt_reader) -> TokenAndSpan {
             return ret_val;
           }
           tt_seq(sp, ref tts, ref sep, zerok) => {
-            match lockstep_iter_size(tt_seq(sp, (*tts), (*sep), zerok), r) {
-              lis_unconstrained => {
-                r.sp_diag.span_fatal(
+              match lockstep_iter_size(tt_seq(sp, (*tts), (*sep), zerok), r) {
+                lis_unconstrained => {
+                  r.sp_diag.span_fatal(
                     sp, /* blame macro writer */
-                    ~"attempted to repeat an expression containing no syntax \
-                     variables matched as repeating at this depth");
-              }
-              lis_contradiction(ref msg) => {
-                /* FIXME #2887 blame macro invoker instead*/
-                r.sp_diag.span_fatal(sp, (*msg));
-              }
-              lis_constraint(len, _) => {
-                if len == 0 {
-                    if !zerok {
+                      ~"attempted to repeat an expression \
+                        containing no syntax \
+                        variables matched as repeating at this depth");
+                  }
+                  lis_contradiction(ref msg) => {
+                      /* FIXME #2887 blame macro invoker instead*/
+                      r.sp_diag.span_fatal(sp, (*msg));
+                  }
+                  lis_constraint(len, _) => {
+                    if len == 0 {
+                      if !zerok {
                         r.sp_diag.span_fatal(sp, /* FIXME #2887 blame invoker
-                                                  */
+                        */
                                              ~"this must repeat at least \
-                                              once");
-                    }
+                                               once");
+                          }
 
                     r.cur.idx += 1u;
                     return tt_next_token(r);