Remove the DelimSpan from NamedMatch::MatchedSeq.

Because it's unused. This then allows the removal of
`MatcherPos::sp_open`. It's a tiny perf win, reducing instruction counts
by 0.1% - 0.2% on a few benchmarks.

Author: nnethercote

src/libsyntax_expand/mbe/macro_parser.rs

@@ -83,7 +83,7 @@ use syntax::print::pprust;
 use syntax::sess::ParseSess;
 use syntax::symbol::{kw, sym, Symbol};
 use syntax::token::{self, DocComment, Nonterminal, Token};
-use syntax::tokenstream::{DelimSpan, TokenStream};
+use syntax::tokenstream::TokenStream;
 
 use errors::{PResult, FatalError};
 use smallvec::{smallvec, SmallVec};
@@ -164,11 +164,6 @@ struct MatcherPos<'root, 'tt> {
     /// The position of the "dot" in this matcher
     idx: usize,
 
-    /// The first span of source that the beginning of this matcher corresponds to. In other
-    /// words, the token in the source whose span is `sp_open` is matched against the first token of
-    /// the matcher.
-    sp_open: Span,
-
     /// For each named metavar in the matcher, we keep track of token trees matched against the
     /// metavar by the black box parser. In particular, there may be more than one match per
     /// metavar if we are in a repetition (each repetition matches each of the variables).
@@ -307,17 +302,15 @@ fn create_matches(len: usize) -> Box<[Lrc<NamedMatchVec>]> {
 }
 
 /// Generates the top-level matcher position in which the "dot" is before the first token of the
-/// matcher `ms` and we are going to start matching at the span `open` in the source.
-fn initial_matcher_pos<'root, 'tt>(ms: &'tt [TokenTree], open: Span) -> MatcherPos<'root, 'tt> {
+/// matcher `ms`.
+fn initial_matcher_pos<'root, 'tt>(ms: &'tt [TokenTree]) -> MatcherPos<'root, 'tt> {
     let match_idx_hi = count_names(ms);
     let matches = create_matches(match_idx_hi);
     MatcherPos {
         // Start with the top level matcher given to us
         top_elts: TtSeq(ms), // "elts" is an abbr. for "elements"
         // The "dot" is before the first token of the matcher
         idx: 0,
-        // We start matching at the span `open` in the source code
-        sp_open: open,
 
         // Initialize `matches` to a bunch of empty `Vec`s -- one for each metavar in `top_elts`.
         // `match_lo` for `top_elts` is 0 and `match_hi` is `matches.len()`. `match_cur` is 0 since
@@ -355,7 +348,7 @@ fn initial_matcher_pos<'root, 'tt>(ms: &'tt [TokenTree], open: Span) -> MatcherP
 /// token tree it was derived from.
 #[derive(Debug, Clone)]
 crate enum NamedMatch {
-    MatchedSeq(Lrc<NamedMatchVec>, DelimSpan),
+    MatchedSeq(Lrc<NamedMatchVec>),
     MatchedNonterminal(Lrc<Nonterminal>),
 }
 
@@ -497,8 +490,7 @@ fn inner_parse_loop<'root, 'tt>(
                     // Add matches from this repetition to the `matches` of `up`
                     for idx in item.match_lo..item.match_hi {
                         let sub = item.matches[idx].clone();
-                        let span = DelimSpan::from_pair(item.sp_open, token.span);
-                        new_pos.push_match(idx, MatchedSeq(sub, span));
+                        new_pos.push_match(idx, MatchedSeq(sub));
                     }
 
                     // Move the "dot" past the repetition in `up`
@@ -552,7 +544,7 @@ fn inner_parse_loop<'root, 'tt>(
                         new_item.match_cur += seq.num_captures;
                         new_item.idx += 1;
                         for idx in item.match_cur..item.match_cur + seq.num_captures {
-                            new_item.push_match(idx, MatchedSeq(Lrc::new(smallvec![]), sp));
+                            new_item.push_match(idx, MatchedSeq(Lrc::new(smallvec![])));
                         }
                         cur_items.push(new_item);
                     }
@@ -568,7 +560,6 @@ fn inner_parse_loop<'root, 'tt>(
                         match_cur: item.match_cur,
                         match_hi: item.match_cur + seq.num_captures,
                         up: Some(item),
-                        sp_open: sp.open,
                         top_elts: Tt(TokenTree::Sequence(sp, seq)),
                     })));
                 }
@@ -663,7 +654,7 @@ pub(super) fn parse(
     //
     // This MatcherPos instance is allocated on the stack. All others -- and
     // there are frequently *no* others! -- are allocated on the heap.
-    let mut initial = initial_matcher_pos(ms, parser.token.span);
+    let mut initial = initial_matcher_pos(ms);
     let mut cur_items = smallvec![MatcherPosHandle::Ref(&mut initial)];
     let mut next_items = Vec::new();
 

src/libsyntax_expand/mbe/macro_rules.rs

@@ -379,7 +379,7 @@ pub fn compile_declarative_macro(
 
     // Extract the arguments:
     let lhses = match argument_map[&lhs_nm] {
-        MatchedSeq(ref s, _) => s
+        MatchedSeq(ref s) => s
             .iter()
             .map(|m| {
                 if let MatchedNonterminal(ref nt) = *m {
@@ -402,7 +402,7 @@ pub fn compile_declarative_macro(
     };
 
     let rhses = match argument_map[&rhs_nm] {
-        MatchedSeq(ref s, _) => s
+        MatchedSeq(ref s) => s
             .iter()
             .map(|m| {
                 if let MatchedNonterminal(ref nt) = *m {

src/libsyntax_expand/mbe/transcribe.rs

@@ -299,7 +299,7 @@ fn lookup_cur_matched<'a>(
         for &(idx, _) in repeats {
             match matched {
                 MatchedNonterminal(_) => break,
-                MatchedSeq(ref ads, _) => matched = ads.get(idx).unwrap(),
+                MatchedSeq(ref ads) => matched = ads.get(idx).unwrap(),
             }
         }
 
@@ -382,7 +382,7 @@ fn lockstep_iter_size(
             match lookup_cur_matched(name, interpolations, repeats) {
                 Some(matched) => match matched {
                     MatchedNonterminal(_) => LockstepIterSize::Unconstrained,
-                    MatchedSeq(ref ads, _) => LockstepIterSize::Constraint(ads.len(), name),
+                    MatchedSeq(ref ads) => LockstepIterSize::Constraint(ads.len(), name),
                 },
                 _ => LockstepIterSize::Unconstrained,
             }