feature gate :vis matcher

1 files changed, 45 insertions, 22 deletions

diff --git a/src/libsyntax/ext/tt/macro_rules.rs b/src/libsyntax/ext/tt/macro_rules.rs
index 00623dabec4..be979960725 100644
--- a/src/libsyntax/ext/tt/macro_rules.rs
+++ b/src/libsyntax/ext/tt/macro_rules.rs
@@ -18,6 +18,7 @@ use ext::tt::macro_parser::{MatchedSeq, MatchedNonterminal};
 use ext::tt::macro_parser::{parse, parse_failure_msg};
 use ext::tt::quoted;
 use ext::tt::transcribe::transcribe;
+use feature_gate::{self, emit_feature_err, Features, GateIssue};
 use parse::{Directory, ParseSess};
 use parse::parser::Parser;
 use parse::token::{self, NtTT};
@@ -25,6 +26,7 @@ use parse::token::Token::*;
 use symbol::Symbol;
 use tokenstream::{TokenStream, TokenTree};
 
+use std::cell::RefCell;
 use std::collections::{HashMap};
 use std::collections::hash_map::{Entry};
 use std::rc::Rc;
@@ -154,7 +156,7 @@ fn generic_extension<'cx>(cx: &'cx ExtCtxt,
 // Holy self-referential!
 
 /// Converts a `macro_rules!` invocation into a syntax extension.
-pub fn compile(sess: &ParseSess, def: &ast::Item) -> SyntaxExtension {
+pub fn compile(sess: &ParseSess, features: &RefCell<Features>, def: &ast::Item) -> SyntaxExtension {
     let lhs_nm = ast::Ident::with_empty_ctxt(Symbol::gensym("lhs"));
     let rhs_nm = ast::Ident::with_empty_ctxt(Symbol::gensym("rhs"));
 
@@ -208,7 +210,7 @@ pub fn compile(sess: &ParseSess, def: &ast::Item) -> SyntaxExtension {
                 if let MatchedNonterminal(ref nt) = **m {
                     if let NtTT(ref tt) = **nt {
                         let tt = quoted::parse(tt.clone().into(), true, sess).pop().unwrap();
-                        valid &= check_lhs_nt_follows(sess, &tt);
+                        valid &= check_lhs_nt_follows(sess, features, &tt);
                         return tt;
                     }
                 }
@@ -251,11 +253,13 @@ pub fn compile(sess: &ParseSess, def: &ast::Item) -> SyntaxExtension {
     NormalTT(exp, Some(def.span), attr::contains_name(&def.attrs, "allow_internal_unstable"))
 }
 
-fn check_lhs_nt_follows(sess: &ParseSess, lhs: &quoted::TokenTree) -> bool {
+fn check_lhs_nt_follows(sess: &ParseSess,
+                        features: &RefCell<Features>,
+                        lhs: &quoted::TokenTree) -> bool {
     // lhs is going to be like TokenTree::Delimited(...), where the
     // entire lhs is those tts. Or, it can be a "bare sequence", not wrapped in parens.
     match lhs {
-        &quoted::TokenTree::Delimited(_, ref tts) => check_matcher(sess, &tts.tts),
+        &quoted::TokenTree::Delimited(_, ref tts) => check_matcher(sess, features, &tts.tts),
         _ => {
             let msg = "invalid macro matcher; matchers must be contained in balanced delimiters";
             sess.span_diagnostic.span_err(lhs.span(), msg);
@@ -307,11 +311,13 @@ fn check_rhs(sess: &ParseSess, rhs: &quoted::TokenTree) -> bool {
     false
 }
 
-fn check_matcher(sess: &ParseSess, matcher: &[quoted::TokenTree]) -> bool {
+fn check_matcher(sess: &ParseSess,
+                 features: &RefCell<Features>,
+                 matcher: &[quoted::TokenTree]) -> bool {
     let first_sets = FirstSets::new(matcher);
     let empty_suffix = TokenSet::empty();
     let err = sess.span_diagnostic.err_count();
-    check_matcher_core(sess, &first_sets, matcher, &empty_suffix);
+    check_matcher_core(sess, features, &first_sets, matcher, &empty_suffix);
     err == sess.span_diagnostic.err_count()
 }
 
@@ -553,6 +559,7 @@ impl TokenSet {
 // Requires that `first_sets` is pre-computed for `matcher`;
 // see `FirstSets::new`.
 fn check_matcher_core(sess: &ParseSess,
+                      features: &RefCell<Features>,
                       first_sets: &FirstSets,
                       matcher: &[quoted::TokenTree],
                       follow: &TokenSet) -> TokenSet {
@@ -583,12 +590,11 @@ fn check_matcher_core(sess: &ParseSess,
         match *token {
             TokenTree::Token(..) | TokenTree::MetaVarDecl(..) => {
                 let can_be_followed_by_any;
-                if let Err(bad_frag) = has_legal_fragment_specifier(token) {
+                if let Err(bad_frag) = has_legal_fragment_specifier(sess, features, token) {
                     let msg = format!("invalid fragment specifier `{}`", bad_frag);
                     sess.span_diagnostic.struct_span_err(token.span(), &msg)
-                        .help("valid fragment specifiers are `ident`, `block`, \
-                               `stmt`, `expr`, `pat`, `ty`, `path`, `meta`, `tt` \
-                               and `item`")
+                        .help("valid fragment specifiers are `ident`, `block`, `stmt`, `expr`, \
+                              `pat`, `ty`, `path`, `meta`, `tt`, `item` and `vis`")
                         .emit();
                     // (This eliminates false positives and duplicates
                     // from error messages.)
@@ -610,7 +616,7 @@ fn check_matcher_core(sess: &ParseSess,
             }
             TokenTree::Delimited(span, ref d) => {
                 let my_suffix = TokenSet::singleton(d.close_tt(span));
-                check_matcher_core(sess, first_sets, &d.tts, &my_suffix);
+                check_matcher_core(sess, features, first_sets, &d.tts, &my_suffix);
                 // don't track non NT tokens
                 last.replace_with_irrelevant();
 
@@ -642,7 +648,7 @@ fn check_matcher_core(sess: &ParseSess,
                 // At this point, `suffix_first` is built, and
                 // `my_suffix` is some TokenSet that we can use
                 // for checking the interior of `seq_rep`.
-                let next = check_matcher_core(sess, first_sets, &seq_rep.tts, my_suffix);
+                let next = check_matcher_core(sess, features, first_sets, &seq_rep.tts, my_suffix);
                 if next.maybe_empty {
                     last.add_all(&next);
                 } else {
@@ -807,27 +813,44 @@ fn is_in_follow(tok: &quoted::TokenTree, frag: &str) -> Result<bool, (String, &'
             "" => Ok(true), // keywords::Invalid
             _ => Err((format!("invalid fragment specifier `{}`", frag),
                      "valid fragment specifiers are `ident`, `block`, \
-                      `stmt`, `expr`, `pat`, `ty`, `path`, `meta`, `tt` \
-                      and `item`"))
+                      `stmt`, `expr`, `pat`, `ty`, `path`, `meta`, `tt`, \
+                      `item` and `vis`"))
         }
     }
 }
 
-fn has_legal_fragment_specifier(tok: &quoted::TokenTree) -> Result<(), String> {
+fn has_legal_fragment_specifier(sess: &ParseSess,
+                                features: &RefCell<Features>,
+                                tok: &quoted::TokenTree) -> Result<(), String> {
     debug!("has_legal_fragment_specifier({:?})", tok);
-    if let quoted::TokenTree::MetaVarDecl(_, _, frag_spec) = *tok {
-        let s = &frag_spec.name.as_str();
-        if !is_legal_fragment_specifier(s) {
-            return Err(s.to_string());
+    if let quoted::TokenTree::MetaVarDecl(_, _, ref frag_spec) = *tok {
+        let frag_name = frag_spec.name.as_str();
+        let frag_span = tok.span();
+        if !is_legal_fragment_specifier(sess, features, &frag_name, frag_span) {
+            return Err(frag_name.to_string());
         }
     }
     Ok(())
 }
 
-fn is_legal_fragment_specifier(frag: &str) -> bool {
-    match frag {
+fn is_legal_fragment_specifier(sess: &ParseSess,
+                               features: &RefCell<Features>,
+                               frag_name: &str,
+                               frag_span: Span) -> bool {
+    match frag_name {
         "item" | "block" | "stmt" | "expr" | "pat" |
-        "path" | "ty" | "ident" | "meta" | "tt" | "vis" | "" => true,
+        "path" | "ty" | "ident" | "meta" | "tt" | "" => true,
+        "vis" => {
+            if !features.borrow().macro_vis_matcher {
+                let explain = feature_gate::EXPLAIN_VIS_MATCHER;
+                emit_feature_err(sess,
+                                 "macro_vis_matcher",
+                                 frag_span,
+                                 GateIssue::Language,
+                                 explain);
+            }
+            true
+        },
         _ => false,
     }
 }