Rollup merge of rust-lang#56072 - da-x:stabilize-literal-matcher, r=petrochenkov

Stabilize macro_literal_matcher

This followed FCP in rust-lang#35625.

Closes rust-lang#35625

Author: pietroalbini

src/doc/unstable-book/src/language-features/macro-literal-matcher.md

@@ -19,7 +19,7 @@ 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 feature_gate::Features;
 use parse::{Directory, ParseSess};
 use parse::parser::Parser;
 use parse::token::{self, NtTT};
@@ -1027,26 +1027,21 @@ fn has_legal_fragment_specifier(sess: &ParseSess,
     Ok(())
 }
 
-fn is_legal_fragment_specifier(sess: &ParseSess,
-                               features: &Features,
-                               attrs: &[ast::Attribute],
+fn is_legal_fragment_specifier(_sess: &ParseSess,
+                               _features: &Features,
+                               _attrs: &[ast::Attribute],
                                frag_name: &str,
-                               frag_span: Span) -> bool {
+                               _frag_span: Span) -> bool {
+    /*
+     * If new fragment specifiers are invented in nightly, `_sess`,
+     * `_features`, `_attrs`, and `_frag_span` will be useful here
+     * for checking against feature gates. See past versions of
+     * this function.
+     */
     match frag_name {
         "item" | "block" | "stmt" | "expr" | "pat" | "lifetime" |
-        "path" | "ty" | "ident" | "meta" | "tt" | "vis" | "" => true,
-        "literal" => {
-            if !features.macro_literal_matcher &&
-               !attr::contains_name(attrs, "allow_internal_unstable") {
-                let explain = feature_gate::EXPLAIN_LITERAL_MATCHER;
-                emit_feature_err(sess,
-                                 "macro_literal_matcher",
-                                 frag_span,
-                                 GateIssue::Language,
-                                 explain);
-            }
-            true
-        },
+        "path" | "ty" | "ident" | "meta" | "tt" | "vis" | "literal" |
+        "" => true,
         _ => false,
     }
 }

src/libsyntax/ext/tt/macro_rules.rs

@@ -436,9 +436,6 @@ declare_features! (
     // Allows irrefutable patterns in if-let and while-let statements (RFC 2086)
     (active, irrefutable_let_patterns, "1.27.0", Some(44495), None),
 
-    // Allows use of the :literal macro fragment specifier (RFC 1576)
-    (active, macro_literal_matcher, "1.27.0", Some(35625), None),
-
     // inconsistent bounds in where clauses
     (active, trivial_bounds, "1.28.0", Some(48214), None),
 
@@ -690,6 +687,8 @@ declare_features! (
     (accepted, impl_header_lifetime_elision, "1.31.0", Some(15872), None),
     // `extern crate foo as bar;` puts `bar` into extern prelude.
     (accepted, extern_crate_item_prelude, "1.31.0", Some(55599), None),
+    // Allows use of the :literal macro fragment specifier (RFC 1576)
+    (accepted, macro_literal_matcher, "1.31.0", Some(35625), None),
 );
 
 // If you change this, please modify src/doc/unstable-book as well. You must
@@ -1425,9 +1424,6 @@ pub const EXPLAIN_DEPR_CUSTOM_DERIVE: &'static str =
 pub const EXPLAIN_DERIVE_UNDERSCORE: &'static str =
     "attributes of the form `#[derive_*]` are reserved for the compiler";
 
-pub const EXPLAIN_LITERAL_MATCHER: &'static str =
-    ":literal fragment specifier is experimental and subject to change";
-
 pub const EXPLAIN_UNSIZED_TUPLE_COERCION: &'static str =
     "unsized tuple coercion is not stable enough for use and is subject to change";
 

src/libsyntax/feature_gate.rs

@@ -9,7 +9,6 @@
 // except according to those terms.
 
 // run-pass
-#![feature(macro_literal_matcher)]
 
 macro_rules! a {
     ($i:literal) => { "right" };

src/test/run-pass/issues/issue-52169.rs

@@ -9,7 +9,6 @@
 // except according to those terms.
 
 // run-pass
-#![feature(macro_literal_matcher)]
 
 macro_rules! mtester {
     ($l:literal) => {