remove feature gate

src/libsyntax/ext/tt/quoted.rs

@@ -576,22 +576,7 @@ fn parse_sep_and_kleene_op_2018<I>(
     let span = match parse_kleene_op(input, span) {
         // #1 is a `?` (needs feature gate)
         Ok(Ok((op, op1_span))) if op == KleeneOp::ZeroOrOne => {
-            if !features.macro_at_most_once_rep
-                && !attr::contains_name(attrs, "allow_internal_unstable")
-            {
-                let explain = feature_gate::EXPLAIN_MACRO_AT_MOST_ONCE_REP;
-                emit_feature_err(
-                    sess,
-                    "macro_at_most_once_rep",
-                    op1_span,
-                    GateIssue::Language,
-                    explain,
-                );
-
-                op1_span
-            } else {
-                return (None, op);
-            }
+            return (None, op);
         }
 
         // #1 is a `+` or `*` KleeneOp
@@ -602,22 +587,10 @@ fn parse_sep_and_kleene_op_2018<I>(
             // #2 is the `?` Kleene op, which does not take a separator (error)
             Ok(Ok((op, op2_span))) if op == KleeneOp::ZeroOrOne => {
                 // Error!
-
-                if !features.macro_at_most_once_rep
-                    && !attr::contains_name(attrs, "allow_internal_unstable")
-                {
-                    // FIXME: when `?` as a Kleene op is stabilized, we only need the "does not
-                    // take a macro separator" error (i.e. the `else` case).
-                    sess.span_diagnostic
-                        .struct_span_err(op2_span, "expected `*` or `+`")
-                        .note("`?` is not a macro repetition operator")
-                        .emit();
-                } else {
-                    sess.span_diagnostic.span_err(
-                        span,
-                        "the `?` macro repetition operator does not take a separator",
-                    );
-                }
+                sess.span_diagnostic.span_err(
+                    span,
+                    "the `?` macro repetition operator does not take a separator",
+                );
 
                 // Return a dummy
                 return (None, KleeneOp::ZeroOrMore);
@@ -638,13 +611,8 @@ fn parse_sep_and_kleene_op_2018<I>(
     };
 
     // If we ever get to this point, we have experienced an "unexpected token" error
-
-    if !features.macro_at_most_once_rep && !attr::contains_name(attrs, "allow_internal_unstable") {
-        sess.span_diagnostic.span_err(span, "expected `*` or `+`");
-    } else {
-        sess.span_diagnostic
-            .span_err(span, "expected one of: `*`, `+`, or `?`");
-    }
+    sess.span_diagnostic
+        .span_err(span, "expected one of: `*`, `+`, or `?`");
 
     // Return a dummy
     (None, KleeneOp::ZeroOrMore)

src/libsyntax/feature_gate.rs

@@ -1426,9 +1426,6 @@ fn leveled_feature_err<'a>(sess: &'a ParseSess, feature: &str, span: Span, issue
 pub const EXPLAIN_UNSIZED_TUPLE_COERCION: &'static str =
     "unsized tuple coercion is not stable enough for use and is subject to change";
 
-pub const EXPLAIN_MACRO_AT_MOST_ONCE_REP: &'static str =
-    "using the `?` macro Kleene operator for \"at most one\" repetition is unstable";
-
 struct PostExpansionVisitor<'a> {
     context: &'a Context<'a>,
 }