3 files changed, 19 insertions, 14 deletions
diff --git a/src/librustc_parse/Cargo.toml b/src/librustc_parse/Cargo.toml
index a9175487a75..95b3256f53a 100644
--- a/src/librustc_parse/Cargo.toml
+++ b/src/librustc_parse/Cargo.toml
@@ -16,6 +16,7 @@ syntax_pos = { path = "../libsyntax_pos" }
 syntax = { path = "../libsyntax" }
 errors = { path = "../librustc_errors", package = "rustc_errors" }
 rustc_data_structures = { path = "../librustc_data_structures" }
+rustc_feature = { path = "../librustc_feature" }
 rustc_lexer = { path = "../librustc_lexer" }
 rustc_target = { path = "../librustc_target" }
 smallvec = { version = "1.0", features = ["union", "may_dangle"] }
diff --git a/src/librustc_parse/config.rs b/src/librustc_parse/config.rs
index 7ce555ed57a..26e51e83d62 100644
--- a/src/librustc_parse/config.rs
+++ b/src/librustc_parse/config.rs
@@ -9,14 +9,9 @@
 //! [#64197]: https://github.com/rust-lang/rust/issues/64197
 
 use crate::validate_attr;
+use rustc_feature::Features;
 use syntax::attr::HasAttrs;
-use syntax::feature_gate::{
-    feature_err,
-    EXPLAIN_STMT_ATTR_SYNTAX,
-    Features,
-    get_features,
-    GateIssue,
-};
+use syntax::feature_gate::{feature_err, get_features};
 use syntax::attr;
 use syntax::ast;
 use syntax::edition::Edition;
@@ -52,7 +47,7 @@ pub fn features(mut krate: ast::Crate, sess: &ParseSess, edition: Edition,
         } else { // the entire crate is unconfigured
             krate.attrs = Vec::new();
             krate.module.items = Vec::new();
-            return (krate, Features::new());
+            return (krate, Features::default());
         }
 
         features = get_features(&sess.span_diagnostic, &krate.attrs, edition, allow_features);
@@ -217,8 +212,7 @@ impl<'a> StripUnconfigured<'a> {
             let mut err = feature_err(self.sess,
                                       sym::stmt_expr_attributes,
                                       attr.span,
-                                      GateIssue::Language,
-                                      EXPLAIN_STMT_ATTR_SYNTAX);
+                                      "attributes on expressions are experimental");
 
             if attr.is_doc_comment() {
                 err.help("`///` is for documentation comments. For a plain comment, use `//`.");
diff --git a/src/librustc_parse/validate_attr.rs b/src/librustc_parse/validate_attr.rs
index bbe0dc1c35f..a3c9e266593 100644
--- a/src/librustc_parse/validate_attr.rs
+++ b/src/librustc_parse/validate_attr.rs
@@ -1,10 +1,10 @@
 //! Meta-syntax validation logic of attributes for post-expansion.
 
 use errors::{PResult, Applicability};
-use syntax::ast::{self, Attribute, AttrKind, Ident, MetaItem};
-use syntax::attr::{AttributeTemplate, mk_name_value_item_str};
+use rustc_feature::{AttributeTemplate, BUILTIN_ATTRIBUTE_MAP};
+use syntax::ast::{self, Attribute, AttrKind, Ident, MetaItem, MetaItemKind};
+use syntax::attr::mk_name_value_item_str;
 use syntax::early_buffered_lints::BufferedEarlyLintId;
-use syntax::feature_gate::BUILTIN_ATTRIBUTE_MAP;
 use syntax::token;
 use syntax::tokenstream::TokenTree;
 use syntax::sess::ParseSess;
@@ -41,6 +41,16 @@ pub fn parse_meta<'a>(sess: &'a ParseSess, attr: &Attribute) -> PResult<'a, Meta
     })
 }
 
+/// Checks that the given meta-item is compatible with this `AttributeTemplate`.
+fn is_attr_template_compatible(template: &AttributeTemplate, meta: &ast::MetaItemKind) -> bool {
+    match meta {
+        MetaItemKind::Word => template.word,
+        MetaItemKind::List(..) => template.list.is_some(),
+        MetaItemKind::NameValue(lit) if lit.kind.is_str() => template.name_value_str.is_some(),
+        MetaItemKind::NameValue(..) => false,
+    }
+}
+
 pub fn check_builtin_attribute(
     sess: &ParseSess,
     attr: &Attribute,
@@ -57,7 +67,7 @@ pub fn check_builtin_attribute(
                              name == sym::test || name == sym::bench;
 
     match parse_meta(sess, attr) {
-        Ok(meta) => if !should_skip(name) && !template.compatible(&meta.kind) {
+        Ok(meta) => if !should_skip(name) && !is_attr_template_compatible(&template, &meta.kind) {
             let error_msg = format!("malformed `{}` attribute input", name);
             let mut msg = "attribute must be of the form ".to_owned();
             let mut suggestions = vec![];