pre-expansion gate const_generics

3 files changed, 8 insertions, 11 deletions

diff --git a/src/libsyntax/feature_gate/check.rs b/src/libsyntax/feature_gate/check.rs
index 58610d8db7e..282b5ae2193 100644
--- a/src/libsyntax/feature_gate/check.rs
+++ b/src/libsyntax/feature_gate/check.rs
@@ -3,7 +3,7 @@ use super::accepted::ACCEPTED_FEATURES;
 use super::removed::{REMOVED_FEATURES, STABLE_REMOVED_FEATURES};
 use super::builtin_attrs::{AttributeGate, BUILTIN_ATTRIBUTE_MAP};
 
-use crate::ast::{self, NodeId, GenericParam, GenericParamKind, PatKind, RangeEnd, VariantData};
+use crate::ast::{self, NodeId, PatKind, RangeEnd, VariantData};
 use crate::attr::{self, check_builtin_attribute};
 use crate::source_map::Spanned;
 use crate::edition::{ALL_EDITIONS, Edition};
@@ -571,16 +571,6 @@ impl<'a> Visitor<'a> for PostExpansionVisitor<'a> {
         visit::walk_fn(self, fn_kind, fn_decl, span)
     }
 
-    fn visit_generic_param(&mut self, param: &'a GenericParam) {
-        match param.kind {
-            GenericParamKind::Const { .. } =>
-                gate_feature_post!(&self, const_generics, param.ident.span,
-                    "const generics are unstable"),
-            _ => {}
-        }
-        visit::walk_generic_param(self, param)
-    }
-
     fn visit_trait_item(&mut self, ti: &'a ast::TraitItem) {
         match ti.kind {
             ast::TraitItemKind::Method(ref sig, ref block) => {
@@ -840,6 +830,7 @@ pub fn check_crate(krate: &ast::Crate,
     gate_all!(trait_alias, "trait aliases are experimental");
     gate_all!(associated_type_bounds, "associated type bounds are unstable");
     gate_all!(crate_visibility_modifier, "`crate` visibility modifier is experimental");
+    gate_all!(const_generics, "const generics are unstable");
 
     visit::walk_crate(&mut visitor, krate);
 }
diff --git a/src/libsyntax/parse/parser/generics.rs b/src/libsyntax/parse/parser/generics.rs
index bfcb0042a75..51caae69c86 100644
--- a/src/libsyntax/parse/parser/generics.rs
+++ b/src/libsyntax/parse/parser/generics.rs
@@ -55,11 +55,15 @@ impl<'a> Parser<'a> {
     }
 
     fn parse_const_param(&mut self, preceding_attrs: Vec<Attribute>) -> PResult<'a, GenericParam> {
+        let lo = self.token.span;
+
         self.expect_keyword(kw::Const)?;
         let ident = self.parse_ident()?;
         self.expect(&token::Colon)?;
         let ty = self.parse_ty()?;
 
+        self.sess.gated_spans.const_generics.borrow_mut().push(lo.to(self.prev_span));
+
         Ok(GenericParam {
             ident,
             id: ast::DUMMY_NODE_ID,
diff --git a/src/libsyntax/sess.rs b/src/libsyntax/sess.rs
index 58a2f89aca9..3d2051b4c78 100644
--- a/src/libsyntax/sess.rs
+++ b/src/libsyntax/sess.rs
@@ -36,6 +36,8 @@ crate struct GatedSpans {
     pub associated_type_bounds: Lock<Vec<Span>>,
     /// Spans collected for gating `crate_visibility_modifier`, e.g. `crate fn`.
     pub crate_visibility_modifier: Lock<Vec<Span>>,
+    /// Spans collected for gating `const_generics`, e.g. `const N: usize`.
+    pub const_generics: Lock<Vec<Span>>,
 }
 
 /// Info about a parsing session.