Revert "pre-expansion gate const_generics"

This reverts commit 49cbfa1.

Author: eddyb

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, PatKind, RangeEnd, VariantData};
+use crate::ast::{self, NodeId, GenericParam, GenericParamKind, PatKind, RangeEnd, VariantData};
 use crate::attr::{self, check_builtin_attribute};
 use crate::source_map::Spanned;
 use crate::edition::{ALL_EDITIONS, Edition};
@@ -594,6 +594,16 @@ 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) => {

src/test/ui/const-generics/const-param-in-trait-ungated.stderr

@@ -1,8 +1,8 @@
 error[E0658]: const generics are unstable
-  --> $DIR/const-param-in-trait-ungated.rs:1:13
+  --> $DIR/const-param-in-trait-ungated.rs:1:19
    |
 LL | trait Trait<const T: ()> {}
-   |             ^^^^^^^^^^^
+   |                   ^
    |
    = note: for more information, see https://github.com/rust-lang/rust/issues/44580
    = help: add `#![feature(const_generics)]` to the crate attributes to enable

src/test/ui/const-generics/const-param-type-depends-on-type-param-ungated.stderr

@@ -1,8 +1,8 @@
 error[E0658]: const generics are unstable
-  --> $DIR/const-param-type-depends-on-type-param-ungated.rs:3:13
+  --> $DIR/const-param-type-depends-on-type-param-ungated.rs:3:19
    |
 LL | struct B<T, const N: T>(PhantomData<[T; N]>);
-   |             ^^^^^^^^^^
+   |                   ^
    |
    = note: for more information, see https://github.com/rust-lang/rust/issues/44580
    = help: add `#![feature(const_generics)]` to the crate attributes to enable

src/test/ui/const-generics/issues/issue-60263.stderr

@@ -1,8 +1,8 @@
 error[E0658]: const generics are unstable
-  --> $DIR/issue-60263.rs:1:10
+  --> $DIR/issue-60263.rs:1:16
    |
 LL | struct B<const I: u8>;
-   |          ^^^^^^^^^^^
+   |                ^
    |
    = note: for more information, see https://github.com/rust-lang/rust/issues/44580
    = help: add `#![feature(const_generics)]` to the crate attributes to enable

src/test/ui/feature-gates/feature-gate-const_generics-ptr.stderr

@@ -1,17 +1,17 @@
 error[E0658]: const generics are unstable
-  --> $DIR/feature-gate-const_generics-ptr.rs:1:16
+  --> $DIR/feature-gate-const_generics-ptr.rs:1:22
    |
 LL | struct ConstFn<const F: fn()>;
-   |                ^^^^^^^^^^^^^
+   |                      ^
    |
    = note: for more information, see https://github.com/rust-lang/rust/issues/44580
    = help: add `#![feature(const_generics)]` to the crate attributes to enable
 
 error[E0658]: const generics are unstable
-  --> $DIR/feature-gate-const_generics-ptr.rs:5:17
+  --> $DIR/feature-gate-const_generics-ptr.rs:5:23
    |
 LL | struct ConstPtr<const P: *const u32>;
-   |                 ^^^^^^^^^^^^^^^^^^^
+   |                       ^
    |
    = note: for more information, see https://github.com/rust-lang/rust/issues/44580
    = help: add `#![feature(const_generics)]` to the crate attributes to enable

src/test/ui/feature-gates/feature-gate-const_generics.rs

@@ -2,9 +2,4 @@ fn foo<const X: ()>() {} //~ ERROR const generics are unstable
 
 struct Foo<const X: usize>([(); X]); //~ ERROR const generics are unstable
 
-macro_rules! accept_item { ($i:item) => {} }
-accept_item! {
-    impl<const X: ()> A {} //~ ERROR const generics are unstable
-}
-
 fn main() {}

src/test/ui/feature-gates/feature-gate-const_generics.stderr

@@ -1,30 +1,21 @@
 error[E0658]: const generics are unstable
-  --> $DIR/feature-gate-const_generics.rs:1:8
+  --> $DIR/feature-gate-const_generics.rs:1:14
    |
 LL | fn foo<const X: ()>() {}
-   |        ^^^^^^^^^^^
+   |              ^
    |
    = note: for more information, see https://github.com/rust-lang/rust/issues/44580
    = help: add `#![feature(const_generics)]` to the crate attributes to enable
 
 error[E0658]: const generics are unstable
-  --> $DIR/feature-gate-const_generics.rs:3:12
+  --> $DIR/feature-gate-const_generics.rs:3:18
    |
 LL | struct Foo<const X: usize>([(); X]);
-   |            ^^^^^^^^^^^^^^
+   |                  ^
    |
    = note: for more information, see https://github.com/rust-lang/rust/issues/44580
    = help: add `#![feature(const_generics)]` to the crate attributes to enable
 
-error[E0658]: const generics are unstable
-  --> $DIR/feature-gate-const_generics.rs:7:10
-   |
-LL |     impl<const X: ()> A {}
-   |          ^^^^^^^^^^^
-   |
-   = note: for more information, see https://github.com/rust-lang/rust/issues/44580
-   = help: add `#![feature(const_generics)]` to the crate attributes to enable
-
-error: aborting due to 3 previous errors
+error: aborting due to 2 previous errors
 
 For more information about this error, try `rustc --explain E0658`.