Correct const_in_array_repeat_expressions feature name

src/librustc/traits/error_reporting.rs

@@ -2176,15 +2176,15 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
                 err.note(&format!("required by cast to type `{}`",
                                   self.ty_to_string(target)));
             }
-            ObligationCauseCode::RepeatVec(suggest_const_in_array_repeat_expression) => {
+            ObligationCauseCode::RepeatVec(suggest_const_in_array_repeat_expressions) => {
                 err.note("the `Copy` trait is required because the \
                           repeated element will be copied");
-                if suggest_const_in_array_repeat_expression {
+                if suggest_const_in_array_repeat_expressions {
                     err.note("this array initializer can be evaluated at compile-time, for more \
                               information, see issue \
                               https://github.com/rust-lang/rust/issues/49147");
                     if tcx.sess.opts.unstable_features.is_nightly_build() {
-                        err.help("add `#![feature(const_in_array_repeat_expression)]` to the \
+                        err.help("add `#![feature(const_in_array_repeat_expressions)]` to the \
                                   crate attributes to enable");
                     }
                 }

src/librustc/traits/mod.rs

@@ -206,7 +206,7 @@ pub enum ObligationCauseCode<'tcx> {
     SizedReturnType,
     /// Yield type must be Sized
     SizedYieldType,
-    /// [T,..n] --> T must be Copy. If `true`, suggest `const_in_array_repeat_expression` feature
+    /// [T,..n] --> T must be Copy. If `true`, suggest `const_in_array_repeat_expressions` feature
     /// flag.
     RepeatVec(bool),
 

src/librustc_mir/borrow_check/nll/type_check/mod.rs

@@ -1987,7 +1987,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
                     let span = body.source_info(location).span;
                     let ty = operand.ty(body, tcx);
                     if !self.infcx.type_is_copy_modulo_regions(self.param_env, ty, span) {
-                        // To determine if `const_in_array_repeat_expression` feature gate should
+                        // To determine if `const_in_array_repeat_expressions` feature gate should
                         // be mentioned, need to check if the rvalue is promotable.
                         let should_suggest =
                             should_suggest_const_in_array_repeat_expressions_attribute(

src/librustc_mir/transform/promote_consts.rs

@@ -1185,7 +1185,7 @@ pub fn promote_candidates<'tcx>(
     promotions
 }
 
-/// This function returns `true` if the `const_in_array_repeat_expression` feature attribute should
+/// This function returns `true` if the `const_in_array_repeat_expressions` feature attribute should
 /// be suggested. This function is probably quite expensive, it shouldn't be run in the happy path.
 /// Feature attribute should be suggested if `operand` can be promoted and the feature is not
 /// enabled.

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

@@ -8,7 +8,7 @@ LL |     let arr: [Option<String>; 2] = [None::<String>; 2];
              <std::option::Option<T> as std::marker::Copy>
    = note: the `Copy` trait is required because the repeated element will be copied
    = note: this array initializer can be evaluated at compile-time, for more information, see issue https://github.com/rust-lang/rust/issues/49147
-   = help: add `#![feature(const_in_array_repeat_expression)]` to the crate attributes to enable
+   = help: add `#![feature(const_in_array_repeat_expressions)]` to the crate attributes to enable
 
 error[E0277]: the trait bound `std::option::Option<std::string::String>: std::marker::Copy` is not satisfied
   --> $DIR/feature-gate-const_in_array_repeat_expressions.rs:14:36