update message

compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs

@@ -1885,21 +1885,21 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
                 err.note(
                     "the `Copy` trait is required because the repeated element will be copied",
                 );
-                if is_const_fn && !self.tcx.sess.is_nightly_build() {
+
+                if is_const_fn {
                     err.help(
                         "consider creating a new `const` item and initializing with the result \
                         of the function call to be used in the repeat position, like \
                         `const VAL: Type = const_fn();` and `let x = [VAL; 42];`",
                     );
-                } else if self.tcx.sess.is_nightly_build() && is_const_fn {
+                }
+
+                if self.tcx.sess.is_nightly_build() && is_const_fn {
                     err.help(
                         "create an inline `const` block, see PR \
                         #2920 <https://github.com/rust-lang/rfcs/pull/2920> \
                         for more information",
                     );
-                } else {
-                    // Don't suggest anything to the user as suggesting the user to make the function `const`
-                    // could lead them down the wrong path.
                 }
             }
             ObligationCauseCode::VariableType(hir_id) => {

src/README.md

@@ -1,4 +1,5 @@
 This directory contains the source code of the rust project, including:
+
 - The test suite
 - The bootstrapping build system
 - Various submodules for tools, like rustdoc, rls, etc.

src/test/ui/consts/const-blocks/fn-call-in-non-const.stderr

@@ -7,6 +7,7 @@ LL |     let _: [Option<Bar>; 2] = [no_copy(); 2];
    = help: the following implementations were found:
              <Option<T> as Copy>
    = note: the `Copy` trait is required because the repeated element will be copied
+   = help: consider creating a new `const` item and initializing with the result of the function call to be used in the repeat position, like `const VAL: Type = const_fn();` and `let x = [VAL; 42];`
    = help: create an inline `const` block, see PR #2920 <https://github.com/rust-lang/rfcs/pull/2920> for more information
 
 error: aborting due to previous error

src/test/ui/consts/const-fn-in-vec.rs

@@ -1,6 +1,6 @@
 fn main() {
-    // should hint to create an inline const block
-    // as all tests are on "nightly"
+    // should hint to create an inline `const` block
+    // or to create a new `const` item
     let strings: [String; 5] = [String::new(); 5];
     //~^ ERROR the trait bound `String: Copy` is not satisfied
     println!("{:?}", strings);

src/test/ui/consts/const-fn-in-vec.stderr

@@ -5,6 +5,7 @@ LL |     let strings: [String; 5] = [String::new(); 5];
    |                                ^^^^^^^^^^^^^^^^^^ the trait `Copy` is not implemented for `String`
    |
    = note: the `Copy` trait is required because the repeated element will be copied
+   = help: consider creating a new `const` item and initializing with the result of the function call to be used in the repeat position, like `const VAL: Type = const_fn();` and `let x = [VAL; 42];`
    = help: create an inline `const` block, see PR #2920 <https://github.com/rust-lang/rfcs/pull/2920> for more information
 
 error: aborting due to previous error