From da6261e07fa892f995703e4ae26832a633fa5a23 Mon Sep 17 00:00:00 2001
From: lcnr <rust@lcnr.de>
Date: Thu, 29 Apr 2021 20:06:11 +0200
Subject: [PATCH] make feature recommendations optional

---
 compiler/rustc_resolve/src/diagnostics.rs  |  8 ++++++-
 compiler/rustc_typeck/src/check/wfcheck.rs | 25 ++++++++++++----------
 2 files changed, 21 insertions(+), 12 deletions(-)

diff --git a/compiler/rustc_resolve/src/diagnostics.rs b/compiler/rustc_resolve/src/diagnostics.rs
index c5f12c0c691b3..6ea46f5c5289e 100644
--- a/compiler/rustc_resolve/src/diagnostics.rs
+++ b/compiler/rustc_resolve/src/diagnostics.rs
@@ -487,7 +487,13 @@ impl<'a> Resolver<'a> {
                         name
                     ));
                 }
-                err.help("use `#![feature(const_generics)]` and `#![feature(const_evaluatable_checked)]` to allow generic const expressions");
+
+                if self.session.is_nightly_build() {
+                    err.help(
+                        "use `#![feature(const_generics)]` and `#![feature(const_evaluatable_checked)]` \
+                        to allow generic const expressions"
+                    );
+                }
 
                 err
             }
diff --git a/compiler/rustc_typeck/src/check/wfcheck.rs b/compiler/rustc_typeck/src/check/wfcheck.rs
index 26871d6f0285c..d25dd9a6e8302 100644
--- a/compiler/rustc_typeck/src/check/wfcheck.rs
+++ b/compiler/rustc_typeck/src/check/wfcheck.rs
@@ -315,17 +315,20 @@ fn check_param_wf(tcx: TyCtxt<'_>, param: &hir::GenericParam<'_>) {
                         ),
                     )
                 } else {
-                    tcx.sess
-                        .struct_span_err(
-                            hir_ty.span,
-                            &format!(
-                                "{} is forbidden as the type of a const generic parameter",
-                                unsupported_type
-                            ),
-                        )
-                        .note("the only supported types are integers, `bool` and `char`")
-                        .help("more complex types are supported with `#![feature(const_generics)]`")
-                        .emit()
+                    let mut err = tcx.sess.struct_span_err(
+                        hir_ty.span,
+                        &format!(
+                            "{} is forbidden as the type of a const generic parameter",
+                            unsupported_type
+                        ),
+                    );
+                    err.note("the only supported types are integers, `bool` and `char`");
+                    if tcx.sess.is_nightly_build() {
+                        err.help(
+                            "more complex types are supported with `#![feature(const_generics)]`",
+                        );
+                    }
+                    err.emit()
                 }
             };