Rollup merge of #84705 - lcnr:const_generics-rec, r=joshtriplett

make feature recommendations optional

this is what we're already doing for other feature gates, so it's better to be consistent

2 files changed, 21 insertions, 12 deletions

diff --git a/compiler/rustc_resolve/src/diagnostics.rs b/compiler/rustc_resolve/src/diagnostics.rs
index c5f12c0c691..6ea46f5c528 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 26871d6f028..d25dd9a6e83 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()
                 }
             };