From 9f7e281d47f27c24a59b30cae30c20435be4083c Mon Sep 17 00:00:00 2001 From: Vishad Goyal Date: Thu, 16 Sep 2021 19:28:03 +0530 Subject: [PATCH] delay error for enabling unstable lib features If #![feature] is used outside the nightly channel for only lib features, the check will be delayed to the stability pass after parsing. This is done so that appropriate help messages can be shown if the #![feature] has been used needlessly --- compiler/rustc_ast_passes/src/feature_gate.rs | 6 ++++++ compiler/rustc_passes/src/stability.rs | 10 ++++++++++ 2 files changed, 16 insertions(+) diff --git a/compiler/rustc_ast_passes/src/feature_gate.rs b/compiler/rustc_ast_passes/src/feature_gate.rs index 30bc4edd7e69c..06e9d9ed32933 100644 --- a/compiler/rustc_ast_passes/src/feature_gate.rs +++ b/compiler/rustc_ast_passes/src/feature_gate.rs @@ -702,10 +702,16 @@ pub fn check_crate(krate: &ast::Crate, sess: &Session) { } fn maybe_stage_features(sess: &Session, krate: &ast::Crate) { + // checks if `#![feature]` has been used to enable any lang feature + // does not check the same for lib features unless there's at least one + // declared lang feature use rustc_errors::Applicability; if !sess.opts.unstable_features.is_nightly_build() { let lang_features = &sess.features_untracked().declared_lang_features; + if lang_features.len() == 0 { + return; + } for attr in krate.attrs.iter().filter(|attr| attr.has_name(sym::feature)) { let mut err = struct_span_err!( sess.parse_sess.span_diagnostic, diff --git a/compiler/rustc_passes/src/stability.rs b/compiler/rustc_passes/src/stability.rs index b7e43b7785da6..d7c354aeb490f 100644 --- a/compiler/rustc_passes/src/stability.rs +++ b/compiler/rustc_passes/src/stability.rs @@ -929,6 +929,16 @@ pub fn check_unused_or_stable_features(tcx: TyCtxt<'_>) { let declared_lib_features = &tcx.features().declared_lib_features; let mut remaining_lib_features = FxHashMap::default(); for (feature, span) in declared_lib_features { + if !tcx.sess.opts.unstable_features.is_nightly_build() { + struct_span_err!( + tcx.sess, + *span, + E0554, + "`#![feature]` may not be used on the {} release channel", + env!("CFG_RELEASE_CHANNEL") + ) + .emit(); + } if remaining_lib_features.contains_key(&feature) { // Warn if the user enables a lib feature multiple times. duplicate_feature_err(tcx.sess, *span, *feature);