From 76f8a90d53a3f212820e95260257105dd1da9910 Mon Sep 17 00:00:00 2001 From: Oliver Scherer Date: Fri, 12 Oct 2018 09:30:28 +0200 Subject: [PATCH] Add comments explaining why some operations are not constant inside normal functions --- src/librustc_mir/transform/qualify_consts.rs | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/src/librustc_mir/transform/qualify_consts.rs b/src/librustc_mir/transform/qualify_consts.rs index 32b570b32d5b9..1281fc96c0da7 100644 --- a/src/librustc_mir/transform/qualify_consts.rs +++ b/src/librustc_mir/transform/qualify_consts.rs @@ -735,8 +735,11 @@ impl<'a, 'tcx> Visitor<'tcx> for Qualifier<'a, 'tcx, 'tcx> { (CastTy::Ptr(_), CastTy::Int(_)) | (CastTy::FnPtr, CastTy::Int(_)) => { if let Mode::Fn = self.mode { + // in normal functions, mark such casts as not promotable self.add(Qualif::NOT_CONST); } else if !self.tcx.sess.features_untracked().const_raw_ptr_to_usize_cast { + // in const fn and constants require the feature gate + // FIXME: make it unsafe inside const fn and constants emit_feature_err( &self.tcx.sess.parse_sess, "const_raw_ptr_to_usize_cast", self.span, GateIssue::Language, @@ -759,8 +762,11 @@ impl<'a, 'tcx> Visitor<'tcx> for Qualifier<'a, 'tcx, 'tcx> { op == BinOp::Offset); if let Mode::Fn = self.mode { + // raw pointer operations are not allowed inside promoteds self.add(Qualif::NOT_CONST); } else if !self.tcx.sess.features_untracked().const_compare_raw_pointers { + // require the feature gate inside constants and const fn + // FIXME: make it unsafe to use these operations emit_feature_err( &self.tcx.sess.parse_sess, "const_compare_raw_pointers",