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Add comments explaining why some operations are not constant inside normal functions

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This commit is contained in:
Oliver Scherer 2018-10-12 09:30:28 +02:00
parent 670d07efbb
commit 76f8a90d53
1 changed files with 6 additions and 0 deletions
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6
src/librustc_mir/transform/qualify_consts.rs
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@ -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",