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const_eval: implies_by in rustc_const_unstable

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Extend support for `implies_by` (from `#[stable]` and `#[unstable]`)
to `#[rustc_const_stable]` and `#[rustc_const_unstable]`.

Signed-off-by: David Wood <david.wood@huawei.com>
This commit is contained in:
David Wood 2023-02-08 13:25:38 +00:00
parent 6eb9f2dd67
commit 912783402f
12 changed files with 177 additions and 7 deletions
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16
compiler/rustc_const_eval/src/transform/check_consts/check.rs
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@ -926,15 +926,24 @@ impl<'tcx> Visitor<'tcx> for Checker<'_, 'tcx> {
// If the `const fn` we are trying to call is not const-stable, ensure that we have
// the proper feature gate enabled.
if let Some(gate) = is_unstable_const_fn(tcx, callee) {
if let Some((gate, implied_by)) = is_unstable_const_fn(tcx, callee) {
trace!(?gate, "calling unstable const fn");
if self.span.allows_unstable(gate) {
return;
}
if let Some(implied_by_gate) = implied_by && self.span.allows_unstable(implied_by_gate) {
return;
}
// Calling an unstable function *always* requires that the corresponding gate
// be enabled, even if the function has `#[rustc_allow_const_fn_unstable(the_gate)]`.
if !tcx.features().declared_lib_features.iter().any(|&(sym, _)| sym == gate) {
// (or implied gate) be enabled, even if the function has
// `#[rustc_allow_const_fn_unstable(the_gate)]`.
let gate_declared = |gate| {
tcx.features().declared_lib_features.iter().any(|&(sym, _)| sym == gate)
};
let feature_gate_declared = gate_declared(gate);
let implied_gate_declared = implied_by.map(gate_declared).unwrap_or(false);
if !feature_gate_declared && !implied_gate_declared {
self.check_op(ops::FnCallUnstable(callee, Some(gate)));
return;
}
@ -947,7 +956,6 @@ impl<'tcx> Visitor<'tcx> for Checker<'_, 'tcx> {
}
// Otherwise, we are something const-stable calling a const-unstable fn.
if super::rustc_allow_const_fn_unstable(tcx, caller, gate) {
trace!("rustc_allow_const_fn_unstable gate active");
return;